Determination of 9 halogenated alkanes in toothpaste by GC⁃MS

Objective To establish a GC-MS method for the detection of 9 halogenated alkanes in toothpastes.

Methods Various brands of toothpastes on the market were collected as the samples. Methanol was used as the extraction solution. After shaking， vortex and centrifugation， the supernatant was filtered by 0.45 μm microporous filter membrane. The content of 9 halogenated alkanes including chloromethane， dichloromethane， chloroform， 1，1，1-trichloroethane， carbon tetrachloride， 1，2-dichloroethane， 1，1，2-trichloroethane， 1，2-dibromoethane， 1，2，3-trichloropropane in the filtrate were determined by GC-MS.

Results The 9 halogenated alkanes showed a good linear relationship in the concentration range of 0.03‒1.00 μg·mL^-1. The correlation coefficient was ≥0.998 7 with the detection limits of 0.015‒0.056 mg·kg^-1. The spiked recoveries were 83.2%‒108.9% with the RSD of 2.0%‒9.8%. In the actual sample analysis， 1，1，2-trichloroethane and 1，2，3-trichloropropane were respectively detected in 6 toothpaste samples from 5 brands.

Conclusion The method is simple， sensitive， accurate， and has good spiked recoveries. It can be used for the determination of halogenated alkanes in toothpastes.