Haihe Jiang

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.

Exhaled gases online measurements for esophageal cancer patients and healthy people by proton transfer reaction mass spectrometry

Esophageal cancer is a prevalent malignancy. There is a considerable demand for developing a fast and noninvasive method to screen out the suspect esophageal cancer patients who may undergo further clinical diagnosis.

Corona Discharge Ion Mobility Spectrometry of Ten Alcohols

Ion mobility spectra for ten alcohols have been studied in an ion mobility spectrometry apparatus equipped with a corona discharge ionization source. Using protonated water cluster ions as the reactant ions and clean air as the drift gas, the alcohols exhibit different product ion characteristic peaks in their ion mobility spectra. The detection limit for these alcohols is at low concentration pmol/L level according to the concentration calibration by exponential dilution method. Based on the measured ion mobilities, several chemical physics parameters of the ion-molecular interaction at atmosphere were obtained, including the ionic collision cross sections, diffusion coefficients, collision rate constants, and the ionic radii under the hard-sphere model approximation.

Application of a self-developed proton transfer reaction-mass spectrometer to on-line monitoring trace volatile organic compounds in ambient air

Real-time and on-line monitoring volatile organic compounds(VOCs) are valuable for real-time evaluating air quality and monitoring the key source of pollution. A self-developed proton transfer reaction-mass spectrometer( PTR-MS) was constructed and applied to on-line monitoring trace VOCs in ambient air in Hefei. With the help of a self-developed catalytic converter, the background signal of the instrument was detected and the stability of the instrument was evaluated. The relative standard deviation of signal at m/z 21 was only 0.74% and the detection limit of PTR-MS was 97 part per trillion(97×10–12, volume ratio). As a case of the air monitoring in Hefei, the ambient air at Dongpu reservoir spot was on-line monitored for 13 d with our self-developed PTR-MS. Meanwhile, a solid-phase micro-extraction(SPME) technique coupled to gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS) was also used for the off-line detection of the air. The results show that our self-developed PTR-MS can be used for the on-line and long-term monitoring of VOCs in air at part per trillion level, and the change trend of VOCs concentration monitored with PTR-MS was consistent with that detected with the conventional SPME-GC-MS. This self-developed PTR-MS can fully satisfy the requirements of air quality monitoring and real-time monitoring of the key pollution sources.

Rapid identification of false peaks in the spectrum of Hadamard transform ion mobility spectrometry with inverse gating technique

With the application of Hadamard transform (HT) technique, the signal to noise ratio of ion mobility spectrometry (IMS) has been improved significantly. Nevertheless, possibly due to the modulation defects, false peaks appear in the demultiplexed data and demonstrate similar features to those of the real signal peaks, which makes them hard to be discriminated. Facing this challenge, a novel method has been presented in this work and achieved the rapid identification of the false peaks in Hadamard multiplexing IMS. Simply by introducing the inverse gating technique to Hadamard multiplexing, the novel inverse Hadamard transform (IHT) method is developed. With the application of this novel method in IMS, most of the false peaks are changed to opposite to the real signal peaks, which makes them easy to be classified as the false peaks. Furthermore, with the help of the single “code” extended method, the amount of the false peaks in inverse Hadamard transform ion mobility spectrometry (IHT-IMS) decreases dramatically, and this makes the identification more accurate. The sample tests further demonstrate that the inverse Hadamard transform (IHT) method is an effective way to address the problem of rapid identification of the false peaks and upgrade the quality analysis of Hadamard multiplexing ion mobility spectrometry.

Negative photoionization chloride ion attachment ion mobility spectrometry for the detection of organic acids

A novel negative photoionization chloride ion attachment ion mobility spectrometry (NP-CA-IMS) instrument has been developed. In this technique, chloride ion attachment technology is first applied to photoionization ion mobility spectrometry in a negative detection mode. The reactant ions are chloride ions, which are generated from the reaction between carbon tetrachloride (CCl4) and low energy electrons induced by the photoionization of acetone (CH3COCH3) with a commercial vacuum ultraviolet Krypton lamp. The generation efficiency of chloride ions was investigated. Subsequently, the performance of the instrument was investigated. A series of volatile straight chain organic carboxylic acids were detected in the order of magnitude of ppb, including acetic acid (CH3COOH), propionate acid (CH3CH2COOH), butyric acid (CH3(CH2)2COOH), valeric acid (CH3(CH2)3COOH), isovaleric acid (2-CH3(CH2)3COOH), hexanoic acid (CH3(CH2)4COOH), heptanoic acid (CH3(CH2)5COOH), and octanoic acid (CH3(CH2)6COOH). Besides, the concentration of acetic acid was calibrated and a mixture of the investigated acids was also studied. Finally, the new methods capability to detect acetic acid in five different brands of edible white vinegar was evaluated. The experimental results show that negative photoionization chloride ion attachment is an excellent nonradioactive source for IMS.

Electron Attachment Studies for CHCl3 Using Ion Mobility Spectrometry

The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry (CD-IMS). The corresponding electron attachment rate constants varied from 1.26×10−8 cm3/(molecules s) to 8.24×10−9 cm3/(molecules s) as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region, the attachment rate constants are also detected at different sample concentration. The ion-molecule reaction rate constants for the further reaction between Cl− and CHCl3 are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl− and CHCl3 are the first time detected using CD-IMS.

Simultaneous Improvement of Resolving Power and Signal-to-Noise Ratio Using a Modified Hadamard Transform-Inverse Ion Mobility Spectrometry Technique

AbstractIn order to improve the resolving power (RP) and signal-to-noise ratio (SNR) of ion mobility spectrometry (IMS) simultaneously, a modified Hadamard transform-inverse ion mobility spectrometry (MHT-IIMS) technique was developed. In this novel technique, a series of isolating codes were appended to each element of the pseudo random binary sequence (PRBS), and then the modified modulation sequence was formed and used to control the ion gate of the inverse IMS (IIMS). Experimental results demonstrate that the MHT-IIMS technique can significantly enhance the resolving power and SNR simultaneously by measuring the spectra of reaction ions. Furthermore, the gas sample CCl4 and CHCl3 were measured for evaluating the capability of detecting those samples which have single and multiple product ions. The results show that this novel technique is able to simultaneously improve the resolving power and SNR notablely for the real sample detection without any significant instrumental changes. Graphical Abstractᅟ

Glass bottle sampling solid phase microextraction gas chromatography mass spectrometry for breath analysis of drug metabolites

Breath analysis is a non-invasive approach which may be applied to disease diagnosis and pharmacokinetic study. In the case of offline analysis, the exhaled gas needs to be collected and the sampling bag is often used as the storage vessel. However, the sampling bag usually releases some extra compounds, which may interfere with the result of the breath test. In this study, a novel breath sampling glass bottle was developed with a syringe needle sampling port for solid phase microextraction (SPME). Such a glass bottle scarcely liberates compounds and can be used to collect exhaled gas for ensuing analysis by gas chromatography-mass spectrometry (GC-MS). The glass bottle sampling SPME-GC-MS analysis was carried out to investigate the breath metabolites of myrtol, a multicompound drug normally used in the treatment of bronchitis and sinusitis. Four compounds, α-pinene, 2,3-dehydro-1,8-cineole, d-limonene and 1,8-cineole were found in the exhaled breath of all eight volunteers who had taken the myrtol. While for other ten subjects who had not used the myrtol, these compounds were undetectable. In the SPME-GC-MS analysis of the headspace of myrtol, three compounds were detected including α-pinene, d-limonene and 1,8-cineole. Comparing the results of breath and headspace analysis, it indicates that 2,3-dehydro-1,8-cineole in the breath is the metabolite of 1,8-cineole. It is the first time that this metabolite was identified in human breath. The study demonstrates that the glass bottle sampling SPME-GC-MS method is applicable to exhaled gas analysis including breath metabolites investigation of drugs like myrtol.

Exhaled breath online measurement for cervical cancer patients and healthy subjects by proton transfer reaction mass spectrometry

Cervical cancer is a common cancer among women and has a high morbidity and mortality. The traditional clinical methods for cervical cancer screening are invasive and limited in terms of cost and time. There is an unmet clinical need for new methods to aid clinicians in the rapid screening and auxiliary diagnosis of cervical precancer. Recently, breath analysis has become an attractive approach for investigation of cancer biomarkers and shows great potential in cancer screening owing to its high sensitivity, quickness, and non-invasive nature. In this pilot study, breath analysis by proton transfer reaction mass spectrometry (PTR-MS) was utilized for online analysis of the exhaled breath of 13 cervical cancer patients and 34 female healthy volunteers. The Mann–Whitney U test and stepwise forward linear discriminant analysis were performed for data statistics. On the basis of the statistical analysis, four characteristic ions at m/z 76, 87, 93, and 121 were found for discriminating cervical cancer. The sensitivity and specificity were calculated to be 92.3% and 88.2%, respectively, using the stepwise discriminant analysis. The possible identities of characteristic ions were also discussed in detail. Although there are some uncertainties in the identification of these characteristic ions and more participants (including cervical cancer patients and healthy volunteers) are needed to further confirm the results, the results in this study demonstrate that the online breath test using PTR-MS is a promising approach for cervical cancer screening.