High Performance Liquid Chromatography-linear Ion Research Articles

Separation and identification of the synthetic cathinone isomers dipentylone and N-ethylpentylone using chromatographic and mass spectral characteristics

Synthetic cathinone isomers exhibit very similar structure and physicochemical properties, which makes them unable to be effectively separated and identified, therefore increasing the likelihood of misidentification. In this study, the chromatographic and mass spectral characteristics of a sample by gas chromatography-mass spectrometry (GC–MS) were highly like those of N-ethylpentylone. The powder, however, was finally identified as dipentylone (also known as N, N-dimethylpentylone) by high performance liquid chromatography-linear ion trap-orbitrap mass spectrometry (HPLC-LTQ-Orbitrap-MS) and nuclear magnetic resonance (NMR). Because of the possibility of misidentification, the collision-induced dissociation (CID) and electron ionization (EI) pathways of dipentylone and its isomer N-ethylpentylone were further examined to assist forensic laboratories in identifying the synthetic cathinone isomers in their case work. The separation of the two isomers was successfully achieved through ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS). These results demonstrate that the methods developed in this study can be used to separate and identify the two isomers.

Integrated transcriptomics and lipidomics investigation of the mechanism underlying the gastrointestinal mucosa damage of Loropetalum chinense (R.Br.) and its representative component

BackgroundLoropetalum chinensis (R.Br) Oliv (Bhjm), a Chinese folk herbal medicine, was traditionally used in the treatment of wound bleeding and skin ulcers. A new drug named JIMUSAN granules used for gastrosia was developed by our group, and clinical trials have been approved. However, as the principal herb, the material basis and underlying mechanisms of Bhjm in attenuating gastrointestinal mucosa damage (GMD) remain to be systemically illuminated. PurposeAn integrated strategy was used to explore the therapeutic effects and mechanisms of Bhjm and ellagic acid (EA) on GMD zebrafish, using network pharmacology, transcriptomics, lipidomics, and real-time quantitative PCR (RT-qPCR) verification. MethodsFirst, network pharmacological analysis was used to infer the major effective constituents and targets of Bhjm. Ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UHPLC-LTQ-Orbitrap HRMS) and ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) were employed to identify the chemical constituents and quantify the different types of constituents. Second, zebrafish model of GMD was established by using 2,4,6-trinitrobenzenesulfonic acid (TNBS) to evaluate the efficacy of Bhjm and EA. The potential mechanism was examined by integrated transcriptomics and lipidomics analysis. Finally, validation tests were implemented using RT-qPCR. ResultsIn this study, targets indentified by network pharmacology were related to inflammation and mucosal damage. Ten representative components that interacted with these targets were simultaneously determined by UHPLC-MS/MS. Sixty four compounds were identified or tentatively characterized, most of which were flavonoids and polyphenols. Bhjm and EA alleviated mucosal damage and reduced inflammation in a TNBS-induced zebrafish GMD model, indicating that EA was the main active compounds. Eight common differentially expressed genes were downregulated by Bhjm and EA, as determined by transcriptomics analysis. Lipidomics analysis confirmed 12 differential lipids, including phosphatidylcholine (PC) and triglyceride (TG). Further network enrichment analysis demonstrated that differential lipid metabolism was regulated by klf4 and hist1h2ba, and were validated by RT-qPCR. ConclusionIn our study, the chemical profile of Bhjm was clarified. Moreover, the GMD repair effect and the mechanism of Bhjm and EA was comprehensively analyzed for the first time, involving inflammation and lipid metabolism. Collectively, these findings will be significantly helpful for deeply exploring the clinical application value of Bhjm.

Overall metabolic network analysis of urine in hyperlipidemic rats treated with Bidens bipinnata L.

Hyperlipidemia has been highlighted as one of the most prominent and global chronic conditions nowadays. Bidens bipinnata L. (BBL), a folk medicine in contemporary China, has efficacy in the treatment of hyperlipidemia (HLP) in China. Although some physiological and pathological function parameters of hyperlipidemia have been investigated, little information about the changes in small metabolites in biofluids has been reported. In the present study, global metabolic profiling with high-performance liquid chromatography-linear ion trap/Orbitrap high-resolution mass spectrometry (HPLC-LTQ/Orbitrap MS) combined with a pattern recognition method was performed to discover the underlying lipid-regulating mechanisms of BBL on hyperlipidemic rats induced by high-fat diet (HFD). The total of four metabolites, up- or down-regulated (p< 0.05 or 0.01), were identified and contributed to the progression of hyperlipidemia. These promising identified biomarkers underpin the metabolic pathway, including glyoxylate and dicarboxylate metabolism, the TCA cycle, sphingolipid metabolism and purine metabolism. They are disturbed in hyperlipidemic rats, and are identified using pathway analysis with MetPA. The altered metabolite indices could be regulated closer to normal levels after BBL intervention. The results demonstrated that urinary metabolomics is a powerful tool in the clinical diagnosis and treatment of hyperlipidemia to provide information on changes in metabolite pathways.

Serum metabonomics coupled with HPLC-LTQ/orbitrap MS and multivariate data analysis on the ameliorative effects of Bidens bipinnata L. in hyperlipidemic rats

Ethnopharmacological relevanceHyperlipidemia (HLP) is a prevalence chronic cardiovascular disease, which is treated by traditional Chinese medicine (TCM) in China. More and more attention has been paid to the application of metabolomics in the study of TCM. Bidens bipinnata L. (BBL), a folk medicine in contemporary China, has the efficacy in the treatment of hyperlipidemia (HLP) in China. However, little is known of the underlying mechanism of BBL. This research aimed to investigate ameliorative effects of BBL on hyperlipidemic rats and explore the mechanism by metabolomics method. Materials and methodsHyperlipidemic rats were established by high fat diet (HFD). Biochemical assay was used to evaluate the efficacy of BBL. A metabolomics approach based on high performance liquid chromatography-linear ion trap/orbitrap high-resolution mass spectrometry (HPLC-LTQ/orbitrap MS) was performed to analyze the serum biomarkers from model group, control group and BBL group. Principle component analysis (PCA) and partial least-squares discriminate analysis (PLS-DA) were utilized to identify differences of metabolic profiles in rats among the three groups. In order to identify possible pathways that were affected by HLP, the identified endogenous metabolites were analyzed by using MetaboAnalyst. In the network pharmacology study, our research group found that PPAR signaling pathway was the most important pathway of BBL in the treatment of HLP. Then, it was found that changes in the major metabolic pathways would affect the PPAR signaling pathway through comprehensive analysis based on KEGG database. Therefore, the expression of key genes in the PPAR signaling pathway was detected by real-time quantitative fluorescence PCR (RT-qPCR). ResultsSix metabolites, which showed a significantly restoring trend from HLP to normal condition, were regarded as potential biomarkers of BBL treatment. The levels of phosphorylcholine, mevalonic acid and leukotriene B4 (LTB4) increased significantly (P < 0.01) in hyperlipidemic rats, while the levels of linoleic acid, arachidonic acid (AA) and lysophosphatidylcholine (18:0) (Lyso PC (18:0)) decreased significantly (P < 0.01) in comparison with control rats. Those endogenous metabolites were chiefly involved in linoleic acid metabolism, AA metabolism and terpenoid backbone biosynthesis. According to the results of RT-qPCR analysis, the mRNA expressions of PPAR α, PPAR β and PPARγ in model group were difference compared with control group. And the expression difference could be regulated closer to normal level after BBL intervention. ConclusionsThe results of biochemical assay, serum metabolic pattern and RT-qPCR analysis showed that BBL could exert a significant improvement on lipid levels, liver function, renal function, as well as the mRNA expression level of PPAR signaling pathway.

Differences of antipyretic effect between Qingkailing soft capsule and hard capsule based on metabonomics

The antipyretic effects of Qingkailing soft capsules and hard capsules were compared based on metabonomics technology,so as to provide basis for clinical rational use and quality control evaluation of its preparations. By using ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry( UPLC-LTQ/Orbitrap),and multivariate tatistical methods such as principal component analysis( PCA),partial least squares-discriminate analysis( PLS-DA) and orthogonal signal correction partial least square discriminant analysis( OPLS-DA),the changes of plasma endogenous metabolites in rat fever model induced by dry yeast were studied,so as to look for biomarkers related to fever. Based on these results,the antipyretic effects of two types of Qingkailing preparations were compared. The results indicated that metabolic profiles of the experimental groups could be distinguished distinctly,and 8 endogenous metabolites showed differences as compared with the normal control group( P<0. 05),including nicotinic acid,choline,hippuric acid,phosphocholine,Lyso PC( 14 ∶ 0),Lyso PC [16 ∶ 1( 9 Z) ],Lyso PC( 18 ∶ 0) and Lyso PC [20 ∶ 3( 5 Z,8 Z,11 Z) ]. They could be regarded as biomarkers related to fever. Qingkailing soft capsule and hard capsule had different effects on the regulation of plasma metabolites in yeast-induced fever model rats. Qingkailing soft capsule had different degrees of callbacks on eight biomarkers,including significant callbacks on nicotinic acid( P<0. 05),hippuric acid( P< 0. 01),phosphocholine( P< 0. 05),and Lyso PC [20 ∶3( 5 Z,8 Z,11 Z) ]( P<0. 05),while hard capsule only had significant callbacks on nicotinic acid( P<0. 05),hippuric acid( P<0. 01),and phosphocholine( P< 0. 05),with no callbacks on choline,Lyso PC( 14 ∶ 0),Lyso PC [16 ∶ 1( 9 Z) ],Lyso PC( 18 ∶0),and Lyso PC [20 ∶3( 5 Z,8 Z,11 Z) ]. This indicated that Qingkailing soft capsule had better callback effect than hard capsule. In this study,Qingkailing soft capsules and hard capsules were used to intervene the changes of related biomarkers in yeast-induced fever rat models,and then the antipyretic effect and mechanism between these two kinds of capsules were compared. The two dosage forms played an antipyretic role mainly by regulating lipid metabolism and controlling inflammation. The callback effect of soft capsule on the potential biomarkers of lysophosphatidylcholine was significantly higher than that of hard capsule. The differences in antipyretic effect of Qingkailing soft capsule and hard capsule were expounded from the point of metabonomics,providing experimental data and theoretical basis for the selection of clinical dosage forms.

Rapid analysis of chemical components in Zizyphi Spinosae Semen by UHPLC-LTQ-Orbitrap-MS

This study aimed to analyze the chemical components of Zizyphi Spinosae Semen by using ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UHPLC-LTQ-Orbitrap-MS). The chromatographic separation of the components was achieved on a Waters Acquity UPLC BEH-C₁₈ column (2.1 mm×50 mm, 1.7 μm), with acetonitrile-water (0.1% formic acid) as mobile phase at a flow rate of 0.3 mL·min⁻¹. Electrospray ionization-(ESI) source was applied and operated in negative ion mode. The parent ion list (PIL)-MS₂ and high energy collision dissociation (HCD) techniques were used to identify triterpene saponins in Zizyphi Spinosae Semen. Through analysis of the mass spectrometry data and literature data, 24 compounds and 4 unknown compounds were identified and inferred, including 21 flavonoids, 5 saponins and 2 triterpenoids. The use of UHPLC-LTQ-Orbitrap-MS technology provide an efficient and rapid analytical method for the qualitative analysis and quality control of the chemical components in Zizyphi Spinosae Semen. It can also provide reference data for the research on the material basis of pharmacodynamics and the resources development and utilization.

Partial Purification, Identification, and Quantitation of Antioxidants from Wild Rice (Zizania latifolia).

To provide further insights into the potential health-promoting antioxidants from wild rice (Zizania latifolia), which is an abundant but underutilized whole grain resource in East Asia, a partial purification based on D101 macroporous resin was carried out for the purification and enrichment of the antioxidants from the bioactive ethanol extracts of wild rice. On that basis, 34 phenolic compounds in the antioxidant fractions were identified by a high-performance liquid chromatography-linear ion trap quadrupole-Orbitrap-mass spectrometry (HPLC-LTQ-Orbitrap-MSn). The results suggested that phenolic acids could be enriched in the 10% ethanol-eluted fraction whereas flavonoids (including procyanidins and flavonoid glycosides) could be enriched in 20–30% ethanol-eluted fractions. A quantitative analysis determined by the multiple reaction monitoring mode of the ultra-performance liquid chromatography-triple quadrupole-tandem mass spectrometry (UPLC-QqQ-MS/MS) revealed a high content of procyanidins in wild rice. Compared with phenolic acids, flavonoids may contribute more to the potent antioxidant activity of wild rice. This is the first study on the antioxidants from wild rice Z. latifolia. These findings provide novel information on the functional components of wild rice, and will be of value to further research and development on Z. latifolia.

Phytochemical Composition, Hepatoprotective, and Antioxidant Activities of Phyllodium pulchellum (L.) Desv.

Phyllodiumpulchellum has been traditionally used as a medicinal herb because of its health-promoting effects, such as its hepatoprotective and antioxidant activities. In the present study, the petroleum ether fraction, ethyl acetate fraction, n-butanol fraction, and aqueous fraction were successively obtained from the ethanol extract of P. pulchellum. Two fractions, ethyl acetate fraction and n-butanol fraction, were found to display hepatoprotective and antioxidant activities. Further chemical investigation of the active fractions led to the isolation of its main constituents, including 11 flavonoids (1–11) and 8 indole alkaloids (12–19). There were 9 flavonoids (1–9) that were obtained from the ethyl acetate fraction, and 2 flavonoids (10 and 11) and 8 alkaloids (12–19) from the n-butanol fraction. Compounds 1–11 and 16–19 were isolated for the first time from P. pulchellum, and 1, 2, 8, 11, and 18 were obtained from the genus Phyllodium initially. Subsequently, the isolated compounds were evaluated for their in vitro hepatoprotective effects on the human normal hepatocyte cell line L-O2 injured by d-galactosamine and radical scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH). The flavonoids (−)-epigallocatechin (5) and (−)-epicatechin (6) exhibited prominent hepatoprotective activities with higher cell viability values (65.53% and 62.40% at 10 μM·mL−1, respectively) than the positive control, silymarin (61.85% at 10 μM·mL−1). In addition, compared with the positive control of vitamin C (IC50: 5.14 μg·mL−1), (−)-gallocatechin (3) and (−)-epigallocatechin (5) exhibited stronger antioxidant activities with IC50 values of 3.80 and 3.97 μg·mL−1, respectively. Furthermore, the total flavonoids from P. pulchellum were characterized using a high-performance liquid chromatography-linear ion trap quadrupole-Orbitrap-mass spectrometry (HPLC-LTQ-Orbitrap-MS). In total, 34 flavonoids were tentatively identified, which had not been previously reported from P. pulchellum. In addition, we performed a semi-quantitative analysis of the isolated flavonoids. The contents of compounds 1–11 were 3.88, 17.73, 140.35, 41.93, 27.80, 4.34, 0.01, 0.20, 9.67, 795.85, and 5.23 μg·g−1, respectively. In conclusion, this study revealed that the flavonoids that were isolated from P. pulchellum showed hepatoprotective and antioxidant activities, indicating that, besides alkaloids, the flavonoids should be the potential pharmacodynamic ingredients that are responsible for the hepatoprotective and antioxidant activities of P. pulchellum.

Metabolite identification and pharmacokinetic profiling of PP242, an ATP-competitive inhibitor of mTOR using ultra high-performance liquid chromatography and mass spectrometry.

PP242 is a second generation novel selective ATP-competitive inhibitor of mTOR that displayed promising anti-cancer activity over several cancer types by inhibiting both the complexes of mTOR (mTORC1 and mTORC2). The purpose of this study is to identify the possible metabolites and to evaluate the pharmacokinetic profile of PP242 after a single oral administration to Sprague-Dawley (SD) rats. Two metabolites, including one phase I and one phase II, were identified by in vitro and in vivo studies using rat liver microsomes (RLMs) as well as rat plasma, urine and feces, respectively, through ultra high-performance liquid chromatography-linear ion trap quadrupole-orbitrap-mass spectrometry (UHPLC-LTQ-Orbitrap-MS). The major biotransformation pathways of PP242 were hydroxylation and glucuronide conjugation. Additionally, a simple and rapid quantification method was developed and validated. The method recovery was within 79.7-84.6%, whereas the matrix effect was 78.1-96.0% in all three quality control (QC) concentrations (low, medium and high) including the LLOQ. Other parameters showed acceptable results according to the US food and drug administration (FDA) guidelines for bioanalytical method validation. Afterwards, pharmacokinetic parameters were evaluated in rat plasma by successfully applying the validated method using liquid chromatography-tandem mass spectrometry (LC-MS/MS). After a single oral administration at a dose of 5mg/kg, the maximum plasma concentration (Cmax) of PP242 was 0.17±0.08μg/mL, while the elimination was moderately fast (T1/2: 172.18±45.54min). All of the obtained information on the metabolite identification and pharmacokinetic parameter elucidation could facilitate the further development of PP242.

Rapid determination of 15 nutrients in rice by ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry

A rapid method was developed for the simultaneous determination of 15 nutrients containing eight vitamin E, six γ-oryzanols and β-carotene in rice by ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UHPLC-LTQ/Orbitrap HRMS). The analytes were extracted by methanol containing 0.05% (v/v) 2,6-di-tert-butyl-4-methylphenol (BHT) under the ultrasonic condition, then separated by a Poroshell 120 PFP column (150 mm×3.0 mm, 2.7 μm) with a gradient elution program using 0.1% (v/v) formic acid aqueous solution and methanol containing 0.1% (v/v) formic acid as mobile phases. The detection was performed using an LTQ/Orbitrap HRMS detector with full scan in positive ion mode. Fifteen nutrients were simultaneously separated within 13 min. Furthermore, matrix effects of the white and brown rices were investigated. The correlation coefficients (r) were ≥ 0.9950 in the linear ranges of the 15 nutrients. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) of the 15 nutrients were 0.2-1.8 μg/L and 0.7-6.1 μg/L, respectively. At the three spiked levels, the recoveries were 73.2%-101.5% with the relative standard deviations (RSDs) ranging from 1.1% to 5.0% (n=3). The method is accurate, efficient and reliable. It is suitable for the simultaneous determination of various nutrients in rice.

Direct analysis of 38 polyphenols in wine by ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry

Wine has been described previously as a rich source of polyphenols. However, an accurate screening of its complete phenolic profile is still lacking. In the present work, the analysis of 38 polyphenols in wine using ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UPLC-LTQ/Orbitrap MS) was explored. Wines were directly detected. The sample was loaded onto a Thermo Hypersil Gold C18 column (100 mmx 2.1 mm, 1.9 µm) using a gradient elution of acetonitrile/water containing 0. 1% (v/v) formic acid for the separation. UPLC-LTQ/Orbitrap mass spectrometer acquired full scan MS date for quantification, and data dependent MS2 product ion spectra for identification and/ or confirmation. The regression coefficients (R2) for the calibration curves (two orders of magnitude up to the lowest calibration level) in the study were ≥ 0.99. The limits of detection for the 38 compounds were 0.002-0.50 mg/kg. The average recoveries at three spiked levels were in the range of 90%-102% with the relative standard deviations (RSDs) of 0.51%-2.56%. Mass errors were always ≤ 5 ppm. This procedure was then successfully applied to the analysis of the polyphenols in wines.

Identification of ustiloxins in false smut balls of rice based on high performance liquid chromatography-high resolution mass spectrometry

A sensitive method was developed for the simultaneous identification of five ustiloxins in the false smut balls of rice by high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (HPLC-LTQ/Orbitrap MS). The samples were extracted with deionized water under ultrasonic condition for 10 min, then purified by a strong cation exchange column (PCX). The ustiloxins were separated on an Xselect HSS T3 column (150 mm x 2.1 mm, 3.5 μm) by using 0.1% (v/v) formic acid water solution and methanol as mobile phases with gradient elution at a flow rate of 0.3 mL/min. The full scan range was m/z 200-1 000. The confirmatory analysis of the target compounds was carried out by the accurate mass of quasi-molecular ion, isotope abundance ratio and qualitative fragments. The results showed that the five ustiloxins (A, B, C, D and F) were identified from the false smut balls with mass accuracy less than 1 x 10(-6) (1 ppm) and the absolute values of the deviation of isotope abundance ratio were not more than 3.3%. The product ions were consistent with the theoretical fragment mode. The recoveries were 90% to 105%. This method is accurate and sensitive for the simultaneous identification of the five ustiloxins, which can provide technical means for the research of the ability in toxin producing by Ustilaginodea virens.

Rapid screening and identification of 22 allergenic disperse dyes in ecological textiles by high performance liquid chromatography- linear ion trap/orbitrap mass spectrometry

A rapid screening method based on high performance liquid chromatography-linear ion trap/orbitrap high-resolution mass spectrometry (HPLC-LTQ/Orbitrap MS) for 22 disperse dyes in ecological textiles has been established. The target compounds were extracted by pyridine/water (1:1, v/v) by shaking extraction in 90 degrees C water bath. The extracts were then separated by a CAPCELL PAK C18 column (100 mm x 2.0 mm, 5 μm) using gradient elution with acetonitrile-5 mmol/L ammonium acetate containing 0.01% (v/v) formic acid as mobile phases, and finally analyzed by HPLC-LTQ/Orbitrap in positive and negative ESI modes. The retention time and accurate mass of parent ion were used for fast screening of 22 disperse dyes, while the confirmatory analysis was obtained by fragments generated by collision-induced dissociation (CID) MS/MS. Target analysis exhibited high mass accuracy (< 5 x 10(-6)). Each target showed a good linearity in its own concentration range and the correlation coefficient was higher than 0.99. The LOQs were 0.125-2.5 mg/kg. Except for Disperse Yellow 49, the average recoveries of most disperse dyes at three spiked levels were 65%-120%, and the relative standard deviations (n = 6) were less than 15%. The method was applied for screening 40 different kinds of textiles, and Disperse Orange 37/76 was detected in one of them. With high selectivity and strong anti-jamming ability, this method is simple, rapid, accurate, and it can be used for the inspection of disperse dyes in textiles.

Identification and elucidation of the structure of in vivo metabolites of diaveridine in chicken.

Diaveridine (DVD) is a popular antibacterial synergist that is widely used in combination with sulfonamide. It has been reported to be genotoxic to mammalian cells, but more studies are required to clarify this. Moreover, there is very little information on its pharmacokinetics, metabolic elimination and mechanism of toxicity. Therefore, in order to gain a better understanding of the metabolism of DVD, we performed high-performance liquid chromatography linear ion trapped orbitrap mass spectrometer (LC-LTQ-Orbitrap). With this approach, we identified 15 metabolites of DVD in chicken after a single oral administration of DVD; 10 of these metabolites have been identified in vivo for the first time. Nine phase I and five phase II metabolites were detected in the plasma, and eight phase I and six phase II metabolites were found in feces. The major phase I metabolites were formed via the O-demethylation and N-oxidation pathways, and the major phase II metabolites were glucuronide conjugates. These results are essential for understanding this compound more clearly and lay the basis for further studies about the metabolism of DVD. Therefore, using this approach, we were able to identify and characterize metabolites of DVD with high sensitivity and resolution. We were able to detect a broad range of metabolites, even some trace ones and some so far unknown metabolites.

Improved Glycation after Ultrasonic Pretreatment Revealed by High-Performance Liquid Chromatography–Linear Ion Trap/Orbitrap High-Resolution Mass Spectrometry

The glycation extent of bovine serum albumin (BSA) before and after ultrasonication was evaluated by MALDI-TOF and Orbitrap mass spectrometry. Ultrasonic pretreatment significantly improved the incorporation of galactose to BSA. Prior to ultrasonic pretreatment, only 12 sites (11 lysines and 1 arginine) were glycated, whereas the number of glycation sites was increased to 42, including 39 lysines and 3 arginines, after treatment. Average degree of substitution per peptide molecule of BSA (DSP) was used to evaluate the glycation level for each glycation site. The ultrasonic pretreatment significantly improved the DSP value of all glycation sites. The prevalently promoted glycation by ultrasonic pretreatment suggests that ultrasonication improves glycation through altering the structure of BSA throughout all three domains. An ultrahigh-resolution linear ion trap Orbitrap mass spectrometer facilitates unambiguous localization of glycation sites, allowing an in-depth analysis of the nature and extent of protein glycation at the molecular level. High-intensity ultrasonication can greatly improve protein glycation and, therefore, opens new routes to modify the functionality of proteins in a positive way.

Screening and confirmation of 24 hormones in cosmetics by ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry

A method of ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UPLC-LTQ/Orbitrap MS) was established to screen and confirm 24 hormones in cosmetics. Various cosmetic samples were extracted with methanol. The extract was loaded onto a Waters ACQUITY UPLC BEH C18 column (50 mm x 2.1 mm, 1.7 microm) using a gradient elution of acetonitrile/water containing 0.1% (v/v) formic acid for the separation. The accurate mass of quasi-molecular ion was acquired by full scanning of electrostatic field orbitrap. The rapid screening was carried out by the accurate mass of quasi-molecular ion. The confirmation analysis for targeted compounds was performed with the retention time and qualitative fragments obtained by data dependent scan mode. Under the optimal conditions, the 24 hormones were routinely detected with mass accuracy error below 3 x 10(-6) (3 ppm), and good linearities were obtained in their respective linear ranges with correlation coefficients higher than 0.99. The LODs (S/N = 3) of the 24 compounds were < or = 10 microg/kg, which can meet the requirements for the actual screening of cosmetic samples. The developed method was applied to screen the hormones in 50 cosmetic samples. The results demonstrate that the method is a useful tool for the rapid screening and identification of the hormones in cosmetics.

Determination of N-methyl carbamate pesticides in diet samples by high performance liquid chromatography-linear ion trap mass spectrometry with gel permeation chromatography cleanup

A method for the determination of N-methyl carbamate (NMC) pesticides in diet samples was developed by high performance liquid chromatography-linear ion trap mass spectrometry (HPLC-LIT-MS). The samples with the isotope internal standard were ultrasonically extracted with acetonitrile saturated with cyclohexane, and then cleaned-up by passing through gel permeation chromatographic (GPC) column. The LC separation was performed on a CAPCELL PAK CR column (100 mm x 2.1 mm, 5 microm; SCX-C18 (1 : 4)) using acetonitrile and 5 mmol/L ammonium formate/0.1% (v/v) formic acid aqueous solution as mobile phases (gradient elution) at a flow rate of 0.2 mL/min. The ionization of the analytes was performed by positive electrospray mode. Selective reaction monitoring (SRM) was used for the monitoring of MS3 transitions for each compound. The internal standard was used for quantitation. The average recoveries were in the range of 60.4% - 114%, and the relative standard deviations (RSDs) were all not more than 16.2%. The limits of detection (LODs) were 0.001-0.010 mg/kg. The method was successfully applied to the determination of 15 compounds of interest in nine foodstuffs from the fourth Chinese Total Diet Study (TDS) performed in 2007, and aldicarb and carbofuran were found in several samples.

Determination of aldicarb and its metabolites in peanuts by high performance liquid chromatography-linear ion trap triple stage mass spectrometry

A high performance liquid chromatography-linear ion trap triple stage mass spectrometry (HPLC-IT/MS3) method was established to detect aldicarb, aldicarb sulfoxide, and aldicarb sulfone in peanuts. The samples were extracted by acetonitrile saturated with cyclohexane, followed by clean-up with gel permeation chromatography (GPC). The determination was performed using HPLC-IT/MS3 for the identification and quantification of the compounds. The separation was carried on a Capcell PAK CR column with gradient elution using 5 mmol/L acetic acid/ammonium acetate/acetonitrile as mobile phase. The ionization of molecules was performed by electrospray mode. Selective reaction monitoring (SRM) was the acquisition mode used for the monitoring of MS3 transitions for each compound using aldicarb-d3 as internal standard for three analytes. Matrix effects were evaluated by comparing the recovery of matrix-matched and solvent-based calibration curves. The calibration graphs were linear in the ranges of 10 - 500 microg/L and the detection limits ranged from 4 to 5 microg/kg. The average recoveries ranged between 81.5% and 115% at three different spiked levels (10, 20 and 40 microg/kg). Satisfactory results were obtained in the determination of real peanut samples by this method.

Rapid screening and confirming carcinogenic banned azo colorants in textiles by high performance liquid chromatography-linear ion trap/orbitrap high-resolution mass spectrometry

A method of high performance liquid chromatography-linear ion trap/orbitrap highresolution mass spectrometry (HPLC-LTP/Orbitrap MS) was ued to screen and confirm-banned azo colorants in textiles rapidly. The analytes were reduced to carcinogenic aromatic amines with sodium dithionite in citrate buffer solution. The reduced solution was extracted bydiatomite, and loadd onto an Acquity UPLC BEH C18 column (50 mm x 2.1 MM. 1.7 microm) with a gradient elution of methanol and 0.1% (v/v) methane acid aqueous solution, and finally detected by linear ion trap/orbitrap high-resolution mass spectrometry in positive ESI mode. In mass spectrometry method, the MS spectrum of high-resolution and the collision induced dissociation (CID) spectrum of data-dependent scan mode were used for screening analysis and conformation, respectively. The calibration curves showed a good linearity in the range of 0.05 -2.00 mg/b, and the correlation coefficients (r) were higher than 0.99. By detecting spiked samples, the limits of quantification were 0.08 mg/kg for all the residues and the recoveries were in the range of 65.5% - 111.5% with the relative standard deviations (RSDs) between 0.87% and 2.49%. The results indicate that the method is simple, rapid, sensitive and suitable for the qualitative and quantitative analysis of carcinogenic aromatic amines in textiles.

Screening and confirmation of carcinogenic dyes in textiles by high performance liquid chromatography-linear ion trap/Orbitrap high resolution mass spectrometry

A method of high performance liquid chromatography-linear ion trap/Orbitrap high resolution mass spectrometry (HPLC-LTQ/Orbitrap MS) was used to screen and confirm carcinogenic dyes in textiles. The analytes were extracted from textile samples with pyridine/water (1/1, v/v) in a water bath under controlled conditions (95 degrees C, 150 r/min), and then filtered with a 0.22 microm polytetrafluoroetylene (PTFE) membrane. The eluates were separated on a CAPCELL PAK C18 column (100 mm x 2.0 mm, 5 microm) using gradient elution with acetonitrile/ 5 mmol/L ammonium acetate aqueous solution containing 0.01% formic acid (in positive mode) and acetonitrile/5 mmol/L ammonium acetate aqueous solution (in negative mode), and finally detected by HPLC-LTQ/Orbitrap MS in ESI modes. Full scan experiments were performed over the range of m/z 200-800. The screening and quantitative analysis were carried out by the accurate mass of quasi-molecular ion and the peak area in extracted chromatogram with accurate mass, respectively. The confirmatory analysis for target compounds was performed with the retention time and qualitative fragments obtained by data-dependent scan mode. Under the optimal conditions, nine carcinogenic dyes were routinely detected with mass accuracy below 5 x 10(-6) (5 ppm), and good linearities were provided in their respective linear ranges with correlation coefficients higher than 0.99. The limits of detection were in the range of 0.125-25 mg/kg. The average recoveries at three spiked levels were in the range of 62.13%116.28% with the relative standard deviations (RSDs) lower than 15%. The proposed method was applied to screen and confirm the nine carcinogenic dyes in textile samples. It is convenient and reliable.