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Analysis of Pesticide Residues by Chromatographic Techniques Coupled with Mass Spectrometry
Published in José L. Tadeo, Analysis of Pesticides in Food and Environmental Samples, 2019
Wan Jing, Jin Maojun, Jae-Han Shim, A.M. Abd El-Aty
Comprehensive two-dimensional gas chromatography (GC×GC) has been proven to be a powerful tool for the separation and analysis of complex systems because the information of GC×GC can be used to reveal the chemical composition of the components. However, qualitative analysis of complex chemical systems requires structural information provided by spectroscopic detectors such as MS. The two-dimensional column of GC×GC is equivalent to a fast chromatography, and the typical peak width of the column is 0.1–0.6 s. This requires that the frequency of the connected detector is fast enough. The acquisition frequency of conventional quadrupoles is too slow to meet the requirements of coupling with GC×GC. The time of flight mass spectrometry (TOFMS) enabled GC×GC–TOFMS to be applied to the identification of complex systems.
Antiepileptic drugs in aquatic environments: Occurrence, toxicity, transformation mechanisms and fate
Published in Critical Reviews in Environmental Science and Technology, 2023
Quanzhen Liu, Long Wang, Xiong Xu, Saihong Yan, Jinmiao Zha, Donghong Wang, Dan Zhu
In the future, more studies should focus on the transformation mechanisms, which is necessary to monitor products of AEDs. Nontarget analysis technologies by means of UPLC-HRMS or comprehensive two-dimensional gas chromatography-time of flight-mass spectrometry (GC × GC-TOF MS) are powerful tools to identify unknown products and intermediates (Du et al., 2022). Several studies have revealed formation pathways of polycyclic aromatic hydrocarbons derivatives and halophenylacetamides during chlorination using nontarget analysis (Hu et al., 2022; Liu et al., 2020). It showed that nontarget analysis has significant advantages in identification of unknown products. Furthermore, development of structure prediction software (CSI:FingerID/SIRIUS 4, MSNovelist, etc.) based on machine learning algorithm will also provide efficient supports on spectral analysis of unknown products (Duhrkop et al., 2019; Stravs et al., 2022), which enable researchers to obtain the corresponding standards more accurately. Thus, it is recommended to combine mechanisms analysis with nontarget analysis to identify the metabolites/transformation products.
Biodegradation Potential of Oil-degrading Bacteria Related to the Genus Thalassospira Isolated from Polluted Coastal Area in Mediterranean Sea
Published in Soil and Sediment Contamination: An International Journal, 2022
Santina Santisi, Mariosimone Zoccali, Valentina Catania, Paola Quatrini, Luigi Mondello, Maria Genovese, Simone Cappello
However, the knowledge on some species of the genus Thalassospira is still limited, and the capabilities and mechanisms of degradation of contaminants are not well known. The main aim of this study was to identify the biodegradation potential and expand the knowledge on catabolic pathways involved in the degradation of hydrocarbons of three bacterial strains isolated from polluted coastal area, affiliated to species of the poorly investigated genus Thalassospira, . To achieve this goal, for the first time, the biotechnological potential of the species T. lucentensis, T. xianhensis and T. profundimaris were analyzed. In particular we evaluated: i) presence/absence of specific catabolic genes, ii) production of biosurfactants and iii) capability to degrade different oil fractions (linear, branched, cyclic alkanes and polycyclic aromatic hydrocarbons). The potential of hydrocarbons degradation was evaluate using a comprehensive two-dimensional gas chromatography method (GC×GC) with a dual detection, flame ionization detector (FID) and single quadrupole (Q MS). The use of this instrument has proven essential in order to achieve a detailed characterization and quantification of the different HC chemical families (Tranchida et al. 2009; Zoccali et al. 2015; Zoccali, Cappello, and Mondello 2018).
Spatial–temporal assessment of hydrocarbon biodegradation mechanisms at a contaminated groundwater site in Serbia
Published in Chemistry and Ecology, 2022
Nenad Marić, Jana Štrbački, Jason Polk, Latinka Slavković Beškoski, Jelena Avdalović, Marija Lješević, Kristina Joksimović, Aleksandra Žerađanin, Vladimir P. Beškoski
The total petroleum hydrocarbons (TPH) were extracted from groundwater samples, as per method ISO 9377–2 [17], followed by a comprehensive two-dimensional gas chromatography-mass spectrometry (GCxGC-MS) analysis (procedure described in detail by Beškoski [18]). Briefly, the oven program was: 40 °C for 5 min, then increase at 5 °C min−1–300 °C. The modulation period was 6 s. The scan range was m/z 70−500. The data were analyzed using GCImage V.2.8 (ZoexCorp.), and compounds were tentatively identified based on the comparison to the NIST 11 and WILEY8library. To estimate the relative amounts of each compound, the volume of each blob was used. Ion chromatography, in accordance with U.S. EPA protocol [19], was used for the determination of NO3- and SO42- anions in water samples. The concentration of HCO3- anions was analyzed volumetrically, as per EN ISO 9963-1:07 [20]. The iron and manganese concentrations were determined using ICP-OES following the U.S. EPA [21], using an iCAP Qc Thermo Scientific (United Kingdom) with a measuring range > 0.0003 µg/L and software version 2.6.2270.44 (32 bit). Determination of ammonia nitrogen concentrations (NH3) was conducted by semi-automated colorimetry, following the U.S. EPA protocol [22]. U.S. EPA protocol [23] was followed for the determination of dissolved organic carbon (DOC).