Paul Buddha D, Jacobs Aaron
Division of Forensic Toxicology, Office of the Armed Forces Medical Examiner, Armed Forces Institute of Pathology, Rockville, Maryland 20850, USA.
J Anal Toxicol. 2005 Oct;29(7):658-63. doi: 10.1093/jat/29.7.658.
Tests for oxidizing adulterants in urine are a continuing challenge to the drug-testing program. Iodine was found to destroy morphine and 6-acetylmorphine almost immediately. The effects were less evident on 11 -nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-acid). When the urine solution was tested for iodine by a chromogenic substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), no iodine was detected. Masking drug and adulterant simultaneously made iodine a preferred oxidizing adulterant for drug abusers. In this study, the reduced iodide was oxidized by sodium nitrite to iodine. The excess nitrite was decomposed by sulfamic acid and the iodine was detected by ABTS. Linearity was 12.7 to 635 mg/L (0.1 to 5 mmol/L, y = 0.9966x + 0.0016, R2 = 1.0000). Precisions (coefficient of variation) were within +/- 4.1% and quantitative accuracies were within 97% of expected values (n=5). Chromate, iodate, periodate, and persulfate interfered with the method. To alleviate the problem, the positive specimens were tested again by an iodine-specific method. After oxidation, the samples were treated with sodium azide and ammonium thiocyanate. In presence of thiocyanate, the azide reduced iodine to iodide almost immediately, and the solutions showed negative response to ABTS. The results were compared with that of a control group tested without thiocyanate. When iodine was present, the ratios of thiocyanate to control were less than 6%. Chromate was also found to destroy THC-acid in urine, and during storage most of the chromate changed to chromic (III). In this study, chromic was oxidized to chromate by hydrogen peroxide and sodium hydroxide and detected by 1,5-diphenylcarbazide. Linearity was 5.2 to 156 mg/L (0.1 to 3.0 mmol/L, y = 1.0285x - 0.0034, R2 = 0.9998). Precisions were within +/- 8.5% and quantitative accuracies were within 92% of expected values (n=5). The test was not interfered by other oxidizing agents. Both iodide and chromic oxidation methods showed urine backgrounds less than 1.27 and 0.52 mg/L, respectively (< 0.01 mmol/L). It indicated that a response more than 10 times of the background could be considered as oxidant contamination or adulteration of urine specimens.
尿液中氧化性掺杂物的检测对药物检测项目而言一直是一项挑战。研究发现碘几乎能立即破坏吗啡和6 - 乙酰吗啡。对11 - 去甲 - Δ9 - 四氢大麻酚 - 9 - 羧酸（THC - 酸）的影响则不太明显。当通过显色底物2,2'- 叠氮基 - 双（3 - 乙基苯并噻唑啉 - 6 - 磺酸）（ABTS）检测尿液溶液中的碘时，未检测到碘。同时掩盖药物和掺杂物使得碘成为吸毒者首选的氧化性掺杂物。在本研究中，亚硝酸盐将还原态的碘化物氧化为碘。过量的亚硝酸盐用氨基磺酸分解，碘用ABTS检测。线性范围为12.7至635 mg/L（0.1至5 mmol/L，y = 0.9966x + 0.0016，R2 = 1.0000）。精密度（变异系数）在±4.1%以内，定量准确度在预期值的97%以内（n = 5）。铬酸盐、碘酸盐、高碘酸盐和过硫酸盐会干扰该方法。为解决这个问题，对阳性样本用碘特异性方法再次检测。氧化后，样品用叠氮化钠和硫氰酸铵处理。在硫氰酸盐存在的情况下，叠氮化物几乎立即将碘还原为碘化物，溶液对ABTS呈阴性反应。将结果与未用硫氰酸盐检测的对照组结果进行比较。当存在碘时，硫氰酸盐与对照组的比值小于6%。还发现铬酸盐会破坏尿液中的THC - 酸，并且在储存过程中大部分铬酸盐会转化为三价铬。在本研究中，用过氧化氢和氢氧化钠将三价铬氧化为铬酸盐，并用1,5 - 二苯基卡巴腙检测。线性范围为5.2至156 mg/L（0.1至3.0 mmol/L，y = 1.0285x - 0.0034，R2 = 0.9998）。精密度在±8.5%以内，定量准确度在预期值的92%以内（n = 5）。该检测不受其他氧化剂干扰。碘化物和三价铬氧化法显示尿液背景分别低于1.27和0.52 mg/L（< 0.01 mmol/L）。这表明响应超过背景值10倍以上可被视为尿液样本被氧化剂污染或掺假。
