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Development and Optimization of the Solid-Phase Extraction Procedure for Determination of Antibiotics in Water Samples by HPLC/DAD Before and After RO/NF Membrane Treatment

At present, one of the most relevant topics in environmental analytical chemistry is water quality. In the last few years, the concentration of some organic compounds, such as pesticides or PAHs has been used to characterize water quality. Nowadays, the increasing use of pharmaceutical compounds in human and in animals is becoming a new environmental problem and, because of that, the interest in having information about their presence in the environment and their possible adverse effects on human and on ecological systems is considerably increasing. Effluents from wastewater-treatment plants comprise one of the most important sources of pharmaceuticals being released into the environment. Solid-phase extraction (SPE) is widely used as sample preparation technique for the determination of contaminants from environmental water samples. The wide spread of pharmaceutical chemical structures (e.g., sulfonamides, tetracyclines, fluoroquinolones and  -lactams) makes sample preparation complex, especially when pharmaceuticals of different groups are in the mixture. Depending on the choice of sorbent, a wide range in polarity and chemical class may be covered. For the extraction of analytes of high polarity, polymeric sorbents often proved to be superior to alkylated silica (e.g. C18) sorbents. A variety of alkylated silica and hyper-cross linked polystyrene-divinylbenzene (PS-DVB) based sorbents is commercially available, differing in the degree of linkage, porosity and surface area. These differences lead inevitable to large differences in preconcentration efficiency. The intention of this work was to evaluate different types of sorbents (SI-1, C18-E, C8, CN, NH2, SCX, SAX, SDB-L, Strata-X and Strata-X-C – all from Phenomenex, USA) for their ability to extract eight selected antibiotics (enrofloxacine, norfloxacine, oxytetracycline, trimethoprim, sulfamethazine, sulfadiazine, sulfaguanidine and penicillin G/procaine) from water for a subsequent use in HPLC– DAD determination. This determination based on cyano modified column LiChrosphere 100 CN, 125mm×4.0 mm, particle size 5 m column (Merck, Darmstadt, Germany) and gradient elution by binary mixture of solvents A (0.01M oxalic acid) and B (acetonitrile) as mobile phase. Strata-X cartridges showed as the best type of SPE material for this group of pharmaceutical compounds. Above mentioned developed method has been applied for investigation efficiency of NF/RO membranes for removal these eight antibiotics from wastewater samples. For these purpose antibiotics were determined in wastewater samples before and after membrane treatment. The complete rejection of all antibiotics is achieved by tight nanofiltration (NF90, Dow/ FilmTec, Midland MI) and typical reverse osmosis (XLE, Dow/ FilmTec, Midland MI) membranes.

Solid-phase extraction (SPE); Antibiotics; SPE cartridges; Wastewater; RO/NF membrane; pilot plant

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