The National Laboratory Certification Program undertook an evaluation of the dynamics of external contamination of hair with cocaine (COC) while developing performance testing materials for Federal Drug-Free Workplace Programs. This characterization was necessary to develop performance materials that could evaluate the efficacy of hair testing industry's decontamination procedures. Hair locks (blonde to dark brown/black) from five different individuals were contaminated with cocaine HCl. Hair locks were then treated with a synthetic sweat solution and hygienic treatments to model real-life conditions. Hair locks were shampooed daily (Monday through Friday) for 10 weeks, and samples of the hair locks were analyzed for COC, benzoylecgonine (BE), cocaethylene (CE), and norcocaine (NCOC). Three commercial analytical laboratories analyzed samples under three protocols: no decontamination procedure, individual laboratory decontamination, or decontamination by an extended buffer procedure at RTI International. Results indicated substantial and persistent association of all four compounds with all hair types. Hair that was not decontaminated had significantly greater quantities of COC and BE than did hair that was decontaminated. The only hair samples below detection limits for all four compounds were those decontaminated 1 h after contamination. Additionally, BE/COC ratios increased significantly over the 10-week study (regardless of decontamination treatment). From 21 days postcontamination until the end of the study, the mean BE/COC ratio for all hair types exceeded 0.05, the proposed Federal Mandatory Guidelines requirement. The largest variability in results was observed for samples decontaminated by participant laboratories. This suggests that current laboratory decontamination strategies will increase variability of performance testing sample results. None of the decontamination strategies used in the study were effective at removing all contamination, and some of the contaminated hair in this study would have been reported as positive for cocaine use based on the proposed Federal Mandatory Guidelines.

Hair specimens were analyzed for cocaine (COC), benzoylecgonine (BE), cocaethylene (CE) and norcocaine (NCOC) by liquid chromatography-tandem mass spectrometry. Drug-free hair was contaminated in vitro with COC from different sources with varied COC analyte concentrations. Results were compared to COC analyte concentrations in drug users' hair following self-reported COC use (Street) and in hair from participants in controlled COC administration studies (Clinical) on a closed clinical research unit. Mean ± standard error analyte concentrations in Street drug users' hair were COC 27,889 ± 7,846 (n = 38); BE 8,132 ± 2,523 (n = 38); CE 901 ± 320 (n = 20); NCOC 345 ± 72 pg/mg (n = 32). Mean percentages to COC concentration were BE 29%, CE 3% and NCOC 1%. Concentrations in hair were lower for Clinical participants. COC contamination with higher CE, BE or NCOC content produced significantly higher concentrations (P = 0.0001) of all analytes. CE/COC and NCOC/COC ratios did not improve differentiation of COC use from COC contamination. COC concentrations in illicit and pharmaceutical COC affect concentrations in contaminated hair. Criteria for distinguishing COC use from contamination under realistic concentrations were not significantly improved by adding CE and NCOC criteria to COC cutoff concentration and BE/COC ratio criteria. Current criteria for COC hair testing in many forensic drug-testing laboratories may not effectively discriminate between COC use and environmental COC exposure.

No abstract

To explore drug-melanin interactions, we examined the in vitro tyrosinase-mediated formation of melanin from tyrosine in the presence of the 3H-cocaine (3H-COC), 3H-flunitrazepam (3H-FLU), and 3H-nicotine (3H-NIC) at 10-100,000 ng/mL. Polymerization in the presence of 10 or 100 ng/mL of each drug resulted in almost complete drug incorporation into the melanin pellet. Only 12% (3H-NIC) to 28% (3H-FLU) of the pellet-associated radioactivity could be released upon treatment with 6 M HCl. At 1000-100,000 ng/mL, between 20 and 50% of label became melanin-associated. In each case a significant percentage of melanin-associated radioactivity was resistant to treatment with 6 M HCl. Nicotine-associated radioactivity in the polymer was subject to much greater quenching than was 3H-COC or 3H-FLU, suggesting a much tighter association with the melanin. The subsequent demonstration of a covalent adduct of a melanin intermediate and nicotine has demonstrated the utility of this polymerization system as a model for further chemical characterization of drug-melanin interactions.

IntroductionThis paper presents a summarv of the effects of various salt and oxi-gen treatments so chosen that they comprise a range of conditions of peculiar interest to the student of salt accumulation.In any account of plant metabolism important processes may evade recognition unless a balance sheet of the principal metabolites can be prepared. Such balance sheets have rarely been attempted although the work of RAISTRICK et al. (31) on fungi is a notable exception. The work of RAISTRICK was concerned, however, with the use of organisms under standardized nutritional conditions to effect organic synthesis and transformations; it did not describe the effect on the metabolism of a given organism of a range of external and nutritional conditions. There is nieed of more attention to balance sheets of plant metabolism and especially so with reference to the vexed problems of respiration. Deviations from the familiar equations C6H1206 + 602 = 6CO2 + 6H20 + 674,000 cal. and C6H1206 = 2C2H50H + 2CO2 + 25,000 cal. often tacitly accepted as representative of plant respiration, are multiplying. The work of GANE and others (11,16,17) has demonstrated the production of volatile substances other than carbon dioxide and large discrepancies between respiration and the simple equations above may be encountered. For example, ARCHBOLD and BARTER (1) observed that the loss of sugar and acid in respiring apples exceeded by 17 to 30 per cent. the carbon dioxide evolved. On the other hand, DASTUR and DESAI (10) founid that in the respiration of rice the carbon dioxide evolved exceeded the utilization of sugar and they believe that acids formed durino the synthesis of protein form the source of the carbon involved. Again Luidegardh (23) states that in excised wheat roots 30 to 60 per cent. more glucose disappears than is accounted for by respiration and he tacitly assumes that the discrepalne is a measure of the sugar used in growth. In experiments with excised roots HOAGLAND has observed cases in which a very rapid disappearance of sugar occurred anid carbon dioxide productioni conitinued after the cells seemed to be free of sugar.2 1 This is the second of a series of papers on The Biochemistry of Salt Absorption by Plants. The authors are inidebted to PROF. HOAGLAND for proof-reading this paper.2 Results privately comlmunicated. PLANT PHYSIOLOGY From our present standpoint the outstanding fault in the above equations is lack of any implication that respiration concerns substances other than carbohydrates or that aerobic respiration and nitrogen metabolism are mutually dependent processes in plants.The variation between replicate samples of standard potato discs is small (47) and the effect of metabolism on the constituents of the tissue can be obtained by difference between the composition of the initial and final, experimentally treated, batches of discs. It is possible, therefore, to draw up a balance sheet with reference to any metabolite, e.g., carbohydrate, the fate of which is known with sufficient certainty so that its pr...