Multiresidue method for identification and quantification of avermectins, benzimidazoles and nitroimidazoles residues in bovine muscle tissue by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) using a QuEChERS approach.

A quantitative and confirmatory multiresidue method for determining the presence of avermectins, benzimidazoles and nitroimidazoles in bovine muscle tissue by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was developed, optimized and validated, using a QuEChERS extraction. The evaluated performance parameters were linearity, selectivity, matrix effect, decision limits (CCα), detection capability (CCß), limits of detection (LOD), limits of quantification (LOQ), accuracy, precision and robustness. The validated method exhibited linearity with coefficient of determination (R2) higher than 0.90 in the working range from 0.5 to 2.0 times the maximum residue limit (MRL) or the minimum required performance level (MRPL) for the studied analytes, except for closantel, for which the linear study range was defined from 50 to 200µgkg-1. The method was selective in the presence of macrolides and lincosamides for all the studied analytes. The LOD varied from 0.007 to 66.715µgkg-1, whereas LOQ values ranging from 0.011 to 113.674µgkg-1 were found. The results of the evaluation of the accuracy and precision were satisfactory for all the studied analytes, and according to the assessment of the robustness, the method was not robust only for the analytes abamectin, moxidectin, doramectin fenbendazole sulfone, closantel, thiabendazole, hydroxyl-metronidazole and ronidazole. The performance parameters demonstrated total method adequacy for the detection and quantification of avermectins, benzimidazoles and nitroimidazoles residues in bovine muscle tissues.

Validation of spectrophotometric method to detect and quantify nitrite in ham pate / Validação de método espectrofotométrico para determinação de nitrito em patê de presunto

The objective of this work was to validate the spectrophotometric method to detect and quantify nitrite using ham pate as a source. The validated analytical conditions were 540 nm wavelength and the samples reading between 40 to 70 minutes after addition of coloring agents. The tested performance criteria were: linearity, matrix effect, selectivity, detection and quantification limit, accuracy, precision and robustness. As the results have obtained linearity in the studied zone (0.125 to 3 g/mL) and matrix effect was not observed, there was not any interference from ascorbic acid, but interference occurred from sodium eritorbate, in concentrations above 2.5 mg/100g. The detection limit was defined as 12.5 mg of nitrite/kg for pate and the quantification limit as 25 mg of nitrite/kg of pate. The method presented repeatability and reproducibility. The accuracy was assessed through recovery values varying from 84 to 110 percent. Respecting robustness, it was observed that the variations applied to the extraction procedure depended on the concentration of nitrite in the pate sample. In conclusion, the methodology was validated under the tested conditions.

O objetivo deste trabalho foi validar o método espectrofotométrico para determinação de nitrito usando como matriz patê de presunto. As condições analíticas usadas foram comprimento de onda de 540 nm e leitura das amostras entre 40 e 70 minutos após a adição dos reagentes complexantes. As características de desempenho testadas foram linearidade, efeito de matriz, seletividade, limite de detecção do equipamento e do método, limite de quantificação, exatidão, precisão e robustez. A linearidade foi obtida na faixa de trabalho estudada (0,125 a 3 μg de nitrito/mL) e não foi observado efeito de matriz. A concentração de ácido ascórbico na amostra não interferiu na análise e o eritorbato de sódio possuiu interferência negativa para concentrações acima de 2,5 mg/100g de amostra. O limite de detecção foi definido em 12,5 mg de nitrito/kg de patê e o limite de quantificação em 25 mg de nitrito/kg de amostra. O método apresentou repetitividade e reprodutibilidade intra-laboratorial. A exatidão foi avaliada através dos valores de recuperação que variaram entre 84 e 110 por cento. Na avaliação da robustez, as variações realizadas no procedimento de extração foram dependentes do nível de concentração existente na amostra. Concluiu-se que a metodologia pôde ser validada nas condições testadas.