Distribution and persistence of cephalosporins in cephalosporin producing wastewater using SPE and UPLC-MS/MS method

- A rapid and reliable measuring method for seven cephalosporins was established.
- Concentration of cephalosporin in its producing wastewater was mostly up to μg/L.
- Cephalosporin discharge load was 1.9 kg/d approximately.
- High temperature and light obviously accelerate degradation rate of cephalosporin.
- Cephalosporin cannot be efficiently degraded in wastewater under normal temperature.

An investigation to study the distribution and persistence of cephalosporins in the cephalosporin producing wastewater was carried out in this paper. The target cephalosporins included ceftriaxone (CRO), cefalexin (CEF), cefotaxime (CTX), cefazolin (CZO), cefuroxime (CXM), cefoxitin (CFX) and cefradine (CF). A rapid and reliable detection method for cephalosporins was established based on solid phase extraction and ultra-performance liquid chromatography - tandem mass spectrometry. In the cephalosporin producing wastewater effluent (CPWWeff), the limit of quantification for the targets ranged from 27.5 ng/L to 131.8 ng/L, and the recoveries for all of the analytes ranged from 73% to 102%. The mean concentrations of the seven cephalosporins were 12.85-141.55 μg/L and 0.05-24.38 μg/L in cephalosporin producing wastewater influent and effluent, respectively. Although high removal efficiencies were achieved for the cephalosporins (78.8-99.7%), up to 1.9 kg of cephalosporins was discharged per day from the investigated C-WWTP. The degradation processes of CRO, CEF, CZO and CXM followed first-order kinetics in CPWWeff under all of the testing conditions. The degradation rates of tested cephalosporins were accelerated by high temperature and light. Persistence of CXM was the highest among the four tested cephalosporins in CPWWeff.

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