engleski

Trace determination of sulfonamide, fluoroquinolone and macrolide antimicrobials in wastewater using liquid chromatography / tandem mass spectrometry (LC/MS/MS)

A sensitive and highly selective method for the simultaneous determination of three classes of the popular antimicrobials, including sulfonamides, fluoroquinolones and macrolides, in wastewater has been developed. The analytes were enriched from wastewater samples by solid-phase extraction using hydrophilic-lipophilic balance (HLB) cartridges. Prior to the extraction samples were acidified with formic acid to obtain 0.1 % solution and a mixture of surrogate standards was also added. Absorbed analytes were eluted from cartridges with 10 ml of 1 % ammonia solution in methanol. After evaporation of the extract, the residue was re-dissolved in 0.1 % formic acid and instrumental internal standards sulfamerazine and josamycin were added. The extracts were analysed by reversed-phase liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (ESI-MS/MS). The detection of all target analytes was performed in positive mode using multiple reaction monitoring (MRM). Quantification of sulfonamides, trimethoprim, fluoroquinolones and macrolides was performed using several deuterated sulfonamides, diaveridine, d5-norfloxacin and azahomoerythromycin as internal standards, respectively. Matrix effects in the extracts of the real municipal wastewater samples were efficiently compensated for by the applied surrogate standards, however for some samples, dilution of original extract prior to LC/MS/MS analysis was necessary due to the strong ion suppression. Recoveries of individual antimicrobials from water samples, spiked at 1  g/L, were in the range from 64 to 109 % with relative standard deviations varying between 1 and 14 %. Detection limits based on 200 ml-water samples ranged from 0.2 to 12 ng/L. The method was successfully applied for the analysis of municipal wastewater samples from Croatia. The most abundant antimicrobials in Croatian municipal wastewaters were sulfametoxazole (19 – 11555 ng/L), sulfapyridine (24 – 931 ng/L), trimethoprim (35 – 2551 ng/L), norfloxacin (16 – 2937 ng/L), ciprofloxacin (23 – 2610 ng/L), azithromycin (26 – 1139 ng/L), and erythromycin (24 – 420 ng/L).

antimicrobials; wastewater; liquid chromatography/tandem mass spectrometry (LC/MS/MS)

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