Liquid Chromatography-triple Quadrupole Mass Spectrometry Research Articles

Quantitative analysis of oxygen heterocyclic compounds using liquid chromatography coupled to tandem mass spectrometry, method development and environmental assessment

The latest trends in the field of laboratory method development concern the validation of fast procedures, and the safety of the operator and environment. The present research is focused on the development of fast and environmentally-friendly analytical method of liquid chromatography-triple quadrupole mass spectrometry for the determination of oxygen heterocyclic compounds in Citrus-flavored products. To the best of the authors’ knowledge, this is the first approach for the characterization of thirty-six oxygen heterocyclic compounds in less than four minutes using water/ethanol as mobile phase. Molecules were characterized in Citrus essential oils and beverages. Figures of merit determined were linearity, precision, limits of detection and quantification. The method was compared in terms of greenness with our two methodologies previously published for analysis of oxygen heterocyclic compounds. The analytical greenness metric approach and the “RGB model” were used. According to these approaches, the method proposed here is faster, safer and more eco-friendly.

Cyclodextrin-based ternary supramolecular deep eutectic solvents for efficient extraction and analysis of trace quinolones and sulfonamides in wastewater by adjusting pH

BackgroundAntibiotics residues can accelerate the growth of drug-resistant bacteria and harm the ecological environment. Under the effect of enrichment and biomagnification, the emergence of drug-resistant pathogenic bacteria may eventually lead to humans being ineffective to drugs in the face of bacterial or fungal disease infections in the future. It is urgent to develop an efficient separation medium and analytical method for simultaneous extraction and determination of antibiotics in the water environment. ResultsThis work doped 2,6-Di-O-methyl-β-cyclodextrin, randomly methyl-β-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin with thymol:fatty acid respectively to construct non-covalent interaction-dominated pH-responsive ternary supramolecular deep eutectic solvents (SUPRADESs), which can undergo a hydrophilic/hydrophobic transition with aqueous phase to achieve an efficient microextraction. Semi-empirical method illustrated that SUPRADESs have a wide range of hydrogen bond receptor sites. We developed a SUPRADES-based analytical method combined with liquid chromatography-triple quadrupole mass spectrometry for the extraction and determination of trace quinolones and sulfonamides in wastewater. The overall limits of detection of the method were 0.0021-0.0334 ng mL-1 and the limits of quantification were 0.0073-0.1114 ng mL-1. The linearity maintained good in the spiked level of 0.01-100 ng mL-1 (R2>0.99). The overall enrichment factors of the method were 157-201 with lower standard deviations (≤ 8.7). SignificanceThe method gave an extraction recovery of 70.1-115.3% for 28 antibiotics in livestock farming wastewater samples from Zhejiang, China, at trace levels (minimum 0.5 ng mL-1). The results demonstrated that inducing the phase transition between SUPRADES and aqueous phase by adjusting pH for extraction is a novel and efficient pretreatment strategy. To our knowledge, this is the first application of cyclodextrin-based ternary SUPRADESs with pH-responsive reversible hydrophobicity-hydrophilicity transition behavior in wastewater analysis.

Unambiguous identification of γ-aminobutyric acid adducts as novel plant biomarkers and their ultra-sensitive detection by UPLC–MS/MS for retrospective analyses of nitrogen mustards exposure

Plants are widely existing in the environments and have been considered as potential sentinel species of toxic chemicals′ exposure. In this study, the deadly toxic chemicals of three nitrogen mustards (NMs, including NH1, NH2 and NH3) were selected as the investigated targets. First, the reactivities of common endogenous plant components with NMs were examined in vitro. Then, the model plant Nicotiana benthamiana Domin was exposed to NMs. Three γ-aminobutyric acid–nitrogen mustard adducts (GABA–NMs) were identified in the living plant by high resolution mass spectrometry and comparison with the synthesized references. A sensitive detection method with the limits of quantification of 0.0500ngmL-1 was developed using ultrahigh performance liquid chromatography–triple quadrupole mass spectrometry. The GABA–NMs could be detected after 120 days of the exposure and even in the dead leaves without obvious decrease. Furthermore, 20 different plant species grown in diverse climate zones were exposed to HN1, and the adduct of GABA–HN1 was identified in all the leaves. The results showed the good universality and specificity of GABA–NMs as plant biomarkers for NMs exposure. This work provides a new approach for the pollution investigation of toxic chemicals through analysing biomarkers in plant materials. Environmental implicationNitrogen mustards (NMs) are lethal blistering agents, which are listed as Schedule 1 toxic chemicals by the Organisation for the Prohibition of Chemical Weapons (OPCW). OPCW has established the worldwide network of laboratories for environmental analysis for the abuse surveillance of the lethal chemicals. NMs entering the environment will cause great harms to organisms, including cytotoxicity and genotoxicity. In this work, γ-aminobutyric acid adducts in plants after exposure to NMs were identified as biomarkers to trace the attack or leakage in the environment. The work provides a novel promising approach to evaluate environmental hazards from toxic chemicals.

Triple quadrupole liquid chromatography–mass spectrometry–mediated evaluation of vitamin D2 accumulation potential, antioxidant capacities, and total polyphenol content of white jelly mushroom (Tremella fuciformis Berk.)

ABSTRACT Tremella fuciformis Berk. (TF), or the white jelly mushroom, is well known for its myriad of pharmacological properties, such as immunomodulatory, anti-inflammatory, antidiabetic, antitumor, and antioxidant activities, and hypocholesterolemic and hepatoprotective effects that boost human health. Most of the studies of TF are concentrated on its polysaccharide (glucuronoxylomannan) composition, which is responsible for its pharmacological as well as rheological properties. It is well established that mushrooms are a great source of dietary vitamin D due to the presence of ergosterol in their cell membrane. There is a lack of published data on TF as a source of vitamin D2. Therefore, this study aimed to evaluate the vitamin D2 composition of the fruiting bodies of TF using triple quadrupole liquid chromatography–mass spectrometry (LC-MS/QQQ). The results showed highest vitamin D2 content (292.02 µg/g dry weight) in the sample irradiated with ultraviolet B (UVB; 310 nm) for 180 min as compared with the control group (52.47 µg/g dry weight) (P ≤ 0.001). The results showed higher accumulation potential of vitamin D2 in TF as compared with published data available for other extensively studied culinary mushrooms, such as Agaricus bisporus, Lentinula edodes, Pleurotus ostreatus, Cordiceps militaris, and Calocybe indica. Moreover, the impact of UV treatment on antioxidant capacities and total polyphenol content of TF was also studied. The accumulation potential of vitamin D in TF reveals a novel commercial source for this nutrient.

Simultaneous determination of six benzodiazepine sedatives residue in aquatic products by high performance liquid chromatography-triple quadrupole mass spectrometry

To establish a method for the simultaneous determination of 6 benzodiazepine sedatives residue in aquatic products by high performance liquid chromatography-triple quadrupole mass spectrometry. The samples were extracted with acetonitrile and purified by C_(18 )solid phase extraction column. The sample solution was separated by Waters ACQUITY UPLC BEH C_(18 )column(2.1 mm×50 mm, 1.7 μm) using 0.1% formic acid and methanol as mobile phase for gradient elution, determined in multiple reaction monitoring mode and quantified by internal standard method. Six benzodiazepine sedatives had a good linear relationship in the range of 1.0-50.0 μg/L with r>0.9990, the limits of detection and limits of quantification were 0.3 and 1.0 μg/kg. Average recoveries for the analytes at 3 spiked levels ranged from 74.2%-108.0% with relative standard deviations of 1.1%-6.7%(n=6). The method is simple, rapid, sensitive and accurate, which is suitable for simultaneous determination of 6 benzodiazepine sedatives residue in aquatic products.

P140 Serum Metabolomic Biomarkers Can Identify and Characterize Associated Subtypes and Phenotypes in Inflammatory Bowel Disease

Abstract Background Metabolomics is increasingly recognized for uncovering pathophysiology and identifying diagnostic and prognostic biomarkers in inflammatory bowel disease (IBD). This study focuses on exploring comprehensive serum metabolomic profiles and corresponding specific metabolic pathways, in order to differentiate IBD patients from healthy individuals and to accurately identify IBD subtypes (Crohn's disease [CD], ulcerative colitis [UC]) through serum biomarkers with high patient acceptability. Methods Serum samples with matched clinical metadata were comprehensively collected from patients with IBD at Kyung Hee University Hospital, Seoul, Korea. Corresponding samples from normal controls (NCs) were obtained for comparison. Untargeted profiling was performed with Gas Chromatography-Time-Of-Flight-Mass Spectrometry, and targeted profiling of bile acids and tryptophan used Liquid Chromatography-Triple Quadrupole-Mass Spectrometry. The identification of distinct metabolites and potential biomarkers was achieved through extensive univariate and multivariate statistical analyses. Receiver operating characteristic (ROC) curves and metabolic pathway analyses were also conducted. Results A total of 346 subjects were analyzed, comprising 258 IBD patients (134 with CD and 124 with UC) and 88 NCs, Table 1. The patients with IBD were clearly clustered from the NCs, while IBD subgroups were not clearly separated from each other in the nontargeted profiling. Tryptophan and indole-3-acetic acid were elevated in both patients with CD and UC, while kynurenine and indole-3-propionic acid increased only in CD. Conversely, patients with UC had lower levels of indole-3-acetic acid, serotonin, and acetylcholine compared to CD. The ratio of primary and secondary bile acids was also significantly decreased in both patient groups compare with NCs. The ROC curves (Figure 1A) showed good discriminatory power for NCs vs CD (AUC:0.9738), NCs vs UC (AUC:0.9887), and UC vs CD (AUC:0.7140). Pathway analysis of the identified metabolites showed a sustained change in glyoxylate and dicarboxylate metabolism/alanine, aspartate and glutamate metabolism/glycine, serine and threonine metabolism associated with all comparisons (NCs vs UC, NCs vs CD, UC vs CD). Beta-alanine, arginine, and proline metabolism were linked to IBD compared to NCs. Glycerolipid metabolism distinctly differed between UC and CD (Figure 1B-1D). Network analysis revealed associations between metabolomic markers and specific clinical phenotypes of IBD subtypes. Conclusion This study demonstrates that serum metabolomic biomarkers are novel and effective tools for diagnosing IBD, as well as for identifying and characterizing its subtypes and associated phenotypes.

Absolute quantification of nicotinamide mononucleotide in biological samples by double isotope-mediated liquid chromatography-tandem mass spectrometry (dimeLC-MS/MS)

Nicotinamide adenine dinucleotide (NAD+) is an essential metabolite for fundamental biological phenomena, including aging. Nicotinamide mononucleotide (NMN) is a key NAD+ intermediate that has been extensively tested as an effective NAD+-boosting compound in mice and humans. However, the accurate measurement of NMN in biological samples has long been a challenge in the field. Here, we have established an accurate, quantitative methodology for measuring NMN by using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) with double isotopic NMN standards. In this new methodology, the matrix effects of biological samples were properly adjusted, and the fate of NMN could be traced during sample processing. We have demonstrated that this methodology can accurately quantitate NMN levels in mouse plasma and confirmed quick, direct NMN uptake into blood circulation and cells. This double isotope-mediated LC-MS/MS (dimeLC-MS/MS) can easily be expanded to other NAD+-related metabolites as a reliable standard methodology for NAD+ biology.

Determination of 145 pharmaceuticals and personal care products in eleven categories in water by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants frequently detected in aquatic environments at trace levels. These chemicals have diverse structures and physicochemical properties and includes pharmaceuticals like antibiotics, antihypertensive drugs, antiviral drugs, and psychotropic drugs that are widely used in large quantities worldwide. Considering the large number of pharmaceuticals currently in usage, it is crucial to establish a priority list of PPCPs that should be monitored and/or treated first. An accurate understanding of the occurrence and levels of PPCPs in aquatic environments is essential for providing objective materials for monitoring these emerging contaminants. Therefore, accurate, efficient, sensitive, and high-throughput screening techniques need to be established for determining and quantifying PPCPs. This study developed a method for the determination of 145 PPCPs (grouped into eleven categories: antibiotics, antihypertensive drugs, antidiabetic drugs, antiviral drugs, β-receptor agonists, nitroimidazoles, H2 receptor antagonists, psychotropic drugs, hypolipidemic drugs, non-steroidal anti-inflammatory drugs, and others) in water. The method was based on large volume direct injection without sample enrichment and cleanup and used ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-MS/MS). Water samples were collected and filtered through a 0.22-μm regenerated cellulose (RC) filter membrane. Subsequently, Na2EDTA was added to the samples to adjust their pH to 6.0-8.0. Internal standards were mixed with the solutions, and because of the addition of Na2EDTA, the interference of metal ions could be eliminated in the determination of compounds, especially for tetracycline and quinolone antibiotics. Among the six filter membranes tested in this study (PES, PFTE-Q, PFTE, MCE, GHP, and RC), RC filter membranes were screened for water sample filtration. The UHPLC-MS/MS parameters were optimized by comparing the results of various mobile phases, as well as by establishing the best instrumental conditions. The 145 PPCPs were separated using an Phenomenex Kinetex C18 column (50 mm×3 mm, 2.6 μm) via gradient elution. The mobile phases were 0.1% (v/v) formic acid aqueous solution containing 5 mmol/L ammonium formate and acetonitrile for positive ion modes, 5 mmol/L aqueous solutions of ammonium formate and acetonitrile for negative ion modes. The samples were quantified using the scheduled multiple reaction monitoring (scheduled-MRM) mode with electrospray ionization in positive and negative ion modes. A standard internal calibration procedure was used to calculate contents of sample. The established method was systematically verified, and it demonstrated a good linear relationship. The average recoveries of the 145 PPCPs at the three spiked levels were in the range of 80.4%-128% with relative standard deviations (RSDs, n=6) of 0.6%-15.6%. The method detection limits (MDLs) ranged from 0.015 to 5.515 ng/L. Finally, the optimization method was applied to analyze the 145 PPCPs in 11 surface water samples and 6 drinking water samples. Overall, 93 (64%) out of the 145 analytes were detected. The total contents of the PPCPs in surface water samples ranged from 276.9 to 2705.7 ng/L. The detection frequencies of antidiabetic, antiviral, and psychotropic drugs were 100%. The total contents of the PPCPs in drinking water samples ranged from 140.5 to 211.5 ng/L, and antibiotics, antidiabetic drugs, and antiviral drugs comprised the largest proportion of analytes (by mass concentration) in drinking water samples. Our method exhibited high analytical speed and high sensitivity. It is thus suitable for the trace analysis and determination of the 145 PPCPs in environmental water and showed improved detection efficiency for PPCPs in water, indicating that it has a high potential for practical applications. This study can extend technical support for further pollution-level analysis of PPCPs in water and provide an objective basis for environmental management.

The determination of underivatized chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean by LC-MS/MS.

In this study, a simple, rapid and sensitive method was developed for the simultaneous determination of chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Analytes were extracted with acetic acid solution, purified on an HLB column, and then filtered through a 0.2 μm hydrophilic microporous filter membrane. They were then separated on an IC column using a separation phase consisting of polyvinyl alcohol particles with quaternary ammonium groups. The mobile phase optimised with water was denoted as mobile phase A and that optimised with 200 mmol L-1 ammonium bicarbonate solution containing 0.05% ammonium hydroxide was denoted as mobile phase B. The residues were detected by tandem mass spectrometry with negative electrospray ionization in a multi-reaction monitoring mode. The correlation coefficient (R ≥ 0.997) showed good linear regressions for all analytes in water as well as in maize and soybean matrices with a wide dynamic range of 0.001 to 0.5 mg L-1 for calibration. The mean recoveries (RSDs) of the analytes were in the range 85.0-106.4% (5.5-14.9%), 81.7-109.5% (2.7-11.0%) and 74.7-104.4% (2.9-6.1%) at three concentration levels (0.05, 0.1 and 1 mg kg-1) for the interday test (n = 15). The limit of quantification (LOQ) and detection (LOD) of the method for different matrices were 0.01 and 0.003 mg kg-1, respectively. In conclusion, the established analytical approach has high sensitivity and good accuracy and precision and is suitable for monitoring chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean.

Determination of 118 pesticide residues in urine by ultra-high performance liquid chromatography-tandem mass spectrometry

Pesticide residues in food and their hazardous effects have attracted much attention given the increased and widespread use of pesticides. The long-term consumption of food containing pesticide residues is an important pathway for the gradual accumulation of pesticides in the human body. Urine is often monitored as a biological sample for low-dose exposure to pesticides, and urine collection is a relatively convenient sampling technique in general population research. In order to effectively monitor residual levels of multiple pesticides in human urine and provide an important technological approach for health risk assessment, a rapid screening and confirmatory detection method for 118 pesticides in urine was established using QuEChERS method as a pretreatment combined with ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-MS/MS). The 118 pesticides analyzed included organophosphorus, carbamate, neonicotinoid, and strobilurin fungicides and other widely used pesticides. Following systematic optimization of the pretreatment process, LC separation conditions, and MS/MS parameters, 118 pesticides were extracted from urine samples and analyzed within 2 h. In brief, the target analytes in 5 mL urine samples were extracted with 10 mL of acetonitrile and added with 5 g of anhydrous MgSO4 and 1 g of NaCl as water-removal and salting-out agents, respectively. After centrifugation, 6 mL of the supernatant was cleaned using the QuEChERS method with 300 mg of C18, 300 mg of primary secondary amine (PSA) and 900 mg of anhydrous MgSO4 as the purification adsorbent. After nitrogen blowing and solubilization, the 118 target analytes were separated on a ZORBAX Eclipse Plus C18 analytical chromatographic column (100 mm×2.1 mm, 1.8 μm) with gradient elution using (A) 0.01% formic acid aqueous solution (containing 2 mmol/L ammonium formate) and (B) 0.01% formic acid methanol solution (containing 2 mmol/L ammonium formate) as mobile phases. The gradient elution program was as follows: 0-0.5 min, 5%B; 0.5-1.5 min, 5%B-20%B; 1.5-2.5 min, 20%B-50%B; 2.5-8.0 min, 50%B-80%B; 8.0-9.0 min, 80%B-98%B; 9.0-11.0 min, 98%B; 11.0-11.5 min, 98%B-5%B; 11.5-15.0 min, 5%B. The analytes were then determined by UHPLC-MS/MS with positive/negative ion switching in dynamic multiple-reaction monitoring mode and quantified using the external standard method. The results indicated that the proposed method can determine 118 pesticides in urine simultaneously and rapidly. The limits of detection and limits of quantification were 0.10 and 0.50 μg/L, respectively, and the matrix effects were less than 20%for all targeted compounds. The recoveries of the 118 pesticides in urine were between 70.2% and 104% at three spiked levels of 0.50, 1.00, and 5.00 μg/L, and the relative standard deviations ranged from 2.8% to 9.3%. The method was applied to 10 actual urine samples, and the results revealed the presence of six pesticides, including thiamethoxam, clothianidin, acetamiprid, dinotefuran, isoproturon, and dimethomorph, with contents ranging from <LOQ to 3.65 μg/L. Thiamethoxam and clothianidin were detected most often in the samples, and their concentrations were highly correlated with the current use of these pesticides in edible agricultural products. The proposed method has the characteristics of high efficiency, sensitivity, and accuracy and is suitable for the rapid screening and determination of the 118 pesticide residues in human urine samples.

Establishment of a Triple Quadrupole HPLC-MS Quantitation Method for Dystrophin Protein in Mouse and Human Skeletal Muscle.

Duchenne muscular dystrophy (DMD) is the most common type of neuromuscular disease caused by mutations in the DMD gene encoding dystrophin protein. To quantitively assess human dystrophin protein in muscle biopsy samples, it is imperative to consistently detect as low as 0.003% of the dystrophin protein relative to the total muscle protein content. The quantitation of dystrophin protein has traditionally been conducted using semiquantitative immunoblotting or immunohistochemistry; however, there is a growing need to establish a more precise quantitative method by employing liquid chromatography-mass spectrometry (LC-MS) to measure dystrophin protein. In this study, a novel quantification method was established using a mouse experiment platform applied to the clinical quantification of human dystrophin protein. The method using a spike-in approach with a triple quadrupole LC-MS quantitated the amount of dystrophin in wild-type and human DMD transgenic mice but not in DMD-null mice. In conclusion, we established a quantitating method of dystrophin using HPLC-LC-MS with a novel spike-in approach. These results indicate that our methodology could be applied to several LC-MS devices to enable the accurate measurement of dystrophin protein in patients with DMD.

Simultaneous determination of typical toxic aldehydes formed during food frying and digestion using isotope dilution UHPLC-QqQ-MS/MS

An isotope dilution ultra-performance liquid chromatography–triple quadrupole mass spectrometry method was developed to simultaneously detect two typical kinds of α,β-unsaturated aldehydes, namely 4-hydroxy-2-hexenal (4-HHE) and 4-hydroxy-2-nonenal (4-HNE), in foods. The proposed method exhibited a linear range of 10–1000 ng/mL with a limit of detection of 0.1–2.0 ng/g and a limit of quantification of 0.3–5.0 ng/g. The recovery rates of these typical toxic aldehydes (i.e., 4-HHE, 4-HNE) and their d3-labeled analogues were 91.54%–105.12% with a low matrix effect. Furthermore, this proposed method was successfully applied to a real frying system and a simulated digestion system, wherein the contents of 4-HHE and 4-HNE were determined for both. Overall, the obtained results provide strong support for further research into the production of 4-HHE and 4-HNE resulting from foods during oil digestion and frying.

Chemical composition analysis and value evaluation of stems and leaves of Astragalus membranaceus var. mongholicus

This study aimed to provide data support for resource utilization of the stems and leaves of Astragalus membranaceus var. mongholicus(SLAM) by analyzing and evaluating the chemical constituents. The crude protein, crude fiber, and soluble saccharide of SLAM were analyzed by Kjeldahl method, filtration method, and UV-Vis spectrophotometry, respectively. The nucleosides, amino acids, flavonoids, and saponins of SLAM were analyzed by ultraperformance liquid chromatography-triple quadrupole mass spectrometry(UPLC-TQ-MS). Combined with principal component analysis(PCA), the quality difference of resource components of SLAM was comprehensively evaluated. The results showed that the average content of crude protein, crude fiber, total polysaccharide, and redu-cing sugar in SLAM was 5.11%, 30.33%, 11.03 mg·g~(-1), and 31.90 mg·g~(-1), respectively. Six nucleosides, 15 amino acids, 22 flavonoids, and one saponin were detected, with an average content of 1.49 mg·g~(-1), 6.00 mg·g~(-1), 1.86 mg·g~(-1), and 35.67 μg·g~(-1), respectively. The content of various types of chemical components in SLAM differed greatly in different harvesting periods and growing years. The results of PCA showed that the quality of SLAM produced in Ningxia was superior. The results can provide references for the utilization of SLAM.

Simultaneous quantification of tiotropium bromide impurities G + H in capsule formulation by LC-MS/MS.

Tiotropium Bromide is a long-acting bronchodilator that is used in the treatment of chronic obstructive pulmonary disease (COPD) and asthma bronchodilator or bronchiolitis, which are substances that expand the bronchi and reduce resistance in the respiratory tract and increase airflow to the lungs. For Tiotropium Bromide found in inhaler capsules to treat COPD, determining the relevant impurities G and H, which are not UV active, is crucial. For this purpose, a new and sensitive liquid chromatography triple-quadrupole mass spectrometry (LC-MS/MS) detection with electrospray ionization by using multiple reaction monitoring in the positive mode method was developed and validated. The identity of the compounds was supported by using LC-Q/TOF. All chromatographic studies were performed with a Zorbax Eclipse XDB-C8 (150 mm x 4.6 mm, 5.0 µm) column with a total injection time of 13 min at a flow rate of 0.4 ml/min as a gradient. The limit of detection (LOD) and limit of quantitation (LOQ) in the current study range were determined as 1.0 ppb and 2.5 ppb, respectively. The results of the validation parameters following the ICH Q2(R1) guideline were determined within the acceptance criteria.

Pesticides in Agricultural Soils: Major Findings from Various Monitoring Campaigns in Switzerland.

Synthetic pesticides are widely applied in modern agriculture, where they are used against diseases, pests, and weeds to secure crop yield and quality. However, their intensive application has led to widespread contamination of the environment, including soils. Due to their inherent toxicity, they might pose a risk to soil health by causing harm to non-target organisms and disrupting ecosystem services in both agricultural and other exposed soils. Following the Swiss National Action Plan on the reduction of pesticide risks, Agroscope has conducted several soil monitoring studies that are briefly presented here. All of them resort to different multi-residue trace analytical approaches to simultaneously quantify up to about 150 modern pesticides by either accelerated solvent, or Quick, Easy, Cheap, Efficient, Rugged, Safe (QuEChERS) extraction, followed by separation and detection with liquid chromatography-triple quadrupole mass spectrometry. While partly still in progress, our investigations led to the following major findings this far: Multiple pesticides are commonly present in soils, with individual concentrations in agricultural soils often reaching up to a few tens of µg/kg. Pesticide occurrence and concentrations in agricultural soils primarily depend on land use, land use history and cultivated crops. Pesticides can prevail much longer than predicted by their half-lives, and were found in soils even decades after conversion from conventional to organic farming. Corresponding residual fractions can be in the order of a few percent of the originally applied amounts. We further found negative associations of pesticide residues with the abundance of beneficial soil life, underpinning their potential risk to the fertility of agricultural soils. Traces of pesticides are also detected in soils to which they were never applied, indicating contamination, e.g., via spray drift or atmospheric deposition. These results confirm the general notion of both scientists and legislators that prospective risk assessments (RA; as executed during registration and use authorization) should be confirmed and adjusted by retrospective RA (e.g., by environmental monitoring studies of currently used compounds) to jointly lead to an overall reduced environmental risk of pesticides.

Determination of 27 bovine plasma amino acids and metabolites using zwitterionic-hydrophilic interaction liquid chromatography coupled with isotope dilution electrospray ionization triple quadrupole liquid chromatography-mass spectrometry and the effect of deproteinization timing

The use of zwitterionic-hydrophilic interaction liquid chromatography (Z-HILIC) columns for analysis of underivatized analytes has allowed simpler sample preparation of bovine plasma for sensitive and selective analysis, when coupled with mass spectrometry (MS). The objective of this study was to evaluate and validate this analytical technique to measure AA and metabolites in bovine plasma at 2 deproteinization times. A robust method using Z-HILIC coupled to a triple quadrupole MS (TQMS) was evaluated and validated to quantitatively analyze 19 AA using isotope dilution and 8 AA metabolites qualitatively in bovine deproteinized plasma. The timing of deproteinization was investigated to determine if plasma should be deproteinized upon collection (on-site) or immediately before analysis (in-lab). Analytes were separated using a Z-HILIC column in a 21 min run and analyzed with a TQMS in positive electrospray ionization for identification and quantification. The method was validated for standard curve linearity, limits of detection (LOD) and quantification (LOQ), intra- and interday precision (% coefficient of variation; CV), recovery (%), and freeze-thaw stability (% CV) after 1 mo. Coefficients of determination (R2) were over 0.993, and LOD and LOQ were below measured values for all AA. The CV for the intraday and interday precision were below 18%, except for cystine (Cys2) and Orn in-lab. Recoveries on-site and in-lab ranged from 75% to 120% for all analytes except Cys2 in-lab. Most analytes were stable after 1 mo of freezing regardless of deproteinization timing, CV <25%, except for hydroxyproline (Hyp). The concentration of Cys2 was affected by deproteinization in-lab compared with on-site, and even though Glu and Hyp were different between the 2 deproteinization timings, the concentrations between the 2 timings were within the standard deviation.

A comparative UPLC-MS-based metabolomics approach for distinguishing four different cultivars of Qiai (Artemisia argyi Lévl. et Van.)

The Artemisia argyi Lévl. et Van. (A. argyi) from Qichun County, Hubei Province, China, also known as Qiai, is the most important crop in the region. The quality of Qiai can be influenced by the cultivar, which is highly associated with its metabolite components. In this study, 63 batches of Qiai samples from four cultivars, Xiangai (XA), Wujian (WJ), Qijian (QJ), and Baiai (BA), were investigated using untargeted ultra-performance liquid chromatography–mass spectrometry (UPLC-MS) and chemometrics. In total, 44 metabolites were tentatively identified by combining ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-Q-TOF/MS) data with the UNIFI platform and its embedded Traditional Medicine Library. Combining principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA), twelve chemical markers were found to distinguish the four cultivars, showing a high degree of cultivar variability. Five of these compounds were quantified by ultra-performance liquid chromatography triple-quadrupole mass spectrometry (UPLC-TQ-MS/MS) to obtain more accurate content information. This comprehensive study constitutes a valuable reference for distinguishing the four Qiai cultivars, as well as other cultivars, and has implications for Qiai breeding.

Characteristics and Ecological Risk Assessment of Pharmaceutical Active Compounds in Guangdong Province

Pharmaceutically active compounds(PhACs) have become a class of new pollutants in the environment after extensive production and use of PhACs in China. To investigate the pollution characteristics of PhACs in Guangdong Province, raw sewage was collected from 186 sewage treatment plants in 21 cities, including 178 townships and administrative districts in Guangdong Province. The pollution levels of ten typical PhACs in influent water of sewage treatment plants were analyzed using automatic solid phase extraction and high performance liquid chromatography-triple quadrupole mass spectrometry. The spatial distribution characteristics of PhACs in Guangdong Province were fully revealed, and the potential ecological risks of PhACs were evaluated. The results showed that PhACs were detected in all wastewater plants, and the mass concentration of PhACs ranged from 21.00 to 9558.25 ng·L-1. Metoprolo, acetaminophen, bezafibrate, and caffeine were the main pollutants. In terms of spatial distribution, the average mass concentration of ΣPhACs in various regions of Guangdong Province was in the following order:Pearl River Delta>North Guangdong>East Guangdong≈West Guangdong. When the mass concentration of ΣPhACs was over 2500 ng·L-1 in the influent water of sewage treatment plants, the concentration of PhACs in effluent was estimated according to the sewage disposal technology. The ecological risk of PhACs was carried out based on the effluent. The results revealed that the ecological risk of PhACs was low in Guangdong Province, and the risk of bezafibrate was moderate in the cities of Shaoguan, Jiangmen, and Shenzhen. The highest ecological risk of ΣPhACs was located in Shaoguan.

High-throughput screening of 54 alternative plasticizers in sesame oil using gas chromatography-quadrupole time-of-flight mass spectrometry

Restrictions on the use of phthalates have led to the wide use of alternative plasticizers (APs) such as organophosphate, adipate, citrate, and sebacate. However, because plasticizers combine with polymers in plastic products via unstable noncovalent bonds, they can easily migrate out of these products, causing environmental pollution. In particular, their migration out of food packaging, containers, and other food-contact materials and into food has raised great concerns. Toxicological studies have shown that APs contain potentially toxic substances that can affect endocrine functions and cause neurotoxicity, genotoxicity, and other adverse effects. Thus, their potential risks to food should not be underestimated. Sesame oil is a necessity in daily cooking. The results of risk monitoring in recent years have indicated that sesame oil often contains phthalates in excess of the standard limits. However, the potential risks of APs in sesame oil have not yet been reported. Some common detection methods for APs include gas chromatography-mass spectrometry, gas chromatography-triple quadrupole mass spectrometry, and liquid chromatography-triple quadrupole mass spectrometry. Unfortunately, these methods use low-resolution mass spectrometry and are limited by the resolution, scan rate, and analysis mode. Gas chromatography-quadrupole time-of-flight mass spectrometry (GC-Q-TOF/MS) has the advantages of high resolution, sensitivity, and analysis speed. In full-scan mode, GC-Q-TOF/MS can accurately collect the full-spectrum mass number of target compounds with low content levels in complex substrates, thereby realizing efficient screening and quantitative analysis. It shows outstanding advantages in the trace analysis of pesticide residues and pollutants. Furthermore, it features strong qualitative and high screening abilities. Establishment of a personal compound database and library (PCDL) addresses limitations in the number of compounds that can be measured and enables the rapid identification of targets without the use of standard products. In addition, increasing the number of targets for synchronous screening enables the retrospective analysis of new targets. In this study, a method based on GC-Q-TOF/MS was developed for the determination of 54 APs in sesame oil. The samples were extracted with acetonitrile and purified using a PSA/silica solid-phase extraction column. The mass-spectral information of the samples was then collected by GC-Q-TOF/MS in full-scan mode, and the 54 APs were searched using an established high-resolution mass-spectrum database to simultaneously achieve the broad-spectrum screening, qualitative identification, and quantitative analysis of multiple targets. The effects of different extraction solvents and purification methods on sample extraction and purification were compared. The accuracy of the screening results was improved by optimizing the GC-separation conditions, quality-extraction window, retention-time deviation, and other screening parameters. The screening detection limits (SDLs) of the 54 APs ranged from 0.01 to 0.02 mg/kg; specifically, the SDL of 41 compounds was 0.01 mg/kg and that of 13 compounds were 0.02 mg/kg. The limits of quantification were in the range of 0.02-0.04 mg/kg. A total of 80 sesame-oil samples were rapidly screened using this method under optimal conditions. Five APs were identified from the 80 sesame-oil samples and quantitatively analyzed using the matrix-matched external-standard method. The results of this quantitative methodology showed that the five APs had good linear relationships in the range of 0.01-0.2 mg/L, with all correlation coefficients greater than 0.99. The accuracy and precision of the method were verified using a standard recovery test with blank sesame-oil samples. Under the three standard levels of 0.04, 0.08, and 0.2 mg/kg, the recoveries of the five APs ranged from 71.3% to 97.8%, and the relative standard deviations (RSDs) ranged from 0.4% to 6.1%(n=6). The developed method is fast, accurate, sensitive, and has high throughput. Thus, it can realize the efficient screening, qualitative identification, and quantitative analysis of the 54 APs in sesame oil and provides a potential solution for the monitoring of other contaminants in food.

Self-catalyst degradation of amoxicillin in alkaline condition driven by superoxide radical

We studied the rate of amoxicillin (AMX) degradation in oxygen-contained (OCG) and oxygen-free (OFG) groups under alkaline conditions by comparing the molecular structure of AMX with penicillin (PG) and penicillin V potassium (PV) resulting from measuring the hydrolysis rate, performing quenching experiments, and analyzing the products of AMX. The pseudo first-order rate constants of AMX hydrolysis were 0.003 h−1 and 0.032 h−1 (pH = 9, 25 ℃) in OCG and OFG, respectively, with both dissolved oxygen and OH− radicals playing important roles in AMX hydrolysis in OCG. According to the quenching experiments, the signal intensity of O2− in OCG appeared after 3 h and increased consistently, which confirmed that the participation of dissolved oxygen in AMX degradation accelerates the reaction and O2− generate from the reaction between dissolved oxygen and the hydrolysis products of AMX. The phenol group was the key functional group involved in the O2− reaction when comparing the molecular structure differences between PG, PV, and AMX. In total, 30 degradation products of AMX were found by liquid-chromatography triple-quadrupole mass spectrometry. Five degradation pathways of AMX were suggested, which are similar to those of photodegradation. Among them, path 3, which involves phenol (phenol, p-carboxyphenol, etc.) reactions, contained reactions with both dissolved oxygen and OH−. Considering there were no extra reagents added to the reaction system, the degradation of AMX in OCG appeared to be a self-catalytic reaction.