Determination and confirmation of nicarbazin, measured as 4,4-dinitrocarbanilide (DNC), in chicken tissues by liquid chromatography with tandem mass spectrometry: First Action 2013.07.

A single-laboratory validation (SLV) study was conducted on an LC/MS/MS method for the determination and confirmation of nicarbazin, expressed as 4,4-dinitrocarbanilide (DNC), in chicken tissues, including liver, kidney, muscle, skin with adhering fat, and eggs. Linearity was demonstrated with DNC standard curve solutions using a weighted (1/x) regression and confirmed with matrix-matched standards. Intertrial repeatability precision (relative standard deviation of repeatability; RSD(r) was from 2.5 to 11.3%, as determined in fortified tissues. The precision was verified with incurred tissue, and varied from 0.53 to 2.5%. Average recoveries ranged from 82% in egg to 98% in kidney. Although the average recoveries across all concentrations were within the acceptable range, the method was improved with the inclusion of an internal standard and the use of matrix-matched standards. Accuracy for the improved method in chicken liver varied from 93 to 99% across all concentrations (100-8000 ng/g) compared to recoveries below 80% at concentrations, between 100-400 ng/g in chicken liver for the original method. The limit of detection was estimated to be less than 3.0 ng/g in all tissue types, and the limit of quantitation was validated at 20 ng/g. Based on confirmatory ion ratios and peak retention times, the false-negative rate was estimated as 0.00% (95% confidence limits 0.00, 0.74%) from 484 fortified samples and 12 incurred residue samples analyzed using the U.S. and EU confirmation criteria. Small variations to the method parameters, with the exception of injection volume, did not have a significant effect on recoveries. Stability was determined for fortified tissues, extracts, and standard curve solutions. The data collected in this study satisfy the requirements of SLV studies established by the AOAC Stakeholder Panel for Veterinary Drug Residue and the method was awarded First Action Official Method status by the Expert Review Panel for Veterinary Drug Residues on May 7, 2013.

Determination and confirmation of parent and total ractopamine in bovine, swine, and turkey tissues by liquid chromatography with tandem mass spectrometry: First Action 2011.23.

A candidate method selected by the AOAC Expert Review Panel (ERP) for Ractopamine for determination and confirmation of parent and total ractopamine by LC/MS/MS was validated in a single laboratory for bovine, swine, and turkey tissues. The candidate method utilizes methanol extraction of the tissues, followed by an optional enzymatic hydrolysis for determination of total (parent plus conjugate) ractopamine. A mixed-mode cation exchange SPE cartridge is used to purify the initial extract before LC/MS/MS. Matrix-matched standards and a ractopamine-d6 internal standard are used for quantification of parent and total ractopamine in unknown samples. Validation data demonstrated that mean intertrial recoveries for ractopamine across all concentrations tested ranged from 79.7 to 102.2% for parent ractopamine and from 79.0 to 100.0% when a hydrolysis step was included. Intertrial repeatability precision ranged from 2.44 to 11.1% for parent ractopamine and 4.97 to 15.0% with hydrolysis. Estimated LOD values were below 0.1 ng/g and LOQ values were validated at 0.25x the maximum residue limits. The data satisfy the requirements of the AOAC Stakeholder Panel for Veterinary Drug Residue Methods for single laboratory validation studies. The method was awarded Official Methods of Analysis First Action 2011.23 by the AOAC ERP on Veterinary Drug Residues.

Determination of ractopamine in swine, bovine, and turkey tissues by HPLC with fluorescence detection: first action 2011.22.

A candidate LC method proposed by the Expert Review Panel (ERP) for ractopamine was evaluated in a single-laboratory validation (SLV) study. The matrixes examined included bovine liver, kidney, muscle, and fat; swine liver, kidney, muscle, and fat; and turkey liver and muscle. Solution standards were shown to provide a linear response with an unweighted regression. The method demonstrated acceptable precision (HorRat, values 0.25 to 1.38) and recovery (75.4 to 88.8%) in all fortified matrixes. Method precision was verified with incurred residue tissues (bovine liver, kidney, and muscle; swine liver, kidney, and muscle; and turkey liver and muscle), which yielded RSDr values below 16% for all tissues and below 7% for most tissues. Estimated LOQ values ranged from 1.8 to 20.7 ng/g and support the utility of the method in the range of the maximum residue limits or tolerances for the various tissues. The data satisfy the requirements of the AOAC Stakeholder Panel on Veterinary Drug Residue for SLV studies, and the method was adopted Official Methods ofAnalysis First Action 2011.22 by the AOAC ERP on Veterinary Drug Residues.

Determination of narasin and monensin in bovine, swine, and chicken tissues by liquid chromatography with tandem mass spectrometry: first action 2011.24.

The single-laboratory validation (SLV) of an LC-MS/MS method for determination and confirmation of two ionophores, narasin and monensin, in animal tissues is described. The data demonstrated linearity of matrix-matched calibration curves using a weighted (1/x) regression and selectivity of the method for narasin and monensin in the presence of lasalocid, salinomycin, maduramycin, nicarbazin, and sulfadiazine. Recoveries varied from 86.2 to 103.5% for narasin and 89.1 to 105.1% for monensin. Intertrial repeatability precision [relative standard deviation of repeatability (RSDr)] varied from 3.9 to 13.8% for narasin and 3.3 to 16.3% for monensin in fortified tissue. Precision of the method was verified in incurred tissues. The LOQ of the method was validated and ranged from 0.45 ng/g in milk, to 4.0 ng/g in chicken fat, but was 0.75 ng/g for most tissues. Two confirmatory ions for each analyte were examined across all matrixes, resulting in estimated false-negative rates of 0.00% (95% confidence interval of 0.00-0.68%) for monensin ions (540 samples) compared to the U.S. and European Union (EU) acceptance criteria. The confirmatory ions for narasin demonstrated 0.00% false-negative rates (95% confidence interval of 0.00-0.58%) when compared to either the U.S. or EU criteria in 630 samples. The method was robust when small changes in method parameters were made and stability of fortified tissues, extracts, and calibration solutions were estimated. The data satisfy the requirements of the AOAC Stakeholder Panel on Veterinary Drug Residue for SLV studies, and the method was adopted Official Methods of Analysis First Action 2011.24 by the AOAC Expert Review Panel on Veterinary Drug Residues.