In-house validation of a liquid chromatography/electrospray tandem mass spectrometry method for confirmation of chloramphenicol residues in muscle according to Decision 2002/657/EC

In this work we present an in-house validation study for the confirmatory analysis of chloramphenicol (CAP) in muscle according to the Commission Decision 2002/657/EC requirements. CAP is extracted in acetonitrile and after liquid-liquid partitioning with n-hexane is identified and quantitatively determined by ion trap liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) analysis in the negative ion mode. CAP was identified using the precursor ion and at least two product ions, meeting the qualitative and quantitative criteria set by the European Commission in the Decision 2002/657/EC for confirmation of prohibited veterinary drug residues. We calculated mean drug recoveries, CCalpha and CCbeta of the method, and reported data on specificity, ruggedness and within-laboratory reproducibility. Finally, we point out and discuss some problems and questions arising from controversy about the application of Decision 2002/657/EC.     

Calculation of the decision limit (CCalpha) and the detection capability (CCbeta) for banned substances: the imperfect marriage between the quantitative and the qualitative criteria

Initially in the Decision 2002/657/EC the criteria for the calculation of the decision limit (CCalpha) and the detection capability (CCbeta) have been estimated as purely quantitative (alpha-error is 1% and beta-error is 5%). In 2004, the European Commission has issued a document to provide guidance for the interpretation of the 2002/657/EC. In this document it is mentioned that also qualitative criteria should be fulfilled. Therefore, the calculated CCalpha and CCbeta must be verified by using fortified samples. The method should be able to detect/identify the target component in 50% of the cases at CCalpha and in 95% of the cases at CCbeta. Analytical methods for the analysis of nitroimidazoles, nitrofurans and corticosteroids with LC-MS/MS have been validated by fortifying blank samples below and above the MRPL. CCalpha and CCbeta were calculated using the ISO 11843 approach. In addition, the frequency of methodical compliance for the qualitative criteria was determined at each concentration level. It was observed that at the calculated CCalpha and CCbeta levels the qualitative criteria were not fulfilled. It was concluded that the detection capability of the analytical method should be calculated by using decreasing fortification levels at and below the MRPL. A protocol validating methods for banned substances by limiting the number of samples is presented and the qualitative criteria for the assessment of CCalpha and CCbeta were verified based on the same set of data without the need of performing additional validation experiments.     

Determination of residual fluoroquinolones in honey by liquid chromatography using metal chelate affinity chromatography

A new analytical method for the simultaneous determination of seven fluoroquinolones, namely, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, orbifloxacin, sarafloxacin, and difloxacin, especially in dark-colored honey, has been developed. Fluoroquinolone antibiotics were extracted from samples with MacIlvaine buffer solution (pH 4.0) containing EDTA disodium salt dihydrate. The extracts were treated with both a polymeric cartridge and a metal chelate affinity column preloaded with ferric ion (Fe3+). LC separation with fluorescence detection was performed at 40 degrees C using an Inertsil ODS-4 analytical column (150 x 4.6 mm, 3 microm). The mobile phase was composed of 20 mM/L citrate buffer solution (pH 3.1)-acetonitrile mixture (70 + 30, v/v) containing 1 mM/L sodium dodecyl sulfate. Lomefloxacin was used as an internal standard. The developed method was validated according to the criteria of European Commission Decision 2002/657/EC. Decision limits and detection capabilities were below 2.9 and 4.4 microg/kg, respectively.     

Performance characteristics of an analytical procedure for determining chloramphenicol residues in muscle tissue by gas chromatography-electron capture detection

Validation of an analytical method for determining chloramphenicol residues in muscle tissue by gas chromatography-electron capture detection (GC-ECD) was performed according to the latest European Union criteria for the analysis of veterinary drugs in food, laid down by Commission Decision 2002/657/EC. The method using the meta isomer of chloramphenicol as an internal standard proved to be very selective, specific to other related phenicols and accurate to within +3.6% at a concentration level of 8.9 microg/kg, as present in the certified reference material available. The correlation coefficient of the calibration curve was 0.9991. At all three fortification levels studied (0.3, 0.45 and 0.6 microg/kg), repeatability and intra-laboratory reproducibility were <8 and < or =9%, respectively. The decision limit (CCalpha) and detection capability (CCbeta) were 0.07 and 0.12 microg/kg, respectively. The validation results and the results of participation in an international inter-laboratory proficiency test indicate that the method presented is completely suited for regulatory control to screen and quantify chloramphenicol residues in various muscle tissues on a routine basis.     

Determination of ochratoxin A at parts-per-trillion levels in cereal products by immunoaffinity column cleanup and high-performance liquid chromatography/mass spectrometry

Ochratoxin A (OTA) is a toxic and potentially carcinogenic fungal toxin found in a variety of food commodities. A new sensitive method has been developed to quantify OTA in cereal products by reversed-phase liquid chromatography (LC) with mass spectrometric (MS) detection. Ochratoxin B was used as the internal standard. OTA was extracted from cereal products with acetonitrile-water, and the extract was diluted with a buffer; the diluted extract was cleaned up on an immunoaffinity column before LC/MS analysis. Two multiple-reaction monitoring transitions were used, one for quantification of OTA and one for confirmation of identity. The method was shown to be highly sensitive, with a low decision limit (CCalpha) of 0.012 microg/kg and a detection capability (CCbeta) of 0.021 microg/kg. Within-laboratory repeatability coefficient of variation values were 7.1, 3.7, and 3.1%, and the corresponding recoveries were 104, 106, and 103% for rice samples fortified with OTA at 0.05, 0.10, and 0.15 microg/kg, respectively. Method validation was performed according to the criteria of European Commission Decision 2002/657/EC. All criteria as presented in the Commission Decision were fulfilled. This method is the first fully validated method using immunoaffinity chromatography for cleanup and MS for detection in the analysis of cereals for OTA. The method was also successfully applied to cereal-derived products. The analytical results for determination of the OTA content of cereal products commercially available in Hong Kong are also reported.     

Influence of matrix on suitability of four methods for organochlorine pesticide analysis in waters

The monitoring of organochlorine pesticides has raised a great concern in the last years due to their toxicity (some of them are carcinogenic and endocrine disruptor compounds) and persistence. European Directive 2008/105/EC establishes very restrictive levels for organochlorine pesticides in surface waters. Therefore, simple, fast, highly sensitive and low cost analytical methods are required to detect and quantify these pollutants in water. In the present work, four procedures for extraction and determination are proposed and compared for the analysis of 28 organochlorine pesticides in tap, surface and sea waters. The suitability of each method of analysis was evaluated for each kind of water. The extraction methods proposed were: two solid-phase extraction methods using C₁₈ laminar disk and Oasis HLB cartridges, a solid-phase microextraction procedure using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre, and a micro liquid–liquid extraction procedure using ethyl acetate as solvent. Determination of pesticides was performed by large volume on-column injector-gas chromatography-electron capture detection (LVOCI-GC-ECD), splitless-GC-ECD and GC-MS (mass spectrometry). All methods present a good sensitivity with method detection limits lower than 10?ng?L^?1, good accuracy with recoveries between 75 and 120% (with some exceptions) and good precision (relative standard deviations <15%), according to the Commission Decision 2002/657/EC criteria. The advantages and disadvantages of each method are discussed in terms of the green chemistry principles, the figures of merit and the matrix effect. This work tries to be a useful guidance for routine and control analysis laboratories.     

Development, validation and data quality assurance of screening methods: a case study

Despite the growing importance of qualitative screening tests in routine laboratories involved in the EU official control, their validation is not as deeply explained in Commission Decision 2002/657/EC as the validation of quantitative confirmatory methods. At the same time, the issue of quality assurance of screening assays defining internal quality control (IQC) procedures as required by accreditation bodies is undoubtedly less developed in this analytical field. As an example the present study describes the development, the validation and the IQC implemented for a commercial enzyme linked immunosorbent assay (ELISA) able to detect 17-α-19-nortestosterone (α-NT) and 17-β-19-nortestosterone (β-NT) isomers in bullock urine. In order to select a suitable sample treatment, two SPE purification protocols were preliminary compared. The chosen method was therefore fully validated determining the mandatory parameters required by Commission Decision 2002/657/EC: specificity, detection capability and robustness. An in-depth discussion was carried out illustrating the possible validation approaches and their implications especially in the assessment of the key performance characteristic: detection capability. Finally, the control charts implemented for continuous method verification during analyses of real samples were reported.     

Validation of HPLC Analysis of 2-Phenoxyethanol, 1-Phenoxypropan-2-ol, Methyl, Ethyl, Propyl, Butyl and Benzyl 4-Hydroxybenzoate (Parabens) in Cosmetic Products, with Emphasis on Decision Limit and Detection Capability

The Commission Decision of August 12, 2002 on the performance of analytical methods and the interpretation of results was applied to the HPLC method for the analysis of parabens, 2-phenoxyethanol and 1-phenoxypropan-2-ol in cosmetic products. This method is published in the seventh Directive 96/45/EC of the European Commission. Non-compliant concentrations, taking into account the data distribution (CC) and the probability of false negative values (CC) were determined. The repeatability and reproducibility amount to <4% and <7%, respectively. These values were obtained with blanc samples that were fortified in the laboratory. Calibration linearity was confirmed by absence of lack of fit for all seven preservatives. Matrix effects on the determinations of the preservatives in body milk or shampoo are negligible.     

High-throughput analysis of amnesic shellfish poisoning toxins in shellfish by ultra-performance rapid resolution LC-MS/MS

The application of ultra-performance rapid resolution LC on a 1.8 microm particle-size column coupled with tandem MS (RRLC-MS/MS) is described for the analysis of amnesic shellfish poisoning (ASP) toxins in shellfish. Complete resolution among domoic acid (DA) and the isomers was achieved in less than 3 min. The method was intralaboratory validated for direct analysis of crude extracts without further cleanup. It showed LODs ranging from 0.05 to 0.09 mg/kg and a working range that complied with the current regulatory level for DA of 20 mg/kg, and with the level of 4.5 mg/kg recently proposed by the European Food Safety Authority. Confirmatory capabilities were demonstrated according to the Commission Decision 2002/657/EC criteria. The results obtained by RRLC-MS/MS agreed with those provided by the reference LC-UV method, both intralaboratory for the analysis of blind samples (R2 = 0.9751) and interlaboratory through participation in the proficiency test for ASP toxins during 2009 (z-score = -0.962 and 0.177 for low- and high-contaminated samples, respectively). RRLC-MS/MS provided fast analysis and additional confirmatory capabilities for direct analysis of crude extracts while the performance and reliability of the results were maintained, even in very complex matrixes.     

Identification and quantification of enrofloxacine in poultry feeding water through excitation emission fluorescence and three-way PARAFAC calibration

In this work an excitation emission molecular fluorescence technique with PARAFAC calibration is proposed for enrofloxacine determination in feeding water from poultry farms. In accordance with the working criteria of the 2002/657/EC European Decision, the proposed method has a capability of detection, CCbeta, of 6.8 microg l(-1), for both probabilities of false positive and false negative of 5%. The accuracy of the method is demonstrated and its precision is 1.7 microg l(-1), expressed as standard deviation. This method allows one to identify and determine the quantity of enrofloxacine present in water samples from poultry farms without it being necessary to determine the possible interferents, nor separate them in a step previous to calibration.     

Multiresidue Screening of Veterinary Drugs in Meat,Milk, Egg,and Fish Using Liquid Chromatography Coupled with Ion Trap Time-of-Flight Mass Spectrometry

New approaches to veterinary drug screening based on liquid chromatography-mass spectrometry (LC-MS/MS) and time-of-flight mass spectrometry (ToF/MS) are rapid and have high selectivity and sensitivity. In this study, we developed a multiresidue method for screening over 100 veterinary drug residues using ion trap (IT)-ToF/MS. The screened compounds comprised major drug classes used in veterinary practice, representing the following: amphenicols, anthelmintics, benzimidazoles, β-lactams, coccidiostats, ionophores, macrolides, non-steroidal anti-inflammatory drugs, quinolones, sulfonamides, tetracyclines, and tranquilizers. The method was developed based on chromatographic retention time, specific accurate mass, isotope distribution, and fragment data. Each compound was validated at three levels, and the mass accuracy, accuracy, and repeatability were calculated. All parameters showed acceptable values and conformed to the Commission Decision 2002/657/EC criteria. This screening method can simultaneously analyze over 100 veterinary drugs in meat, milk, eggs, and fish in a single analytical run.     

Validation of an analytical method to determine sulfamides in kidney by HPLC-DAD and PARAFAC2 with first-order derivative chromatograms

Six sulfamides were extracted from kidney and analysed by high-performance liquid chromatography with diode array detection (HPLC-DAD): sulfadiazine, sulfamethazine, sulfamethoxypyridazine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline.Two main difficulties arose in identifying and quantifying the analytes. Firstly, the chromatographic peaks of the matrix interferences overlapped with those of the analytes. The uniqueness property of PARAFAC2 solved this problem. Secondly, the gradient elution caused a baseline drift. The first-order derivative of the chromatograms minimized its effect.The analytical method was validated. As the performance criteria detailed in the European Decision 2002/657/EC are based on specific signals, this paper generalizes those criteria for higher-order and non-specific signals. In this sense the proposed methodology is general and can be applied to any chromatographic method (HPLC or GC) with a detector that provide a multivariate signal (MS, DAD, EC, etc.).     

Multiresidue HPLC analysis of ten quinolones in milk after solid phase extraction: validation according to the European Union Decision 2002/657/EC

A rapid and sensitive analytical method was developed for the residue analysis of ten quinolones (enoxacin (ENO), ofloxacin (OFL), norfloxacin (NOR), ciprofloxacin (CIP), danofloxacin (DAN), enrofloxacin (ENR), sarafloxacin (SAR), oxolinic acid (OXO), nalidixic acid (NAL), and flumequine (FLU)) in cow's milk. The analytes were extracted from milk by a deproteinization step followed by a simple SPE cleanup procedure using LiChrolut RP-18 Merck cartridges. Recoveries varied between 75 and 92%. HPLC separation was performed at 25 degrees C using an ODS-3 PerfectSil Target (250 x 4 mm(2)) 5 microm analytical column (MZ-Analysentechnik, Germany). The mobile phase consisted of a mixture of TFA 0.1%-CH(3)CN-CH(3)OH, delivered by a gradient program at the flow rate of 1.2 mL/min. Elution of the ten analytes and the internal standard (caffeine, 7.5 ng/microL) was completed within 27 min. Column effluent was monitored using a photodiode array detector, set at 275 and 255 nm. The developed method was validated according to the criteria of Commission Decision 2002/657/EC. The LODs of the specific method of quinolones' determination in milk varied between 1.5 and 6.8 ng/microL.     

A new certified reference material for the quality control of palladium, platinum and rhodium in road dust, BCR-723

Certified Reference Materials (CRMs) represent a key tool for the quality control of chemical analyses. The demand for environmental materials is constantly increasing in complex analytical fields, and the European Commission (EC) (through the Measurements & Testing Generic Activity) is responding to the urgent needs for materials requiring collaborative efforts at the international level. This paper describes the preparation of a new road-dust material (BCR-723), along with homogeneity and stability studies and the analytical work performed for the certification of the contents of palladium, platinum and rhodium, under the EC's PACEPAC project, PACEPAC being the acronym for “Production And CErtification of a road dust reference material for Platinum, palladium and rhodium used in Automotive Catalytic converters”.     

A downscaled multi-residue strategy for detection of anabolic steroids in bovine urine using gas chromatography tandem mass spectrometry (GC-MS3)

Within the scope of the European Community member states' residue monitoring plan, illicit administration of anabolic steroids is monitored at slaughterhouse level as well as on living animals. At farm level, urine is one of the target matrices to detect possible abuse of anabolic steroid growth promoters. Optimisation of the routinely applied analysis method resulted in a procedure for which high performance liquid chromatographic (HPLC) fractionation prior to GC-MS(n) analysis was no longer required. Analytical results could be obtained within 1 day and only 5 mL urine was needed to carry out the screening procedure. Using the downscaled methodology, all validation criteria described in the European Commission document 2002/657/EC could be fulfilled, and the minimum required performance limits (MRPLs) established for anabolic steroids in urine, could be achieved. A higher GC-MS technique's specificity was achieved by detecting the steroids using GC-MS3. Nevertheless, it was decided to screen routinely sampled urine with GC-MS2 whereas GC-MS3 was applied to confirm the presence of anabolic steroid residues in suspected sample extracts.     

Determination of eleven coccidiostats in animal feed by liquid chromatography-tandem mass spectrometry at cross contamination levels

A confirmatory multi-residue method has been developed to allow for the detection, confirmation and quantification of eleven coccidiostats in animal feed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method can be used to determine halofuginone, robenidine, nicarbazin, diclazuril, decoquinate, semduramicin, lasalocid, monensin, salinomycin, narasin, maduramicin at levels relating to unavoidable carry over as stated in Regulation 2009/8/EC. Feed samples are extracted with water and acetonitrile with the addition of anhydrous magnesium sulphate and sodium chloride. The extract then undergoes a freezing out step before being diluted and injected onto the LC-MS/MS system. The LC-MS/MS system is run in MRM mode with both positive and negative electrospray ionisation and can confirm all eleven analytes in a run time of 19 min. The sensitivity of the method allows quantification and confirmation for all coccidiostats at a 0.5% carry over level. The method was validated over three days in accordance with of European legislation; Commission Decision 2002/657/EC. Validation criteria of accuracy, precision, decision limit (CCα), and detection capability (CCβ) along with measurement uncertainty are calculated for all analytes. The method was then successfully used to analyse a number of feed samples that contained various coccidiostat substances.     

Monitoring dioxins in food and feedstuffs using accelerated solvent extraction with a novel integrated carbon fractionation cell in combination with a CAFLUX bioassay

The concentrations of dioxins in fish oil and fish meal were determined with accelerated solvent extraction, using a novel integrated carbon fractionation extraction cell followed by a miniturized multilayer silica column and bioanalysis on a recently-developed chemically-activated fluorescent gene expression cell bioassay. The developed method allows for simultaneous gravimetric lipid weight determination, which was shown for both matrices under study (about 100% lipid recovery of each sample). Initial results practically meet the quality criteria on screening methods for control of dioxins in food and feedstuffs laid down in the EU Commission Directives 2002/69/EC (food) and 2002/70/EC (feed). This demonstrates that the developed method can be used as a screening tool for monitoring dioxins in food and feed after some additional improvements and testing on a greater number of matrices.     

Improvements in methylmercury determination prior to the certification of two tuna fish materials

An account is given of a systematic, collaborative investigation to detect problems and sources of error in the determination of methylmercury (MeHg) in biological samples. The work was done by a group of analytical laboratories under the auspices of the Community Bureau of References (BCR) of the Commission of the European Communities (EC). The paper presents the organization of three intercomparisons on organic mercury in solution and solid matrices, and the results obtained by the participants. The different analytical steps of the methods used (extraction, clean-up, separation, final detection) are compared and assessed.     

Development and validation of a solid-phase extraction method coupled to high-performance liquid chromatography with ultraviolet-diode array detection for the determination of sulfonylurea herbicide residues in bovine milk samples

This study proposes a fast, simple and sensitive liquid chromatography diode array detector (LC/UV-DAD)-based method for the simultaneous determination of eight sulfonylurea herbicides (bensulfuron methyl, chlorsulfuron, metsulfuron methyl, primisulfuron methyl, rimsulfuron, thifensulfuron methyl, triasulfuron and tribenuron methyl) in bovine whole milk at concentrations lower than the default limit of 0.01 mg kg(-1) allowed by current legislation (Regulation EC/396/2005 and following Annexes). An effective one-step solid phase extraction (SPE) and clean up procedure was defined with use of Chem Elut cartridges, providing good recoveries for all the analytes tested and with no matrix effects affecting method accuracy. Separation of herbicides was obtained on a C(18) column by acetonitrile- water gradient elution. Method validation has been performed according to European Commission Decision 2002/657/EC criteria, in terms of linearity, recovery, precision, specificity, decision limit (CC(α)) and detection capability (CC(β)). Typical recoveries ranged between 78.4% and 99.7%, at the maximum residue limits (MRLs) levels established by Regulation EC/396/2005, with relative standard deviations (RSD) no larger than 10%.     

Validation of the analytical procedure for the determination of polyaromatic hydrocarbons in smoke flavourings using high performance liquid chromatography coupled to an ultraviolet,diode array or fluorescence detector

High performance liquid chromatography (HPLC) coupled to an ultraviolet (UV), diode array or fluorescence detector (UV/DAD/FLD) has been used to set up an analytical procedure for the quantification of 16 EU priority polyaromatic hydrocarbons (PAHs) in smoke flavourings. The following parameters have been determined for the 16 EU priority PAHs: limit of detection, limit of quantification, precision (repeatability and intermediate precision), recovery and measurement uncertainty, using the concept of accuracy profiles. They were in close agreement with quality criteria described in the Commission Regulation (EC) no. 627/2006 concerning PAHs in smoke flavourings. Presented at the AOAC Europe Workshop, November 2006, Limassol, Cyprus