Express-identification and determination of natamycin in foodstuffs by method of ultra-high performance liquid chromatography/quadrupol-time-of-flight mass-spectrometry of high-resolution

Abstract

First of all, the method of rapid identification and determination of natamycin in food products (alcoholic and non-alcoholic beverages, cheese) by ultra-high-performance liquid chromatography in combination with quadrupole-time-of-flight mass spectrometry of high-resolution. For sample preparation, it was
proposed to use liquid extraction with a mixture of deionized water and acetonitrile (for alcoholic and nonalcoholic beverages – dilution), followed by centrifugation. The optimal conditions for chromatographic separation were chosen: the composition of the mobile phases, the program of gradient elution, the column temperature, the volume of the injected sample (A) and 0.1% formic acid in acetonitrile (B). The optimal conditions for the gradient elution mode are as follows: 0 min – 5% B, 0.5 min – 5% B, 2 min – 50% B, 5 min – 100% B, 6 min – 5% B, 8 min – 5% B. The flow rate of the mobile phase was 0.4 ml/min. The temperature of the column thermostat is 30 ° C. The volume of the injected sample is 20 μl. The duration of the chromatographic separation was 8 minutes To assess the quantitative content of natamycin in food products used by standard additives, which has already proven itself in determining residual quantities of veterinary drugs in food products, feed and raw materials for their production. Under selected conditions of extraction,separation of extracts and mass spectrometri detection, several samples of the products were analyzed. Of the seven samples in one sample of fruit nectar, in one sample of wine and one sample of cheese (cortical layer), natamycin was found at the level of 15±3, 18±3 and 23±4 ng/g respectively. Natamycin was not detected in the three samples of fruit juice (less than 0.2 ng/ml). The correctness of the analysis was verified by the «introduced-found» method with the addition of natamycin at the level of 50 ng/g. The range of determined contents of natamycin was 0.5-100 ng/ml (ng/g), the detection limit was 0.2 ng/g with a sample mass of 1.00 g.