Abstract: The gas chromatography-tandem mass spectrometry (GC-MS/MS) was employed to detect N-nitrosodimethylamine (NDMA) in spiramycin. The liquid-liquid extraction method was used to extract NDMA. The test sample was first dissolved in sulfuric acid; then, dichloromethane was added for extraction, and the substrate filtrate was extracted to obtain the NDMA solution. Data collection was made using the multi reaction monitoring mode. The NDMA quantitative ion pair is 74→44 and the qualitative ion pair is 74→42. Within the range of 0.25～50 μg/L, the NDMA mass concentration and response present a great linear relationship, and the linear-dependence coefficient is 0.99998. The instrument limit of detection and the limit of quantitation are 0.1260 μg/L and 0.3819 μg/L, respectively. Under low, medium and high levels, the adding standard recovery of sulfuric acid solution is within the range of 100.20%~103.07%, and the RSD is within 0.27%~0.72%; for the spiramycin test sample, the adding standard recovery is between 103.23%～107.87%, and the RSD is within 0.56%～0.64%. The repeatability test results show that the RSD is 4.25%. After the test sample is added with sulfuric acid, it is placed for 0, 2, 4, and 6 h before the extraction test, the RSD is 2.86% based on the results. After the spiramycin test sample is placed for 0~24 h, the RSD of peak area is 3.14%; after the NDMA standard working solution is placed for 0~24 h, the RSD of peak area is 3.42%. This method is employed to detect NDMA in spiramycin, and the results are in accord with the demands.

Key words: Spiramycin, N-Nitrosodimethylamine, Triple quadruple mass spectrometry, Method validation