A new and rapid method for lactose identification and quantification in milk and other liquid dairy products using gas chromatography with a flame-ionisation detector

This study focuses on optimising the pre-treatment, derivatisation processes, and gas chromatography conditions for the determination of lactose in liquid dairy products. Efficiency of sample preparation consists in the coagulation of protein components in methanol, centrifugation, and subsequent drying in a nitrogen stream. Derivatisation of the monitored carbohydrates is performed using a two-step silylation process. The samples were analysed using gas chromatography with flame-ionisation detection (GC-FID). Based on the calibration of lactose content in the range of 0.1—10 % w/v, quantitative determination of this disaccharide was performed in 18 milk samples. The paper presents the results of quantitative analysis as well as dosing and derivatisation repeatability. This method compensates for time-consuming sample preparation by reducing the separation time of mono- and disaccharides to 16 minutes.