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Peak broadening in ion mobility (IM) is a relatively predictable process and abnormally broad peaks can be indicative of the presence of unresolved species. Here, we introduce a new ion mobility peak fitting (IM_FIT) software package for automated and systematic determination of traveling wave ion mobility (TWIM) unresolved species. To identify IM unresolved species, the IM_FIT software generates a trend line by plotting ions' mobility peak widths as a function of their arrival times. Utilizing user-defined thresholds, IM_FIT allows for automated and rapid detection of ions that deviate from the peak width trend line. To demonstrate the advantages of IM_FIT for automated detection of IM unresolved species, IM-mass spectrometry (IM-MS) data from a sample mixture containing polypropylene glycol and multiple peptides were analyzed. A total of 14 out of the 34 observed singly-charged IM peaks above 5% relative abundance ( i.e., signal-to-noise ratios above ∼200) were tagged as potentially co-eluting ions by IM_FIT. Subsequently, the 14 IM peaks tagged as potentially unresolved (presumably, peaks corresponding to co-eluting compounds), were further analyzed by automated IM deconvolution (AIMD), liquid chromatography-IM-MS (LC-IM-MS), and/or ultra-high resolution mass spectrometry. Using the aforementioned techniques, more than 85% of the tagged IM peaks (12 out of 14) were confirmed to contain co-eluting ions. As an additional new finding, IM_FIT facilitated the discovery of an unexpected sequence-scrambled y-type fragment ion. [ABSTRACT FROM AUTHOR]

Highlights: [•] This review paper deals with the applications of electronic noses and electronic tongues to the monitoring of fermentation processes. [•] Positive and negative aspects of the different approaches reviewed are analyzed. [•] Current and future endeavors in this field are also commented. [Copyright &y& Elsevier]

Abstract: In this paper a new prototype of solid phase microextraction–ion mobility spectrometry (SPME–IMS) system was developed to effectively couple the extraction efficiency of SPME with the detection capability of IMS. The main component of this system was the transfer line/desorber, which was a low-thermal-mass (ca. 0.15g) silicosteel coatings stainless steel tube. The transfer line/desorber was designed to rapidly desorb and transfer the analytes extracted by SPME to IMS. A custom-made temperature controller with a proportional–integral–differential (PID) was used to maintain the temperature of the transfer line/desorber stable and avoid overheating or oscillating. The low thermal mass of this interface allowed it to be rapidly heated and cooled with much less electrical power and could substantially reduce the demand for high capacity batteries. The operational characteristics of this system were demonstrated through the analysis of camphor vapour. The precision of reduced mobility and the peak amplitude of camphor were good (R.S.D. 0.62%, n =10; R.S.D. 2.5%, n =10, respectively). SPME–IMS system was also shown to be capable of on-site measurement by monitoring the biogenic volatile organic compounds (BVOCs) emitted from eucalyptus citriodora leaves. In addition, this system was applied to quantitation of diazepam and cocaine in aqueous solution. Limits of detection were 10ng/mL for diazepam and 50ng/mL for cocaine with the reported experimental conditions. This SPME–IMS system exhibits considerable promise as a robust, simple, rapid, energy-saving fieldable approach for on-site analysis of analytes in various matrix. [Copyright &y& Elsevier]

A method for diagnosis of bacterial vaginosis (BV) and other vaginal infections, based on measurement of biogenic amines present in a sample of vaginal fluid by ion mobility spectrometry (IMS) was developed. Sample introduction is through a two step procedure: addition of alkaline solution to release the volatile amines followed by heating and acid addition for emanation of the semi-volatile amines. Addition of n-nonylamine vapors to the carrier gas stream helps control the ionization processes and enhances the selective response to amines, even in the complex environment of biological matrices. A software package was developed for acquisition, storage and processing of the mobility spectra and for providing a diagnosis based on a table of rules. We report the results from testing of 210 samples of vaginal discharge fluid that were diagnosed by a gynecologist according to the widely used reference method (Amsel test) and by the new IMS method. The new method is rapid (less than 2 min per sample), has a high sensitivity (few False Negatives) and specificity (few False Positives) with an accuracy of >95% for BV. The use of this method can reduce the incidence of misdiagnosis, particularly when trichomoniasis is confused with bacterial vaginosis. [Copyright &y& Elsevier]

The extent of spoilage of muscle food products was determined through measurement of volatile biogenic amines that emanated from food samples. The release of the amines was enhanced by addition of a few drops of an alkaline solution and the amines were monitored by ion mobility spectrometry (IMS). The limit of detection of the method for trimethylamine (TMA) was 2 ng and the measurement was completed within <2 min with short and long term reproducibility of 15 and 25%, respectively, for replicate samples. The method provides qualitative information as it distinguishes between different amines, as well as quantitative data for the key compounds. A good correlation was found between the IMS results and the microorganism populations in microbiological cultures. The effects of storage time and temperature and of the type of meat on the formation of biogenic amines were examined, and as expected, the higher the storage temperature the faster the spoilage. Thus, this pilot study shows that the measurement of biogenic amines can serve as an indicator for food spoilage or freshness. [Copyright &y& Elsevier]