Jianquan Li

Thermal desorption extraction proton transfer reaction mass spectrometer (TDE-PTR-MS) for rapid determination of residual solvent and sterilant in disposable medical devices.

Thermal desorption extraction proton transfer reaction mass spectrometer (TDE-PTR-MS) has been exploited to provide rapid determination of residual solvent and sterilant like cyclohexanone (CHX) and ethylene oxide (EO) in disposable medical devices. Two novel methods are proposed for the quantification of residual chemicals in the polyvinyl chloride infusion sets with our homemade PTR-MS. In the first method, EO residue in the solid infusion sets (y, mgset(-1)) is derived through the determination of EO gas concentration within its packaging bag (x, ppm) according to the correlative equation of y=0.00262x. In the second one, residual EO and CHX in the solid infusion sets are determined through a time integral of their respective mass emission rates. The validity of the proposed methods is demonstrated by comparison with the experimental results from the exhaustive extraction method. Due to fast response, absolute concentration determination and high sensitivity, the TDE-PTR-MS is suggested to be a powerful tool for the quality inspection of disposable medical devices including the quantitative determination of residual solvent and sterilant like CHX and EO.

Control of solvent use in medical devices by proton transfer reaction mass spectrometry and ion molecule reaction mass spectrometry

A homemade proton transfer reaction mass spectrometer (PTR-MS) and a commercial ion molecule reaction mass spectrometer (IMR-MS) have been applied to detect volatile organic compounds (VOCs) in the packaging bags of infusion sets made of polyvinylchloride (PVC) plastic. The most abundant characteristic ions in the PTR-MS and IMR-MS measurements are observed at m/z 99 and 98 respectively, which are the results of soft ionizations that a residual chemical undergoes the proton transfer reaction in PTR-MS and the charge transfer reaction in IMR-MS. On the basis of ionic intensity dependence on the reduced-field in the PTR-MS investigation, the residue can be unambiguously identified as cyclohexanone, a commonly used adhesive agent in PVC medical device manufacture. Quantitative measurement by PTR-MS shows that concentrations of cyclohexanone in the packages of two types of infusion sets are 11 and 20 ppm respectively. Due to fast response, absolute concentration detection, and high sensitivity, the PTR-MS and IMR-MS detection methods are proposed for the quality control of medical devices including the detection of illegal or excessive uses of chemical solvents like cyclohexanone.

Emission observation for electronically excited state SO(c1Σ−) in gas phase

Abstract Emission spectra have been observed downstream in a flowing afterglow of the hollow-cathode discharge of an Ar and SO2 mixture. A progression in the 400–600 nm wavelength range is identified as being due to the SO(c1Σ−→X3Σ−) transition based on experimentally derived spectroscopic data ν 00 =28 500 cm −1 , ω e ″ =1155.5 cm −1 and ω e ″ χ e ″ =6.6 cm −1 , and careful comparison with the corresponding transition for SO in solid matrix environments. Such an assignment is also consistent with earlier experimental investigation of photofragment SO translation energy and previous quantum computations. This is the first emission spectrum observed for SO(c1Σ−→X3Σ−) system in gas phase.

Discrimination of isomers and isobars by varying the reduced-field across drift tube in proton-transfer-reaction mass spectrometry (PTR-MS)

Proton-transfer-reaction mass spectrometry (PTR-MS) is a powerful technique for the real time trace gas analysis of volatile organic compounds (VOCs). However, quadrupole mass spectrometer (MS) used in PTR-MS has a relatively low mass resolution and is therefore not suitable for differentiating isobars. Furthermore, because of the lack of chemical separation before analysis, isomers can not be identified, either. In the present study, by varying the reduced-field E/N in the reaction chamber with a range of 50–180 Td in PTR-MS, we studied the product ion distribution (PID) of three sets of isobars/isomers, i.e. n-propanol/iso-propanol/acetic acid, propanal/acetone and four structural isomers of butyl alcohol. The profiles of the reduced-field dependence (PFD) of the PID under the chosen E/N-values show obvious differences which can be used to discriminate between these isobars/isomers thus enabling the titled method. Noticeably, we have observed that even the isomers, in the case of four structural isomers of butyl alcohol, which show little difference with each other at high reduced-field, can be discriminated easily at low reduced-field. Finally, two examples for the application of this method are discussed: (1) cyclohexanone was identified to be a major compound in the headspace of medical infusion sets; and (2) the differentiation and quantification of propanal and acetone in three synthetic mixtures with different ratios. This study presents a potential method to distinguish and quantify isobars/isomers conveniently in practical applications of PTR-MS analysis without additional instrumental configurations.