Multi-residue method for trace level determination of pharmaceuticals in solid samples using pressurized liquid extraction followed by liquid chromatography/quadrupole-linear ion trap mass spectrometry.
ABSTRACT A simple and sensitive method for simultaneous analysis of 43 pharmaceutical compounds in sewage sludge and sediment samples was developed and validated. The target compounds were extracted using pressurized liquid extraction (PLE) and then purified and pre-concentrated by solid phase extraction (SPE) using a hydrophilic-lipophilic balanced polymer. PLE extraction was performed on temperature of 100 degrees C, with methanol/water mixture (1/2, v/v) as extraction solvent. The quantitative analysis was performed by liquid chromatography tandem mass spectrometry using a hybrid triple quadrupole-linear ion trap mass spectrometer (LC-QqLIT-MS). Data acquisition was carried out in selected reaction monitoring (SRM) mode, monitoring two SRM transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the Information Dependent Acquisition (IDA) function. The method was validated through the estimation of the linearity, sensitivity, repeatability, reproducibility and matrix effects. The internal standard approach was used for quantification because it efficiently corrected matrix effects. Despite the strong matrix interferences, the recoveries were generally higher of 50% in both matrixes and the detection and quantification limits were very low. Beside the very good sensitivity provided by LC-QqLIT-MS, an important characteristic of the method is that all the target compounds can be simultaneously extracted, treated and analysed. Hence, it can be used for routine analysis of pharmaceuticals providing large amount of data. The method was applied for the analysis of pharmaceuticals in river sediment and wastewater sludge from three treatment plants with different treatment properties (i.e. capacity, secondary treatment, quality of influent waters). The analysis showed a widespread occurrence of pharmaceuticals in the sludge matrices.
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ABSTRACT: A sample preparation procedure that combines a liquid-liquid extraction (LLE) with a dispersive solid-phase extraction (DSPE) has been devised to determine residues of four phenoxyacid herbicides, two aminopolycarboxylic acids and five acidic anti-inflammatory drugs in small volumes of river water samples. Two aliquots of acetone (3 and 0.5mL) were used to extract the analytes from a 10mL water sample at pH 2 containing 5mg of octadecylsilane (ODS) sorbent and NaCl at a 5.5M concentration. Acetone was isolated by the salting-out effect, collected, evaporated and the extract was treated with BF3/methanol to obtain the methyl esters of the analytes and determine them by GC with mass spectrometric detection. Recoveries were comprised between 82% and 114% with relative standard deviations about 5-15% (n=5) within a concentration range about 0.03-44µgL(-1). The amount of ODS added to sample resulted to be a significant factor in the recovery for most of the analytes as deduced from an experimental design; the sample pH was not a so critical factor. A robustness study of the proposed sample preparation was carried out as defined by Youden and Steiner and an estimation of the uncertainties of the measured concentrations was made following the EURACHEM/CITAC guidelines, too.Talanta 11/2013; 116:678-87. · 3.50 Impact Factor
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ABSTRACT: Metronidazole (MNZ) is an antibacterial and antiprotozoal drug used in veterinary and human medicine. Its continual entry into the environment and its biological properties may have significant, long-term effects on the stability of ecosystems because MNZ and its metabolites possess mutagenic, carcinogenic and toxic properties. For this reason, the application of MNZ in food-producing species is prohibited in the EU, the USA and other countries. To ensure human food safety and to protect the environment, robust and reliable screening and confirmatory tests capable of the low-level detection of MNZ residues are required. The development of methods for MNZ determination in biological and environmental samples is thus an important analytical task in environmental and food science. This work focuses on the evaluation of a method for determining MNZ in water, sediment and fish tissue samples using liquid chromatography - ion trap mass spectrometry (LC-MS/MS). MNZ was extracted from waters on Strata XC cartridges using solid phase extraction (SPE), and from sediments and fish tissues by solid-liquid extraction (sediment: 15mL 0.1M HCl (pH=0.6), 15min; fish tissue: 15mL 1% CH3COOH in ACN, 1min; drying: 5g MgSO4(anhyd.; 30s) with SPE purification of the extracts (from sediment: Strata XC cartridge; from fish tissue: Supelco NH2 cartridge). The optimal procedure that we developed was validated in order to confirm its reliability and sensitivity. Matrix effects (ME) were established. Absolute recoveries ranged from 89.3% to 97.2%, and the method detection limits were 3.4ngL(-1) (water samples), 0.4ngg(-1) (sediment samples) and 0.3ngg(-1) (tissue samples). These methods were used to determine MNZ in surface waters, sediments and fish tissues from the Polish River Gościcina; MNZ was found in all these matrices. The highest concentrations in water, sediment and tissue were 136.2ngL(-1), 12.0ngg(-1) and 1.5ngg(-1) respectively. The results confirmed that these methods are suitable for the simultaneous analysis of waters, sediments and fish tissues for the presence of MNZ.Chemosphere 01/2014; · 3.14 Impact Factor
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ABSTRACT: This work deals with the environmental distribution of nonionic surfactants (nonylphenol and alcohol ethoxylates), their metabolites (NP, nonylphenol; NPEC, nonylphenol ethoxycarboxylates; and PEG, polyethylene glycols) and a selection of 64pharmaceuticals in the Long Island Sound (LIS) Estuary which receives important sewage discharges from New York City (NYC). Most target compounds were efficiently removed (>95%) in one wastewater treatment plant monitored, with the exception of NPEC and some specific drugs (e.g., hydrochlorothiazide). Concentrations of surfactants (1.4-4.5μgL(-1)) and pharmaceuticals (0.1-0.3μgL(-1)) in seawater were influenced by tides and sampling depth, consistent with salinity differences. Surfactants levels in suspended solids samples were higher than 1μgg(-1), whereas only most hydrophobic or positively charged pharmaceuticals could be found (e.g., tamoxifen, clarithromycin). Maximum levels of target compounds in LIS sediments (PEG at highest concentrations, 2.8μgg(-1)) were measured nearest NYC, sharply decreasing with distance from major sewage inputs.Marine pollution bulletin 01/2014; · 2.63 Impact Factor