摘要
通过采集城市污水样品,分析其中毒品含量,从而监测毒品滥用情况的污水流行病学是评估毒情和打击毒品犯罪的重要技术手段。研究建立了城市污水中包含苯丙胺和吗啡在内的12种常见毒品及其代谢物的SPE-UPLC-MS/MS分析方法,优化确立了样品浓缩过程中关键的盐酸-乙腈(5∶95)酸化步骤,保障了针对这些有机氮碱性痕量成分分析的抗交叉污染性,提高了方法的稳定性、专属性和准确性。优化的方法经验证符合复杂污水样本的分析要求,并成功地应用于城市毒情评估。
毒品严重影响人类健康,破坏家庭和睦,危及社会公共安全。毒品的种类、来源、吸毒及致死人数不断发生变化,据统计,全球约有2.7亿人使用过毒品,我国现有吸毒人员约180万,滥用合成毒品人员103
污水流行病学方
污水中毒品含量低,由于稀释效应,浓度一般为ppt级,且干扰成分多,对样品前处理和分析检测技术有较高的要
现常采用固相萃取技术(SPE)对污水样品进行浓缩,然后利用LC-MS/MS对污水样品进行定量测定,常采用同位素内标进行定
本研究对已有的SPE-UPLC-MS/MS分析方法在实际应用过程中存在的问题进行分析,优化了样品前处理的关键条件,在样品浓缩过程中加酸酸化,使目标物呈盐酸盐的形式,保障了针对这些有机氮碱性痕量成分分析的抗交叉污染性,提高了有机氮碱性物质污水分析方法的稳定性、专属性和准确性。建立了城市污水中包含苯丙胺和吗啡在内的12种常见毒品及其代谢物的痕量分析方法,并成功地应用于城市毒情评估。
12种毒品、毒品代谢物的标准品以及各自相应的氘代内标储备液均购于美国Cerilliant公司,包括:吗啡(MOR)、6-单乙酰吗啡(6-MAM)、苯丙胺(AM)、甲基苯丙胺(MAM)、亚甲氧基苯丙胺(MDA)、二亚甲基双氧苯丙胺(MDMA)、甲卡西酮(MC)、可卡因(COC)、苯甲酰爱康宁(BZE)、可待因(COD)、氯胺酮(KET)、去甲氯胺酮(NK)、MOR-D3、6-MAM-D3、AM-D5、MAM-D5、MDA-D5、MDMA-D5、MC-D3、COC-D3、BZE-D3、COD-D6、KET-D4、NK-D4。
甲醇、乙腈(CR级,德国Merck试剂);甲酸、盐酸、氨水(AR级,南京化学试剂有限公司);去离子水(市售娃哈哈纯净水)。
采用Zorbax Eclipse Plus C18色谱柱(50 mm × 2.1 mm, 1.8 μm),流动相A为0.1%甲酸水溶液,流动相B为乙腈,线性梯度洗脱(A∶B):0 min(95∶5)→6 min(75∶25)→6.2 min(0∶100)→8 min(0∶100)→8.1 min(95∶5)→11 min(95∶5)。流速为0.3 mL/min,柱温为40 ℃,进样盘温度为4 ℃,进样量为10 μL。
取6-MAM、AM、MAM、MOR、MDMA、MDA、MC、KET和COC标准品约2 mg,精密称定,分别置于10 mL量瓶中,其中,6-MAM、MOR、MC和COC用乙腈溶解并稀释至刻度,其余目标物用甲醇溶解并稀释至刻度,摇匀,配制成质量浓度约为200 μg/mL的上述各目标物的储备液。精密吸取BZE、NK和COD 1 mg/mL的标准品溶液1 mL,分别置于10 mL量瓶中,用甲醇稀释至刻度,摇匀,配制成质量浓度为100 μg/mL的上述各目标物的储备液。将上述储备液逐级稀释,配制成上述目标物质量浓度为2.5 μg/mL(AM为6.25 μg/mL)的混合对照品溶液。
采集污水厂进水口格栅过滤后未处理的污水样品;样品为24 h混合样(每1小时采1次,每次100 mL,最后混合摇匀),用干净聚丙烯瓶盛装,加入浓盐酸调节pH小于2.0,-20 ℃保存。分析前将污水样品融化,并用玻璃纤维滤膜过滤。
取混合对照品溶液适量,用甲醇逐级稀释,分别配制成含AM 1.25,6.25,12.5,62.5,125,312.5,625 ng/mL;其他目标物含0.5,2.5,5,25,50,125,250 ng/mL的系列标曲混合溶液。
取不同浓度的系列标曲混合溶液100 μL,混合内标溶液100 μL,分别用50 mL纯水稀释,配制成含AM分别为2.5,12.5,25,125,250,625,1 250 ng/L;其他目标物为1,5,10,25,50,100,250,500 ng/L的模拟样品。按“2.3.2”项进行试验,记录色谱图,以各目标物的峰面积比值Y( = As/Ar)对目标物浓度X(ng/L)进行权重(1/
按“2.4.1”项下,配制LLOQ的模拟样品(AM为2.5 ng/L,其他目标物为1 ng/L),平行6份,按“2.3.2”项下方法进行试验,根据当日标准曲线计算每一样本测得浓度。结果表明(
6-MAM: 6-Monoacetylmorphine; AM: Amphetamine; COT: Cotinine; COC: Cocaine; BZE: Benzoylecognine; KET: Ketamine; MDA: 3, 4-Methylene⁃dioxyamphetamine; MDMA: 3, 4-Methylenedioxymethamphetamine; MAM: Methamphetamine; MOR: Morphine; NK: Norketamine; COD: Codeine
按“2.4.1”项下,配制标曲最高浓度的模拟样品(AM为1 250 ng/L,其他目标物为500 ng/L),平行6份,按“2.3”项下方法进行试验,记录各目标物及其内标的峰面积。结果表明(
取污水基质50 mL,按“2.4.1”项下,配制成低(L)、中(M)、高(H)3个浓度的质控样品(AM为5、125、1 000 ng/L,其余目标物为2、50、400 ng/L)各6份,按“2.3.2”项下方法平行操作,作为回收率样品组(基质效应对照组)。另取污水基质50 mL,加入甲醇100 μL,进行固相萃取操作,向洗脱液中加入L、M、H 3个浓度的混合溶液100 µL和混合内标溶液100 µL,每一浓度各6份,按“2.3.2”项下方法起操作,作为回收率对照组。取洗脱液4 mL,加入L、M、H 3个浓度的混合溶液100 µL和混合内标溶液100 µL,每个浓度平行3份,按“2.3.2”项下方法起操作,作为基质效应对照组。记录各目标物及其对应内标峰面积,扣除污水基质中各待测物峰面积后,计算各目标物的回收率和基质效应。结果(
取污水基质50 mL,按“2.4.1”项下,配制成LLOQ、L、M、H 4个质量浓度的质控样品(AM为2.5、5、125、1 000 ng/L,其余目标物为1、2、50、400 ng/L)各6份,按“2.3.2”项下方法平行操作。根据当日标准曲线计算每一样本实际浓度,一个分析批内平行测定多次(n = 6),计算批内变异。不同分析批测定多次(n = 3),计算批间变异。结果(
已有SPE方法
氘是自然界存在的氢同位素,氘代化合物是将化合物分子中某个或某些C-H键中的氢原子替换成氘原子。研究表明,氘代化合物的沸点和未氘代化合物的沸点存在微小差
因此,在样品减压离心浓缩至相对较少体积时,加入盐酸-乙腈(5∶95)进行酸化,使AM、MAM和MC及其内标转化为更加稳定、不易挥发的盐酸盐,减少目标物和氘代内标的挥发,使内标响应稳定,AM、MAM、MC 3个目标物的氘代内标响应值RSD分别为27.80%、20.13%和18.61%。加酸酸化保障了针对这些有机氮碱性痕量成分分析的抗交叉污染性,提高了方法的稳定性、专属性和准确性(
在进行污水流行病学分析时,需要选取一种或几种代谢产物作为该毒品代谢目标分析物(DTR)进行测定,从而反推出该毒品的消耗量。DTR多选取最主要、量最大、在污水中稳定性良好且易于监测的毒品代谢
由于污水中AM的来源较多,AM、冰毒及其他AM类物质均可代谢产生A
对东部某市14家污水处理厂的污水样本分析结果显示,MOR、MAM和KET的浓度较高,6-MAM、BZE、COC均未检出。6-MAM为海洛因的代谢物,海洛因在体内水解成6-MAM,而6-MAM很快就代谢成MO
在实际污水样本测定过程中发现,个别污水样品中个别目标物的内标通道无响应,推测是污水样品中存在氧化剂,内标加入后被氧化。故在污水样品抽滤后加入适量的还原剂(巯基乙醇),结果表明随着还原剂浓度的增加,内标响应恢复,表明个别污水样品中存在氧化剂影响分析结果的准确性。
本研究对已有的污水样品前处理方法进行优化,在挥干过程中加酸调节pH,可以减少AM、MAM和MC的挥发,通过方法学验证,证明优化后的SPE-UPLC-MS/MS检测方法高效可靠。对东部某市14家污水处理厂的污水样本测定结果表明,优化后的前处理方法和UPLC-MS/MS检测方法能够满足分析要求。
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