High Performance Liquid Chromatography-ion Trap Research Articles

Establishment of cluster of differentiation 20 immobilized cell membrane chromatography for the screening of active antitumor components in traditional Chinese medicine

Non-Hodgkin lymphoma (NHL) is a heterogeneous group of malignant tumors occurring in B or T lymphocytes, and no small molecule-positive drugs to treat NHL have been marketed. Cluster of differentiation 20 (CD20) is an important molecule regulating signaling for the life and differentiation of B lymphocytes and possesses the characteristics of a drug target for treating NHL. 2-Methoxyestradiol induces apoptosis in lymphoma Raji cells and CD20 protein is highly expressed by Raji lymphoma cells. Therefore, in this study, a CD20-SNAP-tag/CMC model was developed to validate the interaction of 2-methoxyestradiol with CD20. 2-Methoxyestradiol was used as a small molecule control compound, and the system was validated for good applicability. The cell membrane chromatography model was combined with high-performance liquid chromatography ion trap time-of-flight mass spectroscopy (HPLC-IT-TOF-MS) in a two-dimensional system to successfully identify, analyze, and characterize the potential active compounds of Schisandra chinensis (Turcz.) Baill. extract and Lysionotus pauciflorus Maxim. extract, including Schisandrin A, Schizandrol A, Schizandrol B, Schisantherin B, and Nevadensin, which can act on CD20 receptors. The five potential active compounds were analyzed by non-linear chromatography. The thermodynamic and kinetic parameters of their interaction with CD20 were also analyzed, and the mode of interaction was simulated by molecular docking. Their inhibitory effects on lymphoma cell growth were assessed using a Cell Counting Kit-8 (CCK-8). Nevadensin and Schizandrin A were able to induce apoptosis in Raji cells within a certain concentration range. In conclusion, the present experiments provide some bases for improving NHL treatment and developing small molecule lead compounds targeting CD20 with low toxicity and high specificity.

Analysis of metabolites in simulated gastric fluid of Saposhnikoviae Radix polysaccharides

To fully understand whether Saposhnikoviae Radix polysaccharides(SP) can be metabolized in gastric fluid and the meta-bolic behavior, this study systematically analyzed the metabolites in simulated gastric fluid of SP by high-performance liquid chromatography-ion trap time-of-flight mass spectrometry(HPLC-IT-TOF-MS) technology in combination with zebrafish immune activity evaluation. Based on the obtained accurate relative molecular mass, chromatographic retention behavior, MS fragmentation patterns, refe-rence standards, and relevant literature reports, 19 metabolites were analyzed and identified. Among them, five monosaccharides and 14 oligosaccharides were generated as metabolites. Several reducing sugars, including mannose, glucose, rhamnose, and xylose, were accurately identified in the gastric fluid metabolites. Zebrafish pharmacological evaluation results indicated that SP maintained good immune activity after gastric fluid metabolism, with the most significant increase in immune cell density observed at W3(simulated gastric fluid metabolism for 2 hours). Among the gastric fluid metabolites, M1 and M3(Hex-Hex-Man) may be most closely related to pharmacological activity and could be further studied as potential active fragments.

Yokukansan, a Traditional Japanese Medicine, Suppresses Stress-Induced Sympathetic Activation via Central Responses in Rats

Objectives: Yokukansan (YKS) is a traditional Japanese Kampo medicine approved by the Ministry of Health, Labour and Welfare of Japan. Recently, in addition to its indications as a drug treatment, YKS has been shown to have ameliorative effects on various psychological and behavioral responses such as anxiety, aggression, and stress responses. Stress exposure activates not only the hypothalamic–pituitary–adrenal axis but also the sympathetic nervous system. Sympathetic activation in brain regions such as the paraventricular hypothalamic nucleus (PVN) stimulates elevation of plasma catecholamine (noradrenaline and adrenaline) levels. We previously reported that various stress-related neuropeptides and several kinds of stressors, such as restraint stress (RS), increase plasma catecholamine and that brain prostanoids and their synthases mediate these responses in rats. In the present study, to determine if YKS treatment can affect stress-induced sympathetic activation, we examined the effects of YKS treatment on the RS-induced elevation of plasma catecholamine levels and related prostanoid production in the PVN of rats. Methods: YKS (1000 mg/10 mL/kg, p.o.) or vehicle was administered to rats daily for 14 days, and all rats were exposed to RS for 60 min on day 14. Before and during stress exposure on day 14, blood samples and PVN dialysates were collected and analyzed by high-performance liquid chromatography and liquid chromatography-ion trap tandem mass spectrometry, respectively. Results: Our results showed that repeated administration of YKS suppressed the RS-induced increase in plasma adrenaline but not noradrenaline. Furthermore, YKS administration also suppressed the RS-induced elevation of both prostaglandin E2 and thromboxane B2 levels in the PVN. In addition, we found that repeated administration of YKS suppressed the RS-induced increase in serotonin, gamma-aminobutyric acid, and acetylcholine in the PVN. Conclusion: Our results suggest that YKS can ameliorate stress-induced sympathetic activation via inhibition of stress responses in the brain.

Liquid chromatographic determination of lumacaftor in the presence of ivacaftor and identification of five novel degradation products using high-performance liquid chromatography ion trap time-of-flight mass spectrometry.

Lumacaftor is a transmembrane conductance regulator potentiator drug, prescribed for the treatment of cystic fibrosis in patients who are homozygous for the F508del mutation. Quantitation of lumacaftor besides its degradation products and ivacaftor was achieved on a fused-core silica particle column packed with pentafluorophenylpropyl stationary phase (Ascentis Express F5, 2.7μm particle size 100mm × 4.6mm; Supelco) using gradient elution (A: 0.1% [v/v] formic acid in water, B: 0.1% [v/v] formic acid in acetonitrile [the mobile phase pH 2.5]). A constant flow rate at 1mL/min was applied, and the detection was realized using a photodiode array detector set at 216nm. The pseudo tablet formulation of the lumacaftor/ivacaftor fixed-dose combination preparation, namely, Orkambi®, was prepared in vitro and used for the analytical performance validation and method application studies. In addition, five novel degradation products, four of which even have no Chemical Abstracts Services registry number, were identified using high-resolution mass spectrometry instrument, and their possible mechanisms of formation were proposed. According to current literature, this paper can be regarded as the most comprehensive liquid chromatographic study on lumacaftor determination, among its counterparts.

Development and Validation of a Rapid Method for Identification of New Synthetic Cannabinoids in Hair Based on High-Performance Liquid Chromatography-Ion Trap Mass Spectrometry Using a Simplified User Interface.

The penetration of the new psychoactive substances (NPSs) into the market of clandestine drugs is highly dynamic, causing potentially false-negative results using the current analytical instrumentation, particularly in the screening phase. At present, the suggested approach to perform a comprehensive screening requires the use of high-resolution mass spectrometry (MS) with associated high costs of purchase and maintenance and need of skilled and dedicated personnel. Here we describe the development and validation of a simplified approach based on a high-performance liquid chromatography-ion trap MS system with a user-friendly interface dedicated to toxicological analysis. The system, originally intended for a broad toxicological screening, was tuned to identify new synthetic cannabinoids in hair. After a washing step with dichloromethane, hair (about 50 mg) was incubated for 3 h with 1.5 mL ethanol. One milliliter of this solution was then dried, reconstituted with mobile phase and injected. The peak identification was based on the chromatographic retention times and MS2/MS3 data using a database which included up to 158 NPSs. The method was validated according to international guidelines on a selected panel of NPSs, namely methyl 2-[[1-(5-fluoropentyl)indazole-3-carbonyl]amino]-3,3-dimethylbutanoate (5F-ADB), 1-Pentyfluoro-1H-indole-3-carboxylic acid 8-quinolinyl ester (5F-PB 22), N-[(2S)-1-amino-3-methyl-1-oxobutan-2-yl]-1-(5-chloropentyl)indazole-3-carboxamide (5Cl-AB-PINACA), (S)-N-(1-amino-1-oxo-3-phenylpropan-2-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamide [5F-APP-PICA (PX-1)],: (R)-N-(1-amino-1-oxo-3-phenylpropan-2-yl)-1-(5-fluoropentyl)-1H-indazole-3-carboxamide [5F-APP-PINACA (PX-2)], N-[(2S)-1-Amino-3-methyl-1-oxobutan-2-yl]-1-(cyclohexylmethyl)indazole-3-carboxamide (AB-CHMINACA), N-[(2S)-1-Amino-3-methyl-1-oxobutan-2-yl]-1-[(4-fluorophenyl)methyl] indazole-3-carboxamid (AB-FUBINACA), methyl (2S)-2-[[1-(cyclohexylmethyl)indole-3-carbonyl]amino]-3,3-dimethylbutanoate (MDMB-CHMICA), (S)-Methyl 2-(1-(5-fluoropentyl)-1H-indole-3-carboxamido)-3-methylbutanoate (MMB-2201) and (1-pentylindol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone (UR-144). The tested analytical method showed detection limits between 0.065 and 0.125ng/mg. The intraday imprecision of the method showed average values within the range of 7.3-20%. The estimation of the trueness (bias) of method showed average values within the range of 1.5-12.3%. The analytical performance was also successfully assessed by four proficiency test samples containing NPS. No synthetic cannabinoids were detected in application to 82 hair samples from forensic cases previously analyzed with liquid chromatography-MS triple quadrupole.

A new aerosol flow reactor to study secondary organic aerosol

Abstract. Gas-particle equilibrium partitioning is a fundamental concept used to describe the growth and loss of secondary organic aerosol (SOA). However, recent literature has suggested that gas-particle partitioning may be kinetically limited, preventing volatilization from the aerosol phase as a result of the physical state of the aerosol (e.g. glassy, viscous). Experimental measurements of diffusion constants within viscous aerosol are limited and do not represent the complex chemical composition observed in SOA (i.e. multicomponent mixtures). Motivated by the need to address fundamental questions regarding the effect of the physical state and chemical composition of a particle on gas-particle partitioning, we present the design and operation of a newly built 0.3 m3 continuous-flow reactor (CFR), which can be used as a tool to gain considerable insights into the composition and physical state of SOA. The CFR was used to generate SOA from the photo-oxidation of α-pinene, limonene, β-caryophyllene and toluene under different experimental conditions (i.e. relative humidity, VOC and VOC∕NOx ratios). Up to 102 mg of SOA mass was collected per experiment, allowing the use of highly accurate compositional- and single-particle analysis techniques, which are not usually accessible due to the large quantity of organic aerosol mass required for analysis. A suite of offline analytical techniques was used to determine the chemical composition and physical state of the generated SOA, including attenuated total reflectance infrared spectroscopy; carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis; 1H and 1H-13C nuclear magnetic resonance spectroscopy (NMR); ultra-performance liquid chromatography ultra-high-resolution mass spectrometry (UHRMS); high-performance liquid chromatography ion-trap mass spectrometry (HPLC-ITMS); and an electrodynamic balance (EDB). The oxygen-to-carbon (O∕C) and hydrogen-to-carbon (H∕C) ratios of generated SOA samples (determined using a CHNS elemental analyser) displayed good agreement with literature values and were consistent with the characteristic Van Krevelen diagram trajectory, with an observed slope of −0.41. The elemental composition of two SOA samples formed in separate replicate experiments displayed excellent reproducibility, with the O∕C and H∕C ratios of the SOA samples observed to be within error of the analytical instrumentation (instrument accuracy ±0.15 % to a reference standard). The ability to use a highly accurate CHNS elemental analyser to determine the elemental composition of the SOA samples allowed us to evaluate the accuracy of reported SOA elemental compositions using UHRMS (a commonly used technique). In all of the experiments investigated, the SOA O∕C ratios obtained for each SOA sample using UHRMS were lower than the O∕C ratios obtained from the CHNS analyser (the more accurate and non-selective technique). The average difference in the ΔO∕C ratios ranged from 19 % to 45 % depending on the SOA precursor and formation conditions. α-pinene SOA standards were generated from the collected SOA mass using semi-preparative HPLC-ITMS coupled to an automated fraction collector, followed by 1H NMR spectroscopy. Up to 35.8±1.6 % (propagated error of the uncertainty in the slope of the calibrations graphs) of α-pinene SOA was quantified using this method; a considerable improvement from most previous studies. Single aerosol droplets were generated from the collected SOA samples and trapped within an EDB at different temperatures and relative humidities to investigate the dynamic changes in their physiochemical properties. The volatilization of organic components from toluene and β-caryophyllene SOA particles at 0 % relative humidity was found to be kinetically limited, owing to particle viscosity. The unconventional use of a newly built CFR, combined with comprehensive offline chemical characterization and single-particle measurements, offers a unique approach to further our understanding of the relationship between SOA formation conditions, chemical composition and physiochemical properties.

Development of an in-house mixed-mode solid-phase extraction for the determination of 16 basic drugs in urine by High Performance Liquid Chromatography-Ion Trap Mass Spectrometry

The aim of the present work was to develop a novel in-house mixed-mode SPE sorbent to be used for the HPLC-Ion TrapMS determination of 16 basic drugs in urine.By using a computational modelling, a virtual monomer library was screened identifying three suitable functional monomers, methacrylic acid (MAA), itaconic acid (IA) and 2-acrylamide-2-methylpropane sulfonic acid (AMPSA), respectively. Three different sorbents were then synthetized based on these monomers, and using as cross-linker trimethylolpropane trimethacrylate (TMPTMA).The sorbent characterization analyses brought to the selection of the AMPSA based phase.Using this novel in-house sorbent, a SPE-HPLC-Ion TrapMS method for drug analysis in urine was validated proving to be selective and accurate and showing a sensitivity adequate for toxicological urine analysis. The comparison of the in-house mixed-mode SPE sorbent with two analogous commercial mixed-mode SPE phases showed that the first one was better not only in terms of process efficiency, but also in terms of quality-price rate.To the best of our knowledge, this is the first time in which an in-house SPE procedure has been applied to the toxicological analysis of a complex matrix, such as urine.

Bioaccessible peptides released by in vitro gastrointestinal digestion of fermented goat milks

In this study, ultrafiltered goat milks fermented with the classical starter bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarus subsp. thermophilus or with the classical starter plus the Lactobacillus plantarum C4 probiotic strain were analyzed using ultra-high performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) and/or high performance liquid chromatography-ion trap (HPLC-IT-MS/MS). Partial overlapping of the identified sequences with regard to fermentation culture was observed. Evaluation of the cleavage specificity suggested a lower proteolytic activity of the probiotic strain. Some of the potentially identified peptides had been previously reported as angiotensin-converting enzyme (ACE) inhibitory, antioxidant, and antibacterial and might account for the in vitro activity previously reported for these fermented milks. Simulated digestion of the products was conducted in the presence of a dialysis membrane to retrieve the bioaccessible peptide fraction. Some sequences with reported physiological activity resisted digestion but were found in the non-dialyzable fraction. However, new forms released by digestion, such as the antioxidant αs1-casein 144YFYPQL149, the antihypertensive αs2-casein 90YQKFPQY96, and the antibacterial αs2-casein 165LKKISQ170, were found in the dialyzable fraction of both fermented milks. Moreover, in the fermented milk including the probiotic strain, the k-casein dipeptidyl peptidase IV inhibitor (DPP-IV) 51INNQFLPYPY60 as well as additional ACE inhibitory or antioxidant sequences could be identified. With the aim of anticipating further biological outcomes, quantitative structure activity relationship (QSAR) analysis was applied to the bioaccessible fragments and led to potential ACE inhibitory sequences being proposed. Graphical abstract Ultrafiltered goat milks were fermented with the classical starter bacteria (St) and with St plus the L. plantarum C4 probiotic strain. Samples were analyzed using HPLC-IT-MS/MS and UPLC-Q-TOF-MS/MS. After simulated digestion and dialysis, some of the active sequences remained and new peptides with reported beneficial activities were released.

Water-Soluble Organic Composition of the Arctic Sea Surface Microlayer and Association with Ice Nucleation Ability.

Organic matter in the sea surface microlayer (SML) may be transferred to the atmosphere as sea spray and hence influence the composition and properties of marine aerosol. Recent work has demonstrated that the SML contains material capable of heterogeneously nucleating ice, but the nature of this material remains largely unknown. Water-soluble organic matter was extracted from SML and underlying seawater from the Arctic and analyzed using a combination of mass spectrometric approaches. High performance liquid chromatography-ion trap mass spectrometry (LC-IT-MS), and Fourier transform ion cyclotron resonance MS (FT-ICR-MS), showed seawater extracts to be compositionally similar across all stations, whereas microlayer extracts had a different and more variable composition. LC-IT-MS demonstrated the enrichment of particular ions in the microlayer. Ice nucleation ability (defined as the median droplet freezing temperature) appeared to be related to the relative abundances of some ions, although the extracts themselves did not retain this property. Molecular formulas were assigned using LC-quadrupole time-of-flight MS (LC-TOF-MS2) and FT-ICR-MS. The ice nucleation tracer ions were associated with elevated biogenic trace gases, and were also observed in atmospheric aerosol collected during the summer, but not early spring suggesting a biogenic source of ice nuclei in the Arctic microlayer.

Yew (Taxus) intoxication in free-ranging cervids.

Wild ruminants, including deer species (cervids) have incorrectly been regarded as refractory to yew (Taxus) intoxication. This assumption has been based upon anecdotal observations of individual deer browsing on yew over time without apparent adverse effect. A single case of yew intoxication was reported in a free-ranging Norwegian moose (Alces alces) in 2008. The current report describes five additional cases of yew toxicosis in moose, seven in roe deer (Capreolus capreolus) and two in reindeer (Rangifer tarandus tarandus), all in Norway. The animals were found dead during the winter, close to or within gardens containing yew plants showing signs of browsing. Gross findings included lung congestion and edema, thoracic and pericardial effusion, bilateral heart dilatation, epi- and endocardial hemorrhage, and enlarged (congested) spleen. Yew plant remnants were detected in the rumen of all animals with the exception of a single moose. Histology revealed multifocal acute myocardial degeneration and necrosis with hemorrhage in roe deer, but not in the two other species. A qualitative high performance liquid chromatography–ion trap mass spectrometry analysis was used to tentatively identify five major Taxus alkaloids (taxines) in crude yew extracts and in heart and liver samples from the moose cases. All five major taxines were detected with good signal/noise ratio in tissue samples from the four moose with visible ruminal yew content, whereas lower levels of taxines were detected in the moose without visible ruminal yew content. Possible differences in interspecies tolerance to taxines and role of individual protective adaptation are discussed.

Metabolite identification of AZD8055 in Sprague-Dawley rats after a single oral administration using ultra-performance liquid chromatography and mass spectrometry

AZD8055 is an ATP-competitive specific dual mTOR inhibitor and exhibited potent antitumor activity on several types of solid tumors. However, the metabolism of AZD8055 in the body still remains unknown. In this study, metabolite identification of AZD8055 was performed using ultra high-performance liquid chromatography-ion trap mass spectrometry (UHPLC-IT-MS) through both in vitro and in vivo approaches using rat liver microsomes (RLMs) and rat plasma, urine and feces, respectively. A total of eight putative metabolites (five phase I and three phase II) were identified, and a tentative metabolic pathway was suggested for the first time. Considering the accurate mass and mass fragmentations of the detected metabolites, their plausible structures were suggested. Demethylation, hydroxylation, oxidation and morpholine ring opening were the major biotransformation processes for the phase-I metabolism, while phase-II metabolites were merely generated by the glucuronide conjugation reaction. The cumulative excretion of AZD8055 in urine and feces was 0.13% and 1.11% of the dose, respectively. When the semi-quantitative analysis of the metabolites was performed using UHPLC–MS/MS (ultra-performance liquid chromatography tandem mass spectrometry) to evaluate the overall trend of metabolites formation and excretion, AZD8055 was excreted more in the form of the metabolites than itself and their formation was very fast. Therefore it was presumed that biotransformation was playing a crucial role in its elimination. Ultimately, this study provides novel insights regarding the in vitro and in vivo biotransformations of AZD8055. Further investigations of metabolites of this potent anti-cancer compound could be beneficial for the antitumor drug design and development process.

Application of high performance liquid-ion trap mass spectrometry in analyzing saponins in sodium aescinate

Sodium aescinate, which is produced from saponins of Chinese Buckeye Seed, is a prescription drug for treatment of brain edema and all kinds of swellings caused by surgery. In this article, high-performance liquid chromatography/ion trap (HPLC-IT) mass spectrometry was applied to study the characteristic ions of ten reference substances, namely escin Ⅰa, escin Ⅰb, isoescin Ⅰa, isoescin Ⅰb, aesculiside A, aesculiside B, aesculuside A, escin Ⅳc, escinⅡa and escin Ⅴ, which were isolated from aescinate. Furthermore, 19 saponin compounds were predicted in sodium aescinate, besides the above mentioned reference substances. The study showed that sapogenins in sodium aescinate had two structural types, namely protoaescigenin and barringenol C, and the substituent acetyl, tigloyl or angeloyl was usually located at C-21, C-22 or C-28 position. Among these predicted saponins, their sugar chains were all located at C-3 position consisting of glucose and glucuronide. This study provides experimental data for chemical constituents in sodium aescinate and scientific basis for quality and safety evaluation.

Fast screening of 24 sedative hypnotics illegally added in improving sleep health foods by high performance liquid chromatography-ion trap mass spectrometry

A fast screening method was established for the simultaneous determination of 24 sedative hypnotics illegally added in improving sleep health foods by high performance liquid chromatography-ion trap mass spectrometry (HPLC-IT MS). The method was based on the sonication assisted extraction of the improving sleep health food samples using methanol. The extract was then filtrated with 0.45 µm filter membrane and the filtrate was separated on a Phenomenex Luna C18 column with isocratic elution at a flow rate of 0.3 mL/min. A binary mobile phase was 0.05% (v/v) formic acid (solvent A)-methanol/acetonitrile (15:25, v/v, solvent B). The electrospray ionization (ESI) source in positive ion mode or negative ion mode was used to scan MS1-MS3 spectra for the 24 sedative hypnotics. The MS2 and MS3 spectra were used for qualitative analysis of samples. The calibration graphs were linear in their concentration ranges with the correlation coefficients (r2) more than 0.999. The limits of detection (LODs) were 4.0-446.6 µg/L. The recoveries for all the drugs in the improving sleep health foods were 88.6%-110.3% with the relative standard deviations no more than 9.8% at three spiked levels. Twenty-seven batches of the improving sleep health foods were tested. Melatonin was found in eighteen batches. The method is fast, specific, sensitive, easy and suitable for fast screening of 24 sedative hypnotics illegally added in improving sleep health foods.

Determination of Luteoskyrin in Rice Wine by High-Performance Liquid Chromatography–Ion Trap Tandem Mass Spectrometry

A method for luteoskyrin in Chinese rice wine was developed using high-performance liquid chromatography–ion trap tandem mass spectrometry. The detection limit of luteoskyrin was 0.10 µg/kg. The recovery values of luteoskyrin in fortified Chinese rice wine were between 85.7% and 88.9% at levels between 0.5 µg/kg and 100 µg/kg (R > 0.999). The relative standard deviations were in the range of 1.10% to 3.20%. The method achieved rapid and accurate determination of luteoskyrin in Chinese rice wine while meeting minimum residue measurement requirements.

Metabolism, Distribution, and Excretion of Deoxynivalenol with Combined Techniques of Radiotracing, High-Performance Liquid Chromatography Ion Trap Time-of-Flight Mass Spectrometry, and Online Radiometric Detection

Dispositions of deoxynivalenol (DON) in rats and chickens were investigated, using a radiotracer method coupled with a novel γ-accurate radioisotope counting (γ-ARC) radio-high-performance liquid chromatography ion trap time-of-flight tandem mass spectrometry (radio-HPLC-IT-TOF-MS/MS) system. 3β-(3)H-DON was chemically synthesized and orally administrated to both sexes of rats and chickens as single or multiple doses. The results showed that DON was widely distributed and quickly eliminated in all tissues. The highest concentration was found in the gastrointestinal tract at 6 h post-administration. Substantially lower levels were detected in the kidney, liver, heart, lung, spleen, and brain. Three new metabolites were identified tentatively as 10-deoxynivalenol-sulfonate, 10-deepoxy-deoxynivalenol (DOM-1)-sulfonate, and deoxynivalenol-3α-sulfate. Deoxynivalenol-3α-sulfate was a major metabolite in chickens, while the major forms in rats were DOM-1 and DON. Additionally, a higher excretion rate in urine was observed in female rats than in male rats. The differences in metabolite profiles and excretion rates, which suggested diverse ways to detoxify, may relate to the different tolerances in different genders or species.

Fluorescein-core piperazine as a fluorescent labeling reagent for highly sensitive determination of jasmonic acid by high-performance liquid chromatography

In the present work, a pre-column fluorescent derivatization reagent, fluorescein-core piperazine (FCP) was prepared for labeling jasmonic acid (JA). Based on the enhanced fluorescence after derivatization, a simple and sensitive method was developed for determination of JA by high performance liquid chromatography with fluorescence detection (HPLC/FD). Several key derivatization conditions were examined. The results indicated that FCP labeled JA could be well separated from FCP in the sample within 13 min on a C18 reversed-phase column using a mobile phase of methanol–water (55 : 45, v/v) with fluorescence detection at excitation and emission wavelength of 507 nm and 526 nm, respectively. The detection limit obtained was 0.4 nM (signal to noise ratio of 3), which was lower than most of the existing methods. The method is reproducible and yields single peak for JA regardless of isomer. The specificity of the proposed method was confirmed by high-performance liquid chromatography-ion trap mass spectrometry (HPLC/IT-MS). Finally, it has been demonstrated that the proposed HPLC/FD method can be applied to the assay of JA in plant samples.

The simultaneous determination of vitamins A, E and β-carotene in bovine milk by high performance liquid chromatography–ion trap mass spectrometry (HPLC–MSn)

Bovine milk is considered to be a good dietary source of vitamins A, E and β-carotene. This paper describes a robust method for the simultaneous determination of these compounds using high performance liquid chromatography–ion trap mass spectrometry (HPLC–MSn) as the determinative step. The compounds were separated with a 5 μm Polaris 2.1 × 150 mm C18-A column and an aqueous-methanol mobile phase and the levels determined using the MS2 fragments (vitamin A, m/z 213 and m/z 199, vitamin E m/z 165 and β-carotene m/z 413). The HPLC–MSn was operated in the positive ion APCI mode. The method was validated using repeatability studies, duplicate analyses, recovery experiments, proficiency study data and comparison with previously validated high performance liquid chromatographic ultraviolet/visible (HPLC–UV/Vis) and fluorescence (HPLC–Fl) procedures used in our laboratory. Expanded measurement uncertainties were similar for HPLC–MSn, HPLC–UV/Vis and HPLC–Fl, e.g. vitamin A 45 μg/100 ml, HPLC–MSn ±8%, HPLC–UV ±9%; vitamin E 150 μg/100 ml, HPLC–MSn ±11%, HPLC–Fl ±9%; β-carotene 12 μg/100 ml, HPLC–MSn ±18%, HPLC–Vis ±21%.

Determination of Fluoroquinolones in Grass Carp by High Performance Liquid Chromatography-Ion Trap Mass Spectrometry Using Mixed-templates Imprinted Polymer Extraction

The molecularly imprinted polymer(MIP) has been prepared using levofloxacin and ciprofloxacin as the mixed-templates,α-methacrylic acid(MAA) as functional monomers and trimethylolpropane trimethylacrylate(TRIM) as crosslinker.A method has been established for simultaneous determination of residues of ten fluoroquinolones in grass carp by high performance liquid chromatography-ion trap mass spectrometry(HPLC-ITMS) combining with molecularly imprinted polymer solid phase extraction(MISPE).The samples were extracted with 2% acetic acid in acetonitrile and defatted with n-hexane,then purified by the self-made molecularly imprinted cartridge.The preparation of samples and the separation conditions had been optimized,HPLC was performed with a gradient elution program while acetonitrile and water(containing 0.05% formic acid) were used as mobile phase.The identification and quantification were done with ion trap mass spectrometry.The recove-ries ranged from 80.6% to 104.6% with a relative standard deviations of 8.6%.The limits of detection(LOD) were 0.11-0.25 μg/kg and the limits of quantification(LOQ) were 0.35-0.84 μg/kg.This method is suitable for validation and multi-residue analysis of fluoroquolones in aquatic products.

Qualitative and Quantitative Analysis of Steroidal Saponins in Crude Extract and Bark Powder of Yucca schidigera Roezl.

Steroidal saponins in commercial stem syrup and in extract of a bark of Yucca schidigera were identified with high-performance liquid chromatography ion trap mass spectrometry and quantitated using ultraperformance liquid chromatography with quadrupole mass spectrometric detection. Fragmentation patterns of yucca saponins were generated using collision-induced dissociation and compared with fragmentation of authentic standards as well as with published spectrometric information. In addition to detection of twelve saponins known to occur in Y. schidigera, collected fragmentation data led to tentative identifications of seven new saponins. A quantitation method for all 19 detected compounds was developed and validated. Samples derived from the syrup and the bark of yucca were quantitatively measured and compared. Obtained results indicate that yucca bark accumulates polar, bidesmosidic saponins, while in the stem steroidal glycosides with middle- and short-length saccharide chains are predominant. The newly developed method provides an opportunity to evaluate the composition of yucca products available on the market.

Determination of <I>β</I><SUB>2</SUB>-agonists and <I>β</I>-blockers in urine using high performance liquid chromatography-ion trap mass spectrometry

A method has been developed for the determination of 23 beta2-agonists and 5 beta-blockers in urine samples using high performance liquid chromatography-ion trap mass spectrometry (HPLC-IT-MS). Urine samples were first deproteinized by high-speed frozen centrifugation, and the supernatants were loaded on an Extrelut diatomite column for clean-up. The analytes were eluted by ethyl acetate and concentrated for further analysis. The analytical separation was performed on an AtlantisT3-150 mm chromatographic column with the gradient elution using methanol and water (containing 0.1% formic acid). The detection was carried on a linear ion trap mass spectrometer under multiple reaction monitoring (MRM) mode with the source operated in positive mode of electrospray ionization (ESI+). Nine deuterium labeled beta2-agonists were used as internal standards for quantitative analysis. The results showed that the linear ranges for 23 beta2-agonists and 5 beta-blockers were 0.005-0.16 mg/L, and the limits of detection were all around 0.2 microg/L. The mixed standard solution was added into the blank urine samples, and the recoveries of 23 beta2-agonists and 5 beta-blockers were ranged from 57.1% to 127.7% with the relative standard deviations of 1.1%-31.1%. The results demonstrate that the method is easy, fast, sensitive, and suitable for the confirmation and quantification of 23 beta2-agonists and 5 beta-blockers in urine samples.