Improved liquid chromatographic determination of nine currently used (fluoro)quinolones with fluorescence and mass spectrometric detection for environmental samples

Abstract

An HPLC method using C18-modified silica as stationary phase has been developed for environmental trace analysis of nine (fluoro)quinolones. Detection is done by fluorescence measurement or MS using the modes of SIM and selected reaction monitoring (SRM). Best separation is achieved with a gradient consisting of 50 mM formic acid and methanol, which is fully compatible with MS coupling. LOQs (S/N of 10) for fluorescence detection are between 10 and 60 microg/L, depending on the analyte. MS detection (SIM and SRM) yields LOQs that are better by a factor of at least an order of magnitude. Sample preconcentration and sample clean-up is accomplished by SPE (preconcentration factor of 1000), leading to LOQs in the low ng/L range. Recoveries of the preconcentration procedure are better than 80% for all analytes. The suitability for real samples has been demonstrated by analyzing surface waters, municipal waste waters, sewage treatment plant effluents, sewage sludge, and sediment taken from rivers and fish ponds. The method should also be useful for determination of residues of (fluoro)quinolones in food or other matrices. The degradation of the (fluoro)quinolones has been examined over 5 days in order to get information about the decomposition rate and the degradation products eventually occurring in the environment.

An overview of analytical methodologies for the determination of antibiotics in environmental waters

“…The best results were obtained with Chromabond Tetracycline C 18 modified silica in spite of these columns being recommended for the preconcentration of residues of TCs. The results from this cartridge were closely followed by results obtained on Oasis HLB [55,56].…”

“…However, other types including cation-exchange [51,52], C 18 [36] and Chromabond tetracycline [55] were used. A tandem system using an anion-exchange cartridge on the top together with Oasis HLB was also described [53].…”

“…LC coupled to tandem MS method is nowadays a technique of choice for the determination of very low concentrations of FQs in environmental waters because of its selectivity and specificity. However, LC with FD was used in six works [50][51][52][53][54][55]. FQs are naturally highly fluorescent compounds and RP-LC-FD can be used for their determination.…”

“…They were monitored at excitation wavelength 278 nm and emission wavelength 450 nm. Nevertheless, some studies used different wavelengths for each compound [50,55]. UV detection was also reported for the determination of FQs [36] but it was not as specific as FD.…”

“…For the quantitation and confirmation, SRM experiments were used [35,52,55]. In some studies single MS was utilized together with ESI + and SIM (selected ion monitoring) experiment [51,55,66].…”