Tetracycline residues in royal jelly and honey by liquid chromatography tandem mass spectrometry: validation study according to Commission Decision 2002/657/EC

A specific, sensitive and robust liquid chromatography tandem mass spectrometry method for determining oxytetracycline, tetracycline, chlortetracycline and doxycycline in royal jelly and honey samples is presented. Extraction of drug residues was performed by ammonium acetate buffer as extractant followed by a clean-up with metal chelate affinity chromatography and solid-phase extraction. Tetracycline analysis was performed using liquid chromatography–electrospray ionisation–tandem mass spectrometry. The presented method is the first validated for royal jelly and in accordance with the requirements set by Commission Decision 2002/657/EC. Recoveries of the methods, calculated spiking the samples at 5.0, 10.0, 20.0 and 30.0 μg kg⁻¹, were 79% to 90% for honey and 77% to 90% for royal jelly. The intra-day precision (RSD) ranged between 8.1% and 15.0% for honey and from 9.1% to 16.3% for royal jelly, while inter-day precision values were from 10.2% to 17.6% and from 10.6% to 18.4% respectively for honey and royal jelly. Linearity for the four analytes was calculated from 5.0 to 50.0 μg kg⁻¹. The decision limits (CCα) ranged from 6.2 to 6.4 μg kg⁻¹ and from 6.1 to 6.5 μg kg⁻¹ for honey and royal jelly, respectively. Detection capabilities values (CCβ) ranged between 7.2 and 7.7 μg kg⁻¹ and from 7.3 to 7.9 μg kg⁻¹ respectively for honey and royal jelly. The developed method is currently in use for confirmation of the official control analysis of honey and royal jelly samples.     

Development and in-house validation of an LC-MS/MS method for the determination of stilbenes and resorcylic acid lactones in bovine urine

Stilbenes and zeranol are nonsteroidal estrogenic growth promoters which are banned in the European Union (EU) for use in food-producing animals by Council Directive 96/22/EC. A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed for the screening and confirmation of stilbenes (diethylstilbestrol, dienestrol, hexestrol) and resorcylic acid lactones (zeranol and its metabolites taleranol and zearalanone as well as the mycotoxins α-zearalenol, β-zearalenol and zearalenone) in bovine urine. The method permits the confirmation and quantification of stilbenes and resorcylic acid lactones at levels below 1 μg L⁻¹ and 1.5 μg L⁻¹, respectively. The validation was carried out according to Commission Decision 2002/657/EC, Chap. 3.1.3 “alternative validation” by a matrix-comprehensive in-house validation concept. Decision limit CCα, detection capability CCβ, recovery, repeatabiliy, within-laboratory reproducibility and the uncertainty of measurement were calculated. Furthermore, a factorial effect analysis was carried out to identify factors that have a significant influence on the method. Factors considered to be relevant for the method in routine analysis (e.g. operator, matrix condition, storage duration of the extracts before measurement, different cartridge lots, hydrolysis conditions) were systematically varied on two levels. The factorial analysis showed that different cartridge lots, storage durations and matrix conditions can exert a relevant influence on the method.     

Detectability of testosterone esters and estradiol benzoate in bovine hair and plasma following pour-on treatment

The abuse of synthetic esters of natural steroids such as testosterone and estradiol in cattle fattening and sports is hard to detect via routine urine testing. The esters are rapidly hydrolysed in vivo into substances which are also endogenously present in urine. An interesting alternative can be provided by the analysis of the administered synthetic steroids themselves, i.e., the analysis of intact steroid esters in hair by liquid chromatography tandem mass spectrometry (LC/MS/MS). However, retrospective estimation of the application date following a non-compliant finding is hindered by the complexity of the kinetics of the incorporation of steroid esters in hair. In this study, the incorporation of intact steroid esters in hair following pour-on treatment has been studied and critically compared with results from intramuscular treatment. To this end animals were pour-on treated with a hormone cocktail containing testosterone cypionate, testosterone decanoate and estradiol benzoate in different carriers. The animals were either treated using injection and pour-on application once or three times having 1 week between treatments using injection and pour-on application. Animals were slaughtered from 10–12 weeks after the last treatment. Both hair and blood plasma samples were collected and analysed by LC/MS/MS. From the results, it is concluded that after single treatment the levels of steroid esters in hair drop to CCβ levels (5–20 μg/kg) after 5–7 weeks. When treatment is repeated two times, the CCβ levels are reached after 9–11 weeks. Furthermore, in plasma, no steroid esters were detected; not even at the low microgramme per litre level but—in contrast with the pour-on application—after i.m. injection, significant increase of 17β-testosterone and 17β-estradiol were observed. These observations suggest that transport of steroid esters after pour-on application is not only performed by blood but also by alternative fluids in the animal so probably the steroid esters are already hydrolysed and epimerized before entering the blood.     

Multi-walled carbon nanotubes as solid-phase extraction adsorbent for the ultra-fast determination of chloramphenicol in egg, honey, and milk by fused-core C18-based high-performance liquid chromatography–tandem mass spectrometry

In the present work, a high-performance liquid chromatography–tandem mass spectrometry method has been developed for the residue analysis of chloramphenicol (CAP) in several food matrices. Following the addition of D₅-CAP as internal standard, egg, honey, and milk were extracted and cleaned by means of solid-phase extraction, utilizing multi-walled carbon nanotubes as sorbent. The extracts were separated on a Halo fused-core C18 column (50 mm × 2.1 mm, 2.7 μm) and quantified by a 4000 Q-trap mass spectrometer equipped with a TurboIonSpray™ interface using electrospray ionization and multiple-reaction monitoring mode. The method validation was performed according to the criteria of Commission Decision 2002/657/EC. The decision limit (CCα) and detection capability (CCβ) of CAP in milk were calculated for m/z 320.8 > 151.9. Due to the existence of slight signal suppression, quantification was performed by matrix-matched calibration curves, ranging from 0.1 to 100 ng mL⁻¹, with regression coefficients of 0.9993, 0.9998, and 0.9997 for egg, honey, and milk, respectively. Mean recoveries of the CAP ranged from 95.8% to 102.3%, with the corresponding intra- and inter-day variation (relative standard deviation) less than 7.13% and 8.89%, respectively. The limit of detection and limit of quantification of the method were also reported. This method successfully applied to several food matrixes (egg, honey, and milk) and can serve as a monitoring tool to avoid unacceptable levels of residues of CAP entering the food chain.     

Multiresidue analysis of beta-agonists in bovine and porcine urine,feed and hair using liquid chromatography electrospray ionisation tandem mass spectrometry

The use of β-agonists as growth promoters in cattle breeding is forbidden in many countries for reasons of fair trade and consumer protection. In recent years the use of liquid chromatography (LC) tandem mass spectrometry (MS/MS) has been shown to be the method of choice for the control of β-agonists. In this study an LC-MS/MS multiresidue analysis method is presented for trace analysis of 22 β-agonists. A truly generic concept has been designed based on mixed-mode solid-phase extraction and positive electrospray ionisation LC-MS/MS operated in the multiple reaction monitoring mode. This method allows application to a wide variety of sample matrices such as urine, feed and hair, following minor modifications to the analysis procedure only. The method features fit-for-purpose sensitivity in urine as shown by CCα and CCβ values of less than 0.2 and less than 0.5 μg/l respectively, for all β-agonists studied (terbutaline and reproterol, less than 0.3 and less than 1.0 respectively). Similar but semiquantitative application to feed and hair showed CCβ values of less than 10.0 and less than 5.0 μg/kg, respectively. A further simplification and improvement is demonstrated using Ultra Performance LC (UPLC™) and fast-switching MS/MS. The successful validation of this method following the latest EU requirements and its application to real samples demonstrate that a new versatile tool has been achieved for veterinary control of β-agonists.     

Determination of antibacterials in animal feed by pressurized liquid extraction followed by online purification and liquid chromatography-electrospray tandem mass spectrometry

A fully automated method has been developed for analysis of eighteen antibacterial compounds, including penicillins, cephalosporins and sulfonamides, in animal feed with limits of quantification in the range 0.25–5.79 μg kg⁻¹. The method is based on pressurized liquid extraction of 3 g homogenized feed with water and online clean-up of 500 μL of the extract with C₁₈HD cartridges. The purified sample was directly analysed by liquid chromatography–electrospray tandem mass spectrometry (SPE–LC–ESI-MS–MS). Chromatographic separation was achieved within 10 min by use of a C₁₂ Phenomenex Hydro-RP reversed-phase analytical column and a mobile phase gradient (water + 0.1% formic acid–methanol + 0.1% formic acid). The method was validated, revealing capability for detection of concentrations as low as 0.09 μg kg⁻¹, decision limits (CCα) and detection capabilities (CCβ) in the range 10–174 μg kg⁻¹ and 22–182 μg kg⁻¹, respectively, and inter-day precision ranging from 0.7 to 8.3%. Recovery, with internal standard correction, was in the range 93–134% for all analytes. The method was then applied to analysis of fifteen feed samples, nine of which contained at least one antimicrobial at concentrations between 0.006 and 1.526 mg kg⁻¹. The performance data and results from the method were compared with those from a previous method developed by our group, using offline SPE, by analyzing the same set of samples by both methods. The online SPE approach resulted in slightly improved sensitivity, with LODs of 0.09–2.12 μg kg⁻¹ compared with 0.12–3.94 μg kg⁻¹ by the offline approach. In general, better recovery was achieved by use of online purification (for 72% of the analytes) and the correlation between the two methods was good. The main advantages of the new online method are rapid and automated sample pre-treatment, and reduction of sample manipulation, enabling high-throughput analysis and highly accurate results. Because of all these characteristics, the proposed method is applicable and could be deemed necessary within the field of food control and safety.     

PCDD, PCDF, AND DL-PCB analysis in food: performance evaluation of the high-resolution gas chromatography/low-resolution tandem mass spectrometry technique using consensus-based samples

Due to safety concerns regarding dietary exposure to POPs, regulatory bodies are issuing detailed guidelines for testing for polychlorodibenzodioxins (PCDDs) and polychlorodibenzofurans (PCDFs) ('dioxins') and dioxin‐like (DL)‐PCBs in foods of animal origin. Determination of the aforesaid chemicals at regulatory levels requires highly selective and sensitive testing techniques. The new generation of low‐resolution mass spectrometers (triple quadrupoles) allows very low levels of quantification to be reached (in the order of tens of femtograms), thus suggesting a potential for their application in food and feed analysis. The performance of the low‐resolution tandem mass spectrometry (LRMS/MS) approach with triple quadrupoles was assessed on a qualified set of food samples from proficiency tests (PTs) and defense analysis. Accuracy was tested comparing the results with data from high‐resolution mass spectrometry (HRMS) and with consensus values from PTs. The cumulative TEQ results were characterized by deviations not exceeding 15% of PCDD + PCDF, DL‐PCB, and PCDD + PCDF + DL‐PCB (TEQ_TOT) reference consensus values (sample TEQ_TOT range, 2.29–25.1 pgWHO‐TEQ₉₇/g fat). Congener analytical variabilities did not influence significantly the WHO‐TEQ₉₇ outcome of the corresponding sample. This preliminary performance evaluation highlights the potential of LRMS/MS as a routine technique for quantitative analysis of PCDDs, PCDFs, and DL‐PCBs in food. Copyright © 2011 John Wiley & Sons, Ltd.     

Fast simultaneous determination of 23 veterinary drug residues in fish,poultry, and red meat by liquid chromatography/tandem mass spectrometry

The misuses of veterinary drugs can result in the accumulation of residues in food of animal origin that can make its way to the final consumer. Herein we describe a simple method for the accurate determination of beta-lactams, quinolones, sulphonamides, and tetracyclines in fish, poultry, and red meat. No extraction cartridges were used; instead, the extraction process consisted of the addition of an organic solvents, shaking, centrifugation, and dilution. An extensive validation process demonstrated an excellent linearity (R² ≥ 0.99) for 23-drug residues. The recovery of drugs in different matrices at two concentration levels (n = 6) was in the range of 82–119%. The method was proved to be repeatable and reproducible with intra/inter-day measurements (RSDs lower than 20%). The quantification limits of drug residues were in the range of 0.8 to 45.3 ug/kg, which is well below the maximum residue limits set by most regulatory authorities. This method was successfully applied to the routine analysis of 20 fish, poultry, and red meat samples (n = 60).     

A simple and rapid method for simultaneous determination of benzoic and sorbic acids in food using in-tube solid-phase microextraction coupled with high-performance liquid chromatography

A simple, rapid and sensitive on-line method for the simultaneous determination of benzoic and sorbic acids in food was developed by coupling in-tube solid-phase microextraction (SPME) to high-performance liquid chromatography (HPLC) with UV detection. The diethylamine-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolithic capillary selected as the extraction medium exhibited a high extraction capability towards benzoic and sorbic acids. To obtain optimum extraction performance, several in-tube SPME parameters were investigated, including pH value, inorganic salt, and the organic solvent content of the sample matrix. After simple dilution with 0.02 mol/L phosphate solution (pH 4.0), carbonated drink, juice drink, sauce and jam samples could be directly injected for extraction. For succade samples, a small amount of acetonitrile was required to extract analytes prior to dilution and subsequent extraction. The linearity of the method was investigated over a concentration range of 5–20000 ng/mL for both analytes, and the correlation coefficients (R ² values) were higher than 0.999. The detection limits for benzoic and sorbic acids were 1.2 and 0.9 ng/mL, respectively. The method reproducibility was tested by evaluating the intra- and interday precisions; relative standard deviations of less than 4.4 and 9.9%, respectively, were obtained. Recoveries of compounds from spiked food samples ranged from 84.4 to 106%. The developed method was shown to be suitable for the routine monitoring of benzoic and sorbic acids in various types of food samples.     

Validation Method for the Determination of Sulfonamide Residues in Bovine Milk by HPLC

A simple, rapid, sensitive and reliable high-performance liquid chromatographic method for the simultaneous determination of eight sulfonamides (SAs) in bovine milk was developed (sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxypyridazine, sufamonomethoxine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline) in bovine milk was developed. Samples were prepared by extraction with ethyl acetate and cleaning-up with an anion solid-phase extraction (SPE) column. Analytical separation was performed on an Inertsil ODS-3 column with photodiode-array detection at 270 nm under gradient condition. The whole procedure was evaluated according to the European Commission Decision 2002/657/EC. Specificity, decision limit (CCα), detection capacity (CCβ), trueness and precision were determined during the validation process. It was found that the analytes were isolated from spiked samples with good recoveries between 70.5 and 89.0%. The used analytical conditions allow to successively separating all the tested sulfonamides with good limit of detection between 0.8 and 1.5 μg L⁻¹.     

The influence of a quality system according to ISO/IEC 17025 on the performance of Brazilian laboratories in proficiency testing in the environmental area

This paper presents a performance analysis of laboratories in proficiency testing (PT) with the main objective of evaluating whether having accreditation to ISO/IEC 17025 or not having an implemented quality system has an influence on the performance of these laboratories. This research was conducted with data from an accredited PT scheme of physical–chemical water analyses. Nine metals were considered in the analysis, with a total of 896 results. The performance indicator was z-score. The proposed analysis was conducted through statistical methods of analysis of variance, Dunnett’s test, Chi-square and cross-tabulation. It was verified that there is a significant difference between the performance of accredited laboratories, recognised laboratories, and laboratories that do not have an implemented quality system. It was established that an accredited or recognised quality system has a positive influence on the laboratory performance, resulting in a lower z-score (in module) and in a larger percentage of satisfactory results.     

Using uncertainty functions to predict and specify the performance of analytical methods

In both European legislation relating to the testing of food and the recommendations of the Codex Alimentarius Commission, there is a movement away from specifying particular analytical methods towards specifying performance criteria to which any methods used must adhere. This ‘criteria approach’ has hitherto been based on the features traditionally used to describe analytical performance. This paper proposes replacing the traditional features, namely accuracy, applicability, detection limit and limit of determination, linearity, precision, recovery, selectivity and sensitivity, with a single specification, the uncertainty function, which tells us how the uncertainty varies with concentration. The uncertainty function can be used in two ways, either as a ‘fitness function’, which describes the uncertainty that is fit for purpose, or as a ‘characteristic function’ that describes the performance of a defined method applied to a defined range of test materials. Analytical chemists reporting the outcome of method validations are encouraged to do so in future in terms of the uncertainty function. When no uncertainty function is available, existing traditional information can be used to define one that is suitable for ‘off-the-shelf’ method selection. Some illustrative examples of the use of these functions in methods selection are appended.     

A practitioner's approach to the assessment of the quality of sampling, sample preparation, and subsampling

 The methodology of evaluating the performance of sampling, sample preparation, and subsampling is reviewed. The requirements to be set for a successful experiment are revisited. The central role of the reference method is explained, and so is the choice of the parameters and the measurement methods. Based on the principles of the "Guide to the expression of uncertainty in measurement" (GUM), a statistical model is developed that demonstrates the influence of the experimental design on the outcome of the assessment experiment. This relationship is often overlooked in practice, as it is hardly mentioned in written standards dealing with this kind of quality assessments. The statistical framework thus developed covers the statistical procedures commonly appearing in written standards. Finally, the issue of testing the significance of the bias obtained from the experiment is discussed. Received: 14 June 1997 · Accepted: 2 September 1997     

Separation of polychlorinated dibenzo-p-dioxins/furans,non-ortho/mono/di/tri/tetra-ortho-polychlorinated biphenyls,and polybrominated diphenyl ethers groups of compounds prior to their determination with large volume injection gas chromatography—Quadrupole ion storage tandem mass spectrometry

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are important environmental contaminants. Their maximum legally allowable levels in food and environment are in the low pg g⁻¹ range. Therefore some highly selective and sensitive analytical methods must be used to determine them. Prior to final determination by GC/MS the cleaned-up samples have to be split into some fractions in view of large differences in concentrations of various analytes and existence of numerous chromatographic co-elutions (which in any case cannot be fully avoided). The aim of this study was to: (i) develop a robust, time-saving analytical method to isolate, clean-up and fractionate PCBs, PBDEs and PCDD/Fs prior to their determination with gas chromatography/ion trap mass spectrometry; (ii) assess method performance using laboratory validation data and some certified reference materials; (iii) use the developed method to assess PCB/PBDE/PCDD/F levels in samples of commercially available food. A combination of alumina, florisil, modified silica gel and two carbon columns were used for sample cleanup and fractionation. Separate fractions containing dioxins/furans, PBDE, non-ortho, mono-ortho and di-/tri-/tetra-ortho PCBs were obtained. The method statistical parameters were compatible with 1883/2006 EC Regulation (80–120%, RSD below 15%). The method performance was successfully used to evaluation of some real life food samples.     

急性瘦肉精中毒检材的QuEChERS净化-液质联用快速确证方法

目前液相色谱串联质谱法测定动物源性食品中瘦肉精普遍采用酶水解提取、固相萃取净化的方式处理样品,该方法耗时长、分析成本高。 本研究采用酸水解和酶水解两种提取方式结合QuEChERS(Quick,Easy,Cheap,Effective,Rugged,Safe)净化和高效液相色谱串联质谱建立了动物性食品中特布他林、沙丁胺醇、莱克多巴胺和克伦特罗4种β2受体激动剂的快速定性确证和定量检测方法。 采用酶水解提取-QuEChERS净化处理样品,在电喷雾离子源正离子扫描(ESI+)和多反应监测(MRM)模式下,4种瘦肉精在1.0~20.0 μg/L浓度之间呈线性,线性相关系数均大于0.999,检出限和定量限分别为0.1和0.3 μg/kg,猪肉和牛肉样品中4种化合物的回收率为78.5%~112%,相对标准偏差RSD为2.8%~8.9%。 采用酸水解法代替酶水解提取时,尽管对于样品中莱克多巴胺测定结果稍偏低,但样品前处理时间大大缩短。 两种提取方法结合使用对于提高瘦肉精引起的食物中毒应急处置效率具有重要意义。     

GC/MS detection of central nervous tissues as specified BSE risk material in meat products: validation by an externally controlled blind trial

The addition of central nervous tissues (CNT), such as brain and spinal cord, in the manufacturing of meat products is either forbidden—if the material falls under the legal definition of specified risk material (SRM)—or must be labelled on the packed product. To foster official food control, several CNT detection methods were developed, but only fatty acid patterns as detected by gas chromatography/mass spectrometry (GC/MS) allow the further characterization of the detected CNT as to both the animal species and—surprisingly—the age of the animal from which the CNT was derived in accordance with the legal definition. Complementing a previous report in this journal by Lücker et al. 2010 (doi:) on CNT quantification by GC/MS, we now report results of the validation of this new analytical approach by an externally controlled blind trial elucidating its potential to identify the species and age of the CNT detected. The 72 samples (24 standards of emulsion-type sausage, each heated in three different batches: 75°C, 30 min; 115°C, 25 min; 133°C, 40 min) containing porcine, ovine or bovine muscle tissue and differing amounts of CNT (bovine or ovine brain: 0, 0.1, 0.5, 1.0, 3.0% m/m) were produced externally and provided blind for analyses to our laboratory. In accordance with the previous study, heating had no detectable effect on the GC/MS analysis. Judged by the present sensitivity of this method (cut-off 0.2% CNT), all of the samples containing 0.5% or more CNT (n = 57, 100%) were identified correctly as CNT-positive. The CNT species was identified correctly in 54 samples (94.7%), with three samples of one specific standard (0.5% ovine CNT) falsely classified as bovine CNT. However, the CNT age of these samples was correctly classified (more than 12 months). Overall, 57 samples (100%) were correctly classified as SRM-positive and 15 samples (100%) as SRM-negative. To the best of our knowledge, this is the first time that a legal demand for the (1) detection of traces of a specific tissue in a food matrix, (2) the identification of its taxonomic origin and (3) the classification of its age has been shown to be analytically possible in totally blind samples. The very positive validation results of this externally controlled blind trial recommend the present GC/MS approach for the detection of CNT in meat products as a reference method. However, our results also demonstrate the need for further studies, in particular to increase sensitivity and to conduct ring trials including more than one laboratory.     

Trace analysis of surfactants derived from fatty alcohols I. Optimization of derivatization reaction

Summary Pre-column derivatization of the primary hydroxyl group in fatty alcohols and fatty alcohol ethoxylates using carbazole-9-carbonyl chloride (CC−Cl) and FMOC-Cl is described and compared with derivatization with 1-naphthoyl chloride (N−Cl). As the excess of derivatization reagent leads to a broad and strongly tailing reagent peak, it hinders trace determination of fatty alcohols and fatty alcohol ethoxylates. Therefore, an off-line as well as an on-line solid-phase extraction (SPE) method for removal of excess reagent are described. The on-line method which is based on column switching, shows better reproducibility higher pre-concentration, lower risk of contamination and can be easily automated, while the off-line method is better suited for the analysis of derivatized, fatty alcohol ethoxylates. An example of the trace analysis of fatty alcohols with a concentration of 2 ppb is given.     

Studying variations in the PCDD/PCDF profile across various food products using multivariate statistical analysis

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are widely recognized by the scientific community as persistent organic pollutants due to their toxicity and adverse effects on wildlife and human health. The actual regulation dedicated to the monitoring of dioxins in food is based on the measurement of 17 congener concentrations. The final result is reported as a toxic equivalent value that takes into account the relative toxicity of each congener. This procedure can minimize the qualitative information available from the abundances of each PCDD/PCDF congener: the characteristic contamination profile of the sample. Multivariate statistical techniques, such as principal component analysis (PCA) or linear discriminant analysis (LDA), represent an interesting way to investigate this qualitative information. Nevertheless, they have only been applied to the analysis of contamination data from food products and biological matrices infrequently. The objective of the present study was to analyze a large data set from dioxin analyses performed on various food products of animal origin. The results demonstrate the existence of differences in congener-specific patterns between the analyzed samples. Variability was first demonstrated in terms of the food type (fish, meat, milk, fatty products). Then a variability was observed that was related to the specific animal species for meat and milk samples (bovine, ovine, porcine, caprine and poultry). Some practical applications of these results are discussed. The origin(s) of the observed differences, as well as their significance, now remain to be investigated, both in terms of environmental factors and transfer through living organisms. A better knowledge of the relation between a contamination profile and its specific source and/or food product should be of great interest to scientists working in the fields of contaminant analysis, toxicology and metabolism, as well as to regulatory bodies and risk assessors in charge of final decisions regarding the eventual hazards associated with theses substances.     

Multiresidue method for simultaneous determination of ten quinolone antibacterial residues in multimatrix/multispecies animal tissues by liquid chromatography with fluorescence detection: single laboratory validation study

Quinolone antibacterials are veterinary drugs authorized for use in food animal production. The analysis of residual amounts of drugs in food from animal origin is important for quality control of products for consumers. For this purpose, Maximum Residue Limits (MRLs) have been set up by a European Union Council Regulation on Veterinary Drug Residues (No. 90/2377/EEC and subsequent), and 8 quinolones received MRLs at concentration levels depending on both the matrix and the animal species of interest. A method was developed for screening and confirming 10 quinolone residues (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, flumequine, marbofloxacin, nalidixic acid, norfloxacin, oxolinic acid, sarafloxacin) in a wide variety of matrixes of different animal species. It involves extraction of the residues from the biological tissues/fluids by acidic aqueous solution, centrifugation and filtration prior to injection on a C18 narrow-bore column, and detection through a 3-step-mode fluorescence detector. The method was validated during a 2-week study for a set of 8 species-matrixes (i.e., bovine raw milk, bovine muscle, porcine muscle, porcine kidney, porcine liver, fish flesh and skin, poultry muscle, whole egg). Residues were quantified down to 15 microg/kg with limits of detection and quantitation ranging from 4 to 11 and 13 to 36 microg/kg, respectively, which are sufficient compared to the wide range of MRLs set for these substances (from 30 microg/kg for danofloxacin in milk to 1900 microg/kg for difloxacin in poultry liver). The limit of performance of the method in terms of CCalpha and CCbeta, the critical concentrations stated in the Decision No. 2002/657/EC and the ISO Standard No. 11843, has been calculated for the authorized (MRL) substances but only estimated in the case of the nonauthorized (non-MRL) substances.     

A quantitative method for the detection of sulfonamide residues in meat and milk samples with a high-performance thin-layer chromatographic method.

Sulfonamides are widely used in veterinary medicine for prophylactic purposes and for the treatment of various infections of food-producing animals. This means that residues of these drugs and their possible metabolites may occur in food of animal origin. In Belgium, a zero tolerance level for sulfonamides in edible animal tissues has been set. In order to check this zero level on a routine basis, a rapid and sensitive method has to be available. For this purpose, a quantitative high-performance thin-layer chromatographic (HPTLC) method for the detection of sulfonamide residues in animal tissue and milk samples has been developed. The sample preparation consists of a liquid extraction followed by a solid phase extraction (SPE) on disposable columns for the meat samples and a matrix solid phase dispersion (MSPD) for the milk samples. A three-multiple development chromatographic system is used for the separation and a derivatization with fluorescamine decreases the minimal detectable quantity per spot from 1.42 to 0.32 ng. The limit of quantification is 4 micrograms/kg for milk and meat samples.