GC–MS/MS–based multiresidue pesticide analysis in mealworm (Tenebrio molitor) larvae: Optimization of standard QuEChERS-based method to minimize matrix effects

Food Chemistry: X, Volume 27, April 2025, 102386: Fig. 4. Chromatograms of triadimenol obtained for acetonitrile, control, pure standard (10 µg/kg), matrix-matched standard (10 µg/kg), and mealworm samples (6, 8, 15, 18, 20, 21, 22, 26, 28, 30, and 31).
The study aimed to develop a reliable GC–MS/MS method for multiresidue pesticide analysis in mealworm (Tenebrio molitor) larvae, which are known for their complex composition and high lipid content. The standard QuEChERS-based method was unsuitable for this matrix, so the authors optimized the extraction protocol by using 0.1% formic acid in acetonitrile and PSA-based cleanup to minimize matrix effects and improve analyte recovery.
The final method enabled the detection and quantitation of 247 pesticides with high accuracy and low detection limits. Its application to field samples revealed triadimenol uptake from feed, indicating the method's practical utility. This approach provides a valuable tool for pesticide monitoring in edible insects for regulatory and industry purposes.
The original article
GC–MS/MS–based multiresidue pesticide analysis in mealworm (Tenebrio molitor) larvae: Optimization of standard QuEChERS-based method to minimize matrix effects
Hyun Ho Noh, Chang Jo Kim, So-Hee Kim, Hye-Ran Eun, Yongho Shin, Won Tae Jeong
Food Chemistry: X, Volume 27, April 2025, 102386
https://doi.org/10.1016/j.fochx.2025.102386
licensed under CC-BY 4.0
Selected sections from the article follow. Formats and hyperlinks were adapted from the original.
The consumption of animal products has increased with the increasing global population, and the demand for consumable crop–derived calories and proteins is expected to increase 2.1-fold by 2050 (Hunter et al., 2017). Given the need to promote sustainable food production, considerable attention has been drawn to decreasing the reliance of pest management on chemicals (Rockstrom et al., 2017). However, the fact that wheat, corn, and cotton losses due to pests reached 38.3 % in 1964–2003 (Poppe et al., 2003) indicates the importance of pesticides for preventing crop damage by fungi, insects, mites, weeds, and other pests and thus securing stable food production (Burger et al., 2008). Additionally, climate and weather changes directly and indirectly affect crop production and pest reproduction, distribution, and migration. Thus, food production should be increased while reducing the use of chemicals (Porter et al., 1991).
Insects are rich in proteins (40 %–70 %), minerals, and vitamins, thus holding promise as alternative protein sources for the food industry (Gravel & Doyen, 2020). Over 2000 insect species are consumed in various countries, including those in Asia and Europe (van Huis, 2020). The production of edible insects is more environmentally friendly and sustainable than livestock farming (FAO, 2013), and the growth of the domestic and international insect market is expected to continue. Edible insects include members of the orders Lepidoptera, Coleoptera, Orthoptera, and Hymenoptera (Yoo et al., 2013). In particular, the larvae of the mealworm beetle (Tenebrio molitor) have a protein content of 46.44 % and are nutritionally rich alternative food sources (Ravzanaadii et al., 2012). However, edible insects may contain harmful substances, such as microorganisms, chemicals, and parasites, with numerous studies reporting the detection of pesticides, including organophosphates and benzoquinones (Belluco et al., 2013).
Pesticides are toxic to humans and the environment and can harm the immune, reproductive, and nervous systems. In response to the concerns related to pesticide residues in agricultural products and human exposure (Damalas & Eleftherohorinos, 2011; Lushchak et al., 2018), the European Union (EU) has established 464 maximum residue limits to regulate pesticides in terrestrial invertebrates, including insects (EU, 2024). In South Korea, the Rural Development Administration and Ministry of Food and Drug Safety set safety guidelines and residue limits for various crops, while the National Agricultural Products Quality Management Service and Ministry of Food and Drug Safety conduct safety investigations on harmful substances, including pesticide residues, in domestically produced and distributed agricultural products to ensure safe food production. However, no residue limits have been established for pesticides in edible insects in South Korea, which indicates the need to establish and monitor pesticide residue analysis methods, particularly for applying uniform PLS (positive list system) standards and future maximum residue limits.
Owing to the high protein and fat contents of mealworm larvae, the analysis of pesticide residues therein requires pretreatment to prevent contamination (Ravzanaadii et al., 2012), as exemplified by protein and fat removal based on the QuEChERS method and n-hexane treatment (Houbraken et al., 2016; Ramluckan et al., 2014; Shin et al., 2020). Acetonitrile/hexane partitioning is necessary to improve the recovery rates of high-distribution-coefficient pesticides during gas chromatography-tandem mass spectrometry (GC–MS/MS) analysis (Shin et al., 2018). Additionally, adsorbents commonly employed in the QuEChERS method, such as primary secondary amine (PSA), C18, Z-Sep, Z-Sep+, and HLB (hydrophilic lipophilic balance), should be used to remove potential interferents from the extract. Herein, we aimed to (i) develop a method for the simultaneous analysis of multiple pesticides and related metabolites in mealworm larvae using a GC–MS/MS–based modified QuEChERS approach and (ii) validate the effectiveness of this method by applying it to real mealworm larvae. The method improves routine residual pesticide analysis procedures to provide a breakthrough the analysis of high-protein and high-fat samples.
2. Materials and methods
2.4. Instrumentation
Pesticide analysis was performed using an Agilent 7000C triple-quadrupole mass spectrometer coupled with an Agilent 7890B gas chromatograph (Santa Clara, CA, USA). The carrier gas (helium) was supplied at a flow rate of 1 mL/min. Samples were injected in the solvent vent mode, and the vent flow rate was held at 50 mL/min for the first 1.5 min, decreased to 25 mL/min, and maintained (5 psi) for 0.3 min. The target analytes were separated on an HP-5 ms column (30 m × 250 μm × 0.25 μm). The oven temperature was held at 50 °C for 3 min, increased to 185 °C at 30 °C/min, 250 °C at 5 °C/min, and 300 °C at 10 °C/min, and held for 7 min. The source and transfer line temperatures were set to 250 and 290 °C, respectively. Electron ionization was performed at 70 eV, and all pesticides were analyzed in the dynamic multiple reaction monitoring mode.
3. Result and discussion
3.1.2. Partitioning efficiency
Mealworm larvae have a fat content of 21.9 wt% (Imathiu, 2020) and should therefore be defatted prior to analysis to remove interferents and prevent the contamination of the GC–MS/MS instrument. Therefore, n-hexane, a nonpolar solvent effective for fat removal, was employed (Ramluckan et al., 2014). Additionally, n-hexane (partition coefficient = 3.90) has a higher affinity than acetonitrile (partition coefficient = −0.34) and can therefore extract nonpolar pesticides that may remain in the extraction solvent. Using n-hexane-saturated acetonitrile, we examined the effect of partitioning frequency on recovery rates (Table 2). Each additional partitioning led to a higher pesticide recovery, with four partitions yielding a 22 percentage point increase in recovery (84.6 %) compared with a single partition. At this level, 209 pesticides demonstrated acceptable recovery rates (70 %–120 %) and precisions (RSD ≤ 20 %). Thiocarbamate and organochlorine pesticides exhibited low recovery rates, probably because of their high partition coefficients (log P = 4.1–6.9) due to their low polarities, and were therefore retained in the n-hexane phase (Mathieu et al., 2015; Mdeni et al., 2022). However, the recovery rates of these pesticides increased with the increasing partitioning frequency (Fig. 1). Therefore, partitioning with n-hexane-saturated acetonitrile was concluded to be essential for improving the recovery of pesticides with high partition coefficients, and the optimal number of partitions was identified as four.
Food Chemistry: X, Volume 27, April 2025, 102386: Fig. 1. Recovery rates (bars) and partition coefficients (log P, triangles) of 10 representative pesticides showing a strong dependence of recovery (>25 %) on the number of partitionings (N = 1, 2, 3, and 4). Error bars are the standard deviations of the recovery rates (n = 4).
3.3. Real sample analysis
Among the 24 samples collected from domestic mealworm larva farms, 11 contained the triazole fungicide triadimenol at concentrations of 14–996 μg/kg (Fig. 4) and were therefore noncompliant with the EU residue limit for terrestrial invertebrates (10 μg/kg). Considering that the triadimenol residue limit for wheat, the primary ingredient of bran fed to mealworms, is 100 μg/kg, pesticide absorption probably occurred through bran consumption. Thus, the established method for the multiresidue analysis of 247 pesticides in mealworm larvae was concluded to be applicable in field settings and enable both quantitative and qualitative analyses.
Food Chemistry: X, Volume 27, April 2025, 102386: Fig. 4. Chromatograms of triadimenol obtained for acetonitrile, control, pure standard (10 µg/kg), matrix-matched standard (10 µg/kg), and mealworm samples (6, 8, 15, 18, 20, 21, 22, 26, 28, 30, and 31).
4. Conclusions
A GC–MS/MS–based multiresidue method for the detection and quantitation of 247 pesticides in mealworm larvae was developed, optimizing the standard QuEChERS procedure to account for matrix complexity and high fat content, and validated. Pesticide recovery rates were maximized by combining 0.1 % formic acid in acetonitrile (extraction solvent) with the original QuEChERS packet. Further cleanup (PSA d-SPE) effectively removed matrix interferences without significant analyte loss, enhancing detection accuracy. According to the results of validation tests, the developed method exhibited high linearities, acceptable recovery rates, and low detection limits for most analytes and was therefore concluded to be robust and suitable for both quantitative and qualitative analyses. The analysis of 24 field samples revealed detectable levels of triadimenol, suggesting its potential uptake from bran feed. Thus, this validated approach was concluded to be suitable for application in regulatory and industrial settings, offering a reliable tool for monitoring pesticide residues in mealworm larvae and similar edible insect matrices.
