Hair analysis for cocaine: Factors in laboratory contamination studies and their relevance to proficiency sample preparation and hair testing practices

Hair samples were contaminated by rubbing with cocaine (COC) followed by sweat application, multiple shampoo treatments and storage. The samples were then washed with isopropanol for 15 min, followed by sequential aqueous washes totaling 3.5 h. The amount of drug in the last wash was used to calculate a wash criterion to determine whether samples were positive due to use or contamination. Analyses of cocaine and metabolites were done by LC/MS/MS. These procedures were applied to samples produced by a U.S. government-sponsored cooperative study, in which this laboratory participated, and to samples in a parallel in-house study. All contaminated samples in both studies were correctly identified as contaminated by cutoff, benzoylecgonine (BE) presence, BE ratio, and/or the wash criterion. A method for determining hair porosity was applied to samples in both studies, and porosity characteristics of hair are discussed as they relate to experimental and real-world contamination of hair, preparation of proficiency survey samples, and analysis of unknown hair samples.     

Segmental analysis for cocaine and metabolites by HPLC in hair of suspected drug overdose cases

Hair samples of eight postmortem cases were analyzed in segments of 1 to 3 cm for cocaine, benzoylecgonine and cocaethylene. Samples were prepared for analysis by digestion in 0.1 M HCl and subsequent extraction with mixed-mode solid-phase extraction columns. Measurement was made by reversed-phase, narrow-bore HPLC and fluorescence detection using two laboratory-made internal standards. The concentrations were in the region of 0.29–316 ng/mg of hair for cocaine, 0.43–141 ng/mg of hair for benzoylecgonine and 0.93–1.83 ng/mg of hair for cocaethylene. All eight investigated cases had cocaine-positive segments. In six of the cases, all segments were positive, suggesting regular cocaine use and two showed in-between negative segments indicating an interruption or a change of the abuse intensity. The results showed a second, remarkable observation, i.e. enormous concentration differences (factor >150) for both cocaine and benzoylecgonine between the different subjects. Furthermore, interindividual cocaine/benzoylecgonine ratios ranged from 0.02 to 8.43. We believe these observations could in part be attributed to both some of the still existing limitations in the analytical approach(es), especially the mandatory hair washing steps, and in our still too limited knowledge of the hair incorporation processes. Nevertheless, in some cases, segmental analysis proved to be an important tool to distinguish, together with postmortem examination, deadly chronic abuse from single acute drug overdosage.     

Hair testing for drugs of abuse: evaluation of external cocaine contamination and risk of false positives.

In some laboratories hair testing may be the main method for the evaluation of individual's drug history, however, compelling evidence supports the possibility that the presence of a small amount of drug in hair can derive from external contamination. The aim of the present study is to verify if a single external contamination with a small amount of cocaine will last sufficiently long to make a contaminated subject indistinguishable from active users, and if normal washing practices together with the decontamination procedures are sufficient to completely remove the external contamination. The results obtained using the decontamination methods suggested in literature demonstrate that significant concentrations of cocaine (>1 ng/mg) and moderate quantities of benzoylecgonine (generally <0.5 ng/mg) are still detectable up to 10 weeks after contamination. These results question the reliability of hair testing. In fact, even using the most sophisticated decontamination procedures it is not possible to distinguish a drug-contaminated subject from an active user. Thus, while a negative result excludes both chronic use and "contact" with drugs, a positive result cannot and must not be interpreted as a sure sign of drug addiction, but should be further confirmed by urine analysis.     

Decontamination procedures for drugs of abuse in hair: are they sufficient?

This paper reviews the methods for decontaminating hair exposed to external solutions of drugs of abuse. Exposure of hair to cocaine at 1 μg/ml for 5 min is sufficient to contaminate hair, yet decontamination is a very slow process. Using externally contaminated hair, a number of decontamination procedures were attempted, and none removed all the contamination. The percentage of external contamination removed depended on the hair type, with thick black hair being the most resistant to decontamination. Hair treated by dying incorporated externally applied drugs differently, depending on the hair type. Thick black hair became more absorbent whereas thin brown hair became less absorbent. Kinetic wash criteria are evaluated for their ability/inability to determine if hair has been contaminated from external sources. A theoretical framework for the incorporation and removal of drugs from hair is discussed, and the hypothesis that inaccessible domains exist in hair which trap drugs is critically examined. The results presented in this paper strongly suggest that much more information on the decontamination of hair and the differentiation of exogenously and endogenously incorporated drugs is needed before hair analysis can be employed in most forensic applications. We propose that the radioactive tracer methods discussed herein are well suited for evaluating any new decontamination or extraction technique.     

Application of discriminant analysis to differentiate between incorporation of cocaine and its congeners into hair and contamination

The requirement to differentiate between incorporation and external contamination of drugs into hair is undisputed, in particular when dealing with compounds which are administered by sniffing or inhalation (e.g. cocaine). With the aim of making this discrimination, hair samples from cocaine (COC) users (group IN) and seized cocaine samples (group OUT) were compared regarding the parameters benzoylecgonine (BZE), ecgonine methyl ester (EME), ecgonine (ECG), anhydroecgonine methyl ester (AEME), cocaethylene (CE) and norcocaine (NCOC). Since most of these compounds may be minor by-products of COC or be formed by biotransformation or chemical degradation, the stability of each substance was carefully examined. COC was found to be converted into significant amounts of BZE, EME and ECG even under mild extraction conditions, while traces of NCOC proved to be a ubiquitous by-product of COC. Cocaine positive hairs and seized cocaine samples (diluted to relevant concentrations) were equally preprocessed and analyzed by LC-MS-MS. Out of the metabolites listed above, NCOC, CE and AEME (each normalised to COC) were significantly increased in the incorporation group (i.e. hair samples from cocaine users). Based on this approach, a statistical discriminant analysis enabled us to make a prediction (and estimation of uncertainty) for each cocaine positive hair sample as to its likelihood of belonging to the group of cocaine users or of being contaminated.     

Occupational exposure to cocaine involving crime lab personnel.

The possibility of exposure to cocaine as a result of analyzing it or handling material contaminated by it has been a major concern of laboratory personnel. Several different work environments and simulated situations were examined to assess the likelihood of this type of exposure occurring. Urine specimens were collected and evaluated for cocaine and benzoylecgonine using the Syva ETS System (EMIT). Each specimen was analyzed for the two substances using gas chromatography/mass spectrometry (GC/MS). Urine specimens of laboratory-management personnel not working with drug samples showed no trace of cocaine or benzoylecgonine. A urinary benzoylecgonine level of 227 ng/mL was found in the specimen from one narcotics criminalist who was working on a routine case of 2 kilos of cocaine hydrochloride in the Narcotics Laboratory. A maximal urinary benzoylecgonine concentration of 1570 ng/mL was determined in the urine specimen from one narcotics criminalist who was sampling a case containing 50 kilos of cocaine hydrochloride over a period of 3 h. Decreasing the levels of airborne cocaine dust appears to minimize the amount of cocaine absorbed by the criminalists. Gloves, face masks, and goggles prove to be effective in minimizing exposure.     

The determination of cocaine in hair: a review

The explosion of literature related to the analysis of hair for cocaine and its products is reviewed. In the commonly accepted applications of hair testing for cocaine, those related to criminal or civil investigations and pharmacotoxicologic studies occupy most of the relevant published work. This review uses detailed, ‘binary’ (yes/no) tables to demonstrate trends in the literature, and allows researchers and caseworkers quick access to the literature most important for answering a variety of questions.     

Analysis of hair after contamination with blood containing cocaine and blood containing benzoylecgonine

In post-mortem work, blood is a potential source of external contamination of hair. The present study was carried out to investigate the amount of drug absorbed into hair which has been contaminated with blood containing either cocaine or BE. Solutions were prepared containing 0.05, 0.1, 0.2, 0.5 and 3.0 μg/mL of either cocaine or BE in human blood. Samples of approximately 3.2 g of drug-free hair were contaminated by soaking in the blood solutions for 5 min. They were then removed and left at room temperature. Approximately 0.5 g of hair was collected from each of the blood soaked hair samples at 6 h, 1, 2, 4 and 7 days after contamination. As each hair sample was collected it was shampoo-washed to prevent further drug absorption. Hair samples were analysed in triplicate using a fully validated method described previously. EME and cocaethylene were also measured in order to find out if cocaine or BE was breaking down to these compounds. Both cocaine and BE were absorbed into hair in significant concentrations when the concentration in the blood was 0.5 μg/mL or greater; cocaine was more readily absorbed than BE. Cocaine broke down to EME (<LOQ) at 0.5 μg/mL and to EME (>LOQ) and BE (<LOQ) at 3.0 μg/mL. When the blood concentration of cocaine was 0.5 μg/mL or less, there was no evidence of it breaking down to form BE. From the samples soaked in blood containing BE, there was no evidence of the BE breaking down. The absorption of drug into hair did not increase as the contamination period increased from 6 h to 7 days.     

Accumulation of explosives in hair

The sorption of explosives (TNT, RDX, PETN, TATP, EGDN) to hair during exposure to their vapors is examined. Three colors of hair were simultaneously exposed to explosive vapor. Following exposure of hair, the sorbed explosive was removed by extraction with acetonitrile and quantified. Results show that sorption of explosives, via vapor diffusion, to black hair is significantly greater than to blond, brown or bleached hair. Furthermore, the rate of sorption is directly related to the vapor density of the explosive: EGDN > TATP >TNT > PETN > RDX. In some cases, the explosive-containing hair was subject to repeated washings with sodium dodecylsulfate or simply left out in an open area to determine the persistence of the explosive contamination. While explosive is removed from hair with time or washing, some persists. These results indicate that hair can be a useful indicator of explosive exposure/handling.     

Simultaneous quantification of opiates, cocaine and cannabinoids in hair

The present paper describes a sensitive method developed in our laboratory for the simultaneous analysis of opiates (morphine, codeine and monoacetylmorphine), cocainics (cocaine and benzoylecgonine) and cannabinoids (Δ⁹-tetrahydrocannabinol and 11-nor-Δ⁹-tetrahydrocannabinol-9-carboxylic acid) in hair samples. After decontaminating the sample with dichloromethane, two consecutive hydrolyses were performed in order to achieve the best conditions for extracting the three kinds of drugs from the protein matrix. First the opiate and cocainic compounds were extracted by means of a soft acidic hydrolysis with 0.1 N HCl at 50 °C overnight and organic solvent extraction at pH 9.2. The cannabinoids need a stronger basic hydrolysis with 11.8 N KOH for 10 min at laboratory temperature. After adding maleic acid, the cannabinoids were extracted with an organic solvent. The derivatization was carried out with heptafluorobutyric anhydride and hexafluoropropanol. Calibration curves were linear between 0.5–100 ng/mg of hair. Recovery and reproducibility were assured. The quantification limits ranged between 0.04–0.26 ng/mg of hair. Seventy hair samples from known drug abusers were cut into 1-cm segments and analyzed by this method. The ranges of measured concentrations (ng/mg) were 0.31–89 for cocaine, 0.1–5.76 for benzoylecgonine, 0.34–45.79 for morphine, 0.45–39.59 for codeine, 0.09–48.18 for monoacetylmorphine, 0.06–7.63 for THC and 0.06–3.87 for THC---COOH. The results of sectional analyses agreed with the self reported drug histories. The usefulness of this method is in assessing earlier drug consumption, and also at the same time obtaining a chronological profile of the consumption of these three types of drugs.     

Levels of cocaine and its metabolites in washed hair of demonstrated cocaine users and workplace subjects

In a study of subjects in drug rehabilitation programs, cocaine and cocaine metabolite levels were determined in the hair of 75 subjects who had produced cocaine-positive urine results. The hair was analyzed after being washed with the 3.75 h wash procedure developed by this laboratory. In addition, results of testing 73 non-users are presented, as well as levels of cocaine, benzoylecgonine (BE), cocaethylene, and norcocaine from workplace population samples. The data support a recommendation of reporting as positive a sample with cocaine of 500 pg/mg hair and either a 5% ratio of benzoylecgonine (BE) to cocaine in samples, or the presence of cocaethylene at 50 pg/mg hair, or norcocaine at 50 pg/mg hair for samples < or =2000 pg cocaine/mg hair. For samples with cocaine present at >2000 pg/mg hair, the data indicate that a ratio of 5% BE may be an overly conservative approach. In appropriately washed hair samples, cocaine users can produce hair levels of <5% BE and thus a minimum BE cutoff in lieu of a ratio could be considered.     

Segmental analysis for cocaine and metabolites by HPLC in hair of suspected drug overdose cases

Hair samples of eight postmortem cases were analyzed in segments of 1 to 3 cm for cocaine, benzoylecgonine and cocaethylene. Samples were prepared for analysis by digestion in 0.1 M HCl and subsequent extraction with mixed-mode solid-phase extraction columns. Measurement was made by reversed-phase, narrow-bore HPLC and fluorescence detection using two laboratory-made internal standards. The concentrations were in the region of 0.29-316 ng/mg of hair for cocaine, 0.43-141 ng/mg of hair for benzoylecgonine and 0.93-1.83 ng/mg of hair for cocaethylene. All eight investigated cases had cocaine-positive segments. In six of the cases, all segments were positive, suggesting regular cocaine use and two showed in-between negative segments indicating an interruption or a change of the abuse intensity. The results showed a second, remarkable observation, i.e. enormous concentration differences (factor >150) for both cocaine and benzoylecgonine between the different subjects. Furthermore, interindividual cocaine/benzoylecgonine ratios ranged from 0.02 to 8.43. We believe these observations could in part be attributed to both some of the still existing limitations in the analytical approach(es), especially the mandatory hair washing steps, and in our still too limited knowledge of the hair incorporation processes. Nevertheless, in some cases, segmental analysis proved to be an important tool to distinguish, together with postmortem examination, deadly chronic abuse from single acute drug overdosage.     

Optimized conditions for simultaneous determination of opiates, cocaine and benzoylecgonine in hair samples by GC--MS

The present paper describes a qualitative and quantitative method for the simultaneous detection of opiates, cocaine and benzoylecgonine from human hair samples. Every step of the analytical procedure was studied to find the optimized conditions. Nine different incubation systems were examined. The influence of different pH values of samples on the isolation of analytes from the incubation media by Bond Elut cartridges and the stability of the compounds of interest in the different incubation media and conditions were investigated. The extracting power of different incubation media was studied as well. The phosphate buffer 0.1 N at pH 5 was chosen as the extraction medium in an optimized procedure for simultaneous determination of opiates, cocaine and benzoylecgonine in hair samples. The method developed was validated. Recoveries were 90% for morphine (M), 81% for 6-monoacetylmorphine (6-AM), 90% for codeine (CD), 86% for cocaine (C) and 90% for benzoylecgonine (BE). Relative standard deviation for inter-day precision was better than 12%. The limits of detection resulted as 0.05 ng/mg for M and C, as 0.08 for 6-AM and as 0.2 ng/mg for BE. Forty hair samples collected from drug abusers admitted to centers for detoxification treatment were analyzed obtaining 23 positive results for opiates and/or cocaine. Twelve hair specimens longer than 10 cm were analyzed following a sectional approach. In the six positive cases, it was interesting to find that the 6-AM/M ratio generally decreased for each sample from the proximal segment to the distal segments. Moreover, the 6-AM/M ratio was generally lower than 1 in the intermediate and distal segments.     

Removing and identifying drug contamination in the analysis of human hair

The procedure used in this laboratory for removing and identifying contamination of hair specimens with drugs is demonstrated by its application to hair contaminated by various experimental models. The models include soaking; coating with drug followed by sweat conditions for 6 h; and soaking in a very high concentration of cocaine followed by storage and multiple shampoo treatments. A multi-part wash procedure along with a wash criterion is applied to all samples containing drug above the cutoff. The failure of the wash criterion is a signal that the sample may be positive due to contamination rather than use, and in the absence of other over-riding evidence, the sample would be considered to be negative for drug use. This Wash Criterion has also been tested with hair from subjects demonstrated to be drug users by one or more drug-positive urines; in these studies, all hair samples from demonstrated users passed the Wash Criterion test.     

Hair and urine analysis: relative distribution of drugs and their metabolites

This work studies the distribution of cocaine and heroin metabolites in hair and urine of living polidrug abusers. Cocaine, benzoylecgonine (BEG), ecgonine methyl ester (EME), morphine, codeine and 6-monoacetylmorphine (6-MAM) were simultaneously extracted and analyzed by GC/MS in SIM mode. The results obtained show a different distribution of heroin and cocaine metabolites in urine and hair. In urine, we generally find BEG and EME for cocaine abuse, and morphine for heroin abuse. In hair, we detect cocaine and MAM as major metabolites for cocaine and heroin abuse, respectively.     

Cocaine and benzoylecgonine excretion in humans.

Maximal urinary excretion of unchanged cocaine occurred within 2 h of the intranasal absorption of 1.5 mg/kg body weight of cocaine hydrochloride, and diminished rapidly thereafter. Excretion of benzoylecgonine was maximal 4 to 8 h following administration of the drug and diminished slowly over an interval of several days. Peak cocaine and benzoylecgonine concentrations observed were 24 and 75 microgram/ml, respectively. Benzoylecgonine/cocaine ratios were too varied to allow estimation of cocaine concentrations from benzoylecgonine concentration data or vice versa. Benzoylecgonine concentrations generally exceeded the corresponding cocaine values by a wide margin, but excretion of free cocaine in the absence of benzoylecgonine was observed in one subject. Cocaine was generally detected for only approximately 8 h, and for a maximum of 12 h, whereas benzoylecgonine was generally detected by chromatographic or enzyme immunologic assays for 48 to 72 h. Benzoylecgonine was positively identified in urine by raidoimmunoassay for 96 to 144 h after dosing.     

Analysis of hair after contamination with blood containing 6-acetylmorphine and blood containing morphine

The study was carried out to investigate external contamination of hair by blood in heroin-related post-mortem cases. Solutions were prepared containing 0.05, 0.1, 0.2, 0.5 and 3.0μg/mL of 6-monoacetylmorphine (6-AM) only or morphine only in human blood. Samples of approximately 3.2g of drug-free hair were contaminated by soaking in the blood solutions for 5min. They were then removed and left at room temperature. Approximately 0.5g of hair was collected from each of the blood soaked hair samples at 6h, 1, 2, 4 and 7 days after contamination. As each hair sample was collected it was shampoo-washed to prevent further drug absorption. Hair samples were analysed in triplicate using a fully validated method described previously. 6-AM broke down to morphine in all samples. In hair contaminated with blood containing 0.05, 0.1 and 0.2μg/mL 6-AM or morphine drug was either not detected or was detected below the limit of quantitation (0.2ng/mg hair) at all contamination times. In hair contaminated with blood spiked with 0.5μg/mL morphine, the concentration in hair ranged from 0.54 to 0.91ng/mg and in hair contaminated with blood spiked with 3.0μg/mL, from 3.25 to 5.77ng/mg. The concentrations of 6-AM ranged from 0.65 to 1.11ng/mg and morphine from 0.34 to 0.80ng/mg in hair contaminated with 0.5μg/mL 6-AM in blood. 6-AM ranged from 2.12 to 3.67ng/mg and morphine from 0.84 to 2.05ng/mg in hair contaminated with 3μg/mL 6-AM in blood. For 6-AM and morphine ANOVA statistical evaluation showed no significant difference among the concentrations over time.     

Drug contamination of US paper currency

It is known that US paper currency in the general circulation is contaminated with cocaine. Several mechanisms have been offered to explain this finding, including contamination due to handling during drug deals and the use of rolled up bills for snorting. Drug is then transferred from one contaminated bill to others during counting in financial institutions. The possibility of contamination of currency with other drugs has not been reported. In this study, the author reports the analysis of 10 randomly collected US$ 1 bills from five cities, for cocaine, heroin, 6-acetylmorphine (6-AM), morphine, codeine, methamphetamine, amphetamine and phencyclidine (PCP). Bills were immersed in acetonitrile for 2h prior to extraction and GC-MS analysis. Results showed that 92% of the bills were positive for cocaine with a mean amount of 28.75+/-139.07 microg per bill, a median of 1.37 microg per bill, and a range of 0.01-922.72 microg per bill. Heroin was detected in seven bills in amounts ranging from 0.03 to 168.50 microg per bill: 6-AM and morphine were detected in three bills; methamphetamine and amphetamine in three and one bills, respectively, and PCP was detected in two bills in amounts of 0.78 and 1.87 microg per bill. Codeine was not detected in any of the US$ 1 bills analyzed. This study demonstrated that although paper currency was most often contaminated with cocaine, other drugs of abuse may be detected in bills.     

Measurement of drugs in neonatal hair; a window to fetal exposure

Because the hair neonates are born with grows during the last 3 months of pregnancy, the presence of drugs (e.g. cocaine) or environmental toxins (e.g. nicotine) reflects fetal exposure to such compounds. In the case of cocaine, hair measurement are several fold more sensitive than maternal history or urine measurements. Measurements of cotinine in neonatal hair are capable of distinguishing between fetal exposure to passive versus active smoking. Because most cocaine users also smoke cigarettes, neonatal measurements of both cocaine and cotinine will allow cumulative quantification of fetal risk.     

Validity testing of commercial urine cocaine metabolite assays: IV. Evaluation of the EMIT d.a.u. cocaine metabolite assay in a quantitative mode for detection of cocaine metabolite

The EMIT d.a.u. cocaine metabolite assay (EMIT dau) was evaluated in a quantitative mode for analysis of clinical specimens obtained after controlled cocaine administration to human subjects. The quantitative results showed high concordance with those of gas chromatography/mass spectrometry (GC/MS) assays of the same specimens for benzoylecgonine, and no false positive or false negative results were obtained. The evaluation also included analysis of standardized solutions containing benzoylecgonine, cocaine, and other cocaine metabolites and isomers. The EMIT dau antibody demonstrated high selectivity for benzoylecgonine. The precision was somewhat less than that reported earlier for other commercial cocaine metabolite immunoassays. Quantitation of initial screening results from EMIT dau testing can serve as a useful guide for confirmation by GC/MS in forensic science urine testing.