Cyclohexanone is widely used as adhesive in the production of PVC medical devices. Residual cyclohexanone in PVC medical devices may enter into human body through transfusion or intervention treatment, which can cause potential harm to human body. Therefore, rapid detection of the residual cyclohexanone is important to quality control of PVC medical devices. Based on the conventional electrospray ionization mass spectrometer/mass spectrometer (ESI-MS/MS), an extractive electrospray ionization mass spectrometer/mass spectrometer (EESI-MS/MS) for detection of trace cyclohexanone gas was built. The EESI technique can directly analyze the gas and liquid samples without pre-treatment, and the tandem mass spectrometry can unambiguously identify ions with the scan mode of product ions. To improve the performance of the instrument, effective parameters for rapid detection of cyclohexanone were optimized first of all. Laboratory air as sample, spray voltage of EESI was optimized to be 3000 V; Standard acetone gas as sample, carrier gas flow was optimized to be 11.67 L/min. And then the performance of the EESI-MS/MS was evaluated. The standard acetone gas was used as sample to test response time and repeatability (n=6) of the apparatus. The result showed that the response time of this EESI-MS/MS was less than 2.5 s, providing a real-time detection. And on the basis of 6 injections of the same sample, relative standard deviation (RSD) of signal intensities for acetone was 4.83%. A calibration curve was lined and the (limit of detection) LOD of the instrument was calculated to be 237.1×10^-9 (V/V) with (signal/noise) S/N=3. Finally, EESI-MS/MS was used for fast detection of residual cyclohexanone gas in PVC infusion set. Comparing the mass spectra of standard cyclohexanone gas and air in the PVC infusion set, we found they all contained ions at m/z 99 and m/z 81. MS/MS technology was then used to make further investigation of the origin of the ions at m/z 99 from the air in the PVC infusion set and the production procedure of m/z 81. In detail, product ions' mass spectra of cyclohexanone gas and air in the PVC infusion set was compared when collision energy was set to be 5, 10, and 15 eV. At each collision energy, product ions' mass spectrum of air in PVC infusion set was same to that of cyclohexanone gas. So it can be sure that the air in PVC infusion set contained cyclohexanone. Ion m/z 81 was produced from the fragmentation of protonated cyclohexanone. In addition, the concentration of the cyclohexanone in the PVC infusion set can be calculated to be 362.6×10^-9 (V/V). The result shows the important application value of EESI-MS/MS in quality control of medical devices.

Key words: PVC infusion set, ion source, EESI-MS/MS, cyclohexanone, fast detection