<p><strong>In the week of April 13, the following webinars await you in the field of gas / solid phase and especially Raman, FTIR, GC and GC/MS.</strong></p><blockquote><h4><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinars"><strong>👉 DETAILS AND REGISTRATION IN THE WEBINARS SECTION</strong></a></h4><p><strong>👉 Search and filter in the largest global database</strong> with over <strong>5 500 GC, LC, MS and spectroscopy webinars</strong>.</p></blockquote><div><div><div><div><div><div><h5><strong>1. Agilent Technologies: The Journey of Safer Science through Safer Labs</strong></h5><ul><li>Tu, 14.4.2026 07:30 CEST</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinar/6104">Registration</a></li></ul><p>Agilent Safer Labs webinar highlights best practices in lab safety, including handling, storage, and instrumentation, helping professionals build safer, more efficient laboratory environments.</p><h5><strong>2. Agilent Technologies: Column Confidence: Making the Right Choice for Your GC Needs</strong></h5><ul><li>Tu, 14.4.2026 17:00 CET</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinar/5725">Registration</a></li></ul><p>Learn how to choose the right GC or GC/MS column by understanding stationary phase chemistry and column dimensions. Improve selectivity, peak behavior, and resolution for a more robust analysis.</p><h5><strong>3. Metrohm: Measure smarter, spend less – NIR spectroscopy for polymer analysis</strong></h5><ul><li>Th, 16.4.2026 15:00 CET</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinar/6032">Registration</a></li></ul><p>Discover how NIR spectroscopy enables fast, chemical-free polymer analysis. Learn how manufacturers can streamline quality control, reduce waste, and improve efficiency with rapid multi-parameter measurements.</p><h5><strong>4. C&amp;EN: Precision Lab Solutions for High-End Optics and Coatings</strong></h5><ul><li>Th, 16.4.2026 17:00 CEST</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinar/6096">Registration</a></li></ul><p>Join this presentation and open discussion with industry-leading experts Patrick Muller and Kieran Evans – leaders in UV/Vis and IR analytical methods and testing techniques.</p></div></div></div></div></div></div>

Webinars LabRulezGCMS Week 16/2026

<p><strong>This study introduces atmospheric solids analysis probe high-resolution tandem mass spectrometry with cyclic ion mobility as a novel approach for characterizing Asian lacquers. Applied to 27 historical samples from Japan, China, Vietnam, and Myanmar, the method enabled classification by geographic origin based on phenol and benzenediol derivatives.</strong></p><p>In addition to lacquer identification, the technique simultaneously detected pigments such as arsenic sulfides and associated resins, providing comprehensive chemical insight. This approach expands analytical capabilities for cultural heritage studies, supporting restoration, conservation, and art historical research.</p><blockquote><h4><strong>The original article</strong></h4><h4><a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572"><strong>Characterization of Asian lacquers by atmospheric solids analysis probe high resolution tandem mass spectrometry coupled with cyclic ion mobility separation</strong></a></h4><p>Vojtěch Zemek, Radek Ryšánek, Petra Krejčí, Lukáš Kučera, Jana Nádvorníková, Adéla Tůmová, Helena Heroldová, Adriana Stříbrná, Petr Bednář</p><p>Journal of Cultural Heritage, 77, 2026, 187-196</p><p><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1016/j.culher.2025.11.012">https://doi.org/10.1016/j.culher.2025.11.012</a></p><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/"><strong>CC-BY 4.0</strong></a></h6></blockquote><p><strong>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.</strong></p><div><p>In recent years, an expansion of ambient pressure ionization mass spectrometry in various areas is observed [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0024"><span>24</span></a>,<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0025"><span>25</span></a>]. Atmospheric solids analysis probe mass spectrometry (ASAP-MS) is a powerful technique for direct analysis of even very complex samples, such as polymers [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0026"><span>26</span></a>], foods [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0027"><span>27</span></a>], or petrochemical sources and products [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0024"><span>24</span></a>]. ASAP ionization technique is a modification of atmospheric pressure chemical modification (APCI). In conventional arrangement, the sample is attached to a sampling probe tip (a standard melting point capillary is inserted into powder or liquid sample that sticks to its surface) and the probe is consequently placed into the ion source (commonly adapted ESI or APCI source). The analytes are released into the gas phase using hot gas (nitrogen) and ionized in the corona discharge. The formed ions (quasimolecular ions, radical cations or radical anions) are then transferred to the evacuated part of mass spectrometer [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0024"><span>24</span></a>,<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0025"><span>25</span></a>,<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0028"><span>28</span></a>]. Note that especially at higher vaporization temperatures a portion of the analytes is pyrolyzed and a mixture of parent ions and pyrolysis product ions is commonly observed in the ASAP-MS spectra [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0029"><span>29</span></a>]. The main feature of this direct MS mode is a fast detection of the formed products (including those with a higher mass and perhaps a shorter lifetime). In contrast, due to chromatographic separation in py-GC/MS, only relatively stable and volatile products are detected (the chromatographic step provides an additional selectivity here). In addition, electron impact ionization produces significantly different spectra profiles compared to the atmospheric pressure chemical ionization ongoing in the ASAP source. Both techniques are to a certain extent complementary [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0024"><span>24</span></a>,<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0025"><span>25</span></a>,<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0030"><span>30</span></a>].</p><p>There is a direct possibility of coupling mass spectrometry with ion mobility spectrometry (IMS) to significantly improve the selectivity of analysis (and, to certain extent, to compensate the advantage of the chromatographic step in py-GC/MS while maintaining the direct MS analysis speed). During an ion mobility spectrometry experiment, ions of analytes are flying through the ion mobility cell (e.g., a drift tube or a closed-loop path within a traveling wave ion guide in case of the cyclic ion mobility cell) filled with buffer gas (e.g. helium). In this process, ions collide with the buffer gas. These collisions slow down the ions differently based on their size, shape and charge. Ion mobility spectrometry therefore allows separation of the present analytes in the gas phase according to their collision cross sections (CCS). It also allows separation of isomeric compounds and filtration of the matrix signals, resulting in a higher quality of the MS and MS/MS spectra [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0031"><span>[31]</span></a>, <a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0032"><span>[32]</span></a>, <a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0033"><span>[33]</span></a>].</p><p>ASAP-MS has a high potential for the study of protective and decorative layers on the surfaces of historical objects. To the best of our knowledge, however, ASAP-MS and ASAP-IMS-MS have never been used for characterization of lacquers. This paper deals with the development of ASAP-MS method for characterization of Asian lacquers and its application for classification of oriental historical objects.</p><h4><strong>3. Material and methods</strong></h4><h5><strong>3.3. Instrumentation and experimental setup</strong></h5><p>Analyses were performed using <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/202"><strong>Waters Cyclic IMS high resolution tandem mass spectrometer</strong></a> with an integrated cyclic ion mobility cell and atmospheric solids analysis probe (ASAP) used as ion source (Waters, Milford, MA, USA). Samples (∼ 0.1–0.5 mg) were inserted into a melting point capillary (G119/32, manufacturer SAMCO, United Kingdom) through an in-lab radially drilled hole (hole diameter: approx. 1 mm; distance from the bottom end approximately 5 mm). Solution of 2′,4′,6′-trihydroxyacetophenone monohydrate (THAP) in acetone was used as a standard for lock mass correction (<i>c</i> = 1 mg.ml<sup>-1</sup>). The m/z values were calculated as the means from three repeated measurements of appropriate samples. Approx. 1 μl of standard was deposited onto the capillary using a small pipette tip. Following experimental parameters were used: desolvation temperature of 600 °C, source temperature of 100 °C, corona “current” mode (corona current 2.0 μA), cone voltage of 30 V, source offset of 10 V, cone gas flow of 30 l/min, desolvation gas flow of 500 l/min, nebulizer gas pressure of 6 bar and reference capillary voltage of 2.5 kV. As for the ion mobility separation setup, a cyclic ion mobility cell was used in the following sequence: 1. Inject (10 ms), 2. Separate (37 ms), 3. Inject to Pre-Store (0.50 ms), 4. Eject (0.50 ms), 5. Reinject from Pre-Store (0.63 ms), 6. Eject and Acquire (13.20 ms). TW static height was 11 V, TW ramp start height was 15 V and TW ramp end height was 35 V. Acquisition time was 3 min for the MS scan and 1 min for the MS/MS scan used for identification of analytes. In the MS/MS mode, collision energy 30 V was used for pentadecyl and heptadecylcatechols, 35 V for phenols substituted with (CH<sub>2</sub>)<sub>10</sub>C<sub>6</sub>H<sub>5</sub> and 40 V for catechols substituted with (CH<sub>2</sub>)<sub>12</sub>C<sub>6</sub>H<sub>5</sub> and phenols substituted with CH<sub>2</sub>CO(CH<sub>2</sub>)<sub>10</sub>C<sub>6</sub>H<sub>5</sub>, respectively. Scan time 1 s was used for both scans. At the end of each working day, sample V was measured for confirmation that the instrument measured consistently. Values of m/z were calculated by MassLynx software (version 4.2, SCN 1016) after lock mass correction using the signal of protonated molecule of THAP. Theoretical mass of particular analyte was used for lock mass correction in the MS/MS spectra. Centroid top at 80 % and areas of peaks were used for accurate mass and intensity of signals calculation. The maximal accepted difference from theoretical mass (dtm) of signals was 10 mDa. Peak areas were used to compare the abundance of identified analytes among particular samples. Mobilograms from cyclic ion mobility experiments were produced by DriftScope v2.9 software. In mobilograms, spectra were generated by integration at Full Width at Half Maximum (FWHM) of peaks at drift time 1.72 ms.</p><h4><strong>4. Results and discussion</strong></h4><h5><strong>4.1. Utilization of ASAP-MS</strong></h5><p>In the ASAP-MS spectra of the studied lacquers, signals of a several compounds were observed (<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#fig0002"><span>Fig. 2</span></a>). Signals of radical cations as well as protonated molecules of identified analytes were easily visible. Usually a slightly higher abundance of cation radicals compared to protonated molecules was observed (spectra of all samples are listed in Supplementary material B). The processes observed in the ASAP-MS spectra involve the release of alkyl phenol/alkyl catechol monomer(s) and cleavages of alkyl chain(s) after the carbon linked to the phenol/catechol ring (i.e. cleavage after the first, second and third alkyl carbons) and elimination of water either from polymer or released monomers (the pyrolytic/collision-induced fragmentation processes are discussed below in detail). The analysis of provided samples revealed the most important markers of specific types of lacquers.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Journal_of_Cultural_Heritage_77_2026_187_196_Fig_2_Spectra_of_lacquers_prepared_from_Toxicodendron_vernicifluum_Toxicodendron_succedaneum_and_Gluta_usitata_samples_U_V_and_B_0200c24c06.jpg" alt="Journal of Cultural Heritage, 77, 2026, 187-196: Fig. 2. Spectra of lacquers prepared from Toxicodendron vernicifluum, Toxicodendron succedaneum and Gluta usitata (samples U, V and B)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Journal_of_Cultural_Heritage_77_2026_187_196_Fig_2_Spectra_of_lacquers_prepared_from_Toxicodendron_vernicifluum_Toxicodendron_succedaneum_and_Gluta_usitata_samples_U_V_and_B_0200c24c06.jpg 245w," sizes="100vw" width="2750" height="1269"></p><h5><strong>4.1.4. Study of MS/MS spectra of characteristic markers</strong></h5><p>For all the standard materials, the most important markers were subjected to fragmentation after the collision induced dissociation (CID) in the Trap collision cell of the mass spectrometer (MS/MS experiments; all fragmentation spectra and observed diagnostic fragments including differences from theoretical masses are given in Supplementary material B).</p><p>Signals of fragments with an intensity higher than the specified percentage of well known fragments arising from studied compounds were investigated and identified. Diagnostic fragments are given in Table B.2, Supplementary material B. The threshold signal was set for different compounds. For heptadecyl- and pentadecylcatechols, the threshold signal was defined as 5 % of the signal of dihydroxytropylium that is always an integral component of their collision spectra. For heptadecenyl- and pentadecenylcatechols the threshold signal was 2.5 % of dihydroxytropylium. For pentadecatrienyl catechol it was 100 % of dihydroxytropylium while for dodecylphenylcatechol it was 1 % of dihydroxytropylium. In case of 1-(3-hydroxyphenyl)-12-phenyldodecan-2-one, the threshold signal was defined as 17 % of the signal of hydroxyphenylethan-2-one. Finally, for 10-decylphenylphenol and 12-dodecylphenylphenol, 50 % of the signal of methylphenol was used as the threshold signal. These fragments were used for confirmation of the presence of lacquer compounds in routine measurements (at least one MS/MS spectrum was measured in each sample). The threshold signals were suggested and set in order to reach a sufficient yield of diagnostic fragments for unambiguous identification of individual markers. These signals are intended to be used in long term measurement in practice.</p><div><p>Fragmentation of heptadecylcatechols with 0-3 double bonds (<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#fig0003"><span>Fig. 3</span></a>a-d) is similar to that of pentadecylcatechols with same number of double bonds. In all cases, the signals of the characteristic fragments are well separated from the signals of the matrix.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Journal_of_Cultural_Heritage_77_2026_187_196_Fig_3_Fragmentation_spectra_of_heptadecylcatechols_possessing_0_3_double_bonds_6149330bc3.jpg" alt="Journal of Cultural Heritage, 77, 2026, 187-196: Fig. 3. Fragmentation spectra of heptadecylcatechols possessing 0-3 double bonds, (MS/MS; m/z of parent ions are: a) 342.2559, b) 344.2715, c) 346.2872, d) 348.3028)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Journal_of_Cultural_Heritage_77_2026_187_196_Fig_3_Fragmentation_spectra_of_heptadecylcatechols_possessing_0_3_double_bonds_6149330bc3.jpg 232w," sizes="100vw" width="3000" height="2017"></p><h5><strong>4.2. Principal component analysis</strong></h5><p>Excellent separation of particular types of Asian lacquers in Score Plot (<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#fig0005"><span>Fig. 5</span></a>a-d) was obtained by Principal Component Analysis based on the benzenediol and phenol derivatives described above. The Score Plot contains a set of 20 samples obtained from the Náprstek Museum Prague as well as other samples (BBI, BBO, SBI, SBO, U, V and B) in which lacquer compounds were detected (<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#tbl0002"><span>Table 2</span></a>). Note that in three other samples from The Náprstek Museum Prague, the lacquer compounds were not found at all.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Journal_of_Cultural_Heritage_77_2026_187_196_Fig_5_Score_plot_and_bi_plot_from_PCA_analysis_of_lacquers_taken_from_historic_objects_df82e0592a.jpg" alt="Journal of Cultural Heritage, 77, 2026, 187-196: Fig. 5. Score plot and bi-plot from PCA analysis of lacquers taken from historic objects, a. whole Score PCA plot, b. zoom of the T. succedaneum area, c. zoom of the T. vernicifluum area, d. zoom of the G. usitata area, e. whole PCA bi-plot, f. zoom of the T. succedaneum area in the PCA bi-plot, g. zoom of the T. vernicifluum area in the PCA bi-plot, h. zoom of the G. usitata area in the PCA bi-plot." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Journal_of_Cultural_Heritage_77_2026_187_196_Fig_5_Score_plot_and_bi_plot_from_PCA_analysis_of_lacquers_taken_from_historic_objects_df82e0592a.jpg 156w," sizes="100vw" width="3000" height="2994"></p><p>The significance of suggested markers for the studied lacquers across the whole data matrix was confirmed. The effect of particular markers is reflected in related bi-plots (<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#fig0005"><span>Fig. 5</span></a>e-h). Qualitatively, the results are in accordance with the former study obtained by py-GC/MS [<a target="_blank" rel="noopener noreferrer" href="https://www.sciencedirect.com/science/article/pii/S1296207425002572#bib0001"><span>1</span></a>]. Since both cation-radicals and protonated molecules are formed in ASAP source with significant yield of both ion forms, their sum is an input into the data matrix for each substance (e.g., for pentadecenyl catechol, where the input is the sum of intensities I<sub>(m/z</sub> <sub>=</sub> <sub>318)</sub>+ <i>I</i><sub>(m/z</sub> <sub>=</sub> <sub>319)</sub>), see PCA matrix in Supplementary material C. Measured m/z values of the analyzed compounds are in good agreement with the theoretical values calculated for specific elemental compositions (noted differences from the theoretical mass, dtm is in all cases less than or equal to 10 mDa).</p><h4><strong>5. Conclusion</strong></h4><p>The combination of atmospheric solids analysis probe with high resolution tandem mass spectrometry proved to be a fast and effective tool for analysis of historical Asian lacquer objects, their resolution and classification. The developed method is based on profiling of phenol and benezenediols derivatives. The fragmentation of alkylphenols and alkylbenzene diols after collision activated dissociation in Trap and Transfer collision cells was described. Scission of alkyl chains and elimination of water represent the main fragmentation processes important for identification. Cyclic ion mobility separation appeared to be a useful tool for “cleaning” of signals of the lacquer ions from the matrix signals allowing their better identification from the fragmentation spectra. Moreover, ASAP-MS and MS/MS allowed detection of diterpenic resins, triterpenic resins and arsenic sulphide pigments present along with Asian lacquers. Principal Component Analysis provided complete separation of samples into three clusters of Asian lacquers in Score Plot. A simple classification approach based on direct comparison of newly suggested classification parameters (CPs) allows reliable differentiation of lacquer samples according to their provenance. The developed method is now implemented in routine controls of lacquered objects and could be applied to the analysis of resins and ambers obtained from archaeological findings.</p></div></div>

Characterization of Asian lacquers by atmospheric solids analysis probe high resolution tandem mass spectrometry coupled with cyclic ion mobility separation

<p><strong>This study introduces a portable fluorescence-based microfluidic assay for rapid detection of multiple drugs in urine, including methamphetamine, benzoylecgonine, THC-COOH, and benzodiazepines. The system combines a compact reader with a dual-channel chip containing drug-specific antibodies, enabling simultaneous analysis within 5 minutes.</strong></p><p>Validation with 141 authentic urine samples demonstrated high sensitivity, specificity, and minimal cross-reactivity for both single and multiple drug use. The assay offers a cost-effective and field-deployable alternative to conventional immunoassays, supporting on-site forensic and clinical drug screening.</p><blockquote><h4><strong>The original article</strong></h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027"><strong>On-Site Microfluidic Assay for the Detection of Multiple Drugs in Urine</strong></a></h4><p>Sanghag Ko, Sora An, Hyunjun Bae, Joonseok Seo, Suncheun Kim, Jeongmin Lee, Yohan Jeong, Juhyung Kim, Sangki Lee, Hyung Chul Kim, Seok Chung*, and Heesun Chung*</p><p>ACS Omega 2026, 11, 8, 13697–13705</p><p><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/acsomega.5c11027">https://doi.org/10.1021/acsomega.5c11027</a></p><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/"><strong>CC-BY 4.0</strong></a></h6></blockquote><p><strong>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.</strong></p><div><p>Forensic, clinical, and workplace testing for drugs of abuse in urine typically involves immunoassays and mass spectrometry (MS)-based methods. <a href="javascript:void(0);">(1,2)</a> Immunoassays are commonly used for rapid initial screenings, while MS-based assays are reserved for confirmatory testing. <a href="javascript:void(0);">(3−5)</a></p><p>A variety of immunoassay platforms have been developed for efficient drug screening. The lateral flow assay (LFA), a commonly used presumptive test in point-of-care test kits, offers rapid results within 5–10 min. These portable and inexpensive kits require minimal training, making them suitable for workplaces, schools, and roadside screening. <a href="javascript:void(0);">(6−9)</a> However, they are limited by relatively low sensitivity and specificity, which may lead to false positives and negatives. Therefore, positive results must be confirmed by MS-based methods. <a href="javascript:void(0);">(1,2,4)</a> On the other hand, laboratory-based immunoassays are automated analytical systems employed in forensic and clinical laboratories and utilized in workplace drug testing programs to detect drugs in biological samples with high throughput and precision. These systems commonly employ platforms such as enzyme-linked immunosorbent assay (ELISA), enzyme-multiplied immunoassay technique (EMIT), cloned enzyme donor immunoassay (CEDIA), and chemiluminescent immunoassay (CLIA). Nevertheless, their high operational cost and dependence on complex instrumentation restrict its use in point-of-care settings. <a href="javascript:void(0);">(10−13)</a></p><p>Paper-based microfluidic assays are widely used in point-of-care diagnostics and drug testing because of their simplicity, portability and accessibility. <a href="javascript:void(0);">(14,15)</a> In forensic applications, these platforms have also been developed for the detection of drugs and their metabolites in urine, as well as for alcohol and drug identification. <a href="javascript:void(0);">(16,17)</a> Despite being both user- and manufacturer-friendly, paper-based systems still face limitations inherent to cellulose substrates, including pore size variability, nonspecific binding, and restricted fluid-control precision. <a href="javascript:void(0);">(14,18)</a></p><p>To overcome these challenges, we developed an optimized microfluidic assay featuring nanointerstice integration, enabling rapid testing. <a href="javascript:void(0);">(19−21)</a> Unlike previous systems, our design operates entirely without external forces, instead leveraging capillary pressure to drive flow and nanointerstices to accelerate fluid filling.</p><p>The microfluidic assay in this study includes a portable reader whose size is smaller (dimensions 12.7 cm × 15.0 cm × 20.6 cm, weight 2 kg, <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acsomega.5c11027/suppl_file/ao5c11027_si_001.pdf">Figure S1</a>). Microfluidic chip in which four drug-specific antibodies are immobilized across two channels. The design is optimized to minimize errors and stabilize the flow for precise results.</p><p>To apply this assay, four target drugs were selected based on both global prevalence and recent domestic forensic trends. Globally, drug misuse has risen by approximately 26% over the past decade, with the darknet transactions being largely dominated by cannabis (48%), amphetamine-type stimulants (16%), cocaine (12%), and benzodiazepines (6%). <a href="javascript:void(0);">(22)</a> Recent UNODC and EMCDDA reports similarly emphasize the ongoing increase in methamphetamine trafficking, record-high levels of global cocaine supply, the continued predominance of cannabis use, and the rising nonmedical use and diversion of benzodiazepines. <a href="javascript:void(0);">(23,24)</a> In Korea, forensic drug case analyses in 2024 revealed that methamphetamine and cannabis were the most frequently identified substances. Notably, cocaine cases increased by 291% compared to the previous year, while benzodiazepines-related cases also showed a significant 40% year-overyear increase. <a href="javascript:void(0);">(25)</a> Considering these trends, methamphetamine, cocaine, cannabis, and benzodiazepines were selected as the primary targets of this study. For the detection of these substances in urine, antibodies specific to the parent compounds were used for methamphetamine (MET) and benzodiazepines (BZOs), while detection of cocaine and cannabis was achieved through antibodies against their primary urinary metabolites, benzoylecgonine (BE) and 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH), respectively. <a href="javascript:void(0);">(26−28)</a></p><p>The performance of the developed microfluidic assay was validated using both drug-spiked and authentic urine specimens to ensure its reliability under both controlled and actual forensic testing environments. Drug-spiked specimens were prepared in the laboratory and utilized to optimize assay parameters such as reagent concentration, flow rate, and detection sensitivity. Following the evaluation with drug-spiked specimens, authentic drug-positive urine specimens, provided by the National Forensic Service in Korea (NFS) and Paraguay (Lab HORVATH), were used to assess the practical applicability and diagnostic accuracy of the assay under realistic forensic testing scenarios.</p><p>Therefore, the aim of this study was to develop and validate a portable microfluidic assay optimized for the simultaneous detection of four major drugs of abuse in urine─methamphetamine, cocaine, cannabis, and benzodiazepines─under realistic forensic testing conditions. By integrating nanointerstice technology and drug-specific antibodies within a compact platform, the assay was designed to address the limitations of existing point-of-care and laboratory-based immunoassay methods. Through performance evaluations using both drug-spiked and urine samples, this study was conducted to demonstrate the practical applicability, reliability, and diagnostic accuracy of the microfluidic assay for use in rapid on-site drug screening.</p><h4><strong>2. Materials and Methods</strong></h4><h5><strong>2.4. Standard Preparation and Sample Acquisition</strong></h5><p>Gas chromatography–mass spectrometry (GC-MS) was used to confirm urine specimens requiring verification. Analyses were conducted using an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7890B"><strong>Agilent 7890B GC</strong></a> coupled to an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5977A"><strong>Agilent 5977A mass selective detector</strong></a> (electron–ionization mode). Helium was used as the carrier gas at 1.0 mL/min, and samples (1 μL) were injected in splitless mode. Separation was achieved on an HP-5 ms capillary column (30 m × 0.25 mm × 0.25 μm) with an oven program of 80 °C (1 min), ramped at 10 °C/min to 280 °C and held for 5 min (total run time: 28 min). The inlet and transfer-line temperatures were 280 and 280 °C, respectively. Qualitative identification was performed using selected-ion monitoring (SIM) targeting characteristic ions for each analyte.</p><h4><strong>3. Results</strong></h4><h5><strong>3.1. Microfluidic Chip and Portable Reader</strong></h5><p>This study employs a microfluidic assay that incorporates a simple sample preparation method, in which the urine specimen is diluted with a sample buffer (Absology, cat.no. ASB3) at a 1:10 ratio to minimize urine matrix effects and control the viscosity of the flow in the channel. 50 μL of the mixture is introduced onto a microfluidic chip for analysis with a potable reader (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027#fig1">Figure 1</a>).</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2026_11_8_13697_13705_Figure_1_Microfluidic_assay_8a0cedb715.jpg" alt="ACS Omega 2026, 11, 8, 13697–13705: Figure 1. Microfluidic assay. (A) Pretreatment of the urine specimen. To prepare the measurement, the user mixes the urine specimen with specimen buffer at a 1:10 ratio in the mixture dropper and then loads 50 μL of the mixture into each channel. (B) Photographs of the microfluidic assay. It shows the main elements of the assay system, comprising the microfluidic chip, mixture dropper, disposable pipet, and the portable reader device." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2026_11_8_13697_13705_Figure_1_Microfluidic_assay_8a0cedb715.jpg 130w," sizes="100vw" width="825" height="993"></p><h5><strong>3.5. Measurement of Urine Specimens in the Microfluidic Chip</strong></h5><p>Following the standard validation, we analyzed 141 authentic urine specimens: <i>N</i> = 30 methamphetamine users, <i>N</i> = 38 cocaine users, <i>N</i> = 30 cannabis users, and <i>N</i> = 13 benzodiazepine users, while the nondrug user group included 30 drug-free urine specimens (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acsomega.5c11027/suppl_file/ao5c11027_si_002.xlsx">Supporting Information 2</a>).</p><p>The results obtained from the microfluidic assay were compared with those from the COBAS c311 for MET, THC-COOH, BZOs, and a point-of-care test kit test for BE. <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027#fig6">Figure 6</a>A confirms no detection of MET, BE, THC-COOH, and BZOs in the nondrug user group. In <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027#fig6">Figure 6</a>B, COI values for MET exceeded 1 in all methamphetamine specimens, with THC-COOH in one specimen, and no BE and BZOs detected. The sensitivity of the microfluidic assay─defined as the percentage of true positives─and the specificity─defined as the rate of true negatives─ <a href="javascript:void(0);">(32)</a>were both 100% (30/30) for MET when compared to COBAS c311. <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027#fig6">Figure 6</a>C shows that COI values for BE exceeded 1 in all cocaine specimens, with THC-COOH and BZOs detected in 34 and 9 specimens, respectively. The microfluidic assay demonstrated 100% (38/38) sensitivity and 100% (30/30) specificity in the detection of BE when compared to the point-of-care test kit. In <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027#fig6">Figure 6</a>D, all cannabis specimens had COI values above 1 for THC-COOH, and one specimen showed a COI above 1 for MET; no BE and BZOs were found in these specimens. Sensitivity and specificity for THC-COOH were both 100% (30/30) as compared to COBAS c311. <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027#fig6">Figure 6</a>E indicates that COI values for BZOs exceeded 1 in 6 out of the 13 benzodiazepine specimens, demonstrating a lower sensitivity of 46% (6/13), though specificity remained at 100% (30/30) compared to COBAS c311. In addition to single-drug analysis, specimen-level evaluation revealed that the microfluidic assay was also capable of detecting multidrug users. As shown in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c11027#fig6">Figure 6</a>F, among the total 141 specimens, 30 were drug-free, 75 were single-drug users, and 36 were multidrug users. This demonstrates the assay’s ability to distinguish complex drug use patterns in forensic samples.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2026_11_8_13697_13705_Figure_6_Drug_use_patterns_in_N_141_samples_and_their_cutoff_index_COI_results_eec5e03112.jpg" alt="ACS Omega 2026, 11, 8, 13697–13705: Figure 6. Drug use patterns in N = 141 samples and their cutoff index (COI) results. COI results of (A) N = 30 individuals who did not consume any of the four drugs. (B) N = 30 individuals who consumed at least methamphetamine, compared with GC-MS results. (C) N = 38 individuals who consumed at least cocaine, compared with a rapid test kit. (D) N = 30 individuals who consumed at least cannabis, compared with GC-MS. (E) N = 13 individuals who consumed at least benzodiazepines, compared with LC-MS. (F) Samples consisted of nondrug group (N = 30), abusers who consumed one type of drug (N = 75), and others who took more than two types of drugs (N = 36)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2026_11_8_13697_13705_Figure_6_Drug_use_patterns_in_N_141_samples_and_their_cutoff_index_COI_results_eec5e03112.jpg 99w," sizes="100vw" width="1582" height="2484"></p><h4><strong>5. Conclusions</strong></h4><p>Immunoassay face distinct limitations. LFAs often suffer from low sensitivity and subjective result interpretation, while laboratory-based immunoassay systems require high costs and offer poor portability. In response to these challenges, this study developed a portable microfluidic assay for on-site screening. The assay enables semiquantitative detection of four drugs─methamphetamine, cocaine, cannabis, and benzodiazepines─using a microfluidic chip integrated with drug-specific antibodies. It provides clear positive/negative results, minimizing subjective interpretation, and also supports semiquantitative numerical outputs through COI values. Based on analysis of 141 authentic urine specimens tested, including 36 cases of polydrug use, the microfluidic assay demonstrated accurate and reliable detection across all four major drug classes, enabling robust performance even in polydrug use cases. The total analysis time remains under 5 min, ensuring practical usability for on-site testing. Its multiplexing capability allows for the simultaneous detection of multiple drugs in a single run, improving efficiency and utility in field testing scenarios such as roadside and workplace drug monitoring.</p><p>Given those technological advantages and demonstrated performance, this assay represents a promising tool for broader field applications. Future research may focus on expanding the assay’s applicability to a wider range of detectable drug panel, improving its analytical throughput, or integrating wireless connectivity features for real-time monitoring and cloud-based data sharing.</p></div>

On-Site Microfluidic Assay for the Detection of Multiple Drugs in Urine

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