Department of Geography and Environmental Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
Anal Bioanal Chem. 2012 Jan;402(3):1277-87. doi: 10.1007/s00216-011-5553-7. Epub 2011 Dec 7.
We report a sample pretreatment approach for the analysis of total cocaine residues in wastewater that eliminates the need for two key assumptions often made in estimating cocaine utilization from measurement of its benzoylecgonine metabolite: that benzoylecgonine is neither degraded nor generated during transport in a sewer system, and that it is excreted as a constant fraction of cocaine ingested. By adding NaOH and incubating samples at 55 °C, cocaine and its principal metabolites are efficiently hydrolyzed into ecgonine, anhydroecgonine, and norecgonine. Ecgonine, estimated to represent between 37% and 90% (on a molar basis) of cocaine residues, can be directly determined (without preconcentration via solid-phase extraction (SPE)) by reversed-phase (RP) or hydrophilic interaction liquid chromatography-tandem mass spectrometry (LC/MS/MS). If samples are subjected to SPE, anhydroecgonine can also be determined; this metabolite (and its precursors) represents ≈7% of urinary cocaine residues (based on spot collections from living individuals). Although a reference standard for norecgonine is not commercially available, such nortropanes are also a minor fraction (up to 2%) of urinary cocaine residues. The stability of two human markers (cotinine and creatinine) to the hydrolysis procedure was also investigated. Results obtained by applying the hydrolysis approach for the analysis of total cocaine in an untreated municipal wastewater sample (obtained from Baltimore, MD) were generally in excellent agreement with those obtained from split samples analyzed using a more comprehensive solid-phase extraction RPLC/MS/MS method as described in our previous work. In particular, total tropane-based cocaine residues were found to be hydrolyzed to ecgonine with 98-99% efficiency.
我们报告了一种用于分析废水中总可卡因残留物的样品预处理方法，该方法消除了在通过测量其苯甲酰可卡因代谢物来估计可卡因利用情况时经常做出的两个关键假设的需要：即苯甲酰可卡因在污水系统中运输过程中既不会降解也不会生成，并且它作为摄入可卡因的恒定分数被排泄。通过添加 NaOH 并将样品在 55°C 下孵育，可卡因及其主要代谢物被有效地水解成可卡因、脱水可卡因和去甲可卡因。估计可卡因残留物的 37%至 90%（摩尔基础）之间的可卡因可以通过反相（RP）或亲水相互作用液相色谱-串联质谱（LC/MS/MS）直接测定（无需通过固相萃取（SPE）进行预浓缩）。如果对样品进行 SPE 处理，则也可以测定脱水可卡因；这种代谢物（及其前体）代表尿液中可卡因残留物的 ≈7%（基于对活体个体的点采集）。尽管去甲可卡因的参考标准在商业上不可用，但这些诺特烷类化合物也是尿液中可卡因残留物的次要部分（高达 2%）。还研究了两种人体标志物（可替宁和肌酐）对水解过程的稳定性。通过应用水解方法分析未经处理的市政废水中总可卡因（从马里兰州巴尔的摩获得）的结果与从使用我们之前工作中描述的更全面的固相萃取 RPLC/MS/MS 方法分析的分样中获得的结果通常非常吻合。特别是，基于总托烷的可卡因残留物被发现以 98-99%的效率水解成可卡因。
