US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA; Programa de Investigación y Análisis de Residuos y Contaminantes Químicos (PRINARC), Facultad de Ingeniería Química, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina.
US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
J Chromatogr A. 2021 May 24;1645:462097. doi: 10.1016/j.chroma.2021.462097. Epub 2021 Mar 27.
Hemp has been an agricultural commodity for millennia, and it has been undergoing a resurgence in interest and production due to its high content of cannabinoids, protein, fiber and other ingredients. For legal possession and use throughout the USA, hemp and hemp products must have delta-9-tetrahydrocannabinol (THC) concentration < 0.3%. As with most crops, pesticides may be applied when farming hemp, which need to be monitored in food, feed, and medicinal products. The aim of this work was to evaluate and validate the recently developed "quick, easy, cheap, effective, rugged, safe, efficient, and robust" (QuEChERSER) sample preparation mega-method to determine pesticide residues in hemp plants, flowers, powders, oils, and pellets. High-throughput analysis of final extracts for 106 targeted pesticides and metabolites from North American monitoring lists entailed: 1) ultrahigh-performance liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS) with column back-flushing, and 2) instrument-top sample preparation + low-pressure gas chromatography (ITSP+LPGC-MS/MS). In QuEChERSER, 2 g sample is extracted with 10 mL 4/1 (v/v) acetonitrile/water by mechanical shaking for 10 min, followed by 3 min centrifugation. For LC, 0.2 mL of extract is taken and solvent exchanged into initial mobile phase followed by 5 min ultra-centrifugation prior to the 10 min analysis. For GC-amenable pesticides, the remaining initial extract is partitioned with 4/1 (w/w) anh. MgSO/NaCl, and 1 mL is taken for automated ITSP cleanup in parallel with 10 min LPGC analysis. In the former case, the UHPLC column is back-flushed with 1/1 (v/v) methanol/acetonitrile for 3 min between each injection to keep the system clean and avoid ghost peaks. Multi-level, multi-day validation results achieved 70-120% recoveries with RSDs < 20% for more than 80% of the analytes in hemp protein powder, oil, pellets, and fresh plant (dried hemp plant and flower were too complex). Limits of quantification (LOQs) were < 10 ng/g were achieved for nearly all pesticides, yielding 2.8% false negatives among >13,000 analyte results in the spiked samples. The QuEChERSER method was demonstrated to meet the challenge for several complex hemp matrices.
大麻作为一种农作物已有数千年的历史，由于其高含量的大麻素、蛋白质、纤维和其他成分，它的兴趣和产量正在复苏。在美国，合法拥有和使用大麻及其产品必须将 δ-9-四氢大麻酚 (THC) 浓度控制在<0.3%以下。与大多数作物一样，在种植大麻时可能会使用农药，需要在食品、饲料和医药产品中进行监测。本工作的目的是评估和验证最近开发的“快速、简便、廉价、有效、耐用、安全、高效和强大”（QuEChERSER）样品制备宏方法，以确定大麻植物、花、粉、油和丸剂中的农药残留。采用超高效液相色谱-串联质谱法（UHPLC-MS/MS）和柱反冲洗，对北美监测清单中的 106 种靶向农药和代谢物进行高通量分析：1）对最终提取物进行分析，2）仪器顶部样品制备+低压气相色谱（ITSP+LPGC-MS/MS）。在 QuEChERSER 中，用 10ml4/1（v/v）乙腈/水机械搅拌提取 2g 样品 10min，然后离心 3min。对于 LC，取 0.2ml 提取物并在初始流动相中置换溶剂，然后在 10min 分析前进行 5min 超速离心。对于 GC 相容的农药，用 4/1（w/w）anh MgSO/NaCl 分相剩余初始提取物，然后平行进行 10min LPGC 分析，取 1ml 用于自动 ITSP 净化。在前一种情况下，在每次进样之间用 1/1（v/v）甲醇/乙腈反冲洗 UHPLC 柱 3min，以保持系统清洁并避免鬼峰。在大麻蛋白粉、油、丸剂和新鲜植物（干大麻植物和花太复杂）中，80%以上的分析物的多水平、多日验证结果达到 70-120%的回收率，相对标准偏差（RSD）<20%。几乎所有农药的定量限（LOQs）均<10ng/g，在添加样品中超过 13000 个分析物结果中，假阴性率为 2.8%。QuEChERSER 方法被证明能够满足几种复杂大麻基质的挑战。
