Deteciton And Evaluation Of Drugs In Hair After A Single Dose

Drug-facilitated crimes (DFC) refer to the use of a drug to modify a person's behavior for criminal gain. Drugs used to facilitate crimes can be difficult to detect (active products at low doses, chemical instability), possess amnesic properties and can be rapidly cleared from the body (short half-life). In these situations, blood or even urine can be of low interest. In contrast, hair analysis boasts longer detection window, thus hair was suggested as a valuable specimen in situations where, as a result of a delay in reporting the crime, natural processes have eliminated the drug from typical biological specimens. However, hair analysis after a single dose requires more sensitive and selective methods, which needs to be carried out by tandem mass spectrometry.Liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology has developed rapidly in recent years. It analyzes a wide range of chemicals without derivatization. Selectivity and sensitivity are greatly improved under multiple reaction monitoring (MRM) mode.Based on the published literatures and with the help of advanced analytical technology, we have finished a series of studies focusing on hair analysis after a single dose. The major results and conclusions are listed as follows:1. Screening for drugs involved in DFC in hair with LC-MS/MSAn LC-MS/MS method screening for 54 drugs involved in DFC in hair has been established. The screening system included two steps:at first, each analyte was monitored with one pair of precursor/product ion. When a peak of interest appeared, a following specific method including two ion pairs for each analyte (screening for opiates, amphetamine and ketamine, cocaine, benzodiazepines or other drugs respectively) would be used to confirm the suspecting analyte. By increasing the dwelling time of each pair of ions, the sensitivity of the method was greatly improved and thus adequate to detect trace drugs in hair.2. Evaluation of segmental hair analysis after a single dose of benzodiazepinesSensitive, specific, and reproducible methods for the quantitative determination of 18 benzodiazepines in hair have been developed using LC-MS/MS. LOD (limit of detection) for 18 bezodiazepines range from 0.5pg/mg to 5pg/mg.14 volunteers had ingested a single 1-6mg estazolam tablet. Hair was collected one month after administration and analyzed with the screening method. All the proximal segments were positive for estazolam. The concentration of estazolam detected in hair correlated with the given dosages.The minimal dosage of estazolam detectable in hair was about lmg. The screening method was also applied to two authentic drug-facilitated assualts. Full-length hair samples were collected 5 weeks after the offense. Clonazepam and 7-aminoclonazepam were detected in the proximal hair segment.3. Determination of triazolam and a-hydroxytriazolam in hair after a single doseA sensitive LC-MS/MS method is presented for determination of triazolam and a-hydroxytriazolam in guinea pig hair after a single dose. LOD for triazolam and a-hydroxytriazolam were lpg/mg and 5pg/mg respectively. Eighteen guinea pigs were divided into three dosage groups (10μg/kg,100μg/kg and 500μg/kg) and administrated a single dose of triazolam intragastrically. Before administration, drug-free hair was shaved from their back. Newly grown hair in shaved area had been collected every seven days after administration for 5 weeks. Triazolam and a-hydroxytriazolam could only be detected in hair samples collected in the first week. a-Hydroxytriazolam had a higher concentration than triazolam in guinea pig hair. The concentration of triazolam in hair was related with administration dosage and hair color.100μg/kg was the minimal dosage detectable in guinea pig hair.4. Determination of ketamine and norketamine in hair after a single doseA sensitive LC-MS/MS method is presented for determination of ketmaine and norketamine in guinea pig hair after a single dose. LOD for ketmaine and norketamine were 0.5pg/mg and lpg/mg respectively. Eighteen guinea pigs were divided into three dosage groups (20μg/kg,100μg/kg and 1mg/kg) and administrated a single dose of ketamine hydrochloride intragastrically. Before administration, drug-free hair was shaved from their back. Newly grown hair in shaved area had been collected every seven days after administration for 5 weeks. Ketamine and norketamine could be detected in first two weeks. Ketamine had a higher concentration than norketmaine in guinea pig hair. The concentration of ketamine in hair was related with given dosage and hair color.100μg/kg was the minimal dosage detectable in guinea pig hair.A further volunteer experiment has been carried out.4 female volunteers took a single 10mg of ketamine orally. Scalp hair samples were collected 1,2,3,4,8,12 and 16 weeks after the administration. The window of detection was as long as 16 weeks.The results showed that the peak concentration of ketamine moved along the hair shaft at a speed of 1-1.5cm/month. In some proximal segments, the concentration of norketamine was higher than ketamine and target analytes could be detected in other hair segments apart from the corresponding one. These facts indicated that sweat and sebum may be possible sources of drugs incorporated into hair. 5. Determination of cocaine and benzoylecgonine in hair after a single doseA sensitive LC-MS/MS method is presented for determination of cocaine and benzoylecgonine in guinea pig hair after a single dose. LOD for cocaine and benzoylecgonine was 1pg/mg. Guinea pigs were administrated a single dose of cocaine (10mg/kg or 0.4mg/kg, n=4) intraperitoneaklly. Before administration, drug-free hair was shaved from their back. Newly grown hair in shaved area was collected on the 7th and 14th day after administration. Both cocaine and benzoylecgonine could be detected on the 7th day. Additionally, there was a higher concentration of cocaine than that of benzoylecgonine occurred in hair. Concentrations of cocaine and benzoylecgonine detected in hair were related with given dose and hair color.In conclusion, this study (1) established a screening system for the simultaneous determination of 54 drugs involved in DFC case in hair. The screening method has been proved sensitive enough to detect and confirm trace drugs in hair by successful application in cotrolled experiment and real case. (2) demonstrated the time course of triazolam, ketamine and cocaine in guinea pig hair. The distribution of these analytes and their metabolites in hair, and the effects of given dosage and hair color on analytes concentration were also clarified. Besides, the minimal dosages of these analytes detectable in guinea pig hair were basically addressed. (3) established guidelines for hair sample collection after a single administration, and examined the role of segmental analysis in discriminating single exposure from repeated one.