Development of Quality Control Samples for Qualitative Analysis of Listeria monocytogenes by Time-of-Flight Mass Spectrometry

A quality control sample for the qualitative analysis of Listeria monocytogenes was developed by vacuum freezing drying technology, and the homogeneity and stability of the quality control sample were systematically analyzed. By optimizing the type of lyophilized matrix, the optimal conditions for the development of quality control samples were obtained. The homogeneity and stability of the developed quality control sample were verified by counting the number of cells as well as using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The quality control sample was white in color, spherical in shape and uniform in size. The results of cell counting for uniformity validation showed F = 0.567, which was less than the critical value, indicating good uniformity. In the transportation stability test, the quality control sample remained stable at 37 and 25 ℃. In the storage stability test, the resurrection rate of the quality control sample was 101.5% after 28 days of storage at –20 ℃, and 99.6% after 28 days of storage at 4 ℃, indicating that the sample has good uniformity and stability, and can be used as a positive quality control sample for the detection and quality control of Listeria monocytogenes.