Ultra-high Performance Liquid Chromatography-quadrupole Time-of-flight Mass Spectrometry Research Articles

Depletion study, withdrawal period calculation and bioaccumulation of sulfamethazine in tilapia (Oreochromis niloticus) treated with medicated feed

The residue depletion of sulfamethazine (SMZ) was evaluated in tilapia (Oreochromis niloticus) after 11 days of administration of medicated feed containing SMZ, at the dose of 422 mg/kg body weight (bw). The determination of SMZ in feed and tilapia fillet was carried out using the QuEChERS approach for sample preparation, and high performance liquid chromatography with diode array detector (HPLC-DAD) and ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) for quantitation, respectively. Both methods were validated based on international and Brazilian guidelines and shown to be suitable for the intended purposes. The withdrawal period to reach the maximum residue level (MRL) of 100 μg/kg, according to the European Union (EU) legislative framework to all substances belonging to the sulfonamide (SA) group (EU, 2010), was 10 days (260 °C-day). After treatment, the maximum level of SMZ accumulation in the tilapia muscle was 1.6 mg/kg. SMZ was shown to be quickly excreted by tilapia. Thus, considering the acceptable daily intake of SMZ established by the Codex Commission (0–0.05 mg/kg bw), and a factor of 5 times the upper amount of fish consumption in Brazil (38 kg/year), this study showed that there is a low risk of adverse effects to consumers. This study offers subsidies not only for the establishment of public policies with regard to the use of veterinary drugs currently not allowed in a country by their legal legislative framework for fish farming, but also to fish producers for the proper handling to ensure safe fish fillets.

Determination of 39 veterinary drug residues in Procambarusclarkii by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry

An ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) method was developed for determination of 39 veterinary drugs in Procambarusclarkii. Samples were extracted with acidified acetonitrile and purified with enhanced matrix removal-lipid (EMR-Lipid) adsorbent and graphitized multi-walled carbon nanotubes (GMWNTs). Extracts were analyzed by UHPLC-Q-TOF-MS. Target compounds were screened according to accurate mass, isotopic ratio, and retention time, and confirmed by library search. Target analytes were quantified using the chromatographic peak area of each compound. For each of the drugs of interest, calibration curves were linear in their respective ranges with correlation coefficients greater than 0.99. The limits of quantification (LOQs) were 3-15 μg/kg. The recoveries for target compounds spiked in Procambarusclarkii ranged from 62.4% to 105.8%, with relative standard deviations (RSDs) ranging from 2.5% to 13.5%. This method is simple, rapid, accurate, and suitable for simultaneous determination of 39 veterinary drugs, including sulfonamides, quinolones, and triphenylmethane, extracted from Procambarusclarkii.

Qualitative analysis of illegally adulterated sildenafil and related compounds in dietary supplements by ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry

The presence of illegally adulterated sildenafil and related compounds in dietary supplements was qualitatively analyzed by employing ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Samples were extracted by ultrasonic method using methanol. The analysis was performed on an Agilent Poroshell 120 SB-C18 column (75 mm×3.0 mm, 2.7 μm) using gradient elution with a mixture of aqueous formic acid solution (0.1%, v/v) and acetonitrile as the mobile phase at a flow rate of 0.4 mL/min. Q-TOF-MS equipped with ESI ion source was operated in a positive ionization mode. Qualitative analysis was based on the retention time and the accurate relative molecular mass of elemental compositions of the precursor ion and product ions. The limits of detection (LODs) of sildenafil and other 99 compounds were found to be 0.1-50 mg/kg or 0.1~50 mg/L in 10 different matrices. In this manuscript, the fragmentation behavior of 98 phosphodiesterase-5 inhibitors are categorically summarized, which can provide information for referencing and identification of suspicious compounds. The method was successfully applied to the analysis of actual samples, of which 19 compounds combated the illegal adulteration behavior effectively.

Discrimination of Radix Polygoni Multiflori from different geographical areas by UPLC-QTOF/MS combined with chemometrics

BackgroundNowadays, Radix Polygoni Multiflori (RPM, Heshouwu in Chinese) from different geographical origins were used in clinic. In order to characterize the chemical profiles of different geographical origins of RPM samples, ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-QTOF/MS) combined with chemometrics (partial least squared discriminant analysis, PLS‑DA) method was applied in the present study.MethodsThe chromatography, chemical composition and MS information of RPM samples from 18 geographical origins were acquired and profiled by UPLC-QTOF/MS. The chemical markers contributing the differentiation of RPM samples were observed and characterized by supervised PLS‑DA method of chemometrics.ResultsThe chemical composition differences of RPM samples derived from 18 different geographical origins were observed. Nine chemical markers were tentatively identified which could be used as specific chemical markers for the differentiation of geographical RPM samples.ConclusionsUPLC-QTOF/MS method coupled with chemometrics analysis has potential to be used for discriminating different geographical TCMs. Results will help to develop strategies for conservation and utilization of RPM samples.

Photochemical Transformation of Nicotine in Wastewater Effluent.

Nicotine is a highly toxic tobacco alkaloid that is ubiquitous in wastewater effluent. For the first time, we report the identification of the products and the pathways for the photodegradation of nicotine in an effluent matrix under simulated solar irradiation. Nicotine was found to be degraded by triplet-state organic matter (3OM*), thus indicating that electron transfer is a preferred reaction mechanism. Using the multivariate statistical strategies orthogonal projection to latent structures discriminant analysis (OPLS-DA) and hierarchical clustering, 49 potential transformation products (TPs) of nicotine were successfully extracted from the water matrix via high-resolution ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). Overall, 30 TPs, including 4 groups of nonseparated isomeric photo TPs, were identified with various levels of confidence based on the tandem mass spectrometry information on standard compounds and the isotope-labeling method (using rac-nicotine-2',3',3'-D3, rac-nicotine-13CD3, and rac-nicotine-D4) under air-saturated conditions. The pyrrolidine ring of nicotine was found to be the reactive site under sunlight irradiation. Pseudooxynicotine was the main primary TP from nicotine, with a maximum transformation ratio of 64%. Nicotinic acid, cotinine, 3'-hydroxycotinine, and myosmine were the final stable TPs after 72 h of solar irradiation, with yields of 13%, 3%, 5%, and 5%, respectively.

The identification and analytical characterization of 2,2'-difluorofentanyl.

New psychoactive substances (NPS) have expanded their distribution and become widely available in the global market in recent years. The illicit use of fentanyl and its analogs has become an important worldwide concern linked to their high potency and risk of fatal overdose. This study describes the analytical characterization of a new fentanyl derivative N-(1-(2-fluorophenethyl)-4-piperidinyl)-N-(2-fluorophenyl)propionamide (2,2'-difluorofentanyl). Identification was based on ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UHPLC-QTOF-MS), gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. To our knowledge, this study is the first to report on analytical data for this compound. The most abundant fragment ion in the electrospray ionization (ESI) mass spectrum under collision-induced dissociation (CID) mode was formed by the cleavage between the piperidine ring and the N-phenyl-amide moiety of the protonated molecule. Two diagnostic ions in the electron ionization (EI) mass spectrum were formed by the loss of a tropylium ion (M-91), and by the degradation of the piperidine ring and dissociate of the COC2 H5 moiety altogether, respectively.

Urine Metabonomics Reveals Early Biomarkers in Diabetic Cognitive Dysfunction.

Recently, increasing attention has been paid to diabetic encephalopathy, which is a frequent diabetic complication and affects nearly 30% of diabetics. Because cognitive dysfunction from diabetic encephalopathy might develop into irreversible dementia, early diagnosis and detection of this disease is of great significance for its prevention and treatment. This study is to investigate the early specific metabolites biomarkers in urine prior to the onset of diabetic cognitive dysfunction (DCD) by using metabolomics technology. An ultra-high performance liquid-chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-Q/TOF-MS) platform was used to analyze the urine samples from diabetic mice that were associated with mild cognitive impairment (MCI) and nonassociated with MCI in the stage of diabetes (prior to the onset of DCD). We then screened and validated the early biomarkers using OPLS-DA model and support vector machine (SVM) method. Following multivariate statistical and integration analysis, we found that seven metabolites could be accepted as early biomarkers of DCD, and the SVM results showed that the prediction accuracy is as high as 91.66%. The identities of four biomarkers were determined by mass spectrometry. The identified biomarkers were largely involved in nicotinate and nicotinamide metabolism, glutathione metabolism, tryptophan metabolism, and sphingolipid metabolism. The present study first revealed reliable biomarkers for early diagnosis of DCD. It provides new insight and strategy for the early diagnosis and treatment of DCD.

A Metabolomics-Guided Exploration of the Phytochemical Constituents of Vernonia fastigiata with the Aid of Pressurized Hot Water Extraction and Liquid Chromatography-Mass Spectrometry.

Vernonia fastigiata is a multi-purpose nutraceutical plant with interesting biological properties. However, very little is known about its phytochemical composition and, thus the need for its phytochemical characterization. In the current study, an environmentally friendly method, pressurized hot water extraction (PHWE), was used to extract metabolites from the leaves of V. fastigiata at various temperatures (50 °C, 100 °C, 150 °C and 200 °C). Ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-qTOF-MS) analysis in combination with chemometric methods, particularly principal component analysis (PCA) and liquid/gas chromatography mass spectrometry (XCMS) cloud plots, were used to descriptively visualize the data and identify significant metabolites extracted at various temperatures. A total of 25 different metabolites, including hydroxycinnamic acid derivatives, clovamide, deoxy-clovamide and flavonoids, were noted for the first time in this plant. Overall, an increase in extraction temperature resulted in an increase in metabolite extraction during PHWE. This study is the first scientific report on the phytochemical composition of V. fastigiata, providing insight into the components of the chemo-diversity of this important plant.

Application of ultrahigh-performance liquid chromatography–quadrupole time-of-flight mass spectrometry for the characterization of organic aerosol: Searching for naphthenic acids

Naphthenic acids (NAs) are naturally occurring constituents of hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils), and present in any facilities that extract, process or use crude oil or bitumen for manufacturing. In the Athabasca oil sands region (AOSR) of Alberta, Canada, this diverse group of saturated acyclic, monocyclic, and polycyclic carboxylic acids is present in bitumen and in tailing ponds. Little is known about the occurrence of residual oil sands derived organic material, including NAs, in atmospheric particulate matter (PM). This work describes the optimization of an ultrahigh-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC/QTOF-MS) method to characterize and identify classical NAs in atmospheric PM. Under the optimum conditions, analysis of the Sigma-Aldrich technical NA STD Mix showed the absence of saturated fatty acids, while branched and cyclic NAs isomers with carbon number ranged between 10 and 30, and Z families between 0 and −12 were detected. Higher molecular weight NAs representing compounds with carbon number ranging between 30 and 40 were identified in the analyzed PM samples collected in AOSR. In contrast, isomeric branched acyclic NAs were not detected in the background (PM-R) samples collected far from AOSR. Except for fatty acids (Z=0), other Z homologues were also not detectable or present at very low concentration in the analysed PM-R samples. Preliminary examination of NA profiles showed that the composition of NAs in PM collected in close proximity to surface mining operations is predominantly “refractory” high molecular weight branched NAs, differing from that collected closer to upgraders and tailings ponds. It is suspected that dust released from the mine faces and dry tailings in the AOSR are sources of NAs to atmosphere. Further samples should be examined to confirm findings. This preliminary study presents, to our knowledge, the first direct identification of branched acyclic and cyclic NAs in atmospheric PM.

Comparison of chemical profiles between the root and aerial parts from three Bupleurum species based on a UHPLC-QTOF-MS metabolomics approach

BackgroundBupleuri Radix (Chaihu) represents one of the most successful and widely used herbal medicines in Asia for the treatment of many diseases such as inflammatory disorders and infectious diseases over the past 2000 years. In the Chinese Pharmacopoeia, Chaihu is recorded as the dried roots of Bupleurum chinense DC. and B. scorzonerifolium Willd. (Umbelliferae). However, the widespread demand for the herb has tended to far outstrip the supply. Whether the aerial parts, which account for 70 ~ 85% of the dry weights of Bupleurum species, could be used as an alternative for the root has become an important scientific issue for the sustainable utilization of Bupleurum species. On the other hand, in some areas including the southeast of China as well as in Spain, the aerial parts of Bupleurum species have already been used in the folk medications. Therefore, to clarify whether the root and aerial parts of Bupleurum species are “equivalent” in the types and quantities of chemical constituents which subsequently influence their biological activities and therapeutic effects is of great importance for both the rational and sustainable use of this herb.MethodsIn the present study, the chemical profiles between the root and aerial parts of Bupleurum species from different species and collected from various locations were analyzed and compared by the ultra-high performance liquid chromatography quadrupole/time of flight-mass spectrometry (UHPLC-QTOF-MS).ResultsA total of 56 peaks were identified in the root and/or aerial parts from different batches of Bupleurum species, by comparison of references standards or with those reported in the literature. Principal Component Analysis (PCA) was conducted for displaying the differentiating clustering between these two parts.ConclusionThe results disclosed the distinct variations between them, which indicated that the aerial parts could not be used as an alternative of root from a chemodiversity perspective. The differentiating markers resulted from the PCA analysis could also be utilized for the differentiation between them. Further validation of their biological differences is anticipated in the future study.

Nontargeted metabolomics approach for the differentiation of cultivation ages of mountain cultivated ginseng leaves using UHPLC/QTOF-MS

The adulteration or falsification of the cultivation age of mountain cultivated ginseng (MCG) has been a serious problem in the commercial MCG market. To develop an efficient discrimination tool for the cultivation age and to explore potential age-dependent markers, an optimized ultra high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS)-based metabolomics approach was applied in the global metabolite profiling of 156 MCG leaf (MGL) samples aged from 6 to 18 years. Multivariate statistical methods such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to compare the derived patterns between MGL samples of different cultivation ages. The present study demonstrated that 6–18-year-old MGL samples can be successfully discriminated using two simple successive steps, together with four PLS-DA discrimination models. Furthermore, 39 robust age-dependent markers enabling differentiation among the 6–18-year-old MGL samples were discovered. The results were validated by a permutation test and an external test set to verify the predictability and reliability of the established discrimination models. More importantly, without destroying the MCG roots, the proposed approach could also be applied to discriminate MCG root ages indirectly, using a minimum amount of homophyletic MGL samples combined with the established four PLS-DA models and identified markers. Additionally, to the best of our knowledge, this is the first study in which 6−18-year-old MCG root ages have been nondestructively differentiated by analyzing homophyletic MGL samples using UHPLC/QTOF-MS analysis and two simple successive steps together with four PLS-DA models. The method developed in this study can be used as a standard protocol for discriminating and predicting MGL ages directly and homophyletic MCG root ages indirectly.

Identification and analytical characterization of six synthetic cannabinoids NNL-3, 5F-NPB-22-7N, 5F-AKB-48-7N, 5F-EDMB-PINACA, EMB-FUBINACA, and EG-018.

Clinical and forensic toxicology laboratories are continuously confronted by analytical challenges when dealing with the new psychoactive substances phenomenon. The number of synthetic cannabinoids, the chemical diversity, and the speed of emergence make this group of compounds particularly challenging in terms of detection, monitoring, and responding. Three indazole 7N positional isomer synthetic cannabinoids, two ethyl 2-amino-3-methylbutanoate-type synthetic cannabinoids, and one 9H-carbazole substituted synthetic cannabinoid were identified in seized materials. These six synthetic cannabinoid derivatives included: 1H-benzo[d] [1,2,3]triazol-1-yl 1-(5-fluoropentyl)-1H-pyrrolo[2,3-b]pyridine-3-carboxylate (NNL-3, 1), quinolin-8-yl 1-(5-fluoropentyl)-1H-pyrrolo[2,3-b]pyridine-3-carboxylate (5F-NPB-22-7N, 2), N-((1s,3s)-adamantan-1-yl)-1-(5-fluoropentyl)-1H-pyrrolo[2,3-b]pyridine-3-carboxamide (5F-AKB-48-7N, 3), ethyl 2-(1-(5-fluoropentyl)-1H-indazole-3-carboxamido)-3,3-dimethylbutanoate (5F-EDMB-PINACA, 4), ethyl 2-(1-(4-fluorobenzyl)-1H-indazole-3-carboxamido)-3-methylbutanoate (EMB-FUBINACA, 5), and naphthalen-1-yl(9-pentyl-9H-carbazol-3-yl)methanone (EG-018, 6). The identification was based on ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UHPLC-QTOF-MS), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance spectroscopy (NMR). The analytical characterization of these six synthetic cannabinoids was described, so as to assist forensic laboratories in identifying these compounds or other substances with similar structure in their case work. To our knowledge, no analytical data about the compounds 1-5 have appeared until now, making this the first report on these compounds. The GC-MS data of 6 has been reported, but this study added the LC-MS, NMR, and Fourier transform infrared (FTIR), data to render the analytical data collection process more complete. Copyright © 2017 John Wiley & Sons, Ltd.

Identification and analytical characterization of nine synthetic cathinone derivatives N-ethylhexedrone, 4-Cl-pentedrone, 4-Cl-α-EAPP, propylone, N-ethylnorpentylone, 6-MeO-bk-MDMA, α-PiHP, 4-Cl-α-PHP, and 4-F-α-PHP.

Clinical and forensic toxicology laboratories are continuously confronted by analytical challenges when dealing with the new psychoactive substances (NPS) phenomenon. In this study, the analytical characterization of nine synthetic cathinones is described: 2-(ethylamino)-1-phenylhexan-1-one (N-ethylhexedrone 1), 1-(4-chlorophenyl)-2-(methylamino)pentan-1-one (4-Cl-pentedrone 2), 1-(4-chlorophenyl)-2-(ethylamino)pentan-1-one (4-Cl-α-EAPP 3), 1-(3,4-methylenedioxyphenyl)-2-propylaminopropan-1-one (propylone 4), 1-(3,4-methylenedioxyphenyl)-2-ethylaminopentan-1-one (N-ethylnorpentylone 5), 1-(6-methoxy-3,4-methylenedioxyphenyl)-2-methylaminopropan-1-one (6-MeO-bk-MDMA 6), 4-methyl-1-phenyl-2-(pyrrolidin-1-yl)pentan-1-one (α-PiHP 7), 1-(4-chlorophenyl)-2-(pyrrolidin-1-yl)hexan-1-one (4-Cl-α-PHP 8), and 1-(4-fluorophenyl)-2-(pyrrolidin-1-yl)hexan-1-one (4-F-α-PHP 9). The identification was based on ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UHPLC-QTOF-MS), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR) spectroscopy. The mass-spectral fragmentations of these compounds following collision-induced dissociation (CID) and electron ionization (EI) were studied to assist forensic laboratories in identifying these compounds or other substances with similar structure in their case work. To our knowledge, no analytical data about the compounds 1-4, 7, and 8 have appeared until now, making this the first report on these compounds. The GC-MS data of 5, 6 and 9 has been reported, but this study added the LC-MS, Fourier Transform Infrared (FTIR) and NMR data for additional characterization. Copyright © 2016 John Wiley & Sons, Ltd.

Applicability of ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry for cocaine profiling.

For the first time in China, the chemical profiling of cocaine specimens was performed at the National Narcotics Laboratory. An ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-QTOF-MS) method was developed and validated for simultaneous analysis of 14 cocaine alkaloids and 5 main adulterants. Among them, ecgonine methyl ester, ecgonine, benzoylecgonine, and norcocaine were identified by comparing with the standard materials; tropacocaine, 3,4,5-trimethoxycocaine, cis-/trans-cinnamoylcocaine were tentatively identified based on the exact masses of protonated molecules and product ions; six unidentified alkaloids of 182/1.47, 316/9.54, 659/9.85, 316/9.87, 420/10.34, and 420/10.85 were marked with 'extracted mass/retention time' for convenience. Minimum sample preparation and analysis time were required, which was suitable for routine analysis. Based on the semi-quantitative data set of 14 alkaloid impurities in 131 linked/unlinked cocaine samples, 50 combinations of pretreatment methods and distance/correlation measurements were tested for their potential discrimination power for cocaine profiling, and Logarithm/Pearson exhibited the best result. After hierarchical cluster analysis (HCA), 183 cocaine samples collected from 2011 to 2015 were classified into 7 major groups. Moreover, 37 groups of linked samples were found within and between provinces, which provide intelligence for the case connection and revealing of the distribution networks. Our results highlighted the practical utilities of drug profiling, especially to support the investigation through operational intelligence and to improve the knowledge related to the drug trafficking through strategic intelligence. Copyright © 2016 John Wiley & Sons, Ltd.

Screening of Over 600 Pesticides, Veterinary Drugs, Food-Packaging Contaminants, Mycotoxins, and Other Chemicals in Food by Ultra-High Performance Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (UHPLC-QTOFMS)

In this article, an accurate mass multiresidue screening method has been developed for the determination of over 630 multiclass food contaminants in different matrices using ultra-high performance liquid chromatography/(quadrupole)-time-of-flight mass spectrometry. The compounds included in the study were 426 pesticides, 117 veterinary drugs, 42 food-packaging contaminants, 21 mycotoxins, 10 perfluorinated compounds, 9 nitrosamines, and 5 sweeteners. The separation was carried out by liquid chromatography using a C18 column (50 mm × 2.1 mm, 1.8 μm particle size). The identification of the targeted species was accomplished using accurate masses of the targeted ions (protonated or deprotonated molecule) along with retention time data and characteristic fragment ion for reliable identification, using specific software for automated data mining and exploitation. The performance of the screening method was validated in terms of linearity, matrix effect, and limits of quantification for three representative food matrices (tomato, orange, and baby food) using a generic sample treatment based on liquid partitioning with acetonitrile (QuEChERS). The overall method performance was satisfactory with limits of quantification lower than 10 μg kg −1 for the 44 % of studied compounds. In some cases (ca. 10–15 % of the pesticides depending on the matrix tested, maximum residue levels were not fulfilled). In orange, 15 % of the compounds displayed LOQs above the maximum residue levels (MRLs) set for the studied pesticides, which can be partially attributed to matrix effects. Moderate signal suppression was observed in the three matrices tested in most cases, being orange the matrix which produced the highest matrix effect and baby food the lowest one.

Wide-scope screening of pesticides in fruits and vegetables using information-dependent acquisition employing UHPLC-QTOF-MS and automated MS/MS library searching

This paper presents an application of ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) for simultaneous screening and identification of 427 pesticides in fresh fruit and vegetable samples. Both full MS scan mode for quantification, and an artificial-intelligence-based product ion scan mode information-dependent acquisition (IDA) providing automatic MS to MS/MS switching of product ion spectra for identification, were conducted by one injection. A home-in collision-induced-dissociation all product ions accurate mass spectra library containing more than 1700 spectra was developed prior to actual application. Both qualitative and quantitative validations of the method were carried out. The result showed that 97.4% of the pesticides had the screening detection limit (SDL) less than 50μg kg-1 and more than 86.7% could be confirmed by accurate MS/MS spectra embodied in the home-made library. Meanwhile, calibration curves covering two orders of magnitude were performed, and they were linear over the concentration range studied for the selected matrices (from 5 to 500μg kg-1 for most of the pesticides). Recoveries between 80 and 110% in four matrices (apple, orange, tomato, and spinach) at two spiked levels, 10 and 100μg kg-1, was 88.7 or 86.8%. Furthermore, the overall relative standard deviation (RSD, n = 12) for 94.3% of the pesticides in 10μg kg-1 and 98.1% of the pesticides in 100μg kg-1 spiked levels was less than 20%. In order to validate the suitability for routine analysis, the method was applied to 448 fruit and vegetable samples purchased in different local markets. The results show 83.3% of the analyzed samples have positive findings (higher than the limits of identification and quantification), and 412 commodity-pesticide combinations are identified in our scope. The approach proved to be a cost-effective, time-saving and powerful strategy for routine large-scope screening of pesticides.

Discriminating from species of Curcumae Radix (Yujin) by a UHPLC/Q-TOFMS-based metabolomics approach.

BackgroundChinese medicinal herbs may use more than one species of Curcumae Radix (Yujin) is the tuberous roots of Curcumae wenyujin, C. kwangsiensis, C. phaeocaulis and C. longa. This study aimed to characterize the chemical profiles of these different species of Curcumae Radix, and develop a method for rapid discrimination of these species by ultra-high performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOFMS) combined with multivariate statistical analysis.MethodsThe metabolomes of 33 different batches of Curcumae Radix derived from four Curcumae species were profiled by UHPLC/Q-TOFMS. The resulting sample codes, tR–m/z pairs and ion intensities were processed by unsupervised principal component analysis (PCA) and supervised orthogonal partial least squared discriminant analysis (OPLS-DA) to characterize the chemical composition of Curcumae Radix across the four different species.ResultsObvious differences were observed in the chemical compositions of the Curcumae Radix samples derived from the four different species according to PCA and OPLS-DA. These results suggested that curcumin, curcumenone, curcumenol and zederone could be used as unique chemical markers for C. longa, C. wenyujin, C. phaeocaulis and C. kwangsiensis, respectively.ConclusionsThis study developed a UHPLC/Q-TOFMS method coupled with multivariate statistical analysis to discriminate between Curcumae Radix samples from four different Curcumae species, i.e., C. longa, C. wenyujin, C. phaeocaulis and C. kwangsiensis. Notably, this new approach resulted in the identification of curcumin (a), curcumenone (b), curcumenol (c) and zederone (d) as unique chemical markers for the identification.Electronic supplementary materialThe online version of this article (doi:10.1186/s13020-016-0095-8) contains supplementary material, which is available to authorized users.

Specific targeted quantification combined with non-targeted metabolite profiling for quality evaluation of Gastrodia elata tubers from different geographical origins and cultivars

Gastrodia elata tuber (GET) has been widely used as a famous herbal medicine in China and other East Asian countries. In this work, we developed a comprehensive strategy integrating targeted and non-targeted analyses for quality evaluation and discrimination of GET from different geographical origins and cultivars. Firstly, 43 batches of GET samples of five cultivars from three regions in China were efficiently quantified by a “single standard to determine multi-components” (SSDMC) method. Six marker compounds were simultaneously determined within 11min using gastrodin as the internal standard. It showed that samples from different regions and cultivars could not be differentiated by the contents of six marker compounds. Secondly, a non-targeted metabolite profiling analysis was performed by ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS). Samples from different geographical origins and cultivars were clearly discriminated by principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA). 147 discriminant ions contributing to the group separation were selected from 1194 aligned variables. Furthermore, based on the relative intensities of discriminant ions, support vector machines (SVM) was employed to predict the geographical origins of GET. The obtained SVM model showed excellent prediction performance with an average prediction accuracy of 100%. These results demonstrated that the UHPLC-QTOF/MS-based non-targeted metabolite profiling analysis, as a vital supplement to targeted analysis, can be used to discriminate the geographical origins and cultivars of GET.

Preferential alkali metal adduct formation by cis geometrical isomers of dicaffeoylquinic acids allows for efficient discrimination from their trans isomers during ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.

Caffeoylquinic acid (CQA) derivatives are a group of structurally diverse phytochemicals that have attracted attention due to their many health benefits. The structural diversity of these molecules is due in part to the presence of regio- and geometrical isomerism. This structural diversity hampers the accurate annotation of these molecules in plant extracts. Mass spectrometry (MS) is successfully used to differentiate between the different regioisomers of the CQA derivatives; however, the accurate discrimination of the geometrical isomers of these molecules has proven to be an elusive task. UV-irradiated methanolic solutions of diCQA were analyzed using an ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/QTOFMS) method in negative ionisation mode. An in-source collision-induced dissociation (ISCID) method was optimized by varying both the capillary and cone voltages to achieve differential fragmentation patterns between UV-generated geometrical isomers of the diCQAs during MS analyses. Changes in the capillary voltage did not cause a significant difference to the fragmentation patterns of the four geometrical isomers, while changes in the cone voltage resulted in significant differences in the fragmentation patterns. The results also show, for the first time, the preferential formation of alkali metal (Li(+), Na(+) and K(+)) adducts by the cis geometrical isomers of diCQAs, compared to their trans counterparts. Optimized QTOFMS-based methods may be used to differentiate the geometrical isomers of diCQAs. Finally, additives such as metal salts to induce adduct formation can be applied as an alternative method to differentiate closely related isomers which could have been difficult to differentiate under normal MS settings.

Identification of polypropylene glycols and polyethylene glycol carboxylates in flowback and produced water from hydraulic fracturing

The purpose of the study was to separate and identify the unknown surfactants present in flowback and produced water from oil and gas wells in the Denver-Julesburg Basin (Niobrara Formation) in Weld County, Colorado, USA. Weld County has been drilled extensively during the last five years for oil and gas between 7000–8000 feet below land-surface. Polypropylene glycols (PPGs) and polyethylene glycols carboxylates (PEG-Cs) were found for the first time in these flowback and produced water samples. These ethoxylated surfactants may be used as friction reducers, clay stabilizers, and surfactants. Ultrahigh-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UHPLC/QTOF-MS) was used to separate and identify the different classes of PPGs, PEG-Cs, and their isomers. The Kendrick mass scale was applied along with mass spectrometry/mass spectrometry (MS-MS) with accurate mass for rapid and unequivocal identification. The PPGs and their isomers occur at the ppm concentration range and may be useful as “fingerprints” of hydraulic-fracturing. Comparing these detections to the compounds used in the fracturing process from FracFocus 3.0 (https://fracfocus.org), it appears that both PPGs and polyethylene glycols (PEGs) are commonly named as additives, but the PEG-Cs have not been reported. The PEG-Cs may be trace impurities or degradation products of PEGs.