Systematic derivatization, mass fragmentation and acquisition studies in the analysis of chlorophenols, as their silyl derivatives by gas chromatography–mass spectrometry

Simultaneous determination of 19 bromophenols by gas chromatography-mass spectrometry (GC-MS) after derivatization

Bromophenols (BPs) are a class of ubiquitous emerging halogenated pollutants. Their 19 congeners are problematically separated and detected. This work described the separation and detection of 19 BP congeners by gas chromatography-mass spectrometry (GC-MS). Investigations into the derivatization of bromophenols were carried out using two silylation reagents (N,O-bis(trimethylsilyl)trifluoroacetamide and N-methyl-N-(trimethylsily)trifluoroacetamide), two alkylation reagents (methyl iodide and trimethylsilyldiazomethane) and acetic anhydride prior to GC-MS analysis. Optimal chromatographic separation, sensitivity, and linearity were achieved after BP derivatization using acetic anhydride, featuring the equipment detection limits of 0.39-1.26 pg and correlation coefficients of 0.9948-0.9999 (linear range: 0.5-250 ng mL-1) for all 19 BP congeners. Furthermore, the simultaneous determination of 19 bromophenols and 19 bromoanisoles, common environmental transformation products of BPs, is also demonstrated. The improved analytical performance on GC-MS after derivatization would benefit investigations on the environmental origins, behaviors and fates of BPs and their environmental metabolites.

Development of methods based on low-temperature partitioning (LTP) for monitoring cresols and chlorophenols in sewage sludge, soil, and water in column leaching

Cresols and chlorophenols are chemical contaminants that are potentially toxic to humans and can be found in sewage sludge. These chemical contaminants can migrate into the sludge-soil-water system when sludge is used as a conditioner for agricultural soils. Thus, the objective of this study was to develop methodologies based on extraction with low-temperature partitioning (LTP) to determine cresols and chlorophenols in sewage sludge, soil, and water. The analysis was performed by gas chromatography coupled with mass spectrometry (GC-MS). The validated methods were applied to monitor cresols and chlorophenols in a column-leaching study of a sludge-soil-water system. Satisfactory results were achieved for selectivity, limit of quantification (LOQ), linearity, accuracy, and precision. In the column leaching study, only 2,4,6-trichlorophenol was quantified in sludge samples after 20 days of the experiment. None of the studied compounds were quantified in soil and leached water samples, due to the degradation promoted by the microorganisms present in the sewage sludge. Finally, validated methods were suitable for monitoring cresols and chlorophenols in the sludge-soil-water system.

Occurrence, distribution, and risk assessment of halogenated organic pollutants (HOPs) in marine fish muscle: The case study of Vietnam

Halogenated organic pollutants (HOPs), including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and chlorophenols (CPs), were identified in three marine fish species in Vietnam. Total PCBs, OCPs, and CPs concentrations ranged from 4.5 to 711.6 ng g^-1 lipid weight (lw), 69.9-2360 ng g^-1 lw, and 208.1-3941.2 ng g^-1 lw, respectively. CPs were the most frequently detected pollutants in the marine environment of Vietnam of the three HOPs studied, followed by OCPs and PCBs. There are significant differences in HOPs between three types of seafood in Vietnam, including yellowstripe scad, Indian mackerel, and silver pomfret in this study. Notably, the types and amounts of HOPs found in the fish were differently influenced by the economic and industrial activities of the sampled areas. Despite these findings, the consumption of HOP-contaminated fish from the study areas was found not to pose any significant health risks to Vietnam's coastal population.

Simultaneous determination of 11 antiseptic ingredients in surface water based on polypyrrole decorated magnetic nanoparticles

With the emergence and spread of coronavirus COVID-19, the use of personal cleansing, medical and household disinfectant products have increased significantly. In this work, a new magnetic solid-phase extraction (MSPE) method for the determination of 11 antiseptic ingredients in surface water by high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) for 6 months based on Fe3O4@PPy magnetic nanoparticles (MNPs) was established. The MSPE method possessed the advantages of simple processing, little time consumption and less organic solvent consumption, and the MNPs could be reused several times. The analytical parameters influencing the extraction efficiency, such as sample pH, amount of MNPs and extraction time, were optimized in detail. It was indicated that the method had satisfactory linearities in the range of 0.50 to 1000.0 μg L-1 with the correlation coefficients (r) higher than 0.9996. Additionally, satisfactory spiked recoveries were achieved in the range of 80.21-107.33% with relative standard deviations (RSDs) from 1.98% to 8.05%. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 0.20 to 2.0 μg L-1 and 0.50 to 5.0 μg L-1. Therefore, the developed MSPE-HPLC-MS/MS method has high selectivity and stability, and satisfactory quantitative capability for the antiseptic ingredients in surface water. Furthermore, this method can provide relevant technical support for the development of surface water standards.

Determination of three cresol isomers in sewage sludge by solid-liquid extraction with low temperature purification and gas chromatography-mass spectrometry

Cresols are chemical contaminants derivative from phenol which can be found in sewage sludge. However, little attention has been given to monitoring these compounds in environmental matrices in the literature. Thus, the objective of this study was to develop a simple method based on solid-liquid extraction with low temperature purification for determining three cresol isomers in sludge. The quantification of these compounds was performed by gas chromatography coupled to mass spectrometry with a previous derivatization step. After a detailed study, the cresol recovery was higher than 91%, with relative standard deviation lower than 12% and a limit of quantification of 20 μg kg^-1. Linearity was achieved between 10 and 90 μg L^-1 (R² > 0.98) with the standard solutions prepared in matrix extracts due to the trouble caused by the matrix effect. The proposed method was applied with success for monitoring cresols in sewage sludge samples coming from six different wastewater treatment plants. All samples showed contamination by cresols, mainly p-cresol with values between 32.3 and 516.9 μg kg^-1. The majority of the analyzed samples showed a total sum of the isomers higher than the maximum residue limit established by Brazilian legislation (160 μg kg^-1).

Analysis of phenolic compounds in the dissolved and suspended phases of Lake Balaton water by gas chromatography-tandem mass spectrometry

As a novel approach to characterize the phenolic pollutants of Lake Balaton (Central Europe, western Hungary), 26 endocrine disrupting phenols (chlorophenols, nitrophenols, alkylphenols, triclosan, bisphenol-A) were quantified in dissolved and suspended particulate matter (SPM) phases, alike. Sample collection was performed in the western and eastern basins, at 20 sites in April and October 2014. Solid-phase and ultrasound-assisted extractions to withdraw target phenols from dissolved and suspended phases were employed. Compounds were derivatized with hexamethyldisilazane and trifluoroacetic acid for their quantification as trimethylsilyl derivatives by gas chromatography-tandem mass spectrometry. In Lake Balaton's dissolved phase, 2-chlorophenol (103-164 ng/L), 4-chlorophenol (407-888 ng/L), 2,4-dichlorophenol (20.2-72.0 ng/L), 2,4,6-trichlorophenol (10.4-38.1 ng/L), 2-nitrophenol (31.0-66.5 ng/L), 4-nitrophenol (31.5-94.1 ng/L), and bisphenol-A (20.6-112 ng/L), while in its SPM, 4-chlorophenol (<LOQ-1274 μg/kg, dry matter), 4-nitrophenol (423-714 μg/kg), 4-nonylphenol isomers (1500-2910 μg/kg), and bisphenol-A (250-587 μg/kg) were determined. Since phenolics appear partially or exclusively in the SPM, the analysis of both phases proved to be of primary importance. Graphical Abstract ᅟ.

Matrix effect during the membrane-assisted solvent extraction coupled to liquid chromatography tandem mass spectrometry for the determination of a variety of endocrine disrupting compounds in wastewater

Membrane-assisted solvent extraction (MASE) coupled to liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) was studied for the determination of a variety of emerging and priority compounds in wastewater. Among the target analytes studied certain hormones (estrone (E1), 17β-estradiol (E2), androsterone (ADT), 17α-ethynyl estradiol (EE2), diethylstilbestrol (DES), equilin (EQ), testosterone (TT), mestranol (MeEE2), 19-norethisterone (NT), progesterone (PG) and equilenin (EQN)), alkylphenols (APs) (4-tert-octylphenol (4tOP), nonylphenol technical mixture (NPs) and 4n-octylphenol (4nOP)) and BPA were included. The work was primarily focused in the LC-MS/MS detection step, both in terms of variable optimization and with respect to the matrix effect study. Both, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) were assessed both in the negative and positive mode, including the optimization of MS/MS operating conditions. The best results were obtained, in most of the cases, for ESI using 0.05% ammonium hydroxide as buffer solution in the mobile phase, composed with methanol and water. Under optimum detection conditions, matrix effect during the detection step was thoroughly studied. Dilution, correction with deuterated analogues and clean-up of the extracts were evaluated for matrix effect correction. Clean-up with Florisil together with correction with deuterated analogues provided the most satisfactory results, with apparent recoveries in the 57-136% range and method detection limits in the low ngL(-1) level for most of the analytes. For further validation of the method, two separated extraction procedures, the above mentioned MASE, and conventional solid phase extraction (SPE) were compared during the analysis of real samples and comparable results were successfully obtained for E1, E2, EE2, DES, NT, TT, EQ, PG, BPA, ADT, 4nOP, 4tOP, NPs and EQN.

Evaporative derivatization of phenols with 2-sulfobenzoic anhydride for detection by matrix-assisted laser desorption/ionization mass spectrometry

RATIONALE

Phenols are an important class of analytes, for example as bioactive environmental contaminants. Towards a goal of improving their detection by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) or MALDI-tandem time-of-flight (TOF/TOF)-MS, we studied their derivatization with 2-sulfobenzoic anhydride (SBA). We chose SBA for this purpose since it is commercially available, inexpensive, and forms an anionic derivative.

METHODS

Under the selected conditions developed here for phenols, a reaction mixture of one or more of such compounds in acetonitrile containing SBA and 4-dimethylaminopyridine (DMAP) is evaporated to a solid, heated at 60 °C for 1 h, redissolved in 50% acetonitrile containing matrix, spotted onto a MALDI target, and subjected to negative ion MALDI-TOF/TOF-MS.

RESULTS

While conventional (solution-phase) reaction of 4-phenylphenol (model analyte) with SBA and DMAP only gave a 47% yield of SBA-tagged 4-phenylphenol, evaporative derivatization as above gave a 96% yield, and 25 pmol (4.3 ng) of 4-phenylphenol could be detected in this way by MALDI-TOF/TOF-MS at signal-to-noise ratio (S/N) = 260, whereas even 1 nmol of the nonderivatized phenol was not detected in the absence of derivatization. A wide range of responses was observed when a mixture of 15 phenols was derivatized, with the higher responses coming from phenols with a pKa value above 9. Without derivatization, phenols with pKa values below 5 were the most readily detected.

CONCLUSIONS

Evaporative derivatization with SBA (a convenient reagent) can improve the detection of phenols with relatively high pKa values (above 9) by negative ion MALDI-TOF-MS, and accomplish this in the absence of post-derivatization reaction cleanup.