Systematic Evaluation of the In-Sample Stability of Selected Pharmaceuticals, Illicit Drugs, and Their Metabolites in Wastewater

The in-sample stability of selected pharmaceuticals, illicit drugs,
and their metabolites in wastewater was assessed under six different
conditionsuntreated, addition of hydrochloric acid or sodium
metabisulfite solution, combined with or without sterile filtration,
and at four representative temperatures, at 35 °C for up to 28
days, 22 °C for 56 days, and 4 °C and −20 °C
for 196 days, or freeze/thaw cycles for 24 weeks. Paracetamol, 6-monoacetylmorphine,
morphine, and cocaine were poorly stable in untreated wastewatere.g.,
with 50% transformation within 1.2–8.1 days at 22 °C,
and acidification reduced their in-sample transformations. Acesulfame,
carbamazepine, cotinine, methamphetamine, 3,4-methylenedioxy-methamphetamine
(MDMA), ketamine, norfentanyl, 3,4-methylenedioxy-N-ethylamphetamine (MDEA), and norbuprenorphine were highly or moderately
stable over the observed period, even in untreated wastewater. Fitting
of pseudo-first-order kinetics and the Arrhenius equation was used
to develop a multistage transformation estimation model combined with
an interactive tool to evaluate possible transformation scenarios
of selected biomarkers for the processes from sampling to preanalysis.
However, as the wastewater composition can vary between sites and
over time, the variability of in-sample stability requires further
exploration.

本研究针对废水中选取的药物、违禁药物及其代谢物的样本内稳定性开展评估，共设置6种不同实验条件：未处理组、添加盐酸或焦亚硫酸钠溶液组、结合/不结合无菌过滤组，以及4种代表性温度条件——35℃下培养最长28天、22℃下培养56天、4℃与-20℃下培养196天，以及24周冻融循环。
对乙酰氨基酚（Paracetamol）、6-单乙酰吗啡、吗啡与可卡因在未处理废水中稳定性较差，例如22℃条件下仅1.2~8.1天即可发生50%的转化，而酸化处理可抑制其样本内转化过程。
安赛蜜（Acesulfame）、卡马西平、可替宁、甲基苯丙胺、3,4-亚甲二氧基甲基苯丙胺（MDMA）、氯胺酮、去甲芬太尼、3,4-亚甲二氧基-N-乙基苯丙胺（MDEA）以及去甲丁丙诺啡在整个观测周期内（即使在未处理废水中）均表现出较高或中等的稳定性。
本研究通过拟一级动力学（pseudo-first-order kinetics）与阿伦尼乌斯方程（Arrhenius equation）拟合，构建了多阶段转化估算模型，并配套开发交互式工具，用于评估从采样至预分析全过程中目标生物标志物的潜在转化场景。
但由于废水组分在不同采样点位及随时间均存在差异，样本内稳定性的变异性仍需进一步探索。