Research On Detection Of Ketones By Dipolar Proton Transfer Reaction Mass Spectrometry

Proton transfer reaction mass spectrometry(PTR-MS)is widely used in many fields such as environment,medicine,and public safety due to its advantages such as high sensitivity and fast time response.Based on the previous researches on the traditional PTR-MS and the new Proton extraction reaction mass spectrometry(PER-MS),a novel technology which is called dipolar proton transfer reaction mass spectrometry(DP-PTR-MS)is presented in this paper.The selection of PTR-MS mode and PER-MS mode was achieved by a circuit switch in DP-PTR-MS.This novel technology is applied to the research of ketones,the main contents are as follows.1.Detection of ketone with DP-PTR-MS.Ketone(denoted by M,the molecular weight of ketone is denoted by m)was ionized as protonated ketone[M + H]+(mass-to-charge ratio(m/z)m+1)in PTR-MS mode and deprotonated ketone[M-H]-(m/z m-1)in PER-MS mode.The molecular weight of M can be accurately identified as m through this law.A single kind sample and mixed samples of eight kinds of ketones(acetone,2-butanone,2-pentanone,2-hexanone,2-heptanone,2-octanone,cyclopentanone,and cyclohexanone)were analyzed respectively by DP-PTR-MS.DP-PTR-MS accurately identified the molecular weight of these eight kinds of ketones.And the experimental results show that the PER-MS model has more effective soft ionization ability for ketones.2.The research of the reaction rate coefficient for reactions between OH-and ketone.Taking acetonitrile as the reference,the reaction rate coefficient for OH-reacting with seven kinds of ketone(acetone,2-butanone,2-pentanone,2-hexanone,2-heptanone,cyclopentanone and cyclohexanone)was measured by the comparison method in PER-MS mode of DP-PTR-MS.The results were 3.95,3.82,1.04,3.90,7.55,4.28,and 5.99(×10-9)mol-1·cm3·s-1,respectively.The experimental measurements of acetone and 2-butanone in this paper correspond to the literature values,proving that this method is correct and reliable.3.Quantitative determination of cyclohexanone.When the value of rate coefficients for reaction between OH-and cyclohexanone is known,the concentration of residual cyclohexanone gas in PVC infusion sets have been obtained in PER-MS mode.