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Analytical Methods for Airborne PAH
Published in Alf Bjørseth, Georg Becher, PAH in Work Atmospheres: Occurrence and Determination, 1986
The potential of the combination of liquid chromatography-mass spectrometry (LC-MS) for the separation and identification of organic compounds has generated considerable research in the past few years. The inherent problem of introducing a liquid stream into the high-vacuum system of the MS has led to several approaches which have been reviewed in the literature.128,129 Applications of LC-MS for the identification of low-volatile compounds, including PAH, have been reported.129,130
Application of molecularly imprinted polymers as the sorbent for extraction of chemical contaminants from milk
Published in International Journal of Environmental Health Research, 2023
Fatemeh Hemmati, Hedayat Hosseini, Parisa Mostashari, Aynura Aliyeva, Amin Mousavi Khaneghah
Therefore, there is a need for an effective, economical, and robust technique to detect trace residues of hormones, melamine, and antibiotics in milk. Moreover, milk is an aqueous matrix containing fat, protein, and other components that may interfere with the analysis (Mayor et al. 2017). In the last years, numerous analytical techniques have been used for the determination of these contaminants, such as liquid chromatography-mass spectrometry (LC-MS), high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and enzyme-linked immunosorbent assay. However, because of the low concentration of these compounds and the complexity of milk samples, it is necessary to use sample pre-treatment techniques for their preconcentration and purification before instrumental techniques (Barros et al. 2023; Mohan et al. 2023). Accordingly, molecular imprinting as a method for extracting and determining contaminants from aqueous samples has attracted much attention from many researchers (Chen et al. 2021; Zeng et al. 2021; Hassan et al. 2022). Molecular imprinting polymers (MIPs) are synthetic materials containing specific recognition sites complementary to the target molecule. They have selectivity for a specific analyte or group of compounds and remove the interfering compounds from complex samples (Soledad-Rodríguez et al. 2017; Kamaruzaman et al. 2021). The present article gives an overview of the synthesis of MIPs and their application for extracting antibiotics, hormones, and melamine in milk samples.
Magnetic recyclable heterogeneous catalyst Fe3O4/g-C3N4 for tetracycline hydrochloride degradation via photo-Fenton process under visible light
Published in Environmental Technology, 2022
Kang-Ping Cui, Ting-Ting Yang, Yi-Han Chen, Rohan Weerasooriya, Guang-Hong Li, Kai Zhou, Xing Chen
The residual TC concentrations were detected by high-performance liquid chromatography using oxalic acid, methanol, and acetonitrile mobile phase at 357 nm (HPLC; Agilent 1200 Series). The overall degradation efficiency of TC by the photoreactor system was determined by measuring total organic carbon (TOC) with TOC/TN analysis (Multi N/C 3100). H2O2 was measured spectrophotometrically by the KMnO4 method at 400 nm [35] (UV-Vis; Hitachi, Japan). The total iron concentration in solution was measured by flame atomic absorption spectrophotometry (AAS; AA140, VARIAN). The degradation intermediates were analyzed by high-performance liquid chromatography-mass spectrometry (LC-MS; Agilent 1290/6460, USA). The free radicals generated during the degradation process were detected by electron paramagnetic resonance spectroscopy (ESR; JES-FA200, JEOL, Japan) using a 50 mM 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) scavenger.
Kinetics, mechanism, and identification of photodegradation products of phenazine-1-carboxylic acid
Published in Environmental Technology, 2020
Peng Huasong, Huan Qingwen, Muhammad Bilal, Wei Wang, Xuehong Zhang
For PCA quantification, the fermentation broths (400 µL) were initially acidified to pH 2.0 with 20 µL HCl (6 M) followed by extraction with three volumes of ethyl acetate (3.6 mL) under vigorous shaking. A 400-μL portion of the upper layer was collected and completely evaporated in a rotary evaporator. The resulting residues were dissolved in methanol (1 mL) and analyzed by HPLC (Model 1260 infinity, Agilent Technologies, Santa Clara, USA) with a C-18 reversed- phase column (Agilent Eclipse, XDB-C18, 4.6 mm × 250 mm, 5 μm, Santa Clara, USA) at 30°C. The mobile phase was methanol + 0.1% acetic acid solution (70 + 30 by volume) and eluted at a constant rate of 1.0 mL/min. The eluent was monitored under the spectral peak maxima (254 nm and 268 nm), which are the characteristic of PCA in the designated solvent system. The photodegradation products after the photochemical reaction were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS). The mobile phase comprising methanol + 0.1% acetic acid solution (ration 60:40) was used at a flow rate of 1.0 mL/min, and the injection volume was 5 uL. The UV detection wavelength was 268 nm and the mass spectral scanning range was 80–500 M/Z.