Sørensen Lambert K, Hasselstrøm Jørgen B
Section for Forensic Chemistry, Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
J Anal Toxicol. 2017 Jun 1;41(5):382-391. doi: 10.1093/jat/bkx030.
Direct analysis of Δ9-tetrahydrocannabinol (THC) and other cannabinoids in crude acetonitrile extracts of whole blood by liquid chromatography-tandem mass spectrometry using pneumatically assisted electrospray ionization (LC-ESI-MS-MS) was subjected to pronounced ion suppression from co-eluting phospholipids (PLs). The interferences were mainly caused by the lysophosphatidylcholine and lysophosphatidylethanolamine classes of PLs. The PLs were easily removed from crude extracts by filtration through a sorbent with Lewis acid properties, which typically increased the THC and cannabinol (CBN) signal intensities by a factor of 5. Based on this technique, a simple high-throughput LC-MS-MS method was developed for the determination of cannabinoids in 100 μL samples of whole blood. The lower limits of quantification were 0.2 μg/L for THC, CBN, cannabidiol (CBD) and Δ9-tetrahydrocannabinolic acid A (THCA-A) and 0.5 μg/L for 11-hydroxy-Δ9-tetrahydrocannabinol (THC-OH) and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). The mean ion suppression levels after clean-up were 10% (THC), 9% (CBN), 17% (CBD), 0% (THC-OH), 2% (THC-COOH) and 9% (THCA-A) at blood concentration levels of 1-10 μg/L. The mean true extraction recoveries were 97% (THC), 101% (CBN), 101% (CBD), 98% (THC-OH), 95% (THC-COOH) and 90% (THCA-A) at the same concentration levels. The relative intra-laboratory reproducibility standard deviations were <9% at concentrations of 1 μg/L or higher. The trueness expressed as the relative bias of the test results was within ±4% at concentrations of 1 μg/L or higher.
采用气动辅助电喷雾电离的液相色谱-串联质谱法（LC-ESI-MS-MS）对全血粗乙腈提取物中的Δ9-四氢大麻酚（THC）及其他大麻素进行直接分析时，共洗脱的磷脂（PLs）会产生明显的离子抑制。干扰主要由溶血磷脂酰胆碱和溶血磷脂酰乙醇胺类磷脂引起。通过具有路易斯酸性质的吸附剂过滤，可轻松从粗提取物中去除磷脂，这通常会使THC和大麻酚（CBN）的信号强度增加5倍。基于此技术，开发了一种简单的高通量LC-MS-MS方法，用于测定100μL全血样本中的大麻素。THC、CBN、大麻二酚（CBD）和Δ9-四氢大麻酚酸A（THCA-A）的定量下限为0.2μg/L，11-羟基-Δ9-四氢大麻酚（THC-OH）和11-去甲-9-羧基-Δ9-四氢大麻酚（THC-COOH）的定量下限为0.5μg/L。在1-10μg/L的血药浓度水平下，净化后的平均离子抑制水平分别为1-10μg/L：THC为10%，CBN为9%，CBD为17%，THC-OH为0%，THC-COOH为2%，THCA-A为9%。在相同浓度水平下，平均真实提取回收率分别为：THC为97%，CBN为101%；CBD为1百零一%，THC-OH为98%，THC-COOH为95%，THCA-A为90%。在浓度为1μg/L或更高时，实验室内相对重现性标准偏差<9%。在浓度为1μg/L或更高时，以测试结果的相对偏差表示的准确性在±4%以内。
