LC QTOF Research Articles

The effects of juice processing on black mulberry antioxidants

Black mulberry fruit is processed to juice at significant scale in Turkey. The effect of industrial-scale juice production on black mulberry antioxidants was evaluated using samples collected from the main steps of processing; including the selection of fruits, washing, mechanical milling, mashing, cold pressing, pasteurization, and filling-packing. Two major anthocyanins (cyanidin-3-glucoside and cyanidin-3-rutinoside), two phenolic acids (3- and caffeoylquinic acid) and 3 flavonols (rutin, quercetin-3-glucoside, and quercetin-malonyl-glucoside) were identified using LC–QTOF–MS and were quantified using HPLC. Approximately, 60–70% of the fruit anthocyanins were retained in the final juice, which also contained high levels of caffeoylquinic acids, relative to the fruit. Mashing and pressing were the steps which were effective for the recovery of fruit polyphenolics into the juice fraction. Moreover, an in vitro gastrointestinal digestion model, applied to determine the effect of processing on the bioavailability of mulberry antioxidants, indicated a higher anthocyanin bioavailability for the fruit matrix than for the juice matrix.

Characterization of organic gunshot residues in lead-free ammunition using a new sample collection device for liquid chromatography–quadrupole time-of-flight mass spectrometry

The identification of characteristic organic gunshot residues (OGSR) provides conclusive evidence in the elucidation of elemental profiles when lead-free ammunition is fired. OGSR also prevents false negatives. Toward this aim, a quick and efficient method based on liquid chromatography–quadrupole time-of-flight mass spectrometry (LC–QTOF) was developed to detect and identify 18 gunpowder additives in gunshot residues (GSR). The unequivocal identification of target analytes was assured by using MS/MS mode. Swabs were compared with home-modified tape lift supports covered with a PTFE layer to determine the better sampling technique. The modified tape lift provided better extraction recoveries and enabled the analysis of inorganic and organic GSR simultaneously. The developed method was applied to the analysis of GSR from four different lead-free ammunitions. Diphenylamine and its nitrated degradation products and centralites were identified in all samples, providing strong evidence of GSR.

Analysis of serum phospholipid profiles by liquid chromatography–tandem mass spectrometry in high resolution mode for evaluation of atherosclerotic patients

Atherosclerosis is one of the most frequent etiology for myocardial infarction and death. It is also the main cause of angina pectoris, a perceived symptom that results of a mismatch between myocardial supply and demand, caused by the partial obstruction of the arteries. The correct diagnosis of atherosclerosis can led to a reduction of mortality. In this research, the phospholipids profile of serum samples from patients diagnosed with stable angina and non-ST elevation myocardial infarction (NSTEMI) or unstable angina was obtained by selective solid-phase extraction (SPE) and subsequent LC–QTOF MS/MS analysis in high resolution mode. Comparative statistical analysis allowed finding four potential markers to discriminate between stable angina and NSTEMI/unstable angina: lysoPC(20:5), PC(18:1/18:2), PC(18:0/20:4) and SM(d18:2/14:0). The panel generated by multivariate ROC analysis by combination of the four compounds provided a disease prediction capability in the training set of 70.7 and 66.0% for stable angina and NSTEMI patients, respectively. On the other hand, external validation by application to an independent cohort improved the predictive power for angina stable patients (92.3%), while this was slightly decreased up to 50.0% for NSTEMI/unstable angina patients. In this way, LC–QTOF MS/MS has shown to be a useful strategy for phospholipid profiling in serum and development of tools to aid in clinical diagnostic.

Reductive degradation of perfluorinated compounds in water using Mg-aminoclay coated nanoscale zero valent iron

Perfluorinated compounds (PFCs) are extremely persistent micropollutants that are detected worldwide. We studied the removal of PFCs (perfluorooctanoic acid; PFOA, perfluorononanoic acid; PFNA, perfluorodecanoic acid; PFDA and perfluorooctane sulfonate; PFOS) from water by different types of nanoscale zero-valent iron (nZVI). Batch experiments showed that an iron dose of 1 g L−1 in the form of Mg-aminoclay (MgAC) coated nZVI, at an initial pH of 3.0 effectively removed 38–96% of individual PFCs. An increasing order of removal efficiency was observed of PFOA < PFNA < PFOS ≈ PFDA. Compared to this, PFCs removal was less than 27% using a commercial air stabilized nZVI or freshly synthesized uncoated nZVI, under the same experimental conditions. The effectiveness of PFCs removal by MgAC coated nZVI was further investigated at various initial pH, nZVI dosage, temperature and age of the nZVI. A maximum removal was observed for all PFCs with high nZVI concentration, freshly synthesized nZVI, low pH and low temperature. A mass balance experiment with PFOS in a higher concentration of nZVI revealed that the removal was due to both sorption and degradation. Fluoride production partially matched the observed degradation, while no organic byproducts were detected using LC–QTOF–MS.

Comprehensive metabolomics to evaluate the impact of industrial processing on the phytochemical composition of vegetable purees

The effects of conventional industrial processing steps on global phytochemical composition of broccoli, tomato and carrot purees were investigated by using a range of complementary targeted and untargeted metabolomics approaches including LC–PDA for vitamins, 1H NMR for polar metabolites, accurate mass LC–QTOF MS for semi-polar metabolites, LC–MRM for oxylipins, and headspace GC–MS for volatile compounds. An initial exploratory experiment indicated that the order of blending and thermal treatments had the highest impact on the phytochemicals in the purees. This blending-heating order effect was investigated in more depth by performing alternate blending-heating sequences in triplicate on the same batches of broccoli, tomato and carrot. For each vegetable and particularly in broccoli, a large proportion of the metabolites detected in the purees was significantly influenced by the blending-heating order, amongst which were potential health-related phytochemicals and flavour compounds like vitamins C and E, carotenoids, flavonoids, glucosinolates and oxylipins. Our metabolomics data indicates that during processing the activity of a series of endogenous plant enzymes, such as lipoxygenases, peroxidases and glycosidases, including myrosinase in broccoli, is key to the final metabolite composition and related quality of the purees.

Effect of inclusion of hydroxycinnamic and chlorogenic acids from green coffee bean in β-cyclodextrin on their interactions with whey, egg white and soy protein isolates

The aim of the study was to characterise the interactions of hydroxycinnamic and chlorogenic acids (CHAs) from green coffee, with isolates of proteins from egg white (EWP), whey (WPC) and soy (SPI), depending on pH and temperature. The binding degree was determined by liquid chromatography coupled to a diode array detector and an ultrahigh resolution hybrid quadruple-time-of-flight mass spectrometer with ESI source (LC–QTOF–MS/MS). As a result of binding, the concentration of CHAs in proteins ranged from 9.44–12.2, 11.8–13.1 and 12.1–14.4g/100g for SPI, WPC and EWP, respectively. Thermodynamic parameters of protein–ligand interactions were determined by isothermal titration calorimetry (ITC) and energetics of interactions at the atomic level by molecular modelling. The amount of CHAs released during proteolytic digestion was in the range 0.33–2.67g/100g. Inclusion of CHAs with β-cyclodextrin strongly limited these interactions to a level of 0.03–0.06g/100g.

Ex vivo studies for the passive transdermal delivery of low-dose naltrexone from a cream; detection of naltrexone and its active metabolite, 6β-naltrexol, using a novel LC Q-ToF MS assay

Naltrexone (NTX) is a long-acting opiate antagonist. Low-dose naltrexone (LDN) therapy has shown promising results in the treatment of several autoimmune disorders. Our aim was to formulate NTX into a cream for the delivery of LDN and develop an analytical technique for the quantification of NTX and its active metabolite 6-β-naltrexol (NTXol) during transdermal diffusion cell permeation studies. A 1% w/w NTX cream was formulated and drug permeation was examined over 24 h using static Franz diffusion cells mounted with pig skin. A Liquid Chromatography Quadrupole-Time of Flight Mass Spectrometry (LC-MS Q-ToF) method was developed for the detection of NTX and NTXol in the receptor solution, skin membrane and residual cream on the donor chamber after completion of the diffusion studies. The cream formulation exhibited steady state release of NTX over 24 h after an initial lag time of 2.74 h. The bioconversion of NTX to NTXol in the skin membrane was 1.1%. It was concluded that the cream may be an effective formulation for the sustained transdermal delivery of LDN. The novel LC Q-ToF MS method allowed the accurate measurement of NTX and NTXol levels across the diffusion cell assemblies and the quantification of NTX metabolism in the skin.

Ocimum sanctum leaf extracts attenuate human monocytic (THP-1) cell activation

Ethnopharmacological relevanceOcimum sanctum (OS), commonly known as Holy basil/Tulsi, has been traditionally used to treat cardiovascular diseases (CVD) and manage general cardiac health. The present study is designed to evaluate the antiinflammatory effect of O. sanctum and its phenolic compound and eugenol (EUG) in human monocytic (THP-1) cells and validate its traditional use for treating cardiovascular diseases. Materials and methodsThe phytochemical analysis of alcoholic and water extracts of OS-dry leaves (OSAE and OSWE) was done using LC–QTOF–MS. A phenolic compound, EUG was quantified in both OSAE and OSWE by an LC–MS technique using a mass hunter work station software quantitative analysis system. The effect of both OSAE, OSWE, pure compound EUG and positive control imatinib (IMT) was investigated in THP-1 cells by studying the following markers: lipopolysaccharide (LPS) induced tumor necrosis factor alpha (TNF-α) secretion by ELISA, gene expression of inflammatory markers (TNF-α, IL-6, MIP-1α and MCP-1) by real time PCR and translocation of nuclear factor kappa B (NF-κB) by confocol microscopy. Furthermore, the effect of the extracts, EUG and IMT, was studied on phorbol-12-myristate-13-acetate (PMA) induced monocyte to macrophage differentiation and gene expression of CD14, TLR2 and TLR4. ResultsThe LC–MS analysis of OSAE and OSWE revealed the presence of several bioactive compounds including eugenol. Quantitative analysis revealed that OSAE and OSWE had EUG of 12ng/mgdwt and 19ng/mgdwt respectively. OSAE, OSWE (1mg dwt/mL) pure compound EUG (60µg/mL) and positive control IMT (20µg/mL) showed marked inhibition on LPS induced TNF-α secretion by THP-1 cells. At the selected concentration, the plant extracts, EUG and IMT inhibited gene expression of cytokines and chemokines (IL-6, TNF-α, MIP-1α, MCP-1) and translocation of NF-κB-p65 to the nuclei. In addition, they showed significant inhibition on PMA induced monocyte to macrophage differentiation and the gene expression of CD14, TLR2 and TLR4 markers. ConclusionThe result of the present study validated traditional use of Ocimum sanctum for treating cardiovascular disease for the first time by testing antiinflammatory activity of Ocimum sanctum in acute inflammatory model, LPS induced THP-1 cells. The plant extracts showed significant antiinflammatory activity, however, further to be evaluated using chronic inflammatory animal models like diabetic or apolipoprotein E-deficient mice to make it evidence based medicine. The phenolic compound eugenol (60µg/mL) showed significant antiinflammatory activity. However the amount of eugenol present in 1mg of OSAE and OSWE (12ng/mg and 19ng/mg dwt respectively) used for cell based assays was very low. It suggests that several other metabolites along with eugenol are responsible for the efficacy of the extracts.

A simple liquid chromatography coupled to quadrupole time of flight mass spectrometry method for macrolide determination in tilapia fillets

A method for the identification and quantification of macrolides (erythromycin, josamycin, tilmicosin, tylosin, spiramycin and neospiramycin) in tilapia fillets by liquid chromatography coupled to quadrupole time of flight mass (LC–QToF) spectrometry is presented. Sample preparation was quite simple and low cost: proteins were precipitated and the analytes were extracted with ethanol, extract was defatted with hexane and concentrated by solvent evaporation. The matrix effect was statistically demonstrated during method validation, in which matrix-matched calibration was applied. Matrix effect mechanism was clarified thanks to the capability of QToF mass spectrometer of generating full scan spectra with accurate mass measurement. The limits of quantification were at least 45% lower than the maximum residue limits. The method was able to identify the studied macrolides with relative m/z errors lower than 2.5ppm and to monitor two fragment ions per analyte, which is in accordance with the European Community recommendations for the analysis of contaminants in foods. Samples from the retail market of São Paulo State, Brazil, were analyzed by the developed method and none of them presented positive results for the macrolides studied.

Metabolic profiling of Goji berry extracts for discrimination of geographical origin by non-targeted liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

The fruit of Lycium barbarum (Solanaceae), known as Goji berry, or wolfberry, has long been used in traditional Chinese medicine, and is increasingly becoming popular in Western diets due to its potential health benefits.The majority of commercially produced Goji berries come from certain regions in Asia. In this study we explored the discrimination of phytochemical content between four different geographic origins of Goji berries by applying non-targeted liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC–qTOF–MS) metabolite profiling. Principal component analysis was able to clearly distinguish the berries by the geographic origin when applied to the non-targeted profiling data of Mongolian, Chinese and two Tibetan origin Goji berry extracts. Furthermore, partial least squares discriminant analysis (PLS-DA) provided indicative markers of discrimination between the different origins, and quality threshold cluster analysis classified the most discriminative compounds according to their occurrence between the different origins. The largest cluster included the most discriminative metabolites in the Mongolian variety, which was also seen as the most distant group in the PCA analysis as compared to the other countries of origin.Mongolian Goji berries were mainly characterized by significantly higher levels of several flavonol glycosides, such as quercetin and kaempferol glycosides; isomers of dicaffeoylquinic acid and phenolic acids such as coumaric acid. In addition to the various phytochemical metabolites identified, a pesticide compound was found especially in the extracts of Goji berries from China.The present non-targeted metabolite profiling proved to be a useful approach of the Foodomics field for assessment of geographical origin of berries.

Optimization study for metabolomics analysis of human sweat by liquid chromatography–tandem mass spectrometry in high resolution mode

Sweat has recently gained popularity as a potential tool for diagnostics and biomarker monitoring as it is a non-invasive biofluid the composition of which could be modified by certain pathologies, as is the case with cystic fibrosis, which increases chloride levels in sweat. The aim of the present study was to develop an analytical method for analysis of human sweat by liquid chromatography–mass spectrometry (LC–Q-TOF MS/MS) in high resolution mode. Thus, different sample preparation strategies and different chromatographic modes (HILIC and C18 reverse modes) were compared to check their effect on the profile of sweat metabolites. Forty-one compounds were identified by the MS/MS information obtained with a mass tolerance window below 4ppm. Amino acids, dicarboxylic acids and other interesting metabolites such as inosine, choline, uric acid and tyramine were identified. Among the tested protocols, direct analysis after dilution was a suited option to obtain a representative snapshot of sweat metabolome. In addition, sample clean up by C18 SpinColumn SPE cartridges improved the sensitivity of most identified compounds and reduced the number of interferents. As most of the identified metabolites are involved in key biochemical pathways, this study opens new possibilities to the use of sweat as a source of metabolite biomarkers of specific disorders.

Intakes of whey protein hydrolysate and whole whey proteins are discriminated by LC–MS metabolomics

Whey protein improves fasting lipids and insulin response in overweight and obese individuals. Whey hydrolysate was recently shown to be more active than whole protein but the differences in metabolite profiles after intake remain unknown. This study discriminates plasma profiles after intake of four different whey protein fractions and establishes new hypotheses for the observed effects. Obese, non-diabetic subjects were included in the randomized, blinded, cross-over meal study. Subjects ingested a high-fat meal containing whey isolate (WI), whey concentrate hydrolysate (WH), α-lactalbumin or caseinoglycomacropeptide as the protein source. Plasma samples were collected at five time points and metabolites analysed using LC–Q-TOF–MS. Plasma concentrations of ten amino acids (AAs) were different between the meals. The plasma levels of AAs and AA derivatives were generally directly related to the AA composition of the meals. Highly elevated plasma levels of a number of cyclic dipeptides and other AA metabolites were found following intake of the WH meal and these metabolites are primary candidates to explain the superior insulinotropic effect of WH. The manufacturing process of WH caused oxidization of methionine to methionine sulfoxide which in turn caused in vivo generation of N-phenylacetyl-methionine and N-phenylacetyl-methionine sulfoxide. These two compounds have not previously been described in biological systems.

Investigating the presence of omeprazole in waters by liquid chromatography coupled to low and high resolution mass spectrometry: degradation experiments

Omeprazole is one of the most consumed pharmaceuticals around the world. However, this compound is scarcely detected in urban wastewater and surface water. The absence of this pharmaceutical in the aquatic ecosystem might be due to its degradation in wastewater treatment plants, as well as in receiving water. In this work, different laboratory-controlled degradation experiments have been carried out on surface water in order to elucidate generated omeprazole transformation products (TPs). Surface water spiked with omeprazole was subjected to hydrolysis, photo-degradation under both sunlight and ultraviolet radiation and chlorination. Analyses by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF MS) permitted identification of up to 17 omeprazole TPs. In a subsequent step, the TPs identified were sought in surface water and urban wastewater by LC-QTOF MS and by LC coupled to tandem mass spectrometry with triple quadrupole. The parent omeprazole was not detected in any of the samples, but four TPs were found in several water samples. The most frequently detected compound was OTP 5 (omeprazole sulfide), which might be a reasonable candidate to be included in monitoring programs rather than the parent omeprazole.

Determination of six plant growth regulator residues in strawberry by liquid chromatography-quadrupoletime of flight mass spectrometry

A novel method was established for the determination of six plant growth regulators (PGRs), 2,4-dichlorophenoxy acetic (2,4-D), 4-chlorophenoxy-acetic acid (CAP), 4-(3-indolyl)-butyric acid (BAA), forchlorfenuron (CPPU), abscisic acid (ABA) and trans-zeatin (ZT) in strawberry using liquid chromatography-quadrupole-time of flight mass spectrometry (LC-Q TOF MS). The Quick, Easy, Cheap, Effective, Rugged and Safe method (QuEChERS) has been validated for the extraction. In this QuEChERS method, the sample was extracted by acetonitrile and cleaned up with C18 adsorbent. The extract was measured directly by LC-Q TOF MS with electrospray ionization in negative mode. The compounds were separated on an Eclipse XDB-C8 column (150 mm x 4.6 mm, 5 microm) with acetonitrile-5 mmol/L ammonium acetate-0. 1% formic acid as mobile phase under gradient elution. The confirmatory analysis was carried out by determining the accurate masses of all compounds and fragment ions upon Target MS/MS. The limits of detection (LODs) were between 1 microg/kg and 5 microg/kg. The linear range was 0.005-1.0 mg/L for each analyte. The recoveries ranged from 87% to 107% with the relative standard deviations (RSDs) less than 10% (n = 6). The method was proved to be simple and accurate.

Qualitative validation of a liquid chromatography–quadrupole-time of flight mass spectrometry screening method for organic pollutants in waters

A multiclass wide-scope screening of organic contaminants in natural and waste water has been developed and validated for qualitative purposes, i.e. detection and reliable identification of compounds detected in samples at a certain level of concentration. The screening is based on the use of liquid chromatography coupled to quadrupole-time of flight mass spectrometry (LC–QTOF MS) and has been applied to water samples of different origin and matrix composition (surface water, ground water and effluent urban wastewater). Water samples were spiked with a standard mixture of around 150 organic contaminants from different chemical families (including a number of relevant metabolites/transformation products (TPs), at 0.1 and 1μg/L concentration levels. After solid-phase extraction with Oasis HLB cartridges, sample extracts were analyzed by LC–QTOF MS and the accurate-mass full-spectrum data were processed for qualitative analysis. The presence of at least two ions (typically the (de)protonated molecule and one fragment ion) accurate-mass measured was used for the reliable identification. The screening detection limit (SDL) and the limit of identification (LOI) were established as the main parameters of the screening method. Nearly all compounds could be detected at the lowest concentration tested, but identification was problematic for some compounds at 0.1μg/L level, especially in wastewater samples. The screening procedure was finally applied to different water samples using a home-made database of around 1100 organic contaminants. It allowed the detection and identification of several antibiotics, anti-inflammatory/analgesics drugs and lipid regulators. Cocaine and its metabolite benzoylecgonine were also frequently detected. In addition, triazine herbicides and their TPs, and fungicides like thiabendazol, carbendazim or imazalil, were also identified in some of the samples.

Munition related metals - Combined toxicity of Antimony, Copper, and Lead

The identification of characteristic organic gunshot residues (OGSR) provides conclusive evidence in the elucidation of elemental profiles when lead-free ammunition is fired. OGSR also prevents false negatives. Toward this aim, a quick and efficient method based on liquid chromatography–quadrupole time-of-flight mass spectrometry (LC–QTOF) was developed to detect and identify 18 gunpowder additives in gunshot residues (GSR). The unequivocal identification of target analytes was assured by using MS/MS mode. Swabs were compared with home-modified tape lift supports covered with a PTFE layer to determine the better sampling technique. The modified tape lift provided better extraction recoveries and enabled the analysis of inorganic and organic GSR simultaneously. The developed method was applied to the analysis of GSR from four different lead-free ammunitions. Diphenylamine and its nitrated degradation products and centralites were identified in all samples, providing strong evidence of GSR.

Recent Advances in Metabolite Identification And Quantitative Bioanalysis By Lc–Q-Tof Ms

The need for rapid, sensitive and effective identification and quantitation of drugs and metabolites to accelerate drug discovery and development has given MS its central position in drug metabolism and pharmacokinetic research. This review attempts to orient the readers with respect to hybrid Q-TOF MS, which enables accurate mass measurement and generates information-rich datasets. The key properties of the Q-TOF MS system, including mass accuracy, resolution, scan speed and dynamic range, are herein discussed. Developments on tandem separation techniques (e.g., UHPLC(®) and ion mobility spectrometry), data acquisition and data-mining methods (e.g., mass defect, product/neutral loss, isotope pattern filters and background subtraction) that facilitate qualitative and quantitative analysis are then examined. The performance and versatility of LC-Q-TOF MS are thoroughly illustrated by its applications in metabolite identification and quantitative bioanalysis. Future perspectives are also discussed.

Detection of new exemestane metabolites by liquid chromatography interfaced to electrospray-tandem mass spectrometry

Exemestane is an irreversible aromatase inhibitor used for anticancer therapy. Unfortunately, this drug is also misused in sports to avoid some adverse effects caused by steroids administration. For this reason exemestane has been included in World Anti-Doping Agency prohibited list. Usually, doping control laboratories monitor prohibited substances through their metabolites, because parent compounds are readily metabolized. Thus metabolism studies of these substances are very important. Metabolism of exemestane in humans is not clearly reported and this drug is detected indirectly through analysis of its only known metabolite: 17β-hydroxyexemestane using liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) and gas chromatography coupled to mass spectrometry (GC–MS). This drug is extensively metabolized to several unknown oxidized metabolites. For this purpose LC–MS/MS has been used to propose new urinary exemestane metabolites, mainly oxidized in C6-exomethylene and simultaneously reduced in 17-keto group. Urine samples from four volunteers obtained after administration of a 25 mg dose of exemestane were analyzed separately by LC–MS/MS. Urine samples of each volunteer were hydrolyzed followed by liquid–liquid extraction and injected into a LC–MS/MS system. Three unreported metabolites were detected in all urine samples by LC–MS/MS. The postulated structures of the detected metabolites were based on molecular formulae composition obtained through high accuracy mass determination by liquid chromatography coupled to hybrid quadrupole-time of flight mass spectrometry (LC–QTOF MS) (all mass errors below 2 ppm), electrospray (ESI) product ion spectra and chromatographic behavior.

Identification and quantification of free radical scavengers in the flower buds of Lonicera species by online HPLC‐DPPH assay coupled with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

Flos Lonicerae, derived from the flower buds of several medicinal Lonicera species, is a commonly used herbal medicine with multiple pharmacological activities, one of the major ones being antioxidant activity. In this study, free radical scavengers in the flower buds of six Lonicera species were screened, identified and quantified by online HPLC-DPPH (1,1-diphenyl-2-picrylhydrazyl) assay coupled with LC quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). The antioxidants were firstly screened from the complex plant matrix by the online HPLC-DPPH assay. Then the active compounds were identified by LC Q-TOF MS/MS, and the possible fragmentation pathways were proposed. The reactivity of antioxidants available was investigated using an internal standard method by online LC assay. The contents of 12 antioxidants were also determined or estimated by HPLC coupled with diode array detector. The total antioxidant capability determined by the online method was used as the marker to evaluate the quality of Flos Lonicerae. The results were important to clarify the material basis and therapeutic mechanism of Flos Lonicerae.

Analytical strategy based on the use of liquid chromatography and gas chromatography with triple-quadrupole and time-of-flight MS analyzers for investigating organic contaminants in wastewater

The presence of a wide variety of organic pollutants with different physicochemical characteristics has been investigated in wastewater samples from a municipal solid-waste-treatment plant in Castellón, Spain. An advanced analytical strategy was applied--combined used of two powerful and complementary techniques, GC and LC, both hyphenated with tandem mass spectrometry with triple-quadrupole analyzers. The GC-MS-MS method was based on sample extraction using C(18) SPE cartridges and enabled the determination of approximately 60 compounds from different chemical families, for example PAHs, octyl/nonylphenols, PCBs, organochlorine compounds, insecticides, herbicides, and PBDEs. Most of the compounds selected are included as priority contaminants in the European Union (EU) Water Directive. The UHPLC-MS-MS method, which provided high chromatographic resolution and sensitivity and short analysis time, used sample extraction with Oasis HLB SPE cartridges and enabled the determination of 37 (more polar) pesticides. The methodology developed was applied to the analysis of 41 water samples (20 untreated raw leachates and 21 treated samples) collected between March 2007 and February 2009. Amounts of the contaminants investigated rarely exceeded 0.5 microg L(-1) in the treated (reverse osmosis) water samples analyzed. As expected, in untreated leachates the number of compounds detected and the concentrations found were notably higher than in treated waters. The most commonly detected pollutants were herbicides (simazine, terbuthylazine, terbutryn, terbumeton, terbacil, and diuron), fungicides (thiabendazole and carbendazim), and 4-t-octylphenol. The results obtained proved that use of reverse osmosis for water treatment was efficient and notably reduced the amounts of organic contaminants found in raw leachate samples. In order to investigate the presence of other non-target contaminants, water samples were also analyzed by using GC-TOF MS and LC-QTOF MS. Several organic pollutants that did not form a part of the previous list of target contaminants were identified in the samples, because of the high sensitivity of TOF MS in full-spectrum acquisition mode and the valuable accurate-mass information provided by these instruments. The insecticide diazinon, the fungicide diphenylamide, the UV filter benzophenone, N-butylbenzenesulfonamide (N-BBSA), the insect repellent diethyltoluamide, caffeine, and the pharmaceuticals erythromycin, benzenesulfonanilide, ibuprofen, atenolol, and paracetamol were some of the compounds identified in the water samples analyzed.