engleski

Determination of opioid analgesics and their metabolites in municipal wastewaters by liquid chromatography-tandem mass spectrometry

The major sources of opioid compounds to the aquatic environment are human excretion and dumping of unused medications to the sewer. The existing analytical methods include rather limited number of opioid analgesics (OA) representatives and/or their major human metabolites while the methods that comprise a broad spectrum of OAs are still missing. Therefore, the aim of this work was to develop a multiresidue LC-MS/MS method for the simultaneous determination of trace levels of 28 OAs in municipal wastewaters. The method development included: A) optimization of chromatographic and mass spectrometric conditions for the separation and detection of target analytes, respectively ; B) optimization of extraction procedures for the dissolved and particulate OAs ; C) full validation of analytical protocols for untreated wastewater and secondary effluents and D) the method evaluation for real wastewater samples. In order to optimize chromatographic separation different columns (Synergy Polar, Gemini C18 and ACE C18-PFP) and eluents were evaluated. At the final chromatographic conditions, a complete chromatographic separation of all analytes was achieved by using Synergy Polar column with methanol and water, both containing 0, 1% HAc, as eluting solvents. The enrichment of opioid analgesics from aqueous samples and suspended solids were performed employing solid-phase extraction (SPE) based on mixed cation-exchange (Oasis MCX) cartridges and pressurised liquid extraction (PLE), respectively. During extraction optimisation different SPE cartridges were investigated (Oasis MCX and Oasis HLB) in order to optimise the overall recovery and to reduce the matrix effects. The optimal extraction efficiency of dissolved OAs was obtained by using Oasis MCX cartridges (recoveries: 43-81%). For the extraction of particulate phase ultrasonic extraction and PLE as well as different solvents were tested. The best results were achieved by using PLE with 1% ammonia solution in methanol as a solvent. Recoveries were in range from 72-144% for almost all opioids with exception of 6-acetylmorphyne and glucuronides (15-46%). The method was applied for the assessment of OAs in municipal wastewater from Croatia. Most of the OAs were found in relatively low concentrations ranging from 1-50 ng/L. However, some analytes, such as tramadol, morphine, codeine and methadone showed significantly enhanced levels. The total concentration of tramadol and its metabolites exceeded 1 µg/L.

opioid analgesics ; LC-MS/MS ; wastewaters

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