Study on the stability of antibiotics, pesticides and drugs in water by using a straightforward procedure applying hplc-mass spectrometric determination for analytical purposes

The stability of analytes is a critical point in chemical analysis, especially in the field of trace levels residue analysis. Nowadays, due to advances in analytical technology and in separation sciences, the analyses of water have been improved. Unfortunately, in this context, one of the most critical issues in water analysis include compound stability from sampling station to laboratory procedures. This study was carried out to explore the stability of several compounds in water from sampling to analysis concerning analytes reported in implementing decision 2018/840—Watch List. During method development and validation, the stability of compounds was investigated to detect the best operating conditions concerning sampling, extraction and analysis. In this paper, we report a study on the stability of antibiotics, pesticides and drugs in water determined using a straightforward procedure applying mass spectrometric detection for analytical purposes. The laboratory tests were performed in Milli-Q water and surface water by analyzing samples through direct injection, solvent mixture (Water/ACN) and solid phase extraction system from time 0 to 168 h. All the analytes of the WL are stable in aqueous solutions with the addition of at least 25% ACN even after 168 h, and the analytes have shown a matrix effect on recovery of some analytes such as Famoxadone from sampling results (recovery in surface water 72%). For all the analytes investigated, recoveries were between 70 and 130% by using SPE procedures before UHPLC-MS/MS analysis, which is in good agreement with method validation procedures.