Introduction: Various techniquies have been developed for determination of food contaminants in different matrices. Since food matrices are very complex, the effect of food components on the analyte (ion suppression or ion enhacement) which is known as matrix effect has always been an issue during the development of quantitative methods specially when LC-Mass is involved. Several strategies such as matrix match calibration, standard addition, isotope internal standard, and spike calibration have been proposed with the aim to minimize or eliminate the matrix interferences. A calibration curve which is ploted for a certain matrix would not be suitable for other matrices and according to the guidline by SANCO, a residue analytical method for foodstuff of animal origin should be validated for five representative animal matrices, i.e. milk, eggs, meat (eg. bovine or poultry), fat, liver /kidney. This process is expensive, laber intensive and time consuming. In this study we will focuse on the suitability of a new approach for calibration based in a single level standard addition to overcome the effect of matix and anlyse a large number of samples in a short period of time without the need to go through the construction of calibration curve for every single matrix.Methods: A liquid chromatography-QTRAP-tandem mass spectroscopy was used for determination of Dinitricarbanilide (DNC) in the chicken meat samples. Blank chicken meat samples were spiked with Dinitricarbanilide (DNC) at three different levels MRL level (200 ppb), 10% above MRL level (220 ppb) and 10% below MRL level (180 ppb). DNC-d8 was added to all samples at MRL level (200 ppb).
Chicken meat samples were then extracted and subjected to the LC-MS-MS system in the negative mode. The areas under the curves obtained for natural and labeled standard were compared for the determination of
DNC content in the samples. Since the signals generated by mass spectrometer for the equal amounts of the natural analyte and labeled analyte (surrogate analyte) are identical, comparing the AUC for the two signals will show whether the natural analyte exists in the sample at a level higher than legal limit (MRL=200ppb) or lower than the legal limit. The signals for both natural and labeled (surrogate) analytes will be equally affected by the matrix, and there is no need for constructing a calibration curve for five different commodities.Results: The precision (RSD %) of the
surrogate method and classic internal standard method were between 1.60-2.39% and 1.70-2.52%, respectively. Comparing the recovery of
DNC in two approaches, showed that more accurate results were obtained in the
surrogate method (recovery from 98.96% to103.10%).Conclusion: In this study a new
surrogate analyte approach for the determination of
DNC in the chicken meat was introduced to compensate for the effect of matrix. Since in this method there is no need for drawing calibration curves, it reduces the time needed for the development and validation of the method, compensates the matrix effect, and could be considered as an alternative method for screening purposes.