Solid-phase Extraction Liquid Chromatography Research Articles

Application of Polydopamine-Based Magnetic Solid-Phase Extraction for Highly Sensitive Determination of Aristolochic Acid I from Traditional Chinese Medicine Samples.

A low cost-effective and simple synthesis method combining magnetic solid-phase extraction (MSPE) and high-pressure liquid chromatography was developed for the analysis of aristolochic acids I (AAI) in traditional Chinese medicine samples. A novel polydopamine (PDA) modified magnetic nanoparticles with one single carbon layer (Fe3O4@1C NPs) via one-pot hydrothermal approach was prepared and then successfully employed to extract AAI for the first time. Dopamine (DA) can form a PDA layer on Fe3O4@1C NPs surface through self-polymerization to form Fe3O4@1C@PDA. As a surface modifier of DA, PDA offered more adsorption sites to AAI due to π-π stacking, hydrogen bonding and electrostatic interactions. The parameters of MSPE were optimized by univariate and multivariate methods (Box-Behnken design) in detail. High degree of linearity was obtained in the range of 0.05-200.0μg/mL. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.08 and 0.25μg/mL, respectively. The recoveries of AAI in spiked Xiaoqinglong mixture samples were in the range of 86.7 to 108.5% with the relative standard deviation of less than 5.2%. Thus, a fast, convenient, sensitive and eco-friendly method was successfully proposed and became a promising approach for the determination of AAI in herbal plants or its preparation in the manufacturing procedure.

Simultaneous determination of Obeticholic acid and its two major metabolites in human plasma after administration of Obeticholic acid tablets using ultra-high performance liquid chromatography tandem mass spectrometry

Obeticholic acid (OCA), a semisynthetic bile acid derivative, was approved for its therapeutic use in primary biliary cirrhosis. OCA has a enterohepatic circulation and host-gut microbiota metabolic interaction, which produce various metabolites. Such metabolites, especially structural isomers of OCA, together with the need to achieve idea lower limit of quantitation (LLOQ) with minimum matrix interference, bring about significant difficulties to the bioanalysis of OCA. Herein, by applying a combination of solid-phase extraction (SPE) and ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), we introduced an approach for the bioanalysis of OCA along with its two major metabolites—glyco-OCA (GOA) and tauro-OCA (TOA) in human plasma, the full validation results of which showed excellent performance. The quantitative range is 0.2506 ∼ 100.2 ng/mL for OCA, 0.2500 ∼ 100.0 ng/mL for GOA, as well as 0.1250 ∼ 50.00 ng/mL for TOA, respectively. This method was successfully applied to the pharmacokinetic studies in healthy subjects following administration of OCA tablets.

Determination of calcium β‑hydroxy-β-methylbutyrate content in special medical formula food and sports nutrition food by solid-phase extraction and high performance liquid chromatography

Calcium β‑hydroxy-β-methylbutyrate (CaHMB) can promote muscle growth, prevent muscle atrophy, and enhance immunity, therefore, it is widely used as a nutritional supplement in special medical formula food and sports nutrition food. Many methods for the detection of CaHMB have been reported, but the pretreatment method for these reported literatures directly involves extraction using hydrochloric acid solution, without any purification steps. A method for accurately determining CaHMB in special medical formula food and sports nutrition food was established for the first time using solid-phase extraction (SPE) purification and high-performance liquid chromatography method (HPLC). The samples were extracted and precipitated protein using methanol-water solution, purified using SPE method and analyzed by HPLC on diode array detector (DAD) mode under external standard method. The method obtained excellent calibration linearity (r2>0.9993) and a satisfactory analysis of the targeted compound, which were evaluated with calibration standards over the range of 0.020–2.00 mg/mL. The limit of quantifications (LOQs), which defined as the lowest spiking level, were set at 0.4 g/100 g (special medical formula food) and 1.0 g/100 g (sports nutrition food). The average recoveries were within 92.9–104% for the analytes, and the relative standard deviations (RSDs) were below 3.93%, measured at low, medium, and high concentrations. Moreover, the positive sample analysis results indicated that CaHMB was detected on 10 real special medical formula food and sports nutrition food products, the contents of which were generally consistent with their labeled values, with measured values ranging from 97.1 % to 119 % of the labeled values. These results suggested that the developed highly sensitive and specific method is highly feasible for monitoring of the target analyte in special medical formula food and sports nutrition food.

Antibiotic Residues and Resistance in Three Wastewater Treatment Plants in Romania

This study evaluates antibiotic residues and bacterial loads in influent and effluent samples from three wastewater treatment plants (WWTPs) in Romania, across four seasons from 2021 to 2022. Analytical methods included solid-phase extraction and high-performance liquid chromatography (HPLC) to quantify antibiotic concentrations, while microbiological assays estimated bacterial loads and assessed antibiotic resistance patterns. Statistical analyses explored the impact of environmental factors such as temperature and rainfall on antibiotic levels. The results showed significant seasonal variations, with higher antibiotic concentrations in warmer seasons. Antibiotic removal efficiency varied among WWTPs, with some antibiotics being effectively removed and others persisting in the effluent, posing high environmental risks and potential for antibiotic resistance development. Bacterial loads were higher in spring and summer, correlating with increased temperatures. Eight bacterial strains were isolated, with higher resistance during warmer seasons, particularly to amoxicillin and clarithromycin.

Effective extraction of pyrethroid pesticides from cabbages using Fe3O4@NU-1000 and adsorption mechanism: An experimental and theoretical study

In this paper, a magnetic zirconium-based MOFs (Fe3O4@NU-1000) with good water stability was prepared for effective extraction of pyrethroid pesticides from vegetables. Characterization results showed Fe3O4@NU-1000 has a high specific surface area (435.34 m2·g−1) and a large pore size (4.88 nm), which provides abundant adsorption sites for pesticides molecules. Fe3O4@NU-1000 can achieve rapid magnetic separation from solution within 1 min, greatly reducing the extraction time of pyrethroid pesticides. The results of adsorption kinetics and isotherms showed that the adsorption process of pyrethroid pesticides on Fe3O4@NU-1000 was monolayer adsorption and physisorption. The maximum adsorption capacities of Fe3O4@NU-1000 for beta-cyfluthrin, lambda-cyhalothrin, permethrin, and bifenthrin were up to 1159.11, 1194.16, 1151.48, and 1181.74 mg·g−1, respectively. Molecular dynamics simulations showed that adsorption is driven by hydrophobic interaction. Van der Waals forces and hydrogen bonding accelerate pesticide molecules to approach the surface, and π–π interactions enable stable adsorption of pesticide molecules within the triangular and hexagonal micropores of NU-1000. DFT calculations confirmed that pesticide molecules predominantly adsorb stably within the pores of Fe3O4@NU-1000 through π–π interactions, with additional contributions from CH3–π and Cl–π interactions. Finally, a simple and sensitive method was established for the determination of pyrethroid pesticides in cabbage samples using Fe3O4@NU-1000 based magnetic solid-phase extraction and high-performance liquid chromatography. It provided low limit of detection (0.0011–0.0058 μg·mL−1), a wide linear range (1–25 μg·mL−1), and satisfactory recoveries (81.35–98.64 %), which can achieve effective extraction and trace detection. This study provides a magnetic MOFs material for extraction of pesticides and reveals its adsorptive mechanism at molecular level, which is helpful for rational design of more pretreatment materials for pesticides detection in complex food matrices.

Determination of the urinary concentrations of six bisphenols in public servants by online solid-phase extraction-liquid chromatography tandem mass spectrometry

Bisphenols are widely used as monomers and additives in plastic production. Thus, bisphenol A (BPA) and its most prominent substitutes have been detected in many environmental and human samples. This study proposes an online solid-phase extraction analytical methodology coupled to liquid chromatography with tandem mass spectrometry for the determination of six bisphenols (BPA and bisphenols F (BPF), S (BPS), AF (BPAF), B (BPB), and E (BPE)) in urine samples as an efficient and automated methodology. The method was developed and validated for all bisphenols with good recoveries (92–112%) and repeatability (RSD ≤ 10%) despite the variable matrix effects, except BPAF (which would require a dedicated internal standard), achieving method quantification limits in the 0.05–2.2 ng mL−1 range. The methodology was subsequently applied to 435 urine samples from a non-occupational exposure population (civil servants for the regional government) from Santiago de Compostela (Galicia, Spain). Only BPA, BPF, and BPS were positively detected; the last two presented higher detection frequencies than BPA. When the urinary concentrations are extrapolated to human intake and compared to the European Food Safety Agency (EFSA) tolerable daily intake (TDI) of 2 × 10−4 µg kg−1 day−1 (TDI), all BPA positively identified samples would surpass this threshold. Although no TDI exists currently for the other two identified bisphenols, it is evident that human exposure to bisphenols should be limited. Finally, the results stratification by gender revealed higher levels of exposure to BPF in the women group.

Fast analysis of short-chain and ultra-short-chain fluorinated organics in water by on-line extraction coupled to HPLC-HRMS

A rapid on-line solid-phase extraction liquid chromatography high-resolution mass spectrometry (on-line SPE-LC-HRMS) method was developed to analyze 11 ultra-short and short-chain PFAS in surface water. Analytical optimization involved screening 7 chromatographic columns and 5 on-line SPE columns, as well as evaluating SPE loading conditions, filters, sample acidification, chromatographic mobile phases, and SPE loading mobile phases. The optimized method was then applied to 44 river water samples collected in Eastern Canada, including sites near airports with fire-training areas. Among the 11 targeted PFAS, the most frequently detected were trifluoroacetic acid (TFA, 4.6–220 ng/L), perfluorobutanoic acid (PFBA, 0.85–33 ng/L), perfluoropentanoic acid (PFPeA, 1.2–2100 ng/L), trifluoromethane sulfonic acid (TMS, 0.01–4.3 ng/L), and perfluorobutane sulfonic acid (PFBS, 0.07–450 ng/L). Levels of C3-C5 perfluoroalkyl carboxylic acids (PFCAs), C2-C4 perfluoroalkyl sulfonates (PFSAs) and n:3 polyfluoroalkyl acids (n = 2,3; n:3 acids) were significantly higher in water bodies near fire-training area sites compared with rivers in urban areas. In contrast, TFA, TMS, and 1:3 acid were not significantly elevated, likely reflecting atmospheric deposition or other diffuse sources for these compounds. Nontarget and suspect screening analysis revealed an abundance of other ultra-short and short-chain PFAS in AFFF-impacted water bodies. Perfluoroalkyl sulfonamides (FASA, C2, C3, and C5), perfluoroalkyl sulfonamide propanoic acids (FASA-PrA, C1-C2) and n:3 acids (n = 1, 4, and 5) were detected for the first time in environmental surface waters.

Determination of calcium β-hydroxy-β-methyl butyrate content in milk and dairy products by solid-phase extraction and high performance liquid chromatography

In this paper, an analytical method based on solid-phase extraction (SPE) purification and high-performance liquid chromatography method (HPLC) was developed for the first time to determine the content of calcium β-hydroxy-β-methyl butyrate (CaHMB) in milk and dairy products. The quantitative detection was performed by HPLC with diode array detector (DAD) under external standard method. The limit of quantification (LOQ), calculated as 10 times the standard deviation, was 0.10 g/100 g. The average recoveries were in the range of 92.40–103.00 %, with relative standard deviations (RSDs) of 1.25–3.77 %, measured at three concentration levels. The real sample analysis results showed that CaHMB was detected in infant formula, formulated milk powder, and milkshake samples, the contents of which were in the range of 0.60–8.66 g/100 g, respectively. The developed method features good purification effect, good separation specificity, good repeatability, accuracy and reliability, and can meet the content determination of CaHMB in milk and dairy products.

Determination of Sedative and Anesthetic Drug Residues in Aquatic Food Products Using Solid Phase Extraction (SPE) and Liquid Chromatography–Tandem Mass Spectrometry (LC–MS/MS)

The residues of sedative and anesthetic drugs in aquatic products are an important factor affecting food safety. In order to screen the residues of sedative and anesthesia drugs in aquatic products, a rapid and sensitive method was established using solid phase extraction (SPE) and high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). The samples were extracted by 80% aqueous acetonitrile by an alumina column and separated by a C18 column. The mass spectra were determined in positive ion mode. The standard curves were matrix matched and quantified by the external standard method. The results showed that the linear ranges of the drugs in aquatic products were from 0.5 to 100 μg kg−1. The correlation coefficient (R 2) was greater than 0.990 and the detection limits were between 0.001 and 0.322 μg kg−1. The average recovery rate and relative standard deviation were between 78.64% and 112.15% and from 0.41%-8.26%. Overall, the developed method showed promising results for the simultaneous qualitative and quantitative determination of the drug residues in aquatic products.

Sorption of Polycyclic Aromatic Sulfur Heterocycles (PASH) on Nylon Microplastics at Environmentally Relevant Concentrations.

Microplastics have garnered an infamous reputation as a sorbate for many concerning environmental pollutants and as a delivery vehicle for the aquatic food chain through the ingestion of these contaminated small particulates. While sorption mechanisms have been extensively studied for polycyclic aromatic hydrocarbons, polycyclic aromatic sulfur heterocycles (PASHs) have not been investigated, partly due to their low concentrations in aquatic ecosystems. Herein, an analytical methodology is presented for the analysis of dibenzothiophene, benzo[b]naphtho[1,2-b]thiophene, benzo[b]naphtho[2,1-b]thiophene, benzo[b]naphtho[2,3-b]thiophene, chryseno[4,5-bcd]thiophene and dinaphtho[1,2-b:1',2'-d]thiophene at relevant environmental concentrations based on solid phase extraction and high-performance liquid chromatography. The sorption uptake behavior and the sorption kinetics of the three benzo[b]napthothiophene isomers were then investigated on nylon microplastics to provide original information on their environmental fate and avoid human contamination through the food chain. The obtained information might also prove relevant to the development of successful remediation approaches for aquatic ecosystems.

Optimizing solid phase extraction and HPLC-MS/MS parameters for reliable quantification of COVID-19 pharmaceuticals in Mexico City’s wastewater: A design of experiments approach

Through the COVID-19 health crisis, a plethora of new medications, along with some discontinued pharmaceuticals, were directly tested on population to assess their efficacy in symptom management. Consequently, residues from these treatments were systematically disposed into sewage systems, presenting a novel contamination challenge in urban centers. To effectively address this issue by environmental authorities, the presence of these pollutants in wastewater must be accurately quantified. Herein, we conducted a meticulous study to validate an analytical method based on solid-phase extraction (SPE) and high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) to detect six pharmaceuticals (metformin, famotidine, indomethacin, dexamethasone, azithromycin, and ivermectin) in wastewater. Using a Plackett-Burman design (PBD), the eight parameters significantly impacting on the HPLC-MS/MS technique were established based on the analytical signal of the six analytes. Subsequently, in conjunction with a Box-Behnken design (BBD), optimal analysis conditions were determined as follows: injection volume: 10 µL, column temperature: 20 °C, capillary voltage: 4100 V, drying gas temperature and flow rate of 350 °C and 7 L min−1 respectively, nebulizer pressure: 15 psi, concentration of formic acid and ammonium acetate in the mobile phase of 0.1 % and 10 mmol/L, respectively. SPE was optimized through a univariable experimental design. OASIS HLB cartridges exhibited the highest extraction efficiency compared to highly polar and non-polar adsorbents. The optimal sample loading conditions were set as 250.0 mL of water sample at pH = 9.0. The washing conditions were 5.0 mL of a 95:5 water:methanol solution, while elution conditions were optimal using 6.0 mL of a 98:2 methanol:formic acid solution. After evaporating the eluate to dryness and reconstituting in 1.0 mL of a 98:2 methanol:formic acid solution, a concentration factor of 250 was achieved. The analytical method was validated using for matrices, namely, raw and treated wastewater, wastewater percolated through soil and groundwater. Acceptable levels of precision and accuracy were achieved for all analytes in the tested matrices. Using the validated method, the six pharmaceuticals were quantified in environmental samples, revealing high levels of metformin, dexamethasone, and azithromycin in Mexico City’s sewage. Highly polar compounds displayed mobility through environment as they were present in effluent samples, percolated wastewater, and groundwater.

Ionic liquid-functionalized mesoporous multipod silica for simultaneously effective extraction of aflatoxin B1 and its two precursors from grain

BackgroundAflatoxin B1 (AFB1) and its precursors contaminate food and agricultural products, posing a significant risk to food safety and human health, but simultaneous and effective extraction and determination of AFB1 and its precursors with varied structures is still a challenging task. ResultsIn this study, a bisimidazolium-type ionic liquid functionalized mesoporous multipod silica (SiO2@mPMO-IL(im)2) was fabricated to extract AFB1 and its two precursors, i.e., averantin and sterigmatocystin. The SiO2@mPMO-IL(im)2 could simultaneously extract three targets with varied structures based on the multipods, mesopores, and multifunctional groups. The density functional theory calculations further verified the multiple interactions between SiO2@mPMO-IL(im)2 and targets. The fabricated SiO2@mPMO-IL(im)2 could effectively extract and determine three targets in grains by combing with dispersive solid-phase extraction and high-performance liquid chromatography. Good linearity (r2 > 0.9978), low LODs (0.9–1.5 μg kg−1) and LOQs (3.0–4.5 μg kg−1), satisfactory spiked recoveries (92.5%–106.8%) and high precisions (RSD<6.4%) were observed. Significance and noveltyThis work demonstrates the feasibility of SiO2@mPMO-IL(im)2 for simultaneous and effective extraction of toxins with varied structures and provides a promising sample preparation for the analysis of AFB1 and its precursors in grain samples.

Determination of lipophilic marine biotoxins (azaspiracids, brevetoxins, and okadaic acid group) and domoic acid in mussels by solid-phase extraction and reversed-phase liquid chromatography with tandem mass spectrometry

An accurate and efficient method was developed for the determination of azaspiracid shellfish toxins (azaspiracids-1, -2, and -3), neurotoxic shellfish toxins (brevetoxins-2 and -3), diarrhetic shellfish toxins (okadaic acid and dinophysistoxins-1 and -2), and the amnesic shellfish toxin (domoic acid) in mussels (Mytilus galloprovincialis). Lipophilic marine biotoxins (azaspiracids, brevetoxins, and okadaic acid group) were extracted with 0.5 % acetic acid in methanol under heating at 60°C to improve the extraction efficiency of okadaic acid group toxins and then cleaned up with a C18 solid-phase extraction cartridge. Domoic acid was extracted with 50 % aqueous methanol and then cleaned up with a graphitized carbon solid-phase extraction cartridge. Lipophilic marine biotoxins and domoic acid were quantified by reversed-phase liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The developed method had insignificant matrix effects for the nine analytes and good recoveries in the range of 79.0 % to 97.6 % at three spiking levels for all analytes except brevetoxin-2 (43.8–49.8 %). The developed method was further validated by analyzing mussel tissue certified reference materials, and good agreement was observed between certified and determined values.

WLIP, WLIPβ, and WLIPγ Produced from Pseudomonas canadensis Q3-1 via Precursor-Directed Biosynthesis and Their Roles on Biocontrol of Phytophthora Blight in Peppers.

White line-inducing principle (WLIP, 1), together with two new cyclic lipopeptides (CLPs) WLIPβ (2) and WLIPγ (3), were characterized from the supernatant of Pseudomonas canadensis Q3-1 via precursor-directed biosynthesis (PDB) in the current study. They were purified from the supernatant of P. canadensis Q3-1 by solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC), and their structures were mainly determined via bioinformatic analyses, spectrometric and spectroscopic techniques, as well as single crystal X-ray diffraction (XRD). These WLIPs share (R)-3-hydroxydecanoic acid (HDA), but they differ from each other in the composition of peptidic sequences. In addition, these CLPs showed biocontrol activities against Phytophthora blight (caused by Phytophthora capsici) in peppers. Collectively, this study has shown that PDB could be used for generating new CLPs in Pseudomonas spp. Moreover, we have confirmed that WLIP, WLIPβ, and WLIPγ could be used as lead agrochemicals to control Phytophthora blight in peppers.

Highly selective analysis of glipizide as an antidiabetic drug in urine samples using HPLC-DAD technique via magnetic nanocomposites (Fe3O4@SiO2@tryptophan)

The extraction of endogenous compounds and drugs from complex biological matrices such as bio fluids and solid tissues necessitates an appropriate analytical approach that allows for qualitative and quantitative analysis because of the very low concentrations of the target species. This present work surveys the universe to isolate, purify, and immobilize an antidiabetic drugs such as glipizide biomolecules in urine samples using a magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography (HPLC-DAD). To accomplish this purpose, a synthesis strategy of silica-coated magnetic nanoparticles functionalized with Tryptophan which is known as an amino acid to be applied as sorbent for (MSPE) is elaborated and analyzed. The structural and optical properties of the new magnetic nanocomposite have been investigated using Scanning electron microscope (SEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transformation infrared (FTIR) techniques. In addition, HPLC analysis was carried out for the detection and determination of glipizide concentration in urine samples after magnetic solid phase extraction. After MSPE, the linear range for glipizide molecules (R2 > 0.9942) was obtained in the range of 15.00–900.00 ng mL−1. The calculations yielded a limit of detection (LOD) of 4.38 ng mL−1 and a limit of quantification (LOQ) of 14.71 ng mL−1. Additionally, the relative standard deviation (RSDs %) was found to be below 3.8 %. Furthermore, the recovery values for synthetic urine were 96.5 %, 96.6 %, and 102.5 %, and for human urine were 104.5 %, 106.1 %, and 97.1 %. These findings indicate that the combined use of MSPE with HPLC-DAD is an effective and valuable approach for accurately determining the concentration of glipizide in human urine samples.

Determination of 55 Veterinary Antibiotics in Chicken Manure Using Ultra-High-Performance Liquid Chromatography – Tandem Mass Spectrometry (UPLC-MS/MS)

A highly efficient method for the detection and quantification of 55 veterinary antibiotics (VAs) in chicken manure belonging to six drug classes using solid-phase extraction (SPE) and ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) was developed. The mixture of EDTA–McIlvaine buffer (pH 3.0) and the organic extractant (methanol–acetonitrile, 1:3, v/v) was used to isolate the target VAs from freeze-dried chicken manure. The extract was purified by a hydrophile–lipophile balance cartridge. All antibiotics showed excellent linear relationships in the range between 1 and 100 µg/kg with the coefficients of determination of the standard curves above 0.990. The recoveries of antibiotics were between 35.66% and 103.54% using matrix-matched calibration for quantification. The limits of detection and quantification were from 0.01 to 1.59 µg/kg and 0.04 to 4.76 µg/kg, respectively. The method was demployed to determine VAs in chicken manure from 12 farms, revealing contamination in all samples. A total of 13 VAs belonging to six classes were detected with concentrations up to 41.47 mg/kg. The presence of high concentrations of antibiotic residues in poultry manure poses a potential risk for environmental contamination. This work has identified significant differences in the types of VAs compared to literature reports. Additionally, it detected pleuromutilin antibiotics in chicken manure for the first time.

Thyroid Hormone Metabolites Quantified in Pup and Adult Rat Cerebellum, Cortex and Whole-Brain Samples Using an Automated Online SPE-LC-MS/MS Method.

Changes in thyroid hormone (TH) levels in rat brain at early developmental stages are correlated with adverse effects on offspring development. To characterize the ability of substances to interfere with the TH concentrations in, e.g., rat brain, it is essential to know the mean TH concentrations in this tissue under control conditions. In this publication, an online solid-phase extraction (SPE) liquid chromatography (LC) tandem mass spectrometry (MS/MS) method was validated and used to measure TH metabolites (T4, T3, rT3, T2 and T1) in the brains of untreated rats. Data on TH concentrations in the whole brain and separate data from the cerebellum and the cortex are shown. The corresponding samples were gathered from young rats at postnatal days (PND) 4 and 21/22 and from adult rats. The results show inter alia the high accuracy and precision of the method, and LOQs of 0.02 ng/mL were determined for T1, T2 and rT3 and of 0.15 ng/mL for T3 and T4. Technical variability is low, as shown by the relative standard deviations of 7.5-20%. For our rat model, we found that T4, T3 and T2 concentrations rise from PND4 to PND21, whereas the rT3 concentration decreases; as well as there is no statistical difference between TH concentrations in the male and female rat brain. This method is suitable to analyze TH metabolites in the brain and build up a database of historical TH concentrations in control rats. Together, this yields a robust diagnostic tool to detect potentially adverse disturbances of TH homeostasis in the most vulnerable anatomic structure.

Determination of Phenylethanolamine A Residues in Milk by Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry

A method was established for the determination of phenethanolamine A residue in milk by solid phase extraction, liquid chromatography-tandem mass spectrometry. The samples were extracted with ammonium acetate buffer solution under the condition of enzymatic hydrolysis and purified by MCX solid phase extraction column. The eluent was blown dry with nitrogen at 45℃ and dissolved with 1.0 mL 0.1% formic acid solution. The samples were isolated by Poroshell 120EC-C18, 100 mm ×3.0 mm (i.d.), 2.7 μm column, and then determined by mass spectrometry in multiple reaction monitoring mode, and quantified by internal standard method. The results showed that phenethanolamine A had good linear relationship in the concentration range of 0.5-50.0 μg/L, the correlation coefficient r=0.9984, the limit of detection was 0.17 μg/kg, and the limit of quantitation was 0.57 μg/kg. The average recovery was 98.3-108.7% and the precision was 2.4-3.7% at different supplemental levels. The established method can purify the samples effectively, improve the detection efficiency, and is suitable for the detection of phenethanolamine A residue in milk.

A Review of Global Occurrence of Emerging Pollutants in Wastewater: Present Status, Source/Pathway, Extraction and Detection Techniques

The occurrence of emerging pollutants (EPs) is constantly reported around the world. Despite this, due to their large number, only a few of these compounds have been toxicologically evaluated. In this paper, the literature on EPs found in wastewater was reviewed from 1998 to 2021, with a focus on their occurrence, extraction, and detection methods. Pesticides, microplastics, pharmaceuticals and personal care products, per and polyfluoroalkyl substances were studied for their presence in wastewater in Africa, Oceania, North America, Asia, Europe and South America. The highest concentration of pesticides in wastewater was recorded in Africa (Cameroun) at concentration ranging from 2 to 2993 ng/L whilst the least was recorded in Europe (Spain) at concentrations ranging from 0.02 to 1.94 ng/L; Pharmaceuticals and personal care products had the highest concentration in Africa (Egypt) at 70.6 to 119.4 mg/L whilst the least concentration was found at 0.1 to 646 ng/L in Africa (Tunisia); Per and polyfluoroalkyl substances had the highest concentration in Asia (Thailand) at 662 to 1383 ng/L while the least concentration was found to be in the range 0.2 to 48.6 ng/L in Europe (Denmark); Microplastics were also recorded in this study to have the highest concentration in the range 28.4 to 79.9 particles/L in Asia (China) and the least concentration in the range 0.0008 particles/L in North America (USA). Reliable analytical extraction and detection methods were the solid phase extraction and high-performance liquid chromatography coupled to different detectors respectively, and they were employed for the pesticides, pharmaceuticals and personal care products, per and polyfluoroalkyl substances only whilst the extraction and detection methods employed for the microplastics were filtration and digestion techniques followed by the FT-IR detection method. EPs were more prevalent in the African continent as a result of various socio-economic issues that led to poor sanitation systems and drastic shortages in wastewater treatment plants in many regions, making it difficult to tackle the problem of emerging pollutants.

Occurrence of sulfonamides and tetracyclines in the coastal areas of the Yangtze River (China) Estuary.

Antibiotics have attracted global attention due to the ecological risks to environment. In this paper, solid-phase extraction and ultra-performance liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS) were utilized to analyze the fugitive characteristics of 10 antibiotics of sulfonamides (sulfadiazine, sulfamethazine, sulfadimidine, sulfathiazole, sulfapyridine, sulfamethoxazole) and tetracyclines (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in the coastal waters and surfece sediments of the Yangtze River Estuary and the ecological risks of antibiotics in water were estimated using ecological risk assessment method. The results have showed that 7 of the 10 antibiotics were detected in the water, with total concentrations ranging from 0.652 to 434.47ng/L. 8 antibiotics were detected in the sediment, with total concentrations ranging from 0.091 to 499.23ng/g. The main antibiotic species detected in the sediment and water varied seasonally. Higher concentrations in spatially distributed areas where rivers meet and where human activities have a more significant impact. The ecological risks were found to be higher in spring and autumn than those in winter and summer. Spatial variation in individual microbial communities was not evident in the sediments. The relationship between antibiotics and microorganisms in the environment was predominantly positive. Physical and chemical factors were significantly correlated for both antibiotics and microbial communities. This study can provide research ideas for other types of antibiotics and provide a basis for the prevention of antimicrobial resistance (AMR).