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In this work, both the batch and flow injection chemiluminescence (CL) methods have been proposed for the simultaneous determination of two structurally similar beta-lactams including amoxicillin and clavulanic acid (CLAV). Chemiluminescence spectral overlap of these two structurally similar beta-lactams is the main limitation for the simultaneous analysis of the two compounds. Least squares support vector regression (LS-SVR) was applied to relate concentration of both the compounds to their CL profiles. The parameters of the model, consisting of kernel parameter, sigma(2), and the regularization parameter, gamma, were optimized by constructing different LS-SVR models and the model with the minimum root mean squared error of cross-validation (RMSECV) for the calibration set was selected as the best model and its parameters were chosen as the optimized values. The performance of LS-SVR model was compared with Partial Least Squares (PLS) and the results revealed the superiority of the LS-SVR over PLS model. Under the optimized experimental conditions for both the compounds, when LS-SVR was applied, the detection limits obtained were 0.2 and 0.60 micromol L(-1) in the batch mode and 0.3 and 0.5 micromol L(-1) in the flow injection mode for CLAV and amoxicillin, respectively. The proposed method was utilized for the simultaneous determination of the compounds in pharmaceutical formulations and spiked plasma samples., (2010 Elsevier B.V. All rights reserved.)

The purpose of this study was to develop and validate a method for the determination of clavulanic acid (CLAV) residues in edible tissues of swine by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS). After a simple extraction of CLAV using an aqueous phosphate buffer solution of pH 6.0, an ultrafiltration step was performed for protein removal. Chromatography of CLAV and the internal standard tazobactam (TAZO) was achieved on a reversed-phase PLRP-S polymeric column (150 mm x 2.1 mm i.d., 100 A) using a mixture of 0.05 (v/v)% formic acid in water and acetonitrile. The mass spectrometer was operated in the MS/MS selected reaction monitoring (SRM) mode. The method was validated for the analysis of porcine muscle, skin plus fat, liver and kidney, according to the requirements defined by the European Community. Calibration curves were prepared for all tissues and good linearity was achieved over the concentration ranges tested (correlation coefficient > or = 0.99 and goodness-of-fit coefficient < or = 10%). Limits of quantification of 50 ng g(-1) were obtained for the analysis of CLAV in the various tissues which corresponds in all cases to at least half the maximum residue limits (MRLs). Limits of detection ranged between 8.0 and 15.14 ng g(-1). The within-day, between-day precisions and trueness fell within the ranges specified in the EMEA/CVMP/573-00/FINAL document. Biological samples from pigs that received an oral or intravenous bolus of a commercial amoxicillin/clavulanic acid formulation were analyzed using the described method.

Attenuated total reflectance mid infrared (ATR-MIR) spectroscopy is a potential technique for the near real-time monitoring of filamentous bioprocesses. Here we investigate the utility of ATR-MIR to monitor and predict concentrations of glycerol and product (clavulanic acid) in a complex antibiotic bioprocess. Streptomyces clavuligerus exhibits filamentous growth, thus, as biomass accumulates the process fluid becomes much more viscous, and develops pronounced non-Newtonian behaviour. A multivariate statistical technique, partial least square (PLS) has been used to develop models for the key analytes over the time course of the bioprocess. These models were then validated externally using unseen samples, not used in the original modelling exercise. Despite the heterogeneous nature of the bioprocess and the resulting complexity of the spectra, the models developed had high correlation coefficient values and low prediction error values of 0.302 and 0.009 for glycerol and clavulanic acid, respectively. The findings extend the use of ATR-MIR in these difficult fluids which are typical of filamentous industrial bioprocesses, and demonstrate the practical utility of the technique in the measurement of a range of analyte types, including those present at relatively modest levels compared to the concentrations of biomass and major substrates.