GC Determination of Residual Amounts of Organic Solvents in Milk Powder with Micro-cell Thermal Extraction and Secondary Thermal Desorption

A method of GC with micro-cell thermal extraction-secondary thermal desorption was applied to the determination of residual amounts of 12 organic solvents in milk powder. Equilibrium temperation and time for purging and trapping taken were 80 ℃ and 30 min respectively. DB-624 elastic quartz capillary column (60 m×0.32 mm, 1.8 μm) was used for separation and FID was used for detection in the GC analysis. Linear relationships between values of peak area and mass fraction of 12 organic solvents were kept in the same range of 0.01-0.5 mg·kg-1, with lower limits of determination (10S/N) ranged from 0.003 7 to 0.011 mg·kg-1. Tests for recovery were performed by standard addition method with 6 parallel determinations; results of recovery found were in the range of 91.5%-110% with RSD′s in the range of 2.27%-3.01%.