Field Analysis of Polychlorinated Biphenyls (PCBs) in Soil Using Solid-Phase Microextraction (SPME) and a Portable Gas Chromatography-Mass Spectrometry System

Portable gas chromatography-mass spectrometry method for the in-field screening of organic pollutants in soil and water at pollution incidents

Environmental pollution incidents generate an emergency response from regulatory agencies to ensure that the impact on the environment is minimised. Knowing what pollutants are present provides important intelligence to assist in determining how to respond to the incident. However, responders are limited in their in-field capabilities to identify the pollutants present. This research has developed an in-field, qualitative analytical approach to detect and identify organic pollutants that are commonly detected by regulatory environmental laboratories. A rapid, in-field extraction method was used for water and soil matrices. A coiled microextraction (CME) device was utilised for the introduction of the extracted samples into a portable gas chromatography-mass spectrometry (GC-MS) for analysis. The total combined extraction and analysis time was approximately 6.5 min per sample. Results demonstrated that the in-field extraction and analysis methods can screen for fifty-nine target organic contaminants, including polyaromatic hydrocarbons, monoaromatic hydrocarbons, phenols, phthalates, organophosphorus pesticides, and organochlorine pesticides. The method was also capable of tentatively identifying unknown compounds using library searches, significantly expanding the scope of the methods for the provision of intelligence at pollution incidents of an unknown nature, although a laboratory-based method was able to provide more information due to the higher sensitivity achievable. The methods were evaluated using authentic casework samples and were found to be fit-for-purpose for providing rapid in-field intelligence at pollution incidents. The fact that the in-field methods target the same compounds as the laboratory-based methods provides the added benefit that the in-field results can assist in sample triaging upon submission to the laboratory for quantitation and confirmatory analysis.

Advances in rapid detection of SARS-CoV-2 by mass spectrometry

COVID-19 has already been lasting for more than two years and it has been severely affecting the whole world. Still, detection of SARS-CoV-2 remains the frontline approach to combat the pandemic, and the reverse transcription polymerase chain reaction (RT-PCR)-based method is the well recognized detection method for the enormous analytical demands. However, the RT-PCR method typically takes a relatively long time, and can produce false positive and false negative results. Mass spectrometry (MS) is a very commonly used technique with extraordinary sensitivity, specificity and speed, and can produce qualitative and quantitative information of various analytes, which cannot be achieved by RT-PCR. Since the pandemic outbreak, various mass spectrometric approaches have been developed for rapid detection of SARS-CoV-2, including the LC-MS/MS approaches that could allow analysis of several hundred clinical samples per day with one MS system, MALDI-MS approaches that could directly analyze clinical samples for the detection, and efforts for the on-site detection with portable devices. In this review, these mass spectrometric approaches were summarized, and their pros and cons as well as further development were also discussed.

Direct and fast determination of polychlorinated biphenyls in contaminated soils and sediments by thermal desorption-gas chromatography-tandem mass spectrometry

A direct procedure based on thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS-MS) was developed for the fast extraction of seven polychlorinated biphenyls (PCBs) from sediments and soils. PCBs were directly extracted, from 20 to 75 mg of sample, without any chemical pre-treatment or use of organic solvents, after the addition of 10 µL internal standard (PCB 195) in acetone. Sample treatment was totally automated. PCBs were extracted at 250 °C for 20 min, using a helium flow and the PCBs were trapped in a cryogenic Tenax trap at -10 °C. After that, analytes were directly desorbed at 270 °C and introduced to the GC-MS-MS system. Recoveries were established using spiked soil and sediment from 2.5 to 50 ng g^-1, obtaining values from 74 to 127%. The limits of quantification were from 1.0 to 1.7 ng g^-1 for soil and from 0.3 to 0.4 ng g^-1 for sediments, respectively. Precision, assessed as the relative standard deviation (RSD), was lower than 8 and 11% for sediment and soil analysis, respectively, except for PCB-28 in soil samples which provided a RSD of 18%. Certified reference material and field samples were analysed by the proposed TD-GC-MS-MS method. Results were compared by a paired samples Student's t-test with those obtained by a reference extraction procedure based on pressurized solvent extraction, followed by stir bar sorptive extraction, being statistically comparable (α = 0.05). A comprehensive greenmetric evaluation of the proposed method was carried out, having the TD extraction a negligible environmental impact as compared to conventional extraction procedures.

Progress in the development of olfactory-based bioelectronic chemosensors

Artificial chemosensory devices have a wide range of applications in industry, security, and medicine. The development of these devices has been inspired by the speed, sensitivity, and selectivity by which the olfactory system in animals can probe the chemical nature of the environment. In this review, we examine how molecular and cellular components of natural olfactory systems have been incorporated into artificial chemosensors, or bioelectronic sensors. We focus on the biological material that has been combined with signal transduction systems to develop artificial chemosensory devices. The strengths and limitations of different biological chemosensory material at the heart of these devices, as well as the reported overall effectiveness of the different bioelectronic sensor designs, is examined. This review also discusses future directions and challenges for continuing to advance development of bioelectronic sensors.