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Micro‐pulverized extraction pretreatment for highly sensitive analysis of 11‐nor‐9‐carboxy‐Δ 9 ‐tetrahydrocannabinol in hair by liquid chromatography/tandem mass spectrometry
Author(s) -
Kuwayama Kenji,
Miyaguchi Hajime,
Yamamuro Tadashi,
Tsujikawa Kenji,
Kanamori Tatsuyuki,
Iwata Yuko T.,
Inoue Hiroyuki
Publication year - 2015
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7363
Subject(s) - chemistry , chromatography , liquid chromatography–mass spectrometry , mass spectrometry , extraction (chemistry) , tandem mass spectrometry , selected reaction monitoring
Rationale A primary metabolite of Δ 9 ‐tetrahydrocannabinol, 11‐nor‐9‐carboxytetrahydrocannabinol (THC‐COOH), serves as an effective indicator for cannabis intake. According to the recommendations of the Society of Hair Testing, at least 0.2 pg/mg of THC‐COOH (cut‐off level) must be present in a hair sample to constitute a positive result in a drug test. Typically, hair is digested with an alkaline solution and is subjected to gas chromatography/tandem mass spectrometry (GC/MS/MS) with negative ion chemical ionization (NICI). Methods It is difficult to quantify THC‐COOH at the cut‐off level using liquid chromatography/tandem mass spectrometry (LC/MS/MS) without acquisition of second‐generation product ions in triple quadrupole‐ion trap mass spectrometers, because large amounts of matrix components in the low‐mass range produced by digestion interfere with the THC‐COOH peak. Using the typical pretreatment method (alkaline dissolution) and micro‐pulverized extraction (MPE) with a stainless bullet, we compared the quantification of THC‐COOH using GC/MS/MS and LC/MS/MS. Results MPE reduced the amount of matrix components in the low‐mass range and enabled the quantification of THC‐COOH at 0.2 pg/mg using a conventional triple quadrupole liquid chromatograph coupled to a mass spectrometer. On the other hand, the MPE pretreatment was unsuitable for GC/MS/MS, probably due to matrix components in the high‐mass range. The proper combination of pretreatments and instrumental analyses was shown to be important for detecting trace amounts of THC‐COOH in hair. Conclusions In MPE, samples can be prepared rapidly, and LC/MS/MS is readily available, unlike GC/MS/MS with NICI. The combination of MPE and LC/MS/MS might therefore be used in the initial screening for THC‐COOH in hair prior to confirmatory analysis using GC/MS/MS with NICI. Copyright © 2015 John Wiley & Sons, Ltd.