Quantitation of cocaine in human hair: the effect of centrifugation of hair digests.
Quantitation of cocaine in human hair: the effect of centrifugation of hair digests.
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人头发中可卡因的定量：头发消化物离心的效果。
DOI：
10.1093/jat/22.6.414
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发表时间：
1998
影响因子：
2.5
通讯作者：
Rollins,DE
中科院分区：
文献类型：
--
作者：
Höld,KM;Hubbard,DL;Wilkins,DG;Rollins,DE
毛发色素沉着是解释某些化合物及其代谢物并入毛发中的浓度的关键因素。黑色素是色素沉着的原因。人类头发样本的颜色和黑色素含量在很大范围内不同。一旦沉积到头发中，药物可以在数月至数年的时间内保持可检测性。然而，如果药物进入头发的处置受到归因于头发颜色的那些特性的影响，那么某些人可能比其他人更频繁地测试阳性。在药物分析之前从毛发中去除黑色素可以通过排除与色素结合的药物来降低黑色素对总药物浓度的影响。在这项研究中，研究了通过离心去除毛发中的黑色素对可卡因浓度的影响。从五个可卡因使用者的两组头发样本进行了分析可卡因和代谢物。使用由10 mL 0.5M Tris缓冲液（pH 6.4）组成的溶液消化毛发，向该溶液中加入60 mg D，L-二硫苏糖醇、200 mg SDS和200 U蛋白酶K。将2毫升该溶液加入到20 mg毛发中，并在37°C下在振荡水浴（90次振荡/min）中孵育过夜。将样品从水浴中取出并混合。将一组以2000 rpm离心并分成上清液和黑色素沉淀。另一组未离心。向所有试管中加入内标物。样品进一步提取，衍生化，并通过气相色谱-质谱分析。平均8.8%（标准偏差[SD] 7.0%）的总可卡因浓度（上清液和沉淀物）留在沉淀物中。重复相同的实验，不同之处在于用0.1N HCl再消化黑色素沉淀。黑色素颗粒再消化后，颗粒中的平均可卡因浓度为毛发中总可卡因浓度的3.8% ± 4.0%（平均值± SD）。这些数据表明，在解释可卡因浓度时，通过离心从毛发中去除黑色素并不能消除毛发颜色偏差。
Hair pigmentation is a critical factor in the interpretation of the concentration of certain compounds and their metabolites incorporated into hair. Melanin is responsible for the pigmentation. The color and the melanin content of human hair samples differs over a wide range. Once deposited into hair, drug may remain detectable for a period of months to years. However, if drug disposition into hair is influenced by those properties attributed to hair color, then certain persons may test positive more frequently than other persons. Removal of the melanin from hair digests prior to drug analysis may reduce the effect of melanin on the total drug concentration by excluding the drug bound to the pigment. In this study, the effect of melanin removal by centrifugation of hair digests on cocaine concentrations was investigated. Two sets of hair samples from five cocaine users were analyzed for cocaine and metabolites. A solution consisting of 10 mL of 0.5M Tris buffer (pH 6.4) to which is added 60 mg D,L-dithiothreitol, 200 mg SDS, and 200 U Proteinase K, was used to digest the hair. Two milliliters of this solution was added to 20 mg of hair and incubated at 37°C in a shaking water bath (90 oscillations/rain) overnight. The samples were removed from the water bath and mixed. One set was centrifuged at 2000 rpm and divided into supernatant and melanin pellet. The other set was not centrifuged. Internal standards were added to all tubes. The samples were further extracted, derivatized, and analyzed by gas chromatography-mass spectrometry. A mean of 8.8% (standard deviation [SD] 7.0%) of the total cocaine concentration (supernatant and pellet) was left behind in the pellet. The same experiment was repeated except that the melanin pellet was redigested with 0.1N HCl. After redigestion of the melanin pellet, the mean cocaine concentration in the pellet was 3.8% ± 4.0% (mean ± SD) of the total cocaine concentration in hair. These data demonstrate that removal of melanin from hair digests by centrifugation does not eliminate hair color bias when interpreting cocaine concentrations.