Single-run ultra-high performance liquid chromatography for quantitative determination of ultra-traces of ten popular active pharmaceutical ingredients by quadrupole time-of-flight mass spectrometry after offline preconcentration by solid phase extraction from drinking and river waters as well as treated wastewater

Abstract

A fit-to-purpose ultra-high performance liquid chromatographic high resolution mass spectrometric method was developed for the ultra-trace analysis of 10 active pharmaceutical ingredients in one chromatographic run as follows: atorvastatin, carbamazepine (CARB), ciprofloxacin (CIPR), clarithromycin (CLAR), diclofenac (DICL), metoprolol (METO), naproxen (NAPR), sitagliptin (SITA), sulfamethoxazole (SULF) and tetracycline. By applying Oasis HLB solid phase extraction cartridges, a 1250-fold enrichment was achieved. For quantitative determination, internal standard calibration was applied. Lower limits of quantification for the analytes were ≤0.025 μg/L. Good linearity was found between 0.01 and 5 μg/L in most cases. Generally, overall recovery for drinking, river and treated wastewater samples spiked with the target analytes at one concentration level comparable with the blank values and another one by one order of magnitude higher was between 80 and 120%. The relative standard deviation values were ≤16%. The proposed method has been applied for the aforementioned water matrices sampled monthly between January and March 2019. Concentration of CARB in drinking water per se was about 0.025 μg/L, confirming the low removal rates during river bank filtration applied for drinking water production. Seven compounds were present in the river water in ≤50 ng/L. Eight compounds were detected at least once from the treated wastewater samples including CARB, DICL, NAPR and SITA in >1 μg/L. Concentration of CARB, DICL, METO, SITA used for chronic affections was almost constant during the monitored time period. To the contrary, concentration of CIPR, CLAR, SULF used for acute infections registered peak values in the same samples taken in winter.