Quality analysis of walnut oil extracted by cold press and solvent methods for in vitro phytochemicals, antioxidant activity and GCMS analysis

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 1st September 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!<blockquote>👉 <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library">SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES</a></blockquote><blockquote>👉 Need info about different analytical techniques? Peek into <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library">LabRulezLCMS</a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library">LabRulezICPMS</a> libraries.</blockquote>This week we bring you poster by Agilent Technologies / ASMS and application notes by EST Analytical and Shimadzu!<h3>1. Agilent Technologies / ASMS: Analysis of Phthalates Using GC/MS With Hydrogen Carrier Gas: The Importance of Reducing Interferences and Contamination&nbsp;</h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/ps_5977c_phthalates_hydrogen_gas_asms_2025_mp_359_en_agilent_d51f599179.pdf">Full PDF for download</a></li></ul>Due to the price of helium (He), many laboratories are looking for alternative carrier gases for their gas chromatography/mass spectrometry (GC/MS) methods. This work describes the evaluation of a single quadrupole GC/MS method for the analysis of 19 phthalates using hydrogen carrier gas and an EI source 1 . The method provides excellent peak shape, resolution, sensitivity, and a 13 min run time. Calibration curves were linear for 16 of the phthalates, with the remaining 3 alkoxy phthalates requiring a quadratic fit. Except for DINP and DIDP (mixtures of isomers), all compounds could be quantitated at low pg levels. Specific attention to the consumables used and their preparation before use is discussed and is important for reaching the lowest calibration levels.<h4>Experimental</h4><ul><li>GC: <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8890+gc">Agilent 8890 GC</a> with <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7693A">Agilent 7693A automatic liquid sampler</a> and tray</li><li>Column: Agilent HP-5MS UI 20 m x 0.18 mm id x 0.18 µm (p/n 19091S-577UI)</li><li>MSD: <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5977C+GC%2FMSD">Agilent 5977C Inert Plus GC/MSD</a></li></ul><h4>Conclusions</h4><ul><li>The Agilent 5977C GC/MSD and 8890 GC, when used with the method described here, provide excellent peak shape, resolution, sensitivity, and a 13 min run time..&nbsp;</li><li>The combination of hydrogen carrier and the Agilent J&amp;W HP-5ms 180 µm diameter column allowed for reduced analysis time relative to helium and a 250 µm diameter column .&nbsp;</li><li>Calibration curves were linear for 14 of the phthalates from 1 to 1,000 pg. DMEP and DBEP required quadratic curve fits, and DMEP and DEHP were calibrated from 2.5 to 1,000 pg. DINP and DIDP were calibrated from 50 to 20,000 pg with a linear fit.&nbsp;</li><li>Specific attention to the consumables used and their preparation before use is important for reaching the lowest calibration levels.</li></ul><h3>2. EST Analytical: The Determination of Flavors in E-Liquids Using Purge and Trap Concentration</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/Purge_and_Trap_E_Liquid_Compound_Sampling_Using_Purge_and_Trap_5c709b52f0.pdf">Full PDF for download</a></li></ul>E-liquid can be composed of propylene glycol or vegetable glycerin alone or can be a combination of the two. Propylene glycol is less viscous and carries better flavor. It also acts as a preservative. However, it does produce less vapor and some people are allergic to it. Vegetable glycerin, on the other hand, is much denser, is super hypoallergenic and produces more vapor. The drawback to the vegetable glycerin is that it is not a preservative, so the vape liquid will not last as long. Both glycerin and propylene glycol readily dissolve in water, so preparing the samples to test by purge and trap was relatively easy. Conversely, as the E-liquid emitted a strong odor of the added flavors, only a small amount of the solution could be used for analysis. The volatile flavor components of the vape liquid were examined by dissolving the solution in water and sampling the water using purge and trap.<h4>Experimental</h4>The <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160">Evolution purge and trap concentrator </a>was configured with a Vocarb 3000 trap. The trap was conditioned at 260ºC for one hour. The <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">Centurion WS syringe autosampler</a> was set in water mode in order to run 5 ml samples. Next, samples were prepared using 10ul of vape solution dissolved in 100mls of de-ionized water. The parameters for the autosampler/purge and trap concentrator and the Gas Chromatograph/Mass Spectrometer (GC/MS) are outlined in Tables 1 and 2.<h4>Conclusions</h4>Since vape solution readily dissolves into water, purge and trap sampling proved to be an excellent technique for the determination of the volatile compounds in the E-liquids. Purge and trap sampling is an exhaustive sampling technique, so the results were very reproducible and provided the sensitivity to determine the lower level compounds in the solution. Furthermore, it was found that nicotine addition to the solution has an effect some of the compounds in the solution. So, the taste of the vape liquid is affected by the amount nicotine in the mix.<h3>3. Shimadzu: Determination of Nitrobenzene Compounds in Nifedipine by GCMS&nbsp;</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_03_gcms_589_en_23eda751e7.pdf">Full PDF for download</a></li></ul><h4>User Benefits</h4><ul><li>The direct dissolution protocol without pre-treatment, significantly enhancing analytical efficiency.</li><li>The specificity of the method is ensured by monitoring the characteristic ions of nitrobenzene compounds in selected ion monitoring (SIM) mode, which provides robust resistance to interferences.</li></ul>Nifedipine, a dihydropyridine calcium channel blocker with vasodilatory properties, is primarily indicated for the clinical management of hypertension and angina pectoris. Its synthetic route commences with 2-nitrotoluene as the starting material. Notably, the intermediate 2-nitrobenzyl alcohol, the byproduct 2- nitrobenzyl bromide, the reaction product 2-nitrobenzaldehyde, and potential impurities (3-nitrobenzaldehyde and 4- nitrobenzaldehyde) all contain nitrobenzene moieties, rendering them candidatesfor monitoring as potential genotoxic impurities. Previous studies have demonstrated that 2-nitrobenzaldehyde and 4-nitrobenzaldehyde exhibit mutagenicity in the Ames test, while 2-nitrotoluene has shown carcinogenicity in animal experiments. In accordance with the toxicological concern threshold (TTC) control approach specified in ICH M7, a threshold of 1.5 μg/day is recommended for genotoxic impurities in pharmaceuticals intended for lifelong administration. In this study, a method for the determination of six genotoxic impurities in nifedipine was developed using a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=GCMS-QP2050">Shimadzu GCMSQP2050</a> gas chromatography mass spectrometry. This method features simplified sample preparation, high sensitivity, and favorable repeatability, thereby enabling effective monitoring of the six nitrobenzene compounds as genotoxic impurities in nifedipine pharmaceutical.<h4>Analytical Conditions</h4>The analytical conditions are shown in Table1. <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=GCMS-QP2050">GCMS-QP2050</a> system was used for this Application News.<h4>Conclusion&nbsp;</h4>A GC-MS method was established for the quantification of six nitrobenzene genotoxic impurities in nifedipine pharmaceuticals using a Shimadzu GCMS-QP2050 system. The calibration curves showed excellent linearity within the concentration range of 20-200 μg/L, with correlation coefficients (R&gt;0.999). Precision was evaluated through six replicate injections of the 50 μg/L standard solution, and the relative standard deviations (RSDs) of peak areas for all analytes were less than 4%. Spike recovery experiments were performed at three concentration levels (0.005, 0.01, and 0.032 μg/g) in actual matrices, resulting in recovery rates ranging from 95.85% to 117.64%. This method is characterized by simplified sample preparation, high sensitivity (IDLs of 0.263-0.496 μg/L), and good repeatability. Overall, it provides a validated analytical strategy for quality control monitoring of the target genotoxic impurities.

News from LabRulezGCMS Library - Week 36, 2025

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 22nd September 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!<blockquote>👉 <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library">SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES</a></blockquote><blockquote>👉 Need info about different analytical techniques? Peek into <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library">LabRulezLCMS</a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library">LabRulezICPMS</a> libraries.</blockquote>This week we bring you application notes by Agilent Technologies, EST Analytical, Shimadzu and Thermo Fisher Scientific!<h3>1. Agilent Technologies: A Chemometric Approach for Ambient Air Monitoring Using Thermal Desorption GC/MS</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_voc_8890_chemometric_ambient_air_monitoring_5994_8451en_agilent_fef7d171bb.pdf">Full PDF for download</a></li></ul>Monitoring VOCs is crucial for assessing air quality in industrial and urban settings. These compounds, which include propene, hexachlorobutadiene, and naphthalene, vary in volatility and encompass both polar and nonpolar chemicals. Recognizing the importance of standardized monitoring, the Bureau of Indian Standards (BIS) has developed specific methodologies for these compounds under the IS 5182 series.&nbsp;IS 5182-27 focuses on the measurement of vapor-phase organic chemicals such as vinyl chloride and nC22 hydrocarbons in air and gaseous emissions. This method employs diffusive (passive) sampling onto sorbent tubes or cartridges, followed by TD (see Figure 1) and capillary GC analysis. The passive sampling approach offers advantages in terms of ease of deployment and cost-effectiveness, making it suitable for widespread monitoring applications.To reveal relevant patterns and sources of variation in these large environmental datasets according to the IS-5182 guidance, this application note proposes chemometric analysis using the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=6&amp;search=TD100-xr">Markes TD100-xr automated thermal desorber</a> (Figure 2) and the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8890+gc">Agilent 8890 GC system</a> with <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5977c">5977C GC/MSD</a> (Figure 3). Chemometrics is a discipline that uses mathematics, statistics, and formal logic to design or select optimal experimental procedures. Chemometric techniques commonly used for clustering are the hierarchical agglomerative cluster analysis and PCA with factor analysis.<h4>Conclusion&nbsp;</h4>This application note highlights the comparison of different air sampling strategies and shows their effect on qualitative and quantitative analysis of VOCs. Active (pumped) sampling helped with faster analysis, which is required for controlled and sensitive real-time monitoring of ambient air. Chromatograms of air sampled at various locations showed the presence of VOCs such as benzene, toluene, ethyl benzene, and xylenes. Many common and unique compounds were found at each location. The intensity of these compounds showed variations at different locations. Fewer compounds with lower intensities were observed in air samples from a residential area, whereas more compounds with higher intensities were observed in air samples from a traffic area.&nbsp;Passive sampling was a comparatively cost‑effective and long-term approach and provided consistent replicate results. The chromatographic overlays of different sampling times indicated an increasing trend in peak intensities with respect to time. There was a considerable rise in peak intensities for the 1-week sampling period, as compared to 24-hour sampling. There was a slight rise in peak intensities for the 2-week sampling period, as compared to 1-week sampling. The PCA plot suggested the peak distribution obtained in each dataset. One-week sampling results showed consistent replicate results. Use of the chemometrics software Agilent Mass Profiler Professional added value by providing data visualization for interpretation.<h3>2. EST Analytical: USEPA 524.2 Method Validation Using the Evolution Purge and Trap Concentrator and the Centurion WS Autosampler</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/Purge_and_Trap_524_2_Application_Note_2d327854f2.pdf">Full PDF for download</a></li></ul>USEPA Method 524.2 calls for purge and trap sampling coupled with a Gas Chromatograph (GC) and Mass Spectrometer (MS) for separation and analysis. It has an extensive list of compounds and requires lower detection limits due to its use in drinking water testing. A 20% relative standard deviation for compound response factors is required across the calibration curve while the calibration check standard analytes have to be within 30% of the expected concentration.&nbsp;Currently, this method calls for a 5mL or 25mL purge volume and a four minute desorb time. These method requirements can pose a challenge for the analyst due to the amount of moisture that is created. The negative effects of the increased water vapor include instability of the chromatography, band eluting and poor peak shape to name a few. A side effect of this instability is sample re-runs and lost laboratory productivity. In addition, a common practice for mitigating moisture is increasing the GC inlet split rate. This poses yet another difficulty as the increased split rate can result in reduced sensitivity. EST Analytical’s eight port valve in the Evolution purge and trap concentrator aids in limiting the water exposure because the water management of the system is not part of the desorb pathway. This feature also enables laboratories to use a smaller split ratio at the GC inlet thus increasing sensitivity.<h4>Experimental</h4>The sampling system used for this study was the<a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160"> EST Analytical Evolution purge and trap concentrator </a>and the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">Centurion WS autosampler</a>. The concentrator was affixed with a Vocarb 3000 trap and connected to an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=7890A">Agilent 7890A GC</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=5975C">5975C inert XL MS</a>. The GC was configured with a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=9&amp;search=Rxi-624+Sil+MS">Restek Rxi-624 Sil</a> MS 30m x 0.25mm x 1.4µm column. Sampling parameters are listed in Table 1 while Table 2 enumerates the GC/MS parameters.<h4>Conclusions</h4>This study demonstrated the effectiveness of the Evolution/Centurion purge and trap sampling system. The results passed all of the USEPA Method 524.2 criteria for both linearity and detection limits. Since the Evolution bypasses the water management trap during the four minute desorb process, the amount of water effecting the experiments was limited. Furthermore, the forty to one split ratio at the GC inlet provided excellent detection limits as the system was more sensitive to the low level standard requirements of the method. The lower split rate has an added benefit of reducing laboratory helium consumption when setting it against other system’s higher split ratios. Finally, the precision and percent recovery results showed the reliability of the system in producing accurate experimental findings.<h3>3. Shimadzu: Dual-Column Analysis of Blood AlcoholContent (BAC) Using Nitrogen Carrier Gas with <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Brevis+GC-2050">Brevis GC-2050</a></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_01_00899_en_af0d9bafe7.pdf">Full PDF for download</a></li></ul>Analysis of blood alcohol content (BAC) and other volatile organic compounds (VOCs) is essential for law enforcement agencies to determine alcohol intoxication and its role in traffic accidents, assaults, and injuries, as well as to identify the causes of certain criminal behaviors, poisonings, and so on.&nbsp;Typically, this analysis is performed by a gas chromatograph (GC) that is combined with a headspace sampler (HS) and a flame ionization detector (FID). Since accurate results are essential with BAC analysis, 2 columns can be used with different separation characteristics so that cross-checking can be performed. By using an integrated HS-GC system equipped with 2 FIDs connecting to a dual-column configuration, crosschecking can be performed in a single analysis. In this system, the columns are directly connected to the transfer line using a 2-hole ferrule, which minimizes sample losses due to adsorption.&nbsp;In addition to the high-end <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Nexis+GC-2030">Nexis GC-2030</a>, Shimadzu also offers the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Brevis+GC-2050">Brevis GC-2050</a> as a compact gas chromatography solution, and in this Application News, it is used with an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=HS-20+NX+headspace+sampler">HS-20 NX headspace sampler </a>(Fig. 1) to perform BAC analysis. Hydrogen was used as the carrier gas in a similar experiment in Application News 01-00570, but in this experiment, nitrogen was used because it is a cheaper alternative carrier gas. Nitrogen generally has an adverse effect on separation, so this experiment also investigated the conditions for separation for 10 types of blood VOCs.<h4>Separation of 10 Blood VOCs&nbsp;</h4>A solution of 10 VOCs spiked with blood (0.1 mg/mL) was analyzed to determine the separation of methanol, acetaldehyde, ethanol, isopropyl alcohol, acetonitrile, acetone, tert-butanol, 1-propanol, methyl ethyl ketone, and ethyl acetate. The resulting chromatogram is shown in Fig. 6. All peaks were detected within 6.0 minutes in the BAC PLUS1 column and within 3.5 minutes in the BAC PLUS2 column, indicating good separation. The elution sequence of the 10 blood VOCs differed significantly between the columns, which enhanced the system’s qualitative capability. Table 4 shows the retention time of each compound and the repeatability (n=5) of the peak area ratio for the tert-butanol internal standard.<h4>Conclusion&nbsp;</h4>This experiment involved dual-column analysis of blood alcohol content (BAC) by the compact Brevis GC-2050 and the HS-20 NX. Dual-column configuration enables cross-checking in a single analysis. In addition, nitrogen was used as the carrier gas instead of helium. While hydrogen enables high-speed analysis, it also requires careful handling, so from the perspective of safety, installation of various optional tools such as hydrogen sensor and stop valve have been recommended. Nitrogen gas is relatively inexpensive and easy to handle, and this experiment demonstrated that it also provides reliable results while maintaining good separation.<h3>4. Thermo Fisher Scientific: Routine analysis of 7N high purity gallium phosphide by Glow Discharge Mass Spectrometry</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_003578_ioms_gd_ms_element_gd_plus_gallium_an003578_em_en_1666255eb4.pdf">Full PDF for download</a></li></ul>Gallium phosphide (GaP) is a semiconductor material used in electronic and optoelectronic devices, including light-emitting Diodes (LEDs), solar cells as well as high-frequency and high-power electronics1-5. GaP wafers offer several advances over traditional silicon wafers, including high efficiency, high-speed operation, and highpower handling capabilities4-5.&nbsp;This application note describes the direct analysis of impurities in high purity gallium phosphide with sub-ppb detection limits using the Thermo Scientific <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/products/1690">Element GD PLUS GD Mass Spectrometer</a>.&nbsp;<h4>Experiment&nbsp;</h4>The flat samples are analyzed directly, with no digestion required. Instrumental conditions for the analysis with the Element GD PLUS GD-MS are shown in Table 1. Potential sample surface contaminations were removed by short presputtering within the instrument.&nbsp;<h4>Method development&nbsp;</h4>The developed method ensures a reliable separation of interferences from the analyte ions. The interferences PO, POH and GaGa could potentially lead to falsely high Ti, Ba and Ce results. The formation of these interferences is low in the fast-flow source of the Element GD PLUS GD-MS: 69Ga69Ga/69Ga ≈ 1 ppm and ( 31P16O1 H + 31P17O)/31P ≈ 10 ppm. They can easily be resolved at Medium Mass Resolution (R = M / Δm = 4000). This is visualized in the mass scans shown in Figures 1 and 2 with much wider mass windows than later being used for quantification. Therefore, the Medium Mass Resolution of the Element GD PLUS GD-MS enables interference free measurements of Ti, Ba and Ce in GaP matrix.<h4>Conclusions&nbsp;</h4>Trace contaminations in 7N high purity gallium phosphide can be determined reliably and routinely with the Element GD PLUS GD-MS without prior digestion.&nbsp;While most analytes like Ti, Ba and La are resolved from interferences in medium mass resolution (R = 4000), high mass resolution (R = 10000) is required for Ag because of the GaAr interference. Sub-ppb detection limits, even for elements like Sb and Ge, are achieved by neglectable formation of triatomic interferences and reduced abundance sensitivity. That is enabled by the fast-flow source design and the reverse Nier-Johnson geometry.Semiquantitative quantification of element concentrations can be performed without standard reference materials using the standard RSF factor approach. The high sensitivity of the instrument, the reliable separation of interferences in medium and high mass resolution, the outstanding peak stability, the low formation of interferences and the low abundance sensitivity enable limits of detection of 0.05 to 1 ppb for most elements.&nbsp;The sum of all impurities in the GaP sample was below 50 ppb, implying that a purity of 7N GaP can be assessed with the instrument.

News from LabRulezGCMS Library - Week 39, 2025

<h4>Abstract&nbsp;</h4>Environmental laboratories are always searching for techniques to increase productivity. However, environmental methods demand a large amount of background information in order to ensure sampling and analysis is compliant. The determination of <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=45&amp;search=VOC">Volatile Organic Compounds (VOCs) </a>in the United States Environmental Protection Agency (USEPA) <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=45&amp;search=Method+8260">Method 8260</a> encompasses many different matrices and in doing so has numerous sampling, quality control, and calibration requirements. The matrices of Method 8260 samples can also vary from air to sludge and from clean to extremely contaminated. Furthermore, the method has an extensive calibration range. All of these factors play into the complexity of sampling and analysis thus, creating ways to streamline sampling while still maintaining sample integrity and method compliance is always of interest to environmental laboratories.<h4>Introduction</h4>In order to run Method 8260 samples, a bromofluorobenzene (BFB) tune standard, matrix blank, calibration standard, and laboratory control standard all have to be run and pass method requirements every twelve hours. With the exception of the BFB standard, the other standards and blank matrices have to correspond to the samples to be analyzed. Due to this constraint, the analyst is required to run another three samples if the matrix is changed within the twelve hour time window. Moreover, the calibration must also match the sample matrix. These requirements are very time consuming and can limit laboratory profits. This application note will demonstrate a patented automated water sampling mode using the soil sampling station of the autosampler thus eliminating the need to have separate calibrations and standards for waters and soils.&nbsp;<h4>Discussion</h4>There are a number or techniques that can enable an analyst to save time in an environmental lab. Analysts can decrease analytical trap bake times, change sample purge time and flow, utilize a dual sampling system for one GC/MS, etc. However, one of the most basic ways to save time is by reducing the number of required curves and standards needed.EST Analytical has designed a patented, automated water sampling mode that will allow environmental laboratories to run water samples in the soil mode. Thus, water and soil curves, standards, blanks and samples can use the same sampling parameters. (See steps 1, 2, and 3 below). This innovative sampling mode would eliminate the need to have separate curves, standards, etc. for soils and waters, thus saving laboratories time and money. Please note that this procedure may only be used with auditor approval.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Experimental_9f34a58017.jpg" alt="EST Analytical: Sampling" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Experimental_9f34a58017.jpg 245w," sizes="100vw" width="1386" height="861"><h4>Experimental</h4>The sampling system used for this study was the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">EST Analytical Centurion WS autosampler</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160">Evolution concentrator</a>. The concentrator was affixed with a Vocarb 3000 trap and connected to an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7890A">Agilent 7890A GC</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5975C">5975 inert XL MS</a>. The GC was configured with a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=7&amp;search=Restek+Rxi-624+Sil+MS">Restek Rxi-624 Sil MS</a> 30m x 0.25mm x 1.4µm column. The experiments were run using the extraction mode of the Centurion WS. Sampling method parameters and GC/MS parameters are listed below.<h5>Purge and Trap Parameters</h5><ul><li>Concentrator: EST Evolution</li><li>Trap type: Vocarb 3000</li><li>Valve oven temperature: 150 °C</li><li>Transfer line temperature: 150 °C</li><li>Trap temperature: 35 °C</li><li>Moisture Reduction Trap (MoRT) temperature: 39 °C</li><li>Purge time: 11 min</li><li>Purge flow: 40 mL/min</li><li>Dry purge Temp.: Ambient</li><li>Dry Purge Flow: 40mL/min</li><li>Dry Purge Time: 1.0 min &nbsp;</li><li>Desorb pressure Control: ON</li><li>Desorb Pressure: 5psi</li><li>Desorb time: 0.5 min</li><li>Desorb preheat delay: 5 sec</li><li>Desorb temperature: 260 °C</li><li>MoRT bake temperature: 230 °C</li><li>Bake temperature: 270 °C</li><li>Sparge vessel bake temperature: 120 °C</li><li>Bake time: 8 min</li><li>Bake flow: 40 mL/min</li></ul><h5>Auto-Sampler (EST Centurion WS):</h5><ul><li>Sample type: Water Extraction</li><li>Sample Fill Mode: Syringe</li><li>Sample Volume: 10mL</li><li>IS Volume: 5µl</li><li>Needle Rinse Time: 20 sec</li><li>Needle Sweep Time: 20 sec</li><li>Concentrator Desorb Time: 0.5 min</li><li>Syringe Rinse: On/12mL</li><li>Number of Syringe Rinses: 2</li><li>Sparge Rinse Time: Off</li><li>Water Heater Temp.: 85°C</li></ul><h5>GC/MS Parameters</h5><ul><li>System: Agilent 7890/5975 inert XL</li><li>Inlet: Split mode, 200 °C, 40:1 split ratio, 12.153 psi head pressure</li><li>Column: Restek Rxi-624Sil MS, 30 m × 0.25 mm × 1.4 µm</li><li>Oven program: 45 °C (1 min) → ramp 15 °C/min → 220 °C, hold 1.3 min</li><li>Column flow rate: 1 mL/min helium</li><li>Total flow: 44 mL/min</li><li>Source temperature: 230 °C</li><li>Quadrupole temperature: 150 °C</li><li>Transfer line temperature: 180 °C</li><li>Scan range: m/z 35–265, 3.12 scans/sec</li><li>Solvent delay: 0.7 min</li></ul>The USEPA Method 8260 standards were acquired from Restek. The linear range of the water extraction experiment was established by running a nine point calibration curve with a range of 0.5 to 200ppb. Method detection limits were also established for each compound by examining seven replicate standards of the low calibration point. Finally, precision and accuracy were determined by running seven replicate midpoint standards. Figure 1 displays a 50ppb Method 8260 standard chromatogram of a water sample run in soil mode and experimental results are listed in Table 1.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Obrazek_1_Chromatogram_50_ppb_vzorku_vody_analyzovaneho_v_rezimu_puda_55ffcb4ba3.jpg" alt="EST Analytical: Figure 1: 50ppb Chromatogram of a Water Sample Run in Soil Mode" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Obrazek_1_Chromatogram_50_ppb_vzorku_vody_analyzovaneho_v_rezimu_puda_55ffcb4ba3.jpg 245w," sizes="100vw" width="1444" height="514"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Tabulka_3_Vysledky_experimentu_cast_1_7cadc58cda.jpg" alt="EST Analytical: Table 3: Experimental Results_part 1" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Tabulka_3_Vysledky_experimentu_cast_1_7cadc58cda.jpg 215w," sizes="100vw" width="1568" height="1143"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Tabulka_3_Vysledky_experimentu_cast_2_f676814e52.jpg" alt="EST Analytical: Table 3: Experimental Results_Part 2" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Tabulka_3_Vysledky_experimentu_cast_2_f676814e52.jpg 245w," sizes="100vw" width="1571" height="616"><h4>Conclusion</h4>The patented sampling process of the Centurion WS proved to be a reliable and accurate sampling method for running water samples in the soil mode. The curve linearity and method detection limits both met USEPA Method 8260 requirements, and the precision and accuracy results were excellent. The water extraction option offered with the Centurion WS will save laboratories time and money because only one set of standards, curves, etc. is required for both water and soil samples.

A Single Calibration Method for Water AND Soil Samples Performing EPA Method 8260

News from LabRulezGCMS Library - Week 44, 2025

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 24th November 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!<blockquote>👉 <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library">SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES</a></blockquote><blockquote>👉 Need info about different analytical techniques? Peek into <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library">LabRulezLCMS</a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library">LabRulezICPMS</a> libraries.</blockquote>This week we bring you brochure by Agilent Technologies, poster by LECO /MDCW, and application notes by Shimadzu and Thermo Fisher Scientific!<h3>1. Agilent Technologies: GC workflows for hydrogen vehicles and natural gas blending - Hydrogen Fuel Testing Solutions</h3><ul><li>Brochure</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/ac_hydrogen_fuel_purity_matters_compendium_5994_8643en_agilent_8da57fb7a2.pdf">Full PDF for download</a></li></ul>Agilent’s Hydrogen Fuel Testing Solutions compendium highlights the growing importance of reliable impurity analysis as hydrogen becomes a key clean-energy fuel. Because contaminants such as moisture, sulfur compounds, ammonia, oxygen, or organics can compromise fuel-cell performance and safety, the brochure emphasizes that hydrogen purity must be monitored throughout the entire supply chain—from production to storage, transport, and final distribution. Hydrogen blended into natural gas introduces additional challenges, since existing pipeline infrastructure was not originally designed for hydrogen, making rigorous analytical control essential for preventing corrosion, equipment malfunction, and safety issues.To address these challenges, Agilent presents a comprehensive suite of GC-based hydrogen testing workflows. The compendium showcases key analytical instruments—such as the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8890">Agilent 8890 GC</a>, <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8355+SCD">8355 SCD</a>, 8255 NCD, <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5977C">5977C GC/MSD</a>, and portable <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=990+Micro+GC">990 Micro GC</a>—each tailored for detecting critical impurities at trace levels in accordance with ISO 14687-2019, SAE J2719, and other global standards. Featured application notes demonstrate capabilities including ultratrace ammonia monitoring, analysis of sulfides and halides, sulfur speciation, and fast impurity screening for hydrogen and natural gas streams.Beyond instrumentation, the brochure outlines Agilent’s service ecosystem supporting method deployment, instrument verification, sustainability strategies, and lab operations management through CrossLab services and OpenLab software. These include preventive maintenance programs, financial solutions, certified pre-owned instruments, and consulting for analytical method development.Finally, the brochure connects hydrogen-fuel purity testing with broader sustainability goals. Agilent encourages laboratories to adopt circular-economy practices—reducing waste, extending instrument lifecycles, and improving energy efficiency—emphasizing that clean hydrogen starts with responsible, efficient, and reliable laboratory workflows.<h3>2. LECO / MDCW: BOOSTING NON-TARGETED ANALYSIS WITH COMPREHENSIVE TWO-DIMENSIONAL GAS CHROMATOGRAPHY AND HIGH-RESOLUTION MASS SPECTROMETRY</h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/FL_18_Sebastiano_b4cf417f82.pdf">Full PDF for download</a></li></ul>The presentation by Sebastiano Panto (LECO EATC Berlin) focuses on demonstrating how comprehensive two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry (<a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?instrumentationItems=2-13-3&amp;mainauthorItems=24">GC×GC-HR-TOFMS</a>) significantly enhances non-targeted and targeted screening workflows, particularly in environmental analysis. Using liver extracts from Glaucous gulls (Larus hyperboreus) from the Svalbard region as a case study, the work aims to reveal contamination patterns and improve compound identification confidence.Sample preparation included homogenization, lipid removal, and multi-step cleanup involving GPC/SEC chromatography and Florisil fractionation, yielding separate non-polar and polar fractions for analysis (page 4). Analytical separations were performed on an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8890+GC">Agilent 8890 GC</a> equipped with a dual-column GC×GC setup (Rxi-5SilMS and Rxi-17SilMS), cryogenic modulation, and Helium carrier gas. Detection used the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=24&amp;search=Pegasus+HRT%2B4D+HR-TOFMS">LECO Pegasus® HRT+4D HR-TOFMS</a> with multiple ionization modes—EI, PCI, and ECNI—enabling simultaneous acquisition of structural, isotopic, and exact-mass information (page 5).The results highlight the advantages of GC×GC-HR-TOFMS in non-target screening: improved separation patterns, higher library match scores, exact-mass confirmation, and enhanced structural elucidation. Electron ionization (EI) provided clean spectra with high match scores for classic pollutants (e.g., PCBs, DDE), while electron capture negative ionization (ECNI) greatly improved selectivity and sensitivity for halogenated contaminants such as toxaphenes and brominated flame retardants, enabling confident identification even when EI spectra were ambiguous (pages 6–13). The instrument’s high mass accuracy and isotopic fidelity are shown to be essential for distinguishing closely related halogenated compounds.The study concludes that combining GC×GC separation power with HR-TOFMS accurate-mass detection and complementary ionization modes offers a robust discovery platform for environmental exposomics. This analytical workflow supports more confident annotation of persistent organic pollutants (POPs) and emerging contaminants in complex biological matrices, ultimately helping assess ecological risks in sensitive Arctic ecosystems where these avian species reside (page 15).<h3>3. Shimadzu: High-Sensitivity Gas Analysis Using the GCMS-QP2050 and GI-30 Auto Gas Injector</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_01_00953_en_7e1a865aae.pdf">Full PDF for download</a></li></ul>Gas analysis is conducted across a wide range of fields, including resources, energy, and the environment. Typical targets include inorganic gases such as H2, CO, and CO2, and light hydrocarbon gases starting with CH4, with analyses primarily performed using GC. In Application News No. 01- 00858, examples of gas sample analysis using TCD and BID installed on the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Brevis+GC-2050">Brevis GC-2050</a> were presented.&nbsp;However, qualitative analysis by GC requires standard substances, making the identification of unknown impurities in gas samples difficult. Furthermore, in inorganic gas analysis, complete chromatographic separation of peaks can be challenging, and when GC fails to fully separate them, both qualitative and quantitative analysis become difficult.&nbsp;In contrast, gas analysis using GC-MS enables qualitative identification of unknown components without standard substances through mass spectral library searches. Quantitation in GC-MS is performed using mass chromatograms, allowing accurate measurements even when peaks overlap.&nbsp;In this Application News, high-sensitivity analysis of inorganic gases and light hydrocarbon gases was performed using the compact yet high-performance <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=GCMS-QP2050">GCMS-QP2050</a>. Gas samples were introduced using the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=GI-30">GI-30 Auto Gas Injector</a>, enabling automated, continuous analysis and delivering higher reproducibility than manual sample injection.<h4>Instrument Configuration and Analytical Conditions&nbsp;</h4>A 10 ppm standard mixed gas sample in a cylinder was analyzed using the GCMS-QP2050. Gas sample injection into the GC-MS was performed with the GI-30 Auto Gas Injector (P/N: S221- 89755-41). The instrument configuration is shown in Fig. 1. The analytical conditions used are summarized in Table 1. Under typical ionization settings (ionization voltage 70 V and emission current 60 µA), ionization of the helium carrier gas generates a significant signal at m/z 2, making detection of H2 (monitor ion: m/z 2) difficult. Therefore, for analysis in SIM mode, the ionization voltage was set to 20 V and the emission current to 20 µA to suppress He ionization.<h4>Automated Continuous Analysis Using the GI-30&nbsp;</h4>The GI-30 Auto Gas Injector is a sample pretreatment device that automatically introduces a fixed volume of gas into the GC. It is used by connecting either a gas cylinder or a sample bag. When the GI-30 is connected to a gas cylinder, automated, continuous analysis of gassamples becomes possible.&nbsp;The GI-30 is equipped with an optional valve purge mechanism. Purging the internal valve with gas reduces the ingress of ambient air. This is effective for analyzing components in ambient air, such as N2 and O2, as well as for measuring tracelevel components.&nbsp;Table 2 shows the peak-area repeatability (%RSD) obtained when a 10 ppm standard mixed gas was analyzed automatically and continuously in SIM mode. As an example, an overlay of the CH4 SIM chromatograms is shown in Fig. 3. Because the GI-30 meters a fixed volume of gas into the GC via a sample loop, excellent reproducibility was achieved for all compounds.<h4>Conclusion&nbsp;</h4>Using the GCMS-QP2050, high-sensitivity analysis of inorganic gases, such as H2, and light hydrocarbons was achieved. Gas sample injection was performed with the GI-30 Auto Gas Injector, enabling automated, continuous analysis and delivering higher reproducibility compared with manual sample injection. The compact, high-performance GCMS-QP2050, together with the GI-30, enables automation and high-precision gas analysis, and supports greater efficiency in GC-MS-based gas analysis.<h3>4. Thermo Fisher Scientific: Trace analysis of epichlorohydrin in drinking water using GC-MS coupled with purge and trap</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_003894_gc_single_quad_isq_7610_environmental_an003894_na_en_70123385ae.pdf">Full PDF for download</a></li></ul>Epichlorohydrin (ECH) is a versatile starting material in the production of drugs and polymers and is also used as an insect fumigant and solvent for organic synthesis reactions. ECH-based polymer pipes are commonly used in the production of drinking water due to their durability and resistance to corrosion. However, ECH is known for its high reactivity and toxicity, which poses significant health risks if it contaminates drinking water. Exposure to ECH can cause respiratory issues, skin irritation, and has been classified as a probable human carcinogen.Due to these risks, many countries have imposed strict limits on the amount of ECH allowed in drinking water. Recently, Europe set a minimum detection limit (MDL) of 30 parts per trillion (ppt) for ECH in drinking water.2 Whereas typically required detection limits for most compounds mandated for analysis in Europe can be achieved using methods based on static headspace, the stringent MDL required for ECH requires preconcentration, for example using purge and trap (P&amp;T) technology.3,4 This technology involves purging the water sample with an inert gas to release volatile organic compounds (VOCs), which are then trapped and concentrated for analysis, ensuring reliable detection at very low concentrations. In the United States, the analysis of VOCs in drinking water is mandated by the Environmental Protection Agency (EPA). The EPA requires the use of P&amp;T technology for drinking water analysis to ensure that even trace amounts of harmful compounds like ECH are detected and managed appropriately.&nbsp;The following evaluation describes the use of the ISQ 7610 Single Quadrupole MS system coupled with the Thermo Scientific™ TRACE™ 1610 GC with the Thermo Scientific™ HeSaver-H2 Safer™ split/splitless injector and Teledyne LABS Tekmar Lumin P&amp;T concentrator combined with the AQUATek LVA autosampler for the analysis of ECH in drinking water.<h4>Experimental</h4><h5>GC-MS parameters&nbsp;</h5>A <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/486">TRACE 1610 GC</a> was coupled to the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/484">ISQ 7610 MS</a> equipped with the Thermo Scientific™ NeverVent ™ vacuum probe interlock (VPI) and an ExtractaBrite ion source. A <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/1773">Thermo Scientific™ TraceGOLD™ TG-VMS column</a>, 30 m × 0.25 mm, 1.4 µm film (P/N 26080-3320) was used for compound separation. The HeSaver-H2 Safer SSL injector was utilized to reduce the carrier gas consumption by decoupling the gas used for the chromatographic separation from the gas used to pressurize the inlet and maintain split and purge flows. The critical separations were maintained with a run time of under 15 minutes.For this analysis, the ISQ 7610 MS was operated in Selected Ion Monitoring (SIM) mode for increased selectivity, as required for this application. Extended method parameters for the ISQ 7610 MS are shown in Table 2.<h5>Instrument control and data processing&nbsp;</h5>Data was acquired, processed, and reported using the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/76">Thermo Scientific™ Chromeleon™ Chromatography Data System (CDS)</a>. This software can control both the GC-MS system and the Tekmar Lumin P&amp;T with the AQUATek LVA. This allows a single software to be utilized for the full workflow, simplifying the instrument operation. This application note is available for download via the Thermo Scientific™ AppsLab Library, which contains all the parameters needed to acquire, process, and report the analytical data for analysis of ECH.5<h4>Conclusion&nbsp;</h4>This study demonstrates the capability of the Tekmar Lumin P&amp;T with the AQUATek LVA system connected to the ISQ 7610 Single Quadrupole GC-MS to detect and quantify low-level ECH in drinking water samples, in compliance with EPA requirements.&nbsp;<ul><li>Utilizing the Tekmar Lumin P&amp;T’s ability to purge with nitrogen, along with using the HeSaver-H₂Safer SSL injector, nearly four times less helium was consumed during the analysis without sacrificing system performance.&nbsp;</li><li>The linearity of the calibration curve from 30 ppt to 5,000 ppt passed method requirements.</li><li>The application proved robust during an extended study with 20 samples of a 1,000 ppt ECH standard injected over a series of 124 injections, obtaining 4.4% precision and 118% accuracy of the recovery.</li></ul>

News from LabRulezGCMS Library - Week 48, 2025

Persistent chemicals released into marine environments pose long-term and potentially irreversible risks, particularly when discharged as complex mixtures in large volumes. To address this challenge, we introduce a persistence-directed testing approach that combines environmentally relevant biodegradation experiments with nontarget analytical techniques to better characterize persistent chemical burdens.Produced waters from two offshore oil platforms in the North Sea were used as case studies. After 60 days of incubation under biotic and abiotic conditions, nontarget analyses using SPME–GC-MS and SPE–LC-HRMS identified over 600 chemicals passing quality control. Persistent compounds accounted for 4% of GC-MS detections and 32–44% of LC-HRMS detections, with several annotated as N-substituted aromatic structures. These results demonstrate the effectiveness of persistence-directed testing for revealing previously unidentified persistent chemicals and underscore the need for improved treatment of offshore produced water discharges.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acs.est.5c08802">Persistence-Directed Testing of Chemicals Discharged from Offshore Oil Platforms Combined with Nontargeted Analysis</a></h4>Mette T. Møller*, Heidi Birch, Karina K. Sjøholm, Stefano Papazian, Aina C. Wennberg, Bénilde Bonnefille, Pia M. Kronsbein, Malcolm A. Kelland, Jonathan W. Martin, and Philipp MayerEnviron. Sci. Technol. 2025, 59, 44, 24000–24011<a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/acs.est.5c08802">https://doi.org/10.1021/acs.est.5c08802</a><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.In this study, we introduce “Persistence-Directed Testing”, a concept inspired by effect-directed analysis (EDA). In EDA toxic chemicals in complex mixtures from contaminated environments are singled out by combining fractionation procedures, biotesting, and sensitive chemical analytical methods to identify toxicants. <a href="javascript:void(0);">(13,14)</a> In persistence-directed testing, persistent chemicals in complex discharges are singled out and potentially identified by combining biodegradation tests, sensitive chemical analytical techniques, and focused data treatment schemes.The biodegradation testing method is an advancement of a recently developed biodegradation kinetic testing method, a modified OECD 309. The method was developed for chemicals in mixtures at low concentrations, including hydrophobic and volatile chemicals. <a href="javascript:void(0);">(15,16)</a> In recent years the method has continuously been advanced from testing composed mixtures <a href="javascript:void(0);">(15)</a> to testing samples of unknown or variable composition, complex reaction products, or biological materials (UVCBs), such as petroleum mixtures and essential oils. <a href="javascript:void(0);">(17,18)</a> In the most recent progression of the method, it was used for testing the biodegradation kinetics of chemicals in complex mixtures being discharged to the environment, using native microorganisms in the receiving environment as inoculum. <a href="javascript:void(0);">(19)</a> With this method, biodegradation kinetics were successfully obtained for more than a hundred chemicals discharged from an offshore oil platform measured with solid-phase microextraction (SPME) gas chromatography-mass spectrometry (GC-MS). <a href="javascript:void(0);">(19)</a>The novelty of the persistent-directed testing in the present study is the design of the test and data treatment for persistence rather than biodegradation. This was achieved by combining a discharge sample (complex chemical mixture) and a seawater sample (native microorganisms), for determining the number, fraction, and, if possible, also the identity of those chemicals that are not degraded at the end of the test and are thus found persistent. The experiments were analyzed with both SPME GC-MS and nontarget solid-phase extraction (SPE) liquid chromatography-high-resolution mass spectrometry (LC-HRMS), in order to extend the chemical space coverage and achieve a more comprehensive persistence assessment.Nontarget analysis (NTA) techniques have developed and advanced rapidly in recent years. <a href="javascript:void(0);">(20,21)</a> It is now possible to detect thousands of chemicals in a sample without predetermining targets. By analyzing the sample with HRMS, the exact mass of both the precursor and molecular fragments of each feature detected can be obtained, <a href="javascript:void(0);">(22)</a> which can be used for identification or annotation at various confidence levels. <a href="javascript:void(0);">(23)</a> Limitations of NTA are that exact identification (confidence level 1) and quantification is difficult and time-consuming. <a href="javascript:void(0);">(21)</a> In recent years, new developments of NTA workflows and software tools, such as in silico structure predictions <a href="javascript:void(0);">(24,25)</a> and feature-based molecular networking (FBMN), <a href="javascript:void(0);">(26,27)</a> allow increasingly more automated and higher-throughput molecular annotations (Level 2), structural elucidation (Level 3), and molecular formula assignments (Level 4). This has been successfully showcased for environmental applications. <a href="javascript:void(0);">(28−30)</a>In the present study, we combine biodegradation testing with NTA to directly enable the simultaneous persistence assessment of a large number of chemicals, while providing identification information across varying levels of confidence.The hypotheses were: 1) environmentally relevant biodegradation tests combined with advanced analytical methods can reveal persistent chemicals in complex discharges, and 2) based on a recent feasibility study, <a href="javascript:void(0);">(19)</a> we expect a much higher fraction of persistent chemicals in produced water within the group of polar substances detectable by LC, compared to nonpolar chemicals detectable by GC. We also anticipate that NTA, combined with advanced computational workflows, can allow to reach a deeper molecular-level understanding of the persistent chemicals discovered in complex discharges.<h3>2. Materials and Methods</h3><h4>2.8. Sample Preparation and Chemical Analysis</h4><h5>2.8.1. Solid-Phase Microextraction Coupled to GC-MS</h5>After 60 days, test systems were transferred directly from the incubator to the GC autosampler (PAL RSI 85; CTC Analytics AG, Switzerland) without any pretreatment or conservation. Automated SPME, with a 30 μm PDMS fiber (Supelco, USA), was applied to unopened test systems by direct immersion. The SPME was thermally desorbed on the GC column (122-5562UI DB-5 ms Ultra Inert column, 60 m × 0.25 mm × 0.25 μm, Agilent), where the analytes were separated by the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7890B">GC (7890B</a>; Agilent Technologies, USA). They were then detected by the MS (<a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5977A">5977A MSD</a>; Agilent Technologies, USA), in electron ionization full-scan mode (m/z 50–500) to include a large number of nonpolar chemicals in produced water. The analytical method is described in detail in Møller et al. (2024). <a href="javascript:void(0);">(19)</a> The 1:200 dilution from both platforms was analyzed on day 60. On the following 4 days, the remaining dilutions from both platforms were analyzed, due to the number of samples and the analysis time per sample. Each GC-MS analysis run consisted of triplicate alternating biotic and abiotic test systems at one dilution from one platform, with blanks at the beginning and the end. The biotic and abiotic test systems analyzed directly after each other were used as pairs for calculating the peak area ratios.<h5>2.8.3. LC-HRMS Analysis</h5>Analyses by LC-HRMS for nontarget qualitative profiling were performed using a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/744">Vanquish Horizon system</a> interfaced with heated electrospray ionization (HESI) to an <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/401">Orbitrap Exploris 480</a> (Thermo Fisher). Each sample was acquired twice using ionization in positive (HESI+) and negative (HESI−) modes. Clean extracts were injected (25 μL) on a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1952">C18 Waters Acquity column</a> (UPLC BEH C18, 3.0 mm × 100 mm, 1.7 μm particle) combined with an Acquity precolumn (BEH C18, 2.1 mm × 5 mm, 1.7 μm). Reverse-phase chromatography was performed using LC-MS grade (Optima) mobile phases (A) Milli-Q water with 1 mM ammonium fluoride (NH4F), and (B) 100% MeOH. Spectral acquisition alternated between full-scan MS1 (m/z 90–1000, ∼1.5 Hz, nominal resolution 240,000 at m/z 200) and nontarget data-independent (DIA) MS2 acquisition using four sequential precursor isolation windows of 250 m/z (i.e., m/z 89–341, 339–591, 589–841, 839–1091). Additional details are presented in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.est.5c08802/suppl_file/es5c08802_si_001.pdf">SI 3</a>.<h3>3. Results and Discussion</h3><h4>3.2. Primary Biodegradation and Persistence Assessment</h4>Primary biodegradation and persistence were assessed at a dilution of 1:200 based on peak area ratios (biotic/abiotic) of test systems analyzed (GC) or extracted (LC) on day 60. Features were categorized as persistent, when all triplicate peak area ratios were greater than 0.5, corresponding to less than 50% biodegradation (see <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acs.est.5c08802#sec2_9_2">Section 2.9.2</a>). The results for Platform B are presented in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acs.est.5c08802#fig3">Figure 3</a> (Platform A results and results including the standard error of the mean; see <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.est.5c08802/suppl_file/es5c08802_si_001.pdf">SI 11</a>).<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Environ_Sci_Technol_2025_59_44_24000_24011_Figure_3_Biodegradation_and_persistence_assessment_of_chemicals_in_produced_water_from_Platform_B_eab3376f2c.jpg" alt="Environ. Sci. Technol. 2025, 59, 44, 24000–24011: Figure 3. Biodegradation and persistence assessment of chemicals in produced water from Platform B at 1:200 dilution from mean (n= 3) peak area ratio. A) Features measured with GC-MS and B) Features measured with LC-HRMS. Green = primary biodegraded, yellow = ambiguous, and red = persistent (see Section 2.9.2)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Environ_Sci_Technol_2025_59_44_24000_24011_Figure_3_Biodegradation_and_persistence_assessment_of_chemicals_in_produced_water_from_Platform_B_eab3376f2c.jpg 136w," sizes="100vw" width="1344" height="1544">Assessment of the GC-MS data resulted in 3–4% persistent features for Platform A (6/144 features) and Platform B (10/279 features) (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acs.est.5c08802#fig3">Figure 3</a>A and <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.est.5c08802/suppl_file/es5c08802_si_001.pdf">SI 11</a>), consistent with previous GC-MS results from a biodegradation experiment conducted one year earlier with produced water from Platform A, where the persistent fraction was also 4%. <a href="javascript:void(0);">(19)</a> In the present study, additional assessment performed on LC-HRMS data yielded 32% persistent features (61 of 191 features) for Platform A and 44% persistent features (183 of 416 features) for Platform B (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acs.est.5c08802#fig3">Figure 3</a>B and <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.est.5c08802/suppl_file/es5c08802_si_001.pdf">SI 11</a>). Although the chemical space covered by the two analytical methods has only minor overlap, <a href="javascript:void(0);">(41)</a> some chemicals might still be detected by both GC-MS and LC-HRMS, as for instance was shown for the potentially persistent chemical N-butylbenzenesulfonamide, in our previous feasibility study. <a href="javascript:void(0);">(19)</a> The large extent of biodegradation (&gt;95%) observed in the GC-MS data set shows that microorganisms in the test systems were active (degrading).<named-content></named-content>In the GC-MS data set, 20 of the petrochemicals in the reference mixture were identified in the produced water samples from both platforms, and they were all biodegraded (benzene and toluene elute too early to be included). No spectral library matches were found for the few persistent features in the GC-MS data sets, which thus remained unidentified. In comparison, many more persistent features were detected by LC-HRMS, and the high-resolution MS data was leveraged for tentative identification of these chemicals using a combination of different workflows.<h4>3.3. Tentative Identification of Chemicals in Produced Water (LC-HRMS)</h4><h5>3.3.1. Suspect Screening of Production Chemicals</h5>In total, 55 production chemicals were included in the suspect list (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.est.5c08802/suppl_file/es5c08802_si_001.pdf">SI 7</a>), and 7 of these were annotated in a high-concentration sample of the produced water (1:10 dilution) at either Platform A, B, or both (accurate mass deviation &lt;0.005, as described in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acs.est.5c08802#sec2_11_1">Section 2.11.1</a>). The annotated molecular structures are presented in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acs.est.5c08802#fig4">Figure 4</a>A. These 7 production chemicals did not pass the quality control filter at 1:200 dilution since their peaks were below the blank area cutoff at this dilution. Therefore, this study cannot conclude whether these are primary biodegraded or persistent.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Environ_Sci_Technol_2025_59_44_24000_24011_Figure_4_Comprehensive_characterization_of_chemicals_in_produced_water_83eedbbe8e.jpg" alt="Environ. Sci. Technol. 2025, 59, 44, 24000–24011: Figure 4. Comprehensive characterization of chemicals in produced water. Examples of tentative identifications resulting from different data analysis workflows are shown. A) Suspect screening of production chemicals. B) Spectral library matching. C) Feature-Based Molecular Networking (FBMN) combined with in silico structural predictions in SIRIUS (considering maximum top-6 proposed structures). D) Molecular formula computed in SIRIUS. Suspect screening, spectral library matching, and molecular formula assignments were performed for both LC-HRMS HESI+ and HESI– data sets. The FBMN in (C) shows one example of a cluster from HESI+ (top) and one cluster from HESI– (bottom). Molecular structures highlighted in red correspond to chemicals categorized as persistent. Identification confidence levels refer to Schymanski et al. (2014). (23)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Environ_Sci_Technol_2025_59_44_24000_24011_Figure_4_Comprehensive_characterization_of_chemicals_in_produced_water_83eedbbe8e.jpg 175w," sizes="100vw" width="2092" height="1871"><h4>3.6. Persistence-Directed Testing</h4>This study introduces persistence-directed testing and validates the hypothesis that environmentally relevant biodegradation tests combined with advanced analytical methods can reveal persistent chemicals in complex discharges. A limitation of this study is that the chemicals categorized as “biodegraded” only cover primary biodegradation and not potential persistent metabolites. More research is needed to assess persistent metabolites, e.g., by analyzing peaks that are significantly more abundant in biotic test systems compared to abiotic test systems after 60 days of incubation. If persistent metabolites are found, backtracking the parent molecule in the discharge can be challenging but is possible to approach using predicted degradation pathways, e.g., from specific mass shifts (e.g., 15.996 Da for oxygen attachment) as suggested by Tisler et al. (2022), <a href="javascript:void(0);">(46)</a> or using dedicated software such as BioTransformer (<a target="_blank" rel="noopener noreferrer" href="https://biotransformer.ca/">https://biotransformer.ca/</a>) or EnviPath (<a target="_blank" rel="noopener noreferrer" href="https://envipath.org/">https://envipath.org/</a>).To improve the method, future studies could use sterilized inocula and discharge samples as abiotic controls. Furthermore, as analytical sensitivity increases, future studies can potentially come closer to investigating how the biodegradation process is affected by the extreme dilutions occurring in the ocean, and thereby improving environmental relevance even further.The persistence-directed testing approach introduced in this study can be used to assess the extent of the problem of persistent chemicals in various types of discharges. An advantage of the approach is that a complex mixture of chemicals can be assessed in one biodegradation study, while the highly time-consuming work of feature identification can be narrowed down by focusing on persistent features. If persistence-directed testing approaches are adopted more widely and identification of the persistent fraction becomes easier with the very rapid development of the NTA field, it will become more and more difficult to unnoticed discharge large quantities of persistent chemicals. The approach can also lead to the identification of new groups of persistent molecules and an improved understanding of persistence in the environment.

Persistence-Directed Testing of Chemicals Discharged from Offshore Oil Platforms Combined with Nontargeted Analysis

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