Pharmaceuticals are now well known micro-pollutants of aquatic systems. They are studied due to sanitary and environmental risks they could represent and especially the antibiotics because of the antibiotic resistance phenomenon. We have focused our research on that group of compounds. Antibiotics mainly enter into the environment either via sewage treatment plant (SWTP) effluent (human origin) or via runoff of land fertilized with sludge from SWTP or manure from livestock (veterinary origin). We have worked on that second origin and studied 2 different types of process before the manure spreading: i) the simple storage of the manure during few months in huge tank ; ii) the treatment process with solid/liquid separation system and 2 different ways of treatment for each phase. Whatever the origin of the contamination, it appears to be a chronic contamination and it is necessary to quantify compounds at trace level (ng/L). For this purpose, we have developed a method for the simultaneous quantification of 23 antibiotics belonging to 9 families. The first step is an extraction of molecules by SPE on Oasis HLB cartridges and the second one is the analysis by Rapid Resolution Liquid Chromatography-tandem mass spectrometry (RRLC/MS/MS) with a 5 cm C18 column and an electrospray ionisation source. The preliminary results show an important contamination of stored pig manure by lincomyin, tetracycline, oxytetracycline and sulfadiazine. The results are discussed according to various ways of manure treatment and uses.