Quantitative Procedure for Gas Chromatographic Analysis of Head-Space Vapor Over Sterile Concentrated Milk

An apparatus has been designed in which it is possible to obtain the head-space vapor over sterile concentrated milk in argon under controlled conditions of volume, pressure, and temperature and from which a measured aliquot at atmospheric pressure can be withdrawn for gas-chromatographic analysis. The effect of various factors influencing the sampling and chromatographic procedures were investigated and controls established. The chromatographic assembly and conditions finally selected consisted of a 2.74-m Apiezon-L column at 50C with a Strontium-90 detector. Five-milliliter samples were injected at an argon inlet pressure of 1.62kg/cm 2 gauge. Water vapor in the sample had no significant effect upon the sensitivity of the detector within the range investigated. Saturation of sterile concentrated milks with sodium sulfate did not appreciably increase the concentration of volatile components in the head-space vapor. This procedure is reproducible, with a standard deviation of ±3.86% of the measured peak height, and can demonstrate quantitative differences in composition of head-space vapors over sterile concentrated milks processed and stored under different conditions.