Liquid Chromatography-quadrupole Linear Ion Trap Research Articles

Novel Isotope Dilution High-Performance Liquid Chromatography Quadrupole–Linear Ion Trap Tandem Mass Spectrometry Method for the Determination of Five Steroid Hormones in Human Serum

Accurate measurement of endogenous steroid hormones in serum is a powerful tool for understanding the status of human adrenal diseases. Isotope dilution–liquid chromatography–tandem mass spectrometry is the most commonly used method for determination of steroids in serum. In this study, we used a laboratory-constructed quadrupole-linear ion trap (Q-LIT) tandem mass spectrometer to develop a new method for the quantification of five steroid hormones in serum. A simple and efficient pretreatment was improved, wherein the serum was extracted once by a mixed solvent of 1.0 mL of ethyl acetate and n-hexane. Using the optimized method, the regression coefficients of the calibration curves were all higher than 0.99, the limits of detection were from 0.31 to 1.25 ng mL−1, and the limits of quantification were between 1.00 and 2.50 ng mL−1. The intra-day (n = 3) relative standard deviations ranged from 4.24% to 13.79%, and the inter-day (n = 3) relative standard deviations from 3.99% to 11.43%. After internal standard correction, the relative recoveries of all steroids were from 86.08% to 106.60%. Twenty-two serum samples were analyzed by Q-LIT, which was compared with commercial triple quadrupole mass spectrometer. The results of the instruments had high consistency. Therefore, Q-LIT accurately quantified steroid hormones in human samples and may be used for clinical diagnosis and monitoring of hormone-dependent diseases.

Development of a QuEChERS-based method for the analysis of pharmaceuticals and personal care products in lettuces grown in field-scale agricultural plots irrigated with reclaimed water

The use of reclaimed water for agricultural irrigation is an increasingly common practice, which recently has found its own European regulatory frame. However, the partial removal of organic contaminants together with other xenobiotic substances in current wastewater treatment plants leads to the occurrence of residues of such pollutants in the treated effluents. Wastewater reclamation techniques are thus required to provide reclaimed water fitting the minimum quality standards set up for irrigation of crops intended for human consumption. This work describes the development and validation of a simple QuEChERS-based extraction and liquid chromatography quadrupole-linear ion trap mass spectrometry (LC-QqLIT-MS/MS) method for the simultaneous quantitative analysis of 55 pharmaceuticals and personal care products (PPCPs) in lettuces irrigated with treated wastewater and reclaimed water. The method showed good recovery rates (80–120%) and low detection limits (0.04–0.8 ng/g dw). In comparison with previous analytical methodologies, this method was simpler, faster and, in most cases, more sensitive. Moreover, is the first one analysing selected personal care products in lettuces. The proposed method was applied to assess the potential transfer of contaminants of urban origin in the use of reclaimed water in agriculture. The case study consisted in the evaluation of the lettuce uptake of the selected contaminants at field scale under two irrigation systems, two soil compositions, and two water types. Benzophenone-2, 4-hydroxybenzophenone, 1H-benzotriazole, 2-(2-Benzotriazol-2-yl)-p-cresol, nalidixic acid, diclofenac, carbamazepine 10,11-epoxy, N-des-methylvenlafaxine, and salicylic acid were transferred to all samples. Highest detected values corresponded to 4-hydroxybenzophenone (84.1 ng/g dw), benzophenone-2 (54.4 ng/g dw), and salicylic acid (53.8 ng/g dw). The best combination to minimize the transfer of the target contaminants from the irrigation water to the lettuces was sprinkling irrigation with water reclaimed by soil infiltration through reactive barriers, and clayey soil.

Determination of pesticide levels in wastewater from an agro-food industry: Target, suspect and transformation product analysis.

Agriculture is considered as the main source of water contamination by pesticides. However, food packaging or processing industries are also recognised as relevant point sources of contamination by these compounds, not yet investigated in depth. The objective of this work has been to improve current knowledge about the presence and concentration of pesticides in the effluent of a food processing industry, as well as to investigate their main transformation products (TPs). An analytical strategy combining target and suspect analysis has been applied to provide an evaluation of the effluents. The methodology involves solid-phase extraction (SPE) of wastewater samples followed by (i) liquid chromatography quadrupole-linear ion trap tandem mass spectrometry (LC-QqLIT-MS/MS) for quantitative target analysis and (ii) liquid chromatography coupled to quadrupole-time-of-flight high resolution mass spectrometry (LC-QTOF-HRMS) to identify non-target pesticides and possible TPs. The results revealed the presence of 17 of the target pesticides analysed and 3 additional ones as a result of the suspect screening performed by HRMS. The TPs were investigated for the pesticides found at the highest concentrations: imazalil (7038-19802 ng/L), pyrimethanil (744-9591 ng/L) and thiabendazole (341-926 ng/L). Up to 14 TPs could be tentatively identified, demonstrating the relevance of this type of studies. These data provide a better understanding of the occurrence of pesticides and their TPs in agro-food industrial effluents.

Lysophospholipid profiles of apolipoprotein E-deficient mice reveal potential lipid biomarkers associated with atherosclerosis progression using validated UPLC-QTRAP-MS/MS-based lipidomics approach

Lysophospholipids (Lyso-PLs) are lipid-derived signaling molecules which were demonstrated to have a strong correlation with the progression of atherosclerosis. In this study, we investigated the influence of high-fat diet on Lyso-PL profiles of atherosclerosis-prone apolipoprotein E-deficient (ApoE−/−) mice and wild type C57BL/6 J mice to find out the potential biomarkers associated with atherosclerosis. Firstly, the quantitative profiling method for Lyso-PLs based on ultra-performance liquid chromatography-quadrupole linear ion trap mass spectrometry (UPLC-QTRAP-MS/MS) was established and validated. Secondly, this method was utilized to quantify 169 targeted Lyso-PLs in plasma samples of ApoE−/− mice and wild type C57BL/6 J mice collected at different time points. Finally, 12 of 37 differential Lyso-PLs were identified as more reliable biomarkers by integrating static metabolomics and time-dependent analyses, among which Lyso-PC/15:0, 18:1/Lyso-PI, 22:5/Lyso-PI and 22:4/Lyso-PI were highly correlated with TCand LDL-C levels. Meanwhile, we found that the Lyso-PL profiles of ApoE−/− mice and C57BL/6 J mice were distinguished by altered metabolism of different Lyso-PLs classes, while C57BL/6 J mice fed with high-fat diet and normal diet were discriminated by the content differences of Lyso-PLs with same fatty acid composition. In conclusion, these results provided detailed changes of Lyso-PL profiles associated with atherosclerosis and the differential Lyso-PLs with reasonable change trends may serve as promising biomarkers for atherosclerosis progression.

Determination of Antibiotics in Vegetables Using QuEChERS-Based Method and Liquid Chromatography-Quadrupole Linear Ion Trap Mass Spectrometry

In this study, a simple and reliable method was developed for multiresidue analysis of 49 antibiotics in vegetables based on the quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure and liquid chromatography-quadrupole linear ion trap mass spectrometry determination. Premixed extraction salt packets were first used to simplify the sample extraction procedures. Different buffer systems and other parameters were optimized. Multiple reaction monitoring with information-dependent acquisition of enhanced product ion (MRM-IDA-EPI) mode was used to acquire MS/MS spectra along with MRM survey scan for library searching to prevent false positive/negative identification. The method limit of quantification (LOQs) was between 2 and 5 μg/kg for the target antibiotics. Recoveries for most of antibiotics ranged between 70 and 100% with RSD < 20%. Relative lower recoveries were observed for some of quinolones. The method was applied on quantification of 60 vegetable samples, and the obtained results revealed that 33% of the samples were found to be contaminated with antibiotics. False positive of demeclocycline was avoided benefited from the application of MS/MS library searching.

MCM-41 as novel solid phase sorbent for the pre-concentration of pesticides in environmental waters and determination by microflow liquid chromatography-quadrupole linear ion trap mass spectrometry

The present work describes a novel solid phase extraction method based on the MCM-41 sorbent for the pre-concentration of eight pesticides with different polarity (including organophosphates, carbamates and triazoles) in environmental waters. A microflow liquid chromatography-quadrupole linear ion trap mass spectrometer was used for the determination and extra-confirmation of the pesticides in the water. Variables affecting the retention (pH and ionic strength) and elution (type and volume elution solvent) of the analytes, the sorbent amount and the breakthrough volume were optimized. The effect of the matrix components in the response of the pesticides was investigated in two types of environmental water (river and dam waters). Signal suppression, which was found in all cases depends on the analyte and the kind of the sample; therefore, quantification was carried out using the standard addition approach. Detection and quantification limits achieved in environmental samples were lower than 0.01μgL−1 and 0.05μgL−1, respectively (with the exception of cymoxanil in dam water, which showed a quantitation limit of 0.16μgL−1). Accuracy and precision in environmental samples, at two concentration levels, ranged from 65% to 126% (relative standard deviation≤14%), except for methomyl with recoveries lower than 60%. The method developed herein was applied to the analysis of several environmental waters from Spain in which pesticides were not found in any case. Diffusion NMR methods and 13C CP/MAS NMR were applied in order to establish that MCM-41 selectively interacts in different extent with pesticides of different polarity such as cymoxanil or phosalone.

Fast determination of pesticides and other contaminants of emerging concern in treated wastewater using direct injection coupled to highly sensitive ultra-high performance liquid chromatography-tandem mass spectrometry

It is well known that wastewater treatment plant (WWTP) effluents usually contain micropollutants such as pharmaceuticals (or their transformation products, TPs) or pesticides, which is a major issue when evaluating their possible reuse (e.g. for irrigation in agriculture). In search for an improved accuracy and simplicity, methods based on the direct injection of the sample (DI) represent a recent trend taking advantage of the increasing sensitivity of new mass spectrometry (MS) instruments. Thus, the present study shows the development and validation of a DI-based method by ultra-high-performance liquid chromatography quadrupole-linear ion trap analyser (UHPLC-QqLIT-MS/MS). The proposed method was applied to the monitoring of 115 organic microcontaminants (including pharmaceuticals, TPs and pesticides) at the ngL−1/μgL−1 level in wastewater effluents from urban WWTPs. Sample pre-treatment was reduced to acetonitrile addition and filtration of the mixture previous to LC–MS analysis. Total analysis time was <15min. A subsequent validation protocol was carried out in treated WW (TWW), following indications of SANTE and Eurachem Guidelines. Linearity and matrix effect were evaluated in the range of 10–1000ngL−1. 70% of the analytes showed a moderate matrix effect (≤25%). Trueness (expressed as recovery) and precision (calculated as relative standard deviation, RSD) were evaluated at four concentration levels (20, 50, 500 and 1000ngL−1) in TWW samples. The LODs ranged from 1 to 357ngL−1 and the LOQs from 10 to 500ngL−1. 92% of the compounds showed limits of quantification ≤100ngL−1. In most cases, mean recoveries were in the range 70–120%, and RSD values were ≤20%. The validated method was successfully applied to the analysis of 10 TWW samples, demonstrating the occurrence of 67 target compounds at concentration levels from 26705ngL−1 (4-aminoantipyrine) to 10ngL−1 (tebuconazole and bezafibrate).

Quantification of azoxystrobin and identification of two novel metabolites in lettuce via liquid chromatography–quadrupole-linear ion trap (QTRAP) mass spectrometry

ABSTRACTPesticide metabolite identification is gaining increased attention because of the interest in potential metabolite toxicity. Azoxystrobin is one of the most prevalent pesticide residues in foods in Europe. The majority of azoxystrobin metabolites have been identified using radiolabelled standards, which are either expensive or not readily available. Thus, alternative approaches for metabolite identification are desirable. Here, an LC-MS/MS method for quantifying azoxystrobin and identifying its metabolites using quadrupole-linear ion trap mass spectrometry is reported. Seven metabolites of azoxystrobin were identified 2 and 4 weeks after spraying lettuce with azoxystrobin. Among them, two metabolites are reported for the first time. The hydrolysis, reduction, hydroxylation, photoisomerisation and hydrolytic cleavage of ether bonds are identified as biotransformation processes involved in azoxystrobin metabolism in lettuce.

An integrated strategy for establishment of metabolite profile of endogenous lysoglycerophospholipids by two LC-MS/MS platforms

The methods for detecting endogenous phospholipids (PL) are focused on the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Since the structural relation and similar core structure of glycerophospholipids results in a common and predictable mass spectrometric fragmentation behavior, in the present study, six classes of lysoglycerophospholipid (Lyso-PL) were subjected to a predict-verify approach by multiple reaction monitoring (MRM) mode based on liquid chromatography-quadrupole linear ion trap mass spectrometry (LC-QTRAP-MS/MS) complemented with liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOF-MS/MS) in biological serum samples. A targeted metabolite profile of Lyso-PL was established and represented in the form of a LC-QTRAP-MRM analysis. There were total of 96 Lyso-PL molecular species, consisting of 317 regioisomers detected in serum of human and four rodent species. In addition, the metabolite profile was successfully applied to the analysis of qualitative distribution of Lyso-PLs in serum of human and four rodent species. We believe that this improvement in the method for qualitative analysis of endogenous Lyso-PLs should greatly contribute to identifying the role of lipid molecular species in biological systems. Also, the integrated strategy for establishment of metabolite profile can be applied to targeted qualitative analysis of other endogenous metabolites which occur in a high individual number but sharing either structural similarities or similar functional groups.

An integrated strategy for establishment of curcuminoid profile in turmeric using two LC–MS/MS platforms

Turmeric and curcuminoids are used as natural food coloring and functional food additives in various parts of the world. In this study, ninety-six curcuminoids were fully characterized using a targeted curcuminoid profile, which established by integrated use of two complementary LC–MS/MS platforms (liquid chromatography–quadrupole time of flight mass spectrometry (LC–QTOF-MS/MS) and liquid chromatography–quadrupole linear ion trap mass spectrometry (LC–QTRAP-MS/MS)). The curcuminoid profile was represented in the form of a multiple reaction monitoring (MRM) mode based on LC–QTRAP-MS/MS analysis. It facilitated the qualitative and relative quantitative analysis of curcuminoids in a single injection. Meanwhile, the profile was successfully applied to the quality evaluation of raw materials of turmeric from different regions in China and Myanmar. The structural identification procedures of curcuminoids and the integrated strategy provide a suitable method to analyze targeted plant metabolites which occur in a high number but sharing either structural similarities or similar functional groups.

Determination of vanillin, ethyl vanillin, and coumarin in infant formula by liquid chromatography-quadrupole linear ion trap mass spectrometry

A simple, precise, accurate, and validated liquid chromatography-quadrupole linear ion trap mass spectrometry method was developed for the determination of vanillin, ethyl vanillin, and coumarin in infant formula samples. Following ultrasonic extraction with methanol/water (1:1, vol/vol), and clean-up on an HLB solid-phase extraction cartridge (Waters Corp., Milford, MA), samples were separated on a Waters XSelect HSS T3 column (150×2.1-mm i.d., 5-μm film thickness; Waters Corp.), with 0.1% formic acid solution-acetonitrile as mobile phase at a flow rate of 0.25mL/min. Quantification of the target was performed by the internal standard approach, using isotopically labeled compounds for each chemical group, to correct matrix effects. Data acquisition was carried out in multiple reaction monitoring transitions mode, monitoring 2 multiple reaction monitoring transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the enhanced product ion modus of the linear ion trap. The novel liquid chromatography-quadrupole linear ion trap mass spectrometry platform offers the best sensitivity and specificity for characterization and quantitative determination of vanillin, ethyl vanillin, and coumarin in infant formula and fulfills the quality criteria for routine laboratory application.

Simultaneous determination of hexabromocyclododecane, tetrabromobisphenol A, and related compounds in sewage sludge and sediment samples from Ebro River basin (Spain)

This paper describes the development of a methodology for the simultaneous determination and quantification of hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), and related compounds (bisphenol A, monobromobisphenol A, dibromobisphenol A, and tribromobisphenol A) in sludge and sediment samples. The selected method is based on an extraction with dichloromethane: methanol followed by purification via SPE C(18) cartridges. Instrumental determination was carried out by liquid chromatography-quadrupole linear ion trap mass spectrometry (LC-QqLIT-MS), with quantification based on isotopic dilution method. Analyte recoveries were in the range of 39-120% and 88-126% for spiked sewage and sediment, respectively. Repeatability of replicate extractions was better than 13% relative standard deviation. Linearity was checked in the range of 0.05 and 25 injected nanograms. Limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.6 and 2.7 ng/g and 1.4 and 66 ng/g for sediment and sludge samples, respectively. The developed method was applied to sewage sludge and sediment samples collected along the Ebro River and Cinca River, one of its tributaries (northeast of Spain). TBBPA levels in sewage sludge ranged from not quantified to 1,329 ng/g dw, whereas levels in sediment samples were lower, between not detected and 15 ng/g dw. As regards HBCD, concentrations were between not detected and 375 ng/g for sludge samples and 0.8 and 1850 ng/g for sediments.

Enantiomeric specific determination of hexabromocyclododecane by liquid chromatography–quadrupole linear ion trap mass spectrometry in sediment samples

This paper describes the determination and quantitation of hexabromocyclododecane (HBCD) enantiomers by liquid chromatography–quadrupole linear ion trap mass spectrometry (LC–QqLIT-MS). The method is based on the use of a chiral chromatographic column Nucleodex β-PM (200 mm × 4.0 mm, 5 μm), which allows a good separation between HBCD enantiomers [(±)α, (±)β and (±)γ] in less than 15 min and the detection is performed by a Q-Trap instrument. Linearity was checked between 0.05 and 25 injected ng. Limits of detection (LODs) were in the range of 0.3–1.5 pg, limits of quantification (LOQs) were between 1 and 6 pg, and both values are lower than those published in the literature applying LC–MS–MS methods. The method was applied to sediment samples collected along the Cinca River, a tributary of the Ebro River (northeast of Spain). Samples were extracted and purified following a pressurized liquid extraction method. LODs of the method were between 0.12 and 5.61 ng/g and LOQs, from 0.38 to 1.87 ng/g. Total HBCD levels in these sediments ranged from not detected to 2660 ng/g dry weight. Enantiomeric fractions (EFs) were calculated and compared with EF obtained from standard injections. It is important to note that calculated EFs were corrected using 2H 18-labeled HBCD standards, in order to compensate matrix effect. EFs obtained in sediment samples suggested a higher presence of (+)α-HBCD and (+)γ-HBCD in technical mixture, this suggests that it is not a racemic mixture.