R. Compañó

Analysis of quinolone residues in edible animal products.

A comprehensive review on the analysis of quinolone antibacterials is presented. The review covers most of the methods described for the determination of quinolone residues in edible animal products. Sample handling, chromatographic conditions and detection methods have been discussed. A summary of the most relevant information about the analytical procedures has been included.

Analytical procedures for the determination of organotin compounds in sediment and biota: a critical review.

Analytical procedures reported over the last 10 years for the determination of organotin compounds in sediment and biota have been critically reviewed in terms of sample handling, sensitivity, analytical cost, environmental acceptance, accuracy and precision. Critical steps in the analytical procedures are identified. Finally, research needs in extraction and determination are suggested.

Determination of macrolide antibiotics by liquid chromatography

The liquid chromatographic separation of seven macrolides used in food producing animals in the European Union has been studied. Separation was performed by using an end-capped high-purity silica-based C18 column and mobile phases consisting of phosphate buffer (pH 2.5)-acetonitrile mixtures. The effect of pH and acetonitrile percentage on the separation was examined. Two UV-based detection systems, wavelength programming and diode array, were assayed. Detection limits were in the range 6-33 microg l(-1) for spiramycin, tilmicosin, tylosin, kitasamicin and josamicin and about 400 microg l(-1) for erythromycin and oleandomycin. The suitability of the method for multiresidue determination of the five macrolides is demonstrated by the analysis of spiked samples of chicken muscle.

Estimation of figures of merit using univariate statistics for quantitative second-order multivariate curve resolution

Abstract In this study, a straightforward approach is proposed for determining the figures of merit in multivariate curve resolution. The method is based on the recovery of the pure response profiles of the analytes after a curve resolution procedure. Figures of merit such as limit of detection, sensitivity, precision and accuracy are estimated from these pure analyte responses using univariate statistics directly from a calibration graph, as usual in univariate calibration. Examples of the calculation of the figures of merit in the determination of triphenyltin in synthetic and natural sea water samples by using excitation–emission matrix fluorescence are given.

Residue analysis of macrolides in poultry muscle by liquid chromatography-electrospray mass spectrometry.

A liquid chromatography-mass spectrometry method is proposed for the determination of seven macrolides authorised in the EU as veterinary drugs for food-producing animals. Sample treatment involves extraction of the analytes with a water-methanol mixture containing metaphosphoric acid and clean-up by SPE with a cation-exchange cartridge. Separation was carried out in an end-capped silica-based C18 column and mobile phases consisting of water/acetonitrile mixtures containing trifluoroacetic acid. A gradient elution, from 28 to 40% acetonitrile was used. Detection was performed by mass spectrometry with electrospray ionisation in the positive mode. Several parameters affecting the mass spectra were studied. The protonated molecular ion was selected for quantitation purposes under selected ion monitoring mode. Detection limits were in the range 1-20 microg l(-1). Recoveries ranged between 56 and 93% with RSD lower than 12%. The method has been successfully applied for multiresidue determination of seven macrolides below the MRLs established by the European Union.

Detection techniques in speciation analysis of organotin compounds by liquid chromatography

Analysis of organotin (OT) species in the environment demands very selective, sensitive methods. Liquid chromatography (LC) with a suitable detection system is one of the techniques of choice. The constraints imposed by the required sensitivity mean that, among the instrumental techniques used for detection with LC, only inductively-coupled plasma-mass spectrometry (ICP-MS), mass spectrometry (MS) and fluorimetry are well suited to environmental OT analysis. This article reviews the applications and compares the performances of these detection systems coupled with LC for OT analysis.

Spectrofluorimetric detection of zinc and cadmium with 8-(benzenesulfonamido)-quinoline immobilized on a polymeric matrix

A chelating resin, 8-(benzenesulfonamido)quinoline immobilized on an XAD-7 support, was prepared and its use for the spectrofluorimetric determination of Zn and Cd was investigated. The immobilized material was placed in a flow cell in a spectrofluorimeter and used in a flow injection system; the fluorescent complex was formed and immobilized in the cell. The chelating resin could be stored for at least three months and used repeatedly without any appreciable amount of reagent being lost. Calibration graphs were linear for up to 500 µg l–1 of Zn or Cd. Detection limits were 1.6 µg l–1 for Zn and 1.9 µg l–1 for Cd. Quantification limits were 5.5 µg l–1 for Zn and 6.8 µg l–1 for Cd. Precisions at 50 µg l–1 were 1.7% for Zn and 1.2% for Cd. Detection limits can be improved by injecting larger volumes of sample. Preconcentration factors of up to 10 were obtained for both metal ions.

Comparison of the Kjeldahl method and a combustion method for total nitrogen determination in animal feed

The features of the Dumas combustion method (CM) and those of the Kjeldahl method (KM) were compared as they apply to total nitrogen determination in animal feed. Both methods achieved similar repeatability (S.D., 0.11-0.38 from Kjeldahl and 0.15-0.36 from combustion) and similar intra-laboratory reproducibility (S.D., 0.11-0.39 from Kjeldahl and 0.15-0.37 from combustion). R.S.D. is always below 2%. These results show that the CM is suitable for the analysis of protein content in animal feed (5-75% protein content). The CM is recommended owing to its shorter analysis time, its cost and its environmental suitability.

Determination of ciprofloxacin and enrofloxacin in edible animal tissues by terbium-sensitized luminescence†

A terbium-sensitized luminescence method is described for the determination of the sum of residues of enrofloxacin and its major metabolite ciprofloxacin in edible animal tissues. Several parameters affecting both detection and extraction were studied. Analytes were extracted from spiked samples of chicken and trout tissues with pH 7.4 buffer-dichloromethane. The organic extract was evaporated and the residue dissolved in aqueous nitric acid and defatted with hexane. Determination was carried out directly in the aqueous phase (in a micellar medium). The calibration curves were linear up to 75 micrograms l-1. The detection limit was 3.5 micrograms kg-1 (for a 5 g sample) and the repeatability was 7.0% (n = 7). The sensitivity was similar for both quinolones and therefore calibration can be carried out with either ciprofloxacin or enrofloxacin. In any case, the differences were < 10%.

Assessment of Different Fluorimetric Reactions for Cyanide Determination in Flow Systems

Several fluorimetric reactions for the determination of cyanide by means of flow injection systems were tested. The first reaction is based on the displacement of 8-hydroxyquinoline-5-sulfonic acid (HQS) from the Pd(HQS) 2 complex by cyanide ion and the subsequent reaction of free HQS with Mg II to form a fluorescent species. Secondly, the inhibitory effect of cyanide on the reaction between iodine and fluorescein was also evaluated as a method to quantify cyanide. The third method is based on the detection of an isoindole derivative formed by the reaction of o-phthalaldehyde (OPA) or 2,3-naphthalenedialdehyde (NDA) with glycine in the presence of cyanide. Chemical and hydrodynamic parameters were optimized for each system and the analytical performance of the methods was established. Detection limits of 5 µg l - 1 (fluorescein–iodine method), 0.40 µg l - 1 (Pd–HQS–Mg method), 0.25 µg l - 1 (OPA method) and 0.03 µg l - 1 (NDA method) were obtained.