Determination of 12 methylsiloxanes residues in Baijiu contacting materials by GC-MS/MS

To investigate methylsiloxanes residues in Baijiu contacting materials, a method for determination of 12 methylsiloxanes (cyclic methylsiloxanes, numbered as D3-D8; linear methylsiloxanes, numbered as L3-L8) in Baijiu contacting materials was established by gas chromatography-tandem mass spectrometry (GC-MS/MS). The methylsiloxane compounds were extracted from the sample by hexane and ultrasonic extraction for 40 min. It was separated by HP-5MS UI capillary column (30 m×0.25 mm, 0.25 μm) with the post running temperature of 270 ℃ and the time of 4 min. The results showed that the linear relationship of 12 methylsiloxanes were good in the mass concentration range of 0.05-2.00 mg/kg, the correlation coefficient R² were 0.995 3-0.999 5, and the spiked recovery rates were 85.00%-98.44%, the relative standard deviations (RSD) of precision and repeatability tests results were 2.65%-6.86% and 1.56%-4.42%, respectively. The method was used to detect various types of Baijiu contacting materials in the market, and only decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), tetecamethylcycloheptasiloxane (D7) and hexadecame-thylcyclononylsiloxane (D8) residues were detected in silicone rubber contacting materials, with the contents ranging from 8.56 mg/kg to 34.74 mg/kg. The method had good precision, repeatability and high accuracy, and was suitable for the determination and monitoring of 12 methylsiloxanes residues in Baijiu contacting materials.