Comprehensive screening of target, non-target and unknown pesticides in food by LC-TOF-MS

Development of a Non-Target Screening and Quantitative Analysis Strategy Based on UPLC-Q-TOF/MS and UPLC-QQQ/MS to Improve the Quality Control of Wuling Capsule

Herbal medicine has been widely valued because of its remarkable efficacy and minimal side effects. The quantitative analysis of herbal medicines is essential to ensure their safety and efficacy. The simultaneous detection of multiple quality markers (Q-markers) has emerged as an important approach and trend in herbal medicine quality control. In recent years, non-targeted screening has become an effective strategy for the discovery and identification of unknown compounds. This study developed a non-targeted screening and quantitative analysis strategy to discover, identify and quantify the multiple components that truly represent the efficacy of Wuling capsule. Within this strategy, 18 types of flavonoids were tentatively discovered and identified from Wuling capsule by analyzing mass cleavage pathways, the precise molecular weights of compounds, and comparing the data with a database. Ten types of flavonoids were determined after the comparison of the standards. Additionally, following the evaluation of the regression equation, linear range, limit of detection (LOD), limit of quantitation (LOQ), precision, repeatability, and recovery of the proposed quantitative method, six flavonoids were quantified. This method successfully screened, identified, and quantified the potential active components in Wuling capsule, providing insights for improving the quality control standards in other herbal medicines.

Exploring applications of non-targeted analysis in the characterization of the prenatal exposome

Capturing the breadth of chemical exposures in utero is critical in understanding their long-term health effects for mother and child. We explored methodological adaptations in a Non-Targeted Analysis (NTA) pipeline and evaluated the effects on chemical annotation and discovery for maternal and infant exposure. We focus on lesser-known/underreported chemicals in maternal and umbilical cord serum analyzed with liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). The samples were collected from a demographically diverse cohort of 296 maternal-cord pairs (n = 592) recruited in San Francisco Bay area. We developed and evaluated two data processing pipelines, primarily differing by detection frequency cut-off, to extract chemical features from non-targeted analysis (NTA). We annotated the detected chemical features by matching with EPA CompTox Chemicals Dashboard (n = 860,000 chemicals) and Human Metabolome Database (n = 3140 chemicals) and applied a Kendrick Mass Defect filter to detect homologous series. We collected fragmentation spectra (MS/MS) on a subset of serum samples and matched to an experimental MS/MS database within the MS-Dial website and other experimental MS/MS spectra collected from standards in our lab. We annotated ~72 % of the features (total features = 32,197, levels 1-4). We confirmed 22 compounds with analytical standards, tentatively identified 88 compounds with MS/MS spectra, and annotated 4862 exogenous chemicals with an in-house developed annotation algorithm. We detected 36 chemicals that appear to not have been previously reported in human blood and 9 chemicals that were reported in less than five studies. Our findings underline the importance of NTA in the discovery of lesser-known/unreported chemicals important to characterize human exposures.

Towards non-target proactive food safety: identification of active compounds in convenience tomato products by ten-dimensional hyphenation with integrated simulated gastrointestinal digestion

Current strategies for non-target food screening focus mainly on known hazardous chemicals (adulterants, residues, contaminants, packaging migrants, etc.) instead of bioactive constituents in general and exclude the biological effect detection. To widen the perspective, a more proactive non-target effect-directed strategy is introduced to complement food safety in order to detect not only known but also unknown bioactive compounds. The developed 10-dimensional hyphenation included on-surface digestion (1D), planar chromatographic separation (2D), visualization using white light (3D), UV light (4D), fluorescence light (5D), effect-directed assay analysis (6D), heart-cut zone elution to an orthogonal reversed phase column chromatography including online desalting (7D) with subsequent diode array detection (8D), high-resolution mass spectrometry (9D), and fragmentation (10D). Metabolism, i.e., intestinal digestion of each sample, was simulated and integrated on the same adsorbent surface to study any changes in the compound profiles. As proof of principle, nine convenience tomato products and a freshly prepared tomato soup were screened via five different planar assays in a non-targeted mode. Non-digested and digested samples were compared side by side. In their effect-directed profiles, 14 bioactive compounds from classes of lipids, plant hormones, spices, and pesticides were identified. In particular, bioactive compounds coming from the lipid class were increased by gastrointestinal digestion, while spices and pesticides remained unaffected. With regard to food safety, the determination of the two dinitrophenol herbicides dinoterb and dinoseb in highly processed tomato products should be given special attention. The hyphenation covered a broad analyte spectrum and showed robust and reliable results.

Target and non-target analytical method for potential hazardous substances in livestock and pet hair using liquid- and gas chromatography quadrupole time-of-flight mass spectrometry

Extraction using acetonitrile and water and quadrupole time-of-flight mass spectrometry (LC and GC-QTOF/MS) techniques were used to screen for potential hazardous substances in livestock and pet hair. In addition, LC-MS/MS and GC-MS/MS techniques were used for verification of the analytical method and quantitative analysis of pesticides, veterinary drugs, mycotoxins and antioxidants in hair. Optimized sample preparation involves extracting 0.05 g of sample with 0.6 mL of ACN and 0.4 mL of distilled water. In addition, the two layers were separated by adding 0.1 g of NaCl. Then, both the ACN and water layers were analyzed by LC-TOF/MS, and the ACN layer was analyzed by GC-TOF/MS. Most of the matrix effects of livestock and pet hair were less than 50%, but some matrices and components showed high results, so matrix matching correction was applied for more precise quantification. Method validation was performed for 394 constituents (293 pesticides, 93 veterinary drugs, 6 mycotoxins and 2 preservatives) in dog, cat, cow and pig hair and chicken and duck feathers. All components showed good linearity (r2 ≥0.98) in the developed assay. The quantification limit of all compounds was set at 0.02 mg/kg, which is the lowest level that satisfies the recovery rate standard. The recovery experiment was repeated 8 times at 3 concentrations. Most of the components were extracted with the ACN layer, and the recovery rate was 63.35-119.98%. In order to confirm the efficiency of extracting harmful substances from actual samples, 30 hairs of livestock and pets were screened.

Retention Time Trajectory Matching for Peak Identification in Chromatographic Analysis

Retention time drift caused by fluctuations in physical factors such as temperature ramping rate and carrier gas flow rate is ubiquitous in chromatographic measurements. Proper peak matching and identification across different chromatograms is critical prior to any subsequent analysis but is challenging without using mass spectrometry. The purpose of this work was to describe and validate a peak matching and identification method called retention time trajectory (RTT) matching that can be used in targeted analyses free of mass spectrometry. This method uses chromatographic retention times as the only input and identifies peaks associated with any subset of a predefined set of target compounds. An RTT is a two-dimensional (2D) curve formed uniquely by the retention times of the chromatographic peaks. The RTTs obtained from the chromatogram of a sample under test and those pre-installed in a library are matched and statistically compared. The best matched pair implies identification. Unlike most existing peak-alignment methods, no mathematical warping or transformation is involved. Based on the experimentally characterized RTT, an RTT hybridization method was also developed to rapidly generate more RTTs and expand the library without performing actual time-consuming chromatographic measurements, which enables successful peak matching even for chromatograms with severe retention time drifts. Additionally, 3.15 × 10⁵ tests using experimentally obtained gas chromatograms and 2 × 10¹² tests using two publicly available fruit metabolomics datasets validated the proposed method, demonstrating real-time peak/interferent identification.

Target and suspect screening of pesticide residues in soil samples from peach orchards using liquid chromatography quadrupole time-of-flight mass spectrometry

Agricultural soil contamination by pesticide residues has become a serious issue of increasing concern due to their high persistence and toxicity to non-target species. However, as the world's largest peach producer, national scale surveys on pesticide residues in peach orchard soils are scarce in China. In this study, a target and suspect screening method covering over 200 pesticides commonly used in peach orchards was developed using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry in MS^E. An identification strategy using different data processing parameters was developed to identify the pesticide occurrence in soil. The method was applied to soil samples from typical peach orchards in 12 regions across China. The present work also discusses in detail the frequency of occurrence, concentration of pesticides, spatial distribution of multiresidues, and relationship between pesticide occurrence and soil properties. In the tested soil samples, 21 herbicides (level 1), 31 fungicides (level 2a), 24 insecticides (level 2a), and 3 growth regulators (level 2a) were identified. The total concentrations of quantifiable herbicides in the soil samples ranged from 1.05 to 327 ng/g. Only in 5.4% of the soil samples, no pesticide residues were present. By contrast, more than 86% of the total contained multiple residues. This study represents the first large-scale survey of pesticides in soil from peach orchards and provides comprehensive and accurate information on the pesticide residue status for risk assessment.

Scalable Analysis of Untargeted LC-HRMS Data by Means of SQL Database Archiving

Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) is widely used to detect chemicals with a broad range of physiochemical properties in complex biological samples. However, the current data analysis strategies are not sufficiently scalable because of data complexity and amplitude. In this article, we report a novel data analysis strategy for HRMS data founded on structured query language database archiving. A database called ScreenDB was populated with parsed untargeted LC-HRMS data after peak deconvolution from forensic drug screening data. The data were acquired using the same analytical method over 8 years. ScreenDB currently holds data from around 40,000 data files, including forensic cases and quality control samples that can be readily sliced and diced across data layers. Long-term monitoring of system performance, retrospective data analysis for new targets, and identification of alternative analytical targets for poorly ionized analytes are examples of ScreenDB applications. These examples demonstrate that ScreenDB makes a significant improvement to forensic services and that the concept has potential for broad applications for all large-scale biomonitoring projects that rely on untargeted LC-HRMS data.

Application of rapid air sampling and non-targeted analysis using thermal desorption comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry to accidental fire

To be able to gauge the health risks and biological effects of e-waste fires, it is of key importance to know what types and amounts of chemicals are released when they occur. In this case study, we pumped 6-24 L of air from an accidental fire at a recycling depot through a Tenax-TA tube and conducted comprehensive (non-targeted) analysis by thermal desorption/comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (TD/GC × GC/ToFMS). A special focus was placed on the search for halogenated compounds. More than 5000 components were detected in the atmosphere around the fire; however, component separation was insufficient, even when using GC × GC. The number of organohalogen compounds retrieved was increased about 1.8-fold by the refinement process of the exact mass spectrum using mass defect filtering (MDF) software. After processed by MDF, 386 peaks were concluded to be halogenated compounds. The major retrieved substances included chlorinated (or chlorinated-brominated) dioxins, chlorinated (or brominated) phenols, benzene, and various other halogenated aromatic compounds. Direct comparison of mass spectra was carried out to investigate the potential for qualitative and quantitative comparison of detected peaks without specific identification. The approximate quantitative values are summarized for each compound in the estimated substance group. Their ratios were estimated to be halogenated phenols: 13%, benzenes: 9.6%, dibenzo-p-dioxins: 9.6%, dibenzofurans: 8.4%, biphenyls; 7.4% and toluenes: 6.4%.

Sample preparation techniques for suspect and non-target screening of emerging contaminants

The progress in sensitivity and resolution in mass spectrometers in recent years provides the possibility to detect a broad range of organic compounds in a single procedure. For this reason, suspect and non-target screening techniques are gaining attention since they enable the detection of hundreds of known and unknown emerging contaminants in various matrices of environmental, food and human sources. Sample preparation is a critical step before analysis as it can significantly affect selectivity, sensitivity and reproducibility. The lack of generic sample preparation protocols is obvious in this fast-growing analytical field, and most studies use those of traditional targeted analysis methods. Among them, solvent extraction and solid phase extraction (SPE) are widely used to extract emerging contaminants from solid and liquid sample types, respectively. Sequential solvent extraction and a combination of different SPE sorbents can cover a broad range of chemicals in the samples. Gel permeation chromatography (GPC) and adsorption chromatography, including acidification, are typically used to remove matrix components such as lipids from complex matrices, but usually at the expense of compound losses. Ideally, the purification of samples intended for non-target analysis should be selective of matrix interferences. Recent studies have suggested quality assurance/quality control measures for suspect and non-target screening, based on expansion and extrapolation of target compound lists, but method validations remain challenging in the absence of analytical standards and harmonized sample preparation approaches.

Alternative method’s results for the non targeted determination of xenobiotics in food by means of high resolution and accuracy mass spectrometry

The application of a high resolution and accurate mass spectrometry (HRAMS) approach to detect xenobiotics in different food matrices by means of non targeted determination by UHPLC-Orbitrap followed by data processing analysis was described. Three case studies were reported to demonstrate the possibility to identify unexpected substances in different food commodities overcomes targeted method. This innovative approach could lay the foundation for its applicability to routine analysis in the near future giving the possibility to open new horizons to the research of a wide range of xenobiotics.

Non-target bioanalytical eight-dimensional hyphenation including bioassay, heart-cut trapping, online desalting, orthogonal separations and mass spectrometry

It is still a challenge to discover and identify individual bioactive compounds directly in multicomponent mixtures. Current workflows are too tedious for routine use. Hence, the hyphenation of separation and detection techniques is a powerful tool to maximize the information obtained by a single sample run. A robust eight-dimensional (8D) hyphenation was developed. Orthogonal separations, biological assay detection, analyte trapping, desalting, and physico-chemical detections were arranged in the following order, i.e. 1) normal phase high-performance thin-layer chromatography (NP-HPTLC) separation, 2) Vis detection, 3) UV detection, 4) fluorescence detection (FLD), 5) bioassay for effect-directed analysis (EDA), 6) heart-cut trapping/desalting/elution to reversed phase high-performance liquid chromatography (RP-HPLC) separation, 7) photodiode array (PDA) and 8) mass spectrometry (MS) detection. For the first time, the hyphenation exploited online analyte trapping to desalt the eluted bioactive zone from the plate containing highly salted bioassay media. Subsequent valve switching guided the trapped analyte(s) to the main column, followed by multiple detection. As proof-of-principle, cinnamon samples were analyzed by NP-HPTLC-UV/Vis/FLD-EDA-RP-HPLC-PDA-MS, whereby a bioactive zone was separated into two distinct peaks detected by PDA and MS to be 2-methoxy cinnamaldehyde and cinnamaldehyde. The developed 8D hyphenation is applicable for routine, allowing the non-target high-throughput screening of complex samples for individual bioactive compounds.

Characterization of wines with liquid chromatography electrospray ionization mass spectrometry: Quantification of amino acids via ionization efficiency values

Quantification of analysis results for the suspect and non-targeted screening is essential for obtaining meaningful insight from the measurements. Ionization efficiency predictions is a possible approach to enable quantitation without standard substances. This is, however, especially challenging for the analysis carried out by combining the full scan mode either with fragmentation experiments in data-dependent or data-independent acquisition mode. Here we investigate the correlation of ionization efficiency values measured in full scan mode with the response factors measured in multiple reaction monitoring (MRM) mode for derivatized amino acids. We observe good correlation (R² of 0.80) for 6-Aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatized amino acids. This encourages the use of the measured ionization efficiency values to estimate amino acid concentrations in different beverages. We apply the measured ionization efficiency values for estimating the concentration of amino acids for measurements done both in full scan as well as in MRM mode in wines and beers. We show that the calculated concentrations are in very good correlation with measured values (R² of 0.71 to 1.00). The method possesses average trueness of 70.5% and shows an insignificant matrix effect.

A review of Fourier Transform Infrared (FTIR) spectroscopy used in food adulteration and authenticity investigations

The increasing demand for food and the globalisation of the supply chain have resulted in a rise in food fraud, and recent high profile cases, such as the Chinese milk scandal in 2008 and the EU horsemeat scandal in 2013 have emphasised the vulnerability of the food supply system to adulteration and authenticity frauds. Fourier Transform Infrared (FTIR) spectroscopy is routinely used in cases of suspected food fraud as it offers a rapid, easy and reliable detection method for these investigations. In this review, we first present a brief summary of the concepts of food adulteration and authenticity as well as a discussion of the current legislation regarding these crimes. Thereafter, we give an extensive overview of FTIR as an analytical technique and the different foods where FTIR analysis has been employed for food fraud investigations as well as the subsequent multivariate data analyses that have been applied successfully to investigate the case of adulteration or authenticity. Finally, we give a critical discussion of the applications and limitations of FTIR, either as a standalone technique or incorporated in a test battery, in the fight against food fraud.

Comparative study of esterase activities in different tissues of marine fish species Trachurus trachurus, Merluccius merluccius and Trisopterus luscus

Pesticides are one of the most frequently anthropogenic xenobiotics detected in water. Among these, the organophosphorus pesticides (OPs) are very widely used in agriculture due to their broad spectrum of activity and their low price, but they also have high potent effects as neurotoxic compounds in non-target organisms. The aim of this study was to evaluate biomarkers acetylcholinesterase (AChE), butyrylcholinesterase (BChE), propionylcholinesterase (PChE) and carboxylesterase (CbE) in the representative Atlantic fish species Trachurus trachurus, Merluccius merluccius and Trisopterus luscus from "Rías Gallegas", a traditional Spanish fishing area. These esterase activities were evaluated in the brain, muscle and liver to determine the most adequate tissue to measure such enzymatic activities. The sensitivity of AChE and CbE activities from different tissues the widely used organophosphorus insecticide chlorpyrifos (CP), and its toxic metabolite (CP-oxon) was also tested. AChE activity was predominant in all tissues of the analysed species (particularly in brain constituting from 78.33%, 89.83% and 88.43% of total ChEs in Trachurus trachurus, Merluccius merluccius and Trisopterus luscus, respectively). Under in vitro exposure, esterases were shown to be highly sensitive to CP and especially to CP-oxon. Moreover, a similar effect observed on AChE and CbE activities could suggest that CbE activity might contribute efficiently against the toxic effects of CP, especially in muscle and the liver. The presence of BChE, PChE and upper CbE activities in muscle and the liver and their OP-sensibilities can be used to study their function in the pesticide biochemical detoxification pathways with a prominent role as a safeguarding mechanism against pesticide toxicity.

Development of UPLC-Q-TOF-MS Coupled with Cation-exchange Solid-phase Extraction Method for the Determination of Ten Pyrrolizidine Alkaloids in Herbal Medicines

Pyrrolizidine alkaloids are secondary metabolites of plants and can cause significant hepatotoxicity in humans. In this study, a fast and simple method was developed to determine ten pyrrolizidine alkaloids (PAs) in six types of herbal medicines using ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS). An efficient solid-phase extraction procedure was carried out by using strong cation-exchange cartridges and the parameters were optimized. The established analytical method was validated and the results showed that the method presented satisfactory accuracy and precision. The established method was successfully applied for the determination of PAs in six herbal plants, including Senecionis Scandentis Hebra, Arnebiae Radix, Asteris Radix Et Rhizoma, Farfarae Flos, Senecionis Cannabifolii Herba and Emilia sonchifolia. PAs were found in all of these herbal plant samples. Eight types of related commercial herbal drugs were also detected, six of them were detected with different amounts of PAs. This work not only provided a powerful technical platform for both qualitative and quantitative analysis of PAs in herbal medicines, but also obtained information concerning PAs in these herbal samples, which could provide reference to the government regulatory authorities and non-governmental organizations.

Determining pesticide residues in wheat flour by ultrahigh-performance liquid chromatography/quadrupole time-of-flight mass spectrometry with QuEChERS extraction

Pesticides are used to increase crop yields and preserve quality by protecting crops against pests; however, their overuse can adversely affect human health and the environment. Herein, we report the development of a multi-pesticide screening method using optimized QuEChERS coupled with liquid chromatography/quadrupole time-of-flight (QTOF) mass spectrometry for the analysis of 13 pesticides in wheat flour. Mass accuracies with errors of less than 2.4 ppm were obtained for all analysed pesticides, and the method provided satisfactory recovery and linearity. Repeatabilities of 0.3-12.7% and reproducibilities of 2.5-15.2% were observed in full-scan TOF mode. The performance of the developed full-scan TOF method was compared to that obtained in high-resolution multiple reaction monitoring (MRM-HR) mode. The limits of quantification for the full-scan TOF and MRM-HR modes ranged from 2 to 10, and 3 to 9 μg kg^-1, respectively. The two quantification methods exhibited high sensitivities (limit of detections: 1-3 μg kg^-1 in full-scan TOF, and 1-3 μg kg^-1 for MRM-HR mode). No pesticide residues were detected when the developed method was applied to 22 real wheat flour samples.

Optimization of the Data Treatment Steps of a Non-targeted LC-MS-Based Workflow for the Identification of Trace Chemical Residues in Honey

Non-targeted screening (e.g., suspected-target) is emerging as an attractive tool to investigate the occurrence of contaminants in food. The sample preparation and instrument analysis steps are known to influence the identification of analytes with non-targeted workflows, especially for complex matrices. However, for methods based on mass spectrometry, the impact of the post-analysis data treatment (e.g., feature extraction) on the capacity to correctly identify a contaminant at trace level is currently not well understood. The aim of the study was to investigate the influence of seven post-analysis data treatment parameters on the non-targeted identification of trace contaminants in honey using high-performance liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS). Seven compounds reported as veterinary drugs for honeybees were applied as model compounds. Among the parameters studied, the expansion window for chromatogram extraction and the average scans included in the spectra influenced significantly the identification process results. The optimized data treatment was applied to the non-targeted screening of veterinary drugs, pesticides, and other contaminants in 55 honey samples as a proof of concept. Among the 43 compounds included in a library of honey-related compounds that was used for screening, eight compounds were tentatively identified in at least one honey sample. The tentative identity of two of these compounds (tylosin A and hydroxymethylfurfural) was further confirmed with analytical standards. Graphical Abstract.

Nontargeted Detection Methods for Food Safety and Integrity

Nontargeted workflows for chemical hazard analyses are highly desirable in the food safety and integrity fields to ensure human health. Two different analytical strategies, nontargeted metabolomics and chemical database filtering, can be used to screen unknown contaminants in food matrices. Sufficient mass and chromatographic resolutions are necessary for the detection of compounds and subsequent componentization and interpretation of candidate ions. Analytical chemistry–based technologies, including gas chromatography–mass spectrometry (GC-MS), liquid chromatography–mass spectrometry (LC-MS), nuclear magnetic resonance (NMR), and capillary electrophoresis–mass spectrometry (CE-MS), combined with chemometrics analysis are being used to generate molecular formulas of compounds of interest. The construction of a chemical database plays a crucial role in nontargeted detection. This review provides an overview of the current sample preparation, analytical chemistry–based techniques, and data analysis as well as the limitations and challenges of nontargeted detection methods for analyzing complex food matrices. Improvements in sample preparation and analytical platforms may enhance the relevance of food authenticity, quality, and safety.

Comparison of Two Methods for the Determination of Selected Pesticides in Honey and Honeybee Samples

Developed and validated analytical methods for the determination of a wide spectrum of pesticide residues in honey and honeybee samples after the modification of QuEChERS extraction in combination with gas chromatography–tandem quadrupole mass spectrometry (GC-MS/MS) and liquid chromatography–tandem quadrupole mass spectrometry (LC-MS/MS) were discussed and compared. The developed methods were evaluated regarding the utilized equipment and reagents using Eco-Scale and compared in terms of extraction time, accuracy, precision, sensitivity and versatility, with similar procedures. The results proved that the QuEChERS protocol in combination with LC and GC techniques fulfills the requirements of green analytical chemistry, so it can be used as a tool in environmental monitoring. The recovery was 85–116% for honey and 85.5–103.5% for honeybee samples. The developed methods were successfully applied in monitoring real samples collected from three districts of Pomerania in Poland. Analysis of real samples revealed the presence of the following pesticides: bifenthrin, fenpyroximate, methidathione, spinosad, thiamethoxam, triazophos, metconazole and cypermethrin at levels higher than the MRLs established by the EU.

Exploring the chemistry of complex samples by tentative identification and semiquantification: A food contact material case

In fields such as food safety and environmental chemistry, ensuring safety is greatly challenged by large numbers of unknown substances occurring. Even with current state-of-the-art mass spectrometers, dealing with nonidentified substances is a very laborious process as it includes structure elucidation of a vast number of unknowns, of which only a fraction may be relevant. Here, we present an exploration and prioritization approach based on high-resolution mass spectrometry. The method uses algorithm-based precursor/product-ion correlations on quadrupole time-of-flight tandem mass spectrometry data to retrieve the most likely chemical match from a structure database. In addition, time-of-flight-only data are used to estimate analyte concentration via semiquantification. The method is demonstrated in recycled paper food contact material. Here, 585 chromatographic peaks were discovered, of which 117 were unique to the sample and could be tentatively elucidated via accurate mass, isotopic pattern, and precursor/product-ion correlations. Nearly 85% of these 117 peaks were matched with database entries, which provided varying certainty of information about the analyte structure. Semiquantitative concentration ranges of investigated compounds were between 0.7 and 1600 μg dm^-2 . With these data, a subgroup of chemicals was risk-categorized and prioritized by using the most likely candidate structure(s) obtained. Prioritization based on expected health impact was possible by using the tentatively assigned data. Overall, the described method not only is a valuable chemical exploration tool for nonidentified substances but may also be used as a preliminary prioritization tool for substances expected to have the highest health impact, for example, in food contact materials.

Simultaneous analysis of multiple pesticide residues in minor fruits by ultrahigh-performance liquid chromatography/hybrid quadrupole time-of-fight mass spectrometry

An ultrahigh-performance liquid chromatography/hybrid quadrupole time-of-fight mass spectrometry (UPLC/QTOF-MS) method for the simultaneous identification and quantification of 50 multi-class pesticides in minor fruits is reported. The method consists of a sample extraction step, followed by analysis of the pesticides by UPLC/QTOF-MS. Satisfactory chromatographic separation was achieved over a 20min runtime. The pesticides were identified by the accurate mass measurements of the protonated molecules ([M+H]⁺) and their main fragment ions, isotopic pattern analysis and retention time matching. The mass accuracy obtained was below 2ppm error for all the pesticides analysed. The method was validated by spiking starfruit with the 50 analytes. Satisfactory results regarding sensitivity and linearity were obtained. The method was successfully applied to the analysis of 87 real-world starfruit and Indian jujube samples, demonstrating its applicability for the routine analysis of multiple pesticide residues in minor tropical fruits.

Screening for Polar Chemicals in Water by Trifunctional Mixed-Mode Liquid Chromatography-High Resolution Mass Spectrometry

The presence of persistent and mobile organic contaminants (PMOC) in aquatic environments is a matter of high concern due to their capability of crossing through natural and anthropogenic barriers, even reaching drinking water. Most analytical methods rely on reversed-phase liquid chromatography (RPLC), which is quite limited for the detection of very polar chemicals. Thus, many of these PMOCs may have not been recognized as water pollutants yet, due to the lack of analytical methods capable to detect them. Mixed-mode LC (MMLC), providing the combination of RP and ion-exchange functionalities is explored in this work with a trifunctional column, combining RPLC, anion and cation exchange, which allows the simultaneous determination of analytes with extremely different properties. A nondiscriminant sample concentration step followed by a MMLC-high resolution mass spectrometry method was developed for a group of 37 very polar model chemicals with different acid/base functionalities. The overall method performance was satisfactory with a mean limit of detection of 50 ng/L, relative standard deviation lower than 20% and overall recoveries (including matrix effects) higher than 60% for 54% of model compounds. Then, the method was applied to 15 real water samples, by a suspect screening approach. For those detected PMOC with standard available, a preliminary estimation of concentrations was also performed. Thus, 22 compounds were unequivocally identified in a range of expected concentrations from 6 ng/L to 540 μg/L. Some of them are well-known PMOC, such as acesulfame, perfluorobutanoic acid or metformin, but other novel pollutants were also identified, as for example di-o-tolylguanidine or trifluoromethanesulfonic acid, which had not or were scarcely studied in water so far.

Ion-Mobility-Derived Collision Cross Section as an Additional Identification Point for Multiresidue Screening of Pesticides in Fish Feed

Ion mobility spectrometry allows for the measurement of the collision cross section (CCS), which provides information about the shape of an ionic molecule in the gas phase. Although the hyphenation of traveling-wave ion mobility spectrometry (TWIMS) with high-resolution quadrupole time-of-flight mass spectrometry (QTOFMS) has been mainly used for structural elucidation purposes, its potential for fast screening of small molecules in complex samples has not yet been thoroughly evaluated. The current work explores the capabilities of ultrahigh-performance liquid chromatography (UHPLC) coupled to a new design TWIMS-QTOFMS for the screening and identification of a large set of pesticides in complex salmon feed matrices. A database containing TWIMS-derived CCS values for more than 200 pesticides is hereby presented. CCS measurements showed high intra- and interday repeatability (RSD < 1%), and they were not affected by the complexity of the investigated matrices (ΔCCS ≤ 1.8%). The use of TWIMS in combination with QTOFMS was demonstrated to provide an extra-dimension, which resulted in increased peak capacity and selectivity in real samples. Thus, many false-positive detections could be straightforwardly discarded just by applying a maximum ΔCCS tolerance of ±2%. CCS was proposed as a valuable additional identification point in the pesticides screening workflow. Several commercial fish feed samples were finally analyzed to demonstrate the applicability of the proposed approach. Ethoxyquin and pirimiphos-methyl were identified in most of the analyzed samples, whereas tebuconazole and piperonil butoxide were identified for the first time in fish feed samples.

Target and non-target identification of chemical components in Lamiophlomis rotata by liquid chromatography/quadrupole time-of-flight mass spectrometry using a three-step protocol

RATIONALE

As a herbal plant used in traditional Chinese medicine, Lamiophlomis rotata (Benth.) Kudo mainly displays its pharmacological effect by promoting blood circulation and hemostasis, dispelling wind, and acting as an analgesic. To identify the components contained in L. rotata, global detection and structural elucidation of both target and non-target components in the medicinal material was performed.

METHODS

L. rotata was ultrasonically extracted with methanol. Separation and analysis were achieved using liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOF-MS). A three-step protocol which included (1) potential components screening, (2) collection of qualitative information, and (3) database searching and structural elucidation was used for target and non-target identification.

RESULTS

A total of 42 components were tentatively identified, which included 12 iridoids (2 aglycones and 10 glucosides), 11 flavonoids (4 aglycones and 7 glucosides), and 13 phenylethanoid glycosides. Moreover, components of L. rotata extract belonging to the three main structural categories could be well separated in a 3D point plot according to their retention times, mass defects and degrees of unsaturation, facilitating the structural classification and identification in the subsequent studies.

CONCLUSIONS

The results provide a reasonable picture of the components contained in L. rotata extract and promote the further pharmacodynamic and/or pharmacokinetic characterization of this medical material, meanwhile demonstrating the utility of a universal methodology for the systematical study of herbal medicines. Copyright © 2016 John Wiley & Sons, Ltd.

Evaluating a Tap Water Contamination Incident Attributed to Oil Contamination by Nontargeted Screening Strategies

The present study applied nontargeted screening techniques as a novel approach to evaluate the tap water samples collected during the "4.11" tap water pollution incident occurred on April 11, 2014 in Lanzhou in west China. Multivariate analysis (PCA and OPLS-DA) of about 3000 chemical features obtained in extracts of tap water samples by ultrahigh-pressure liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) analysis showed significantly different chemical profiles in tap water from pollution regions versus reference regions during the event. These different chemical profiles in samples from different regions were not observed in samples collected during the nonpollution period. The compounds responsible for the differences in profiles between regions were identified as naphthenic acids (NAs) and oxidized NAs (oxy-NAs) after the sample extracts underwent bromination to explore saturations, dansylation to identify hydroxylations and corresponding MS/MS mode analysis. A consistent finding was further observed in the targeted analysis of NA mixtures, demonstrating that the Lanzhou "4.11" tap water pollution incident could be attributed to oil spill pollution, and NA mixtures would be a marker for oil contamination. Such evaluations can help to rapidly discriminate pollution sources in accidental pollution events and contribute to regular water monitoring management of water safety issues.

Quantitative analysis of pesticide residues in vegetables and fruits by liquid chromatography quadrupole time-of-flight mass spectrometry

The applicability of liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) for the quantitative analysis of pesticide residues in vegetables and fruits was demonstrated. The LC-QTOF-MS parameters, such as cone voltage, capillary voltage, collision energy and mass extraction window, were carefully optimised for the analysis of pesticide residues. The LC-QTOF-MS method was validated for 149 pesticides in four vegetables and fruits, i.e. apple, potato, cabbage and spinach, at a spiking level of 0.01 mg kg(-1). The samples were prepared according to the Japanese official multi-residue method with a modification to the column clean-up procedure. Of the 149 pesticides, recoveries in the range of 70-120% were achieved for 147 pesticides in apple, 145 in potato, 141 in cabbage and 131 in spinach, with intra-day precisions (RSDs) of < 25% and inter-day precisions (RSDs) of < 30%, which are within the acceptable range given in the Japanese method validation guideline. Matrix effects were negligible for the majority of the target pesticides. Except for spiroxamine in spinach, no interfering peaks were observed in the blank samples. The target pesticides, except those with low sensitivity, achieved calibration curves with satisfactory linearity, with correlation coefficients (r) greater than 0.995 in the concentration range of 0.002-0.1 μg ml(-1). Furthermore, the majority of the target pesticides provided more than one fragment ion or isotope ion that could be used for confirmation. The overall results suggest that LC-QTOF-MS is a powerful tool for the quantification of pesticide residues in vegetables and fruits at the level of 0.01 mg kg(-1).

Qualitative and Quantitative Analysis of the Major Constituents in Shexiang Tongxin Dropping Pill by HPLC-Q-TOF-MS/MS and UPLC-QqQ-MS/MS

Shexiang Tongxin dropping pill (STP) is a traditional Chinese medicine formula that consists of total saponins of ginseng, synthetic Calculus bovis, bear gall, Venenum bufonis, borneol and Salvia miltiorrhiza. STP has been widely used in China and Southeast Asia for the treatment of cardiovascular diseases. In this study, a qualitative analytical method using high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was developed for identification of the major constituents in STP. Based on the retention time and MS spectra, 41 components were identified by comparison with reference compounds and literature data. Moreover, using ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry in multiple-reaction monitoring mode, we quantified 13 of the identified constituents (ginsenoside Rg1, ginsenoside Rk3, cinobufagin, arenobufagin, bufalin, resibufogenin, tanshinone IIA, taurine, tauroursodeoxycholic acid, taurocholic acid, cholic acid, deoxycholic acid, and chenodeoxycholic acid). These results suggest that this new approach is applicable for the routine analysis and quality control of STP products and provides fundamental data for further in vivo pharmacokinetical studies.

Identification strategies for flame retardants employing time-of-flight mass spectrometric detectors along with spectral and spectra-less databases

In the past, the preferred strategy for the identification of unknown compounds was to search in an appropriate mass spectral database for spectra obtained using either electron ionisation (GC-MS analyses) or collision-induced dissociation (LC-MS/MS analyses). Recently, an increase has been seen in the use of accurate mass instruments and spectra-less databases, based on monoisotopic accurate mass alone. In this article, we describe a systematic workflow for the screening and identification of new flame retardants. This approach utilises LC-quadrupole-time-of-flight MS and spectra-less databases based only on monoisotopic accurate mass for the identification of 'unknowns'. An in-house database was built, and the input parameters used in the data analysis process were optimised for flame retardant chemicals, so that it can be easily transferred to other laboratories. The procedure was successfully applied to dust, foam and textiles from car interiors and indoor consumer products. The developed method was demonstrated for the main new flame retardant present in Antiblaze V6 and for the three unreported reaction by-products/impurities present in the same technical mixture. Copyright © 2015 John Wiley & Sons, Ltd.

Homolog-focused profiling of ginsenosides based on the integration of step-wise formate anion-to-deprotonated ion transition screening and scheduled multiple reaction monitoring

Homolog-focused profiling is a favored option to bridge targeted metabolomics toward non-targeted metabolomics. In current study, an attempt was made for the large-scale ginsenoside-specific analysis in ginseng (G) and American ginseng (AG). When formic acid (0.1%, v/v) was introduced as the mobile phase additive, formate anion-to-deprotonated ion transitions ([M+HCOO](-)>[M-H](-)) with an optimal collision energy (-32eV) could result in satisfactory responses for ginsenosides. Therefore, a step-wise multiple reaction monitoring (MRM)-based method employing [M+HCOO](-)>[M-H](-) ion pairs was constructed to screen ginsenosides among 501-1250u (for Q1) with a step-size of 2u, and MRM also served as a survey experiment to trigger enhanced product ion scans for MS(2) spectrum acquisition on a hybrid triple quadrupole-linear ion trap mass spectrometer; then, the identification of those observed ginsenosides was achieved on the basis of the well-defined mass cracking patterns for ginsenosides; afterwards, scheduled MRM was introduced for large-scale relatively quantitative analysis of all detected ginsenosides. Finally, comparative metabolomics were performed to differentiate G, AG, and their processed products. Method validation was carried out using thirteen authentic compounds. A total of 221 ginsenosides, among which 185 ones were annotated, were observed and relatively quantitated. All crude materials were obviously classified into groups I-III. Above all, the MRM-based homolog-focused profiling of ginsenosides could be used as a reliable tool to gain an in-depth view for ginsenoside-enriched herbal products.

Qualitative Multiresidue Screening Method for 143 Veterinary Drugs and Pharmaceuticals in Milk and Fish Tissue Using Liquid Chromatography Quadrupole-Time-of-Flight Mass Spectrometry

A wide-scope screening methodology has been developed for the identification of veterinary drugs and pharmaceuticals in fish tissue and milk using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). The method was validated using a qualitative approach at two concentration levels. The detection of the residues was accomplished by retention time, accurate mass, and the isotopic fit using an in-house database. Product-ion spectra were used for unequivocal identification of the compounds. Generic sample treatment was applied. The majority of the compounds were successfully detected and identified at concentration levels of 150 ng mL(-1) in milk and 200 μg kg(-1) in fish (>80% of the compounds in both matrices), whereas satisfactory results were also obtained at concentration levels of 15 ng mL(-1) in milk and 20 μg kg(-1) in fish (>60% of the compounds detected and identified).