Liam Regan

Dublin Institute of Technology, Dublin, L, Ireland

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Publications (21)49.17 Total impact

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    ABSTRACT: 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.
    Analytica chimica acta 08/2011; 700(1-2):26-33. · 4.31 Impact Factor
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    ABSTRACT: A liquid chromatography-tandem mass spectrometry method, recently developed, validated and accredited, was used to screen for metronidazole, ronidazole dimetridazole ipronidazole, ternidazole, tinidazole, ornidazole carnidazole and three hydroxy metabolites (hydroxy-metronidazole, HMMNI and hydroxy-ipronidazole) in Irish retail egg samples. The method used had decision limits (CCα) in the range 0.33-1.26 µg kg(-1) and detection capabilities (CCβ) ranging 0.56-2.15 µg kg(-1) for all analytes. Internal standard-corrected recovery, calculated for the various analytes, ranged 87.2-106.2%, while the coefficient of variance, expressed as % CV, ranged 3.7-11.3%. The method was applied to 160 samples of caged, free range and organic hen and duck eggs available on the Irish retail market as well as two incurred proficiency test egg samples. No nitroimidazole residues were detected in the survey samples above the CCα and the results achieved for the two proficiency test samples were acceptable when compared with the assigned values.
    Food Additives and Contaminants: Part B Surveillance 06/2011; 4(2):79-87.
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    ABSTRACT: A simple, new method permitting the simultaneous determination and confirmation of trace residues of 24 different growth promoters and metabolites using liquid chromatography-mass spectrometry was developed and validated. The compounds were extracted from bovine tissue using acetonitrile; sodium sulphate was also added at this stage to aid with purification. The resulting mixture was then evaporated to approximately 1 ml and subsequently centrifuged at high speed and an aliquot injected onto the LC-MS/MS system. The calculated CCα values ranged between 0.11 and 0.46 µg kg(-1); calculated CCβ were in the range 0.19-0.79 µg kg(-1). Accuracy, measurement of uncertainty, repeatability and linearity were also determined for each analyte. The analytical method was applied to a number of bovine tissue samples imported into Ireland from third countries. Levels of progesterone were found in a number of samples at concentrations ranging between 0.28 and 30.30 µg kg(-1). Levels of alpha- and beta-testosterone were also found in a number of samples at concentrations ranging between 0.22 and 8.63 µg kg(-1) and between 0.16 and 2.08 µg kg(-1) respectively.
    Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment 05/2011; 28(5):597-607.
  • Geraldine Dowling, Liam Regan
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    ABSTRACT: A rapid method has been developed to analyse morphine, codeine, 6-monoacetylmorphine, cocaine, benzoylecgonine, dihydrocodeine, cocaethylene, 3,4-methylenedioxyamphetamine, ketamine, 3,4-methylenedioxymethamphetamine, pseudoephedrine, lignocaine, benzylpiperazine, methamphetamine, amphetamine, methadone, phenethylamine and levamisole in human blood. Blood samples were cleaned up using mixed mode solid phase extraction using Evolute™ CX solid phase extraction cartridges and the sample aliquots were analysed by hybrid triple quadrupole linear ion trap (QTRAP) mass spectrometry with a runtime of 12.5 min. Multiple reaction monitoring (MRM) as survey scan and an enhanced product ion (EPI) scan as dependent scan were performed in an information-dependent acquisition (IDA) experiment. Finally, drug identification and confirmation was carried out by library search with a developed in-house MS/MS library based on EPI spectra at a collision energy spread of 35 ± 15 in positive mode and MRM ratios. The method was validated in blood, according to the criteria defined in Commission Decision 2002/657/EC. At least two MRM transitions for each substance were monitored in addition to EPI spectra. Deuterated analogues of analytes were used as internal standards for quantitation where possible. The method proved to be simple and time efficient and was implemented as an analytical strategy for the illicit drug monitoring of opioids, cocaines, amphetamines and adulterants in forensic cases of crime offenders, abusers or victims in the Republic of Ireland.
    Journal of pharmaceutical and biomedical analysis 04/2011; 54(5):1136-45. · 2.45 Impact Factor
  • Geraldine Dowling, Liam Regan
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    ABSTRACT: A rapid method has been developed to analyse CP 47, 497 in human urine. Urine samples were diluted with water:acetonitrile (90:10, v/v) and sample aliquots were analysed by triple quadrupole tandem mass spectrometry with a runtime of 5 min. Multiple reaction monitoring (MRM) as survey scan was performed. The method was validated in urine, according to an in-house validation protocol based on the criteria defined in Commission Decision 2002/657/EC. Three MRM transitions were monitored. The decision limit (CCα) was 0.01μg mL⁻¹ and for the detection capability a (CCβ) value of 0.02 μg mL⁻¹ was obtained. The measurement uncertainty of the method was 21%. Fortifying human urine samples (n=18) in three separate assays, show the accuracy of the method to be between 95 and 96%. The precision of the method, expressed as RSD values for the within-lab reproducibility at the three levels of fortification (0.1, 0.15 and 0.2 μg mL⁻¹) was less than 10% respectively. The method proved to be simple, robust and time efficient. To the best of our knowledge there are no LC-MS methods for the determination of CP 47, 497 with validation data in urine.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 02/2011; 879(3-4):253-9. · 2.78 Impact Factor
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    ABSTRACT: A confirmatory method has been developed to allow for the analysis of fourteen prohibited medicinal additives in pig and poultry compound feed. These compounds are prohibited for use as feed additives although some are still authorised for use in medicated feed. Feed samples are extracted by acetonitrile with addition of sodium sulfate. The extracts undergo a hexane wash to aid with sample purification. The extracts are then evaporated to dryness and reconstituted in initial mobile phase. The samples undergo an ultracentrifugation step prior to injection onto the LC-MS/MS system and are analysed in a run time of 26 min. The LC-MS/MS system is run in MRM mode with both positive and negative electrospray ionisation. The method was validated over three days and is capable of quantitatively analysing for metronidazole, dimetridazole, ronidazole, ipronidazole, chloramphenicol, sulfamethazine, dinitolimide, ethopabate, carbadox and clopidol. The method is also capable of qualitatively analysing for sulfadiazine, tylosin, virginiamycin and avilamycin. A level of 100 microg kg(-1) was used for validation purposes and the method is capable of analysing to this level for all the compounds. Validation criteria of trueness, precision, repeatability and reproducibility along with measurement uncertainty are calculated for all analytes.
    Journal of pharmaceutical and biomedical analysis 12/2010; 53(4):929-38. · 2.45 Impact Factor
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    ABSTRACT: A rapid method has been developed to analyse morphine, codeine, morphine-3-glucuronide, 6-monoacetylmorphine, cocaine, benzoylegonine, buprenorphine, dihydrocodeine, cocaethylene, 3,4-methylenedioxyamphetamine, ketamine, 3,4-methylenedioxymethamphetamine, pseudoephedrine, lignocaine, benzylpiperazine, methamphetamine, amphetamine, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine and methadone in human urine. Urine samples were diluted with methanol:water (1:1, v/v) and sample aliquots were analysed by hybrid linear ion trap-triple quadrupole mass spectrometry with a runtime of 12.5 min. Multiple reaction monitoring (MRM) as survey scan and an enhanced product ion (EPI) scan as dependent scan were performed in an information-dependent acquisition (IDA) experiment. Finally, drug identification and confirmation was carried out by library search with a developed in-house MS/MS library based on EPI spectra at a collision energy spread of 35±15 in positive mode and MRM ratios. The method was validated in urine, according to the criteria defined in Commission Decision 2002/657/EC. At least two MRM transitions for each substance were monitored in addition to EPI spectra and deuterated analytes were used as internal standards for quantitation. The reporting level was 0.05 μg mL(-1) for the range of analytes tested. The regression coefficients (r(2)) for the calibration curves (0-4 μg mL(-1)) in the study were ≥0.98. The method proved to be simple and time efficient and was implemented as an analytical strategy for the illicit drug monitoring of opioids, cocaines and amphetamines in criminal samples from crime offenders, abusers or victims in the Republic of Ireland. To the best of our knowledge there are no hybrid LC-MS applications using MRM mode and product ion spectra in the linear ion trap mode for opioids, cocaines or amphetamines with validation data in urine.
    Journal of Chromatography A 10/2010; 1217(44):6857-66. · 4.61 Impact Factor
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    ABSTRACT: A confirmatory method was developed to allow for the analysis of eleven nitroimidazoles and also chloramphenicol in milk and honey samples. These compounds are classified as A6 compounds in Annex IV of Council Regulation 2377/90 (European Commission 1990) and therefore prohibited for use in animal husbandry. Milk samples were extracted by acetonitrile with the addition of NaCl; honey samples were first dissolved in water before a similar extraction. Honey extracts underwent a hexane wash to remove impurities. Both milk and honey extracts were evaporated to dryness and reconstituted in initial mobile phase. These were then injected onto a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system and analysed in less than 9 min. The MS/MS was operated in multiple reaction monitoring (MRM) mode with positive and negative electrospray ionization. The method was validated in accordance with Commission Decision 2002/657/EC and is capable of analysing metronidazole, dimetridazole, ronidazole, ipronidazole and there hydroxy metabolites hydroxymetronidazole, 2-hydroxymethyl-1-methyl-5-nitroimidazole, and hydroxyipronidazole. The method can also analyse for carnidazole, ornidazole, ternidazole, tinidazole, and chloramphenicol. A recommended level of 3 microg l(-1)/microg kg(-1) for methods for metronidazole, dimetridazole, and ronidazole has been recommended by the Community Reference Laboratory (CRL) responsible for this substance group, and this method can easily detect all nitroimidazoles at this level. A minimum required performance level of 0.3 microg l(-1)/microg kg(-1) is in place for chloramphenicol which the method can also easily detect. For nitroimidazoles, the decision limits (CCalpha) and detection capabilities (CCbeta) ranged from 0.41 to 1.55 microg l(-1) and from 0.70 to 2.64 microg l(-1), respectively, in milk; and from 0.38 to 1.16 microg kg(-1) and from 0.66 to 1.98 microg kg(-1), respectively, in honey. For chloramphenicol, the values are 0.07 and 0.11 microg l(-1) in milk and 0.08 and 0.13 microg kg(-1) in honey. Validation criteria of accuracy, precision, repeatability, and reproducibility along with measurement uncertainty were calculated for all analytes in both matrices.
    Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment 09/2010; 27(9):1233-46.
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    ABSTRACT: A rapid liquid chromatographic-tandem mass spectrometric (LC-MS/MS) multi-residue method for the simultaneous quantitation and identification of sixteen synthetic growth promoters and bisphenol A in bovine milk has been developed and validated. Sample preparation was straightforward, efficient and economically advantageous. Milk was extracted with acetonitrile followed by phase separation with NaCl. After centrifugation, the extract was purified by dispersive solid-phase extraction with C18 sorbent material. The compounds were analysed by reversed-phase LC-MS/MS using both positive and negative ionization and operated in multiple reaction monitoring (MRM) mode, acquiring two diagnostic product ions from each of the chosen precursor ions for unambiguous confirmation. Total chromatographic run time was less than 10 min for each sample. The method was validated at a level of 1 microg L(-1). A wide variety of deuterated internal standards were used to improve method performance. The accuracy and precision of the method were satisfactory for all analytes. The confirmative quantitative liquid chromatographic tandem mass spectrometric (LC-MS/MS) method was validated according to Commission Decision 2002/657/EC. The decision limit (CCalpha) and the detection capability (CCbeta) were found to be below the chosen validation level of 1 microg L(-1) for all compounds.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 03/2010; 878(15-16):1077-84. · 2.78 Impact Factor
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    ABSTRACT: An LC/MS/MS method was developed and validated for the simultaneous identification, confirmation, and quantification of 12 glucocorticoids in bovine milk. The method was validated in accordance with the criteria defined in Commission Decision 2002/657/EC. The developed method can detect and confirm the presence of dexamethasone, betamethasone, prednisolone, flumethasone, 6alpha-methylprednisolone, fluorometholone, triamcinolone acetonide, prednisone, cortisone, hydrocortisone, clobetasol propionate, and clobetasol butyrate in bovine milk. Milk samples are extracted with acetonitrile; sodium chloride is subsequently added to aid partition of the milk and acetonitrile mixture. The acetonitrile extract is then subjected to liquid-liquid purification by the addition of hexane. The purified extract is evaporated to dryness and reconstituted in a water-acetonitrile mixture, and determination is carried out by LC/MS/MS. The method permits analysis of up to 30 samples in 1 day.
    Journal of AOAC International 01/2010; 93(5):1656-65. · 1.23 Impact Factor
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    ABSTRACT: A confirmatory method has been developed and validated that allows for the simultaneous detection of medroxyprogesterone acetate (MPA), megestrol acetate (MGA), melengestrol acetate (MLA), chlormadinone acetate (CMA) and delmadinone acetate (DMA) in animal kidney fat using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The compounds were extracted from kidney fat using acetonitrile, defatted using a hexane wash and subsequent saponification. Extracts were then purified on Isolute CN solid-phase extraction cartridges and analysed by LC-MS/MS. The method was validated in animal kidney fat in accordance with the criteria defined in Commission Decision 2002/657/EC. The decision limit (CCalpha) was calculated to be 0.12, 0.48, 0.40, 0.63 and 0.54 microg kg(-1), respectively, for MPA, MGA, MLA, DMA and CMA, with respective detection capability (CCbeta) values of 0.20, 0.81, 0.68, 1.07 and 0.92 microg kg(-1). The measurement uncertainty of the method was estimated at 16, 16, 19, 27 and 26% for MPA, MGA, MLA, DMA and CMA, respectively. Fortifying kidney fat samples (n = 18) in three separate assays showed the accuracy of the method to be between 98 and 100%. The precision of the method, expressed as % RSD, for within-laboratory reproducibility at three levels of fortification (1, 1.5 and 2 microg kg(-1) for MPA, 5, 7.5 and 10 microg kg(-1) for MGA, MLA, DMA and CMA) was less than 5% for all analytes.
    Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment 06/2009; 26(5):672-82.
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    ABSTRACT: A rapid confirmatory method has been developed and validated for the simultaneous identification, confirmation and quantitation of 11 nitroimidazoles in eggs by liquid chromatography tandem mass spectrometry (LC-MS/MS). The method is validated in accordance with Commission Decision 2002/657/EC and is capable of analysing metronidazole (MNZ), dimetridazole (DMZ), ronidazole (RNZ), ipronidazole (IPZ) and their hydroxy metabolites MNZ-OH, HMMNI (hydroxymethyl, methyl nitroimidazole), IPZ-OH. The method is also capable of analysing carnidazole (CRZ), ornidazole (ORZ), tinidazole (TNZ) and ternidazole (TRZ). MNZ, DMZ and RNZ have been assigned a recommended level (RL) of 3 microg kg(-1) by the Community Reference Laboratory (CRL) in Berlin. The developed method described in this study is easily able to detect all the nitroimidazole compounds investigated at this level and below. Egg samples are extracted with acetonitrile, and NaCl is added to help remove matrix contaminants. The acetonitrile extract undergoes a liquid-liquid wash step with hexane; it is then evaporated and reconstituted in mobile phase. The reconstituted samples are analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The decision limits (CCalpha) range from 0.33 to 1.26 microg kg(-1) and the detection capabilities (CCbeta), range from 0.56 to 2.15 microg kg(-1). The results of the in ter-assay study, which was performed by fortifying hen egg samples (n=18) on three separate days, show the accuracy calculated for the various analytes to range between 87.2 and 106.2%. The precision of the method, expressed as %CV values for the inter-assay variation of each analyte at the three levels of fortification (3, 4.5 and 6.0 microg kg(-1)), ranged between 3.7 and 11.3%. A Day 4 analysis was carried out to examine species variances in eggs from different birds such as duck and quail and investigating differences in various battery and free range hen eggs.
    Journal of Chromatography A 06/2009; 1216(46):8101-9. · 4.61 Impact Factor
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    ABSTRACT: A rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous identification, confirmation and quantitation of seven licensed anti-inflammatory drugs (AIDs) in bovine milk. The method was validated in accordance with the criteria defined in Commission Decision 2002/657/EC. Two classes of AIDs were investigated, corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs). The developed method is capable of detecting and confirming dexamethasone (DXM), betamethasone (BTM), prednisolone (PRED), tolfenamic acid (TLF), 5-hydroxy flunixin (5-OH-FLU), meloxicam (MLX) and 4-methyl amino antipyrine (4-MAA) at their associated maximum residue limits (MRLs). These compounds represent all the corticosteroids and NSAIDs licensed for use in bovine animals producing milk for human consumption. These compounds have never been analysed before in the same method and also 4-methyl amino antipyrine has never been analysed with the other licensed NSAIDs. The method can be considered rapid as permits the analysis of up to 30 samples in one day. Milk samples are extracted with acetonitrile; sodium chloride is added to aid partition of the milk and acetonitrile mixture. The acetonitrile extract is then subjected to liquid-liquid purification by the addition of hexane. The purified extract is finally evaporated to dryness and reconstituted in a water/acetonitrile mixture and determination is carried out by LC-MS/MS. Decision limit (CCalpha) values and detection capability (CCbeta) values have been established for each compound.
    Journal of Chromatography A 06/2009; 1216(46):8132-40. · 4.61 Impact Factor
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    ABSTRACT: A rapid method has been developed to analyse carprofen (CPF), diclofenac (DCF), mefenamic acid (MFN), niflumic acid (NIFLU), naproxen (NAP), oxyphenylbutazone (OXYPHEN), phenylbutazone (PBZ) and suxibuzone (SUXI) residues in bovine milk. Milk samples are extracted with acetonitrile and sample extracts were purified on Evolute ABN solid phase extraction cartridges. Aliquots were analysed by rapid resolution liquid chromatography tandem mass spectrometry (RRLC-MS/MS) with a runtime of 6.5 min. The method was validated in bovine milk, according to the criteria defined in Commission Decision 2002/657/EC. CCalpha values of 0.46, 1.08, 0.92, 1.26, 1.29, 2.12, 0.55 and 2.86 ng mL(-1) were determined for CPF, DCF, MFN, NIFLU, NAP, OXYPHEN, PBZ and SUXI, respectively. CCbeta values of 0.79, 1.85, 1.56, 2.15, 2.19, 3.62, 0.94 and 4.87 ng mL(-1) were determined for CPF, DCF, MFN, NIFLU, NAP, OXYPHEN, PBZ and SUXI, respectively. The measurement uncertainty of the method was estimated at 9, 28, 28, 45, 46, 45, 10 and 39% for CPF, DCF, MFN, NIFLU, NAP, OXYPHEN, PBZ and SUXI. Fortifying bovine milk samples (n=18) in three separate assays, show the accuracy of the method to be between 82 and 108%. The precision of the method, expressed as RSD values for the within-lab reproducibility at the three levels of fortification (5, 7.5 and 10 ng mL(-1)) was less than 16%, respectively. The advantage of the method is that low ng mL(-1) levels can be detected and quantitatively confirmed rapidly in milk and that 3 batches of samples can be analysed within a single day using RRLC-MS/MS with a runtime of 6.5 min.
    Journal of Chromatography A 06/2009; 1216(46):8117-31. · 4.61 Impact Factor
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    ABSTRACT: A rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous identification, confirmation and quantitation of thirteen synthetic growth promoters in bovine muscle. The method was validated in accordance with the criteria defined in Commission Decision 2002/657/EC. A value of 1mugkg(-1) was chosen as the required performance level (RPL) for all analytes. The growth promoters investigated were alpha and beta trenbolone, 16-beta-OH stanozolol, methylboldenone, fluoxymesterone, methyltestosterone, medroxyprogesterone acetate, megestrol acetate, melengestrol acetate, dexamethasone, flumethasone, dienestrol and hexestrol. The method involved enzymatic hydrolysis, purification by solid phase extraction followed by analysis by UPLC-MS/MS using electrospray ionization operated in both positive and negative polarities with a total run time of 14 min. The decision limit (CCalpha) values obtained, ranged from 0.09 to 0.19 microgkg(-1) and the detection capability (CCbeta) values obtained, ranged from 0.15 to 0.32 microgkg(-1). The results of the inter-assay study, which was performed by fortifying bovine muscle samples (n=18) on three separate days, show the accuracy calculated for the various analytes to range between 98% and 102%. The precision of the method, expressed as R.S.D. values for the inter-assay variation of each analyte at the three levels of fortification (1, 1.5 and 2.0 microgkg(-1)), ranged between 3.1% and 5.8%. A Day 4 assay was carried out to examine variations due to different animals and different muscle types.
    Analytica chimica acta 05/2009; 637(1-2):112-20. · 4.31 Impact Factor
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    ABSTRACT: A rapid LC-MS/MS method has been developed and validated for the simultaneous identification, confirmation and quantitation of 10 nitroimidazoles in plasma. The method validated in accordance with Commission Decision (CD) 2002/657/EC is capable of analysing for metronidazole (MNZ), dimetridazole (DMZ), ronidazole (RNZ), ipronidazole (IPZ) and their hydroxy metabolites MNZ-OH, HMMNI (hydroxymethyl, methyl nitroimidazole), IPZ-OH. The method is also capable of analysing carnidazole (CRZ), ornidazole (ORZ) and ternidazole (TRZ) which are rarely analysed by modern methods. MNZ, DMZ and RNZ have a recommended level (RL) of 3 ng mL(-1) which this method is easily able to detect for all the nitroimidazole compounds. Plasma samples are extracted with acetonitrile, and NaCl is added to help remove matrix contaminants. The acetonitrile extract undergoes a liquid-liquid wash step with hexane; it is then evaporated and reconstituted in mobile phase. The reconstituted samples are analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The decision limits (CCalpha) range from 0.5 to 1.6 ng mL(-1) and the detection capabilities (CCbeta), range from 0.8 to 2.6 ng mL(-1). The results of the inter-assay study, which was performed by fortifying bovine plasma samples (n=18) on three separate days, show the accuracy calculated for the various analytes range between 101% and 108%. The precision of the method, expressed as CV% values for the inter-assay variation of each analyte at the three levels of fortification (3, 4.5 and 6.0 ng mL(-1)), ranged between 4.9% and 15.2%. A day 4 analysis was carried out to examine species variances in animals such as avian, ovine, porcine and equine.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 04/2009; 877(14-15):1494-500. · 2.78 Impact Factor
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    ABSTRACT: A rapid method has been developed to analyse for firocoxib (FIRO) residue in bovine milk. Milk samples were extracted with acetonitrile and sample extracts were purified on Evolute ABN solid phase extraction cartridges. Aliquots were analysed by rapid resolution liquid chromatography tandem mass spectrometry (RRLC-MS/MS). The method was validated in bovine milk, according to the criteria defined in Commission Decision 2002/657/EC. The decision limit (CCalpha) was 1.18ng/mL and for the detection capability a (CCbeta) value of 2.02ng/mL was obtained. The measurement uncertainty of the method was 27%. Fortifying bovine milk samples (n=18) in three separate assays, show the accuracy of the method to be between 96 and 105%. The precision of the method, expressed as RSD values for the within-lab reproducibility at the three levels of fortification (5, 7.5 and 10ng/mL) was less than 11% respectively.
    Journal of Chromatography B 02/2009; 877(5-6):541-6. · 2.49 Impact Factor
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    ABSTRACT: A method has been developed to analyse for ibuprofen (IBP), ketoprofen (KPF), diclofenac (DCF) and phenylbutazone (PBZ) residues in bovine milk. Milk samples were extracted with acetonitrile and sample extracts were purified on Isolute C(18) solid-phase extraction cartridges. Aliquots were analysed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The method was validated in bovine milk, according to the criteria defined in Commission Decision 2002/657/EC. The decision limits (CCalpha were 0.59, 2.69, 0.90 and 0.70 ng ml(-1), respectively, for IBP, KPF, DCF and PBZ, and detection capabilities (CCbeta) of 1.01, 4.58, 1.54 and 1.19 ng ml(-1), respectively, were obtained. The measurement uncertainty of the method was 17.8%, 80.9%, 28.2% and 20.2% for IBP, KPF, DCF and PBZ, respectively. Fortifying bovine milk samples (n = 18) in three separate assays show the accuracy of the method to be between 104% and 112%. The precision of the method, expressed as relative standard deviations for the within-laboratory reproducibility at the three levels of fortification (5, 7.5 and 10 ng ml(-1)) was less than 8% for IBP, DCF and PBZ, respectively. Poor precision was obtained for KPF with a relative standard deviation of 28%.
    Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment 01/2009; 25(12):1497-508.
  • Journal of chromatography A. 01/2009;
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    Food Additives and Contaminants Part B 01/2008; · 0.83 Impact Factor