An online SPE LC-MS/MS method for the analysis of antibiotics in environmental water.

A fast and simple method for the analysis of 17 commonly used antibiotics in Finland in water samples was developed. The method combines online solid phase extraction using a reusable online trapping column combined with analytical separation on a C18 analytical column and detection by a triple quadrupole mass spectrometer. The method was fully validated for detection and quantification limits as well as linearity, repeatability, and matrix effects. The method gave an excellent linear response (r 2 > 0.99) and detection limits for all compounds (1-10 ng-1), except for tetracycline (20 ng l-1) and roxithromycin (50 ng l-1). The repeatability was evaluated at two concentrations, and the values at 5 ng l-1 ranged from 5 to 39% and at 100 ng l-1 ranged from 3 to 19%. To test the method on real samples at low environmental concentrations, water samples collected from a river receiving discharges from two wastewater treatment plants were analyzed as well as samples from a pristine river. Seven antibiotics as well as carbamazepine were detected in the samples. The concentration of the compounds ranged from 5 to 81 ng l-1.