Rapid Analysis of Volatiles in Disposable Syringe by Extractive Electrospray Ionization Quadrupole Time of Flight Mass Spectrometry

Residual volatiles in disposable syringe can be injected into human body, which is considered as a potential health risk. Traditional method like gas chromatography (GC), liquid chromatography (LC) and gas chromatography-mass spectrometry (GC/MS) are relative time consuming for detection. In this study, extractive electrospray –ionization quadrupole time of flight mass spectrometry (EESI-Q TOF MS) was used for rapid analysis of volatiles in disposable syringe. The EESI ion source allows direct sampling of mixture, while the Q TOF promises an accurate measurement of m/z value as a high resolution mass spectrometry. The mass spectra were recorded in the mass range of m/z 20-200 in positive ion mode. To assist identification of compounds, collision induced dissociation (CID) analysis was performed with collision energy of (20±10) eV. Analytes were sampled via a T-tube, and sucked into the source chamber from the bypass through an 80 cm long, 1.5 mm inner-diameter PTEF tube. The PTFE tube was heated to a constant temperature of 100 ℃ to avoid condensation which may lead to compound losses. The curtain gas was set at 4.0 L/min and 200 ℃. Ion source parameters were optimized using cyclohexanone, and the optimal sampling flow rate and capillary voltage were set at 3.5 L/min and 4 000 V, respectively. Various volatiles were detected from 9 syringes in 10 mL with 3 brands. Results showed that volatile compounds are similar in syringes with the same brands, but significantly different in species and content for syringes with different brands. Based on CID analysis, a total of 10 compounds with intensity over 5 000 are identified including dimethylformamide-(m/z 74.060 2), dimethyl sulfoxide (m/z 79.021 1), morpholine (m/z 88.076 5), cyclohexanone (m/z 99.080 2), ethylbenzene (m/z 107.085 9), 4-vinyl-1-cyclohexene (m/z 109.101 6), diethyl urea (m/z 117.102 8), 4-methyl-4-vinyl-1,4-butanolide (m/z 127.075 6), benzothiazole (m/z 136.021 9) and dibutylformamide (m/z 158.154 5). According to previous studies, some of these volatile compounds are toxic and harmful to human body. Detection of syringes in different capacity including 10 mL, 20 mL and 50 mL were also performed. And the result showed that syringes in larger volume would cause more residual volatiles. To estimate the content of residual volatiles, semi-quantitative analysis of cyclohexanone was carried out, and the limit of detection (LOD) is calculated to be 0.13 μg/L. Concentration of cyclohexanone in 10 mL syringe ranges from 0.39 to 0.64 μg/L. Maximum concentration of 2.52 μg/L is detected in 50 mL syringe. This study provides an effective way for rapid analysis of volatiles, and shows great potential in quality control of disposable syringe.