Performance Liquid Chromatography-triple Quadrupole Research Articles

Autopolyploidization, geographic origin, and metabolome evolution in Arabidopsis thaliana.

Autopolyploidy, or whole-genome duplication, is a recurrent phenomenon in plant evolution. Its existence can be inferred from the presence of massive levels of genetic redundancy revealed by comparative plant phylogenomics. Whole-genome duplication is theoretically associated with evolutionary novelties such as the development of new metabolic reactions and therefore contributes to the evolution of new plant metabolic profiles. However, very little is yet known about the impact of autopolyploidy on the metabolism of recently formed autopolyploids. This study provides a better understanding of the relevance of this evolutionary process. In this study, we compared the metabolic profiles of wild diploids, wild autotetraploids, and artificial autotetraploids of Arabidopsis thaliana using targeted ultra-high performance liquid chromatography-triple quadrupole- mass spectrometry (UPLC-QqQ-MS) metabolomics. We found that wild and artificial A. thaliana autotetraploids display different metabolic profiles. Furthermore, wild autotetraploids display unique metabolic profiles associated with their geographic origin. Autopolyploidy might help plants adapt to challenging environmental conditions by allowing the evolution of novel metabolic profiles not present in the parental diploids. We elaborate on the causes and consequences leading to these distinct profiles.

Determination of 17 Plant Growth Regulator Residues by Ultra-High Performance Liquid Chromatography-Triple Quadrupole Linear Ion Trap Mass Spectrometry Based on Modified QuEChERS Method

A new method combining modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) with ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UHPLC-QTrap-MS/MS) was developed for simultaneous determination of 17 plant growth regulator (PGR) residues in vegetables. Quantitative data acquisition was accomplished in multiple reaction monitoring (MRM) mode, and qualitative analysis and identification of target compounds was achieved by using linear ion trap scan functions. Qualitative and quantitative analysis can be simultaneously achieved by a pair of ions in UHPLC-QTrap-MS/MS. More importantly, QTrap system can minimize the risk of false positive and negative results. To achieve the optimum performance towards the target analytes, several parameters including the content of formic acid in mobile phase and scanning mode were investigated. In the optimized conditions, 17 PGRs showed good linearity over the range of 2~50 μg/L with correlation coefficients of 0.9902~0.9999. The limits of detections (LODs) were in the range of 0.01~1.32 μg/kg. The recoveries of 17 PGRs ranged from 78.5 to 119.2% with the spiked levels of 1, 2, and 5 μg/kg into homogenized radish, and the relative standard deviations (RSDs) ranged from 0.8 to 14.8%. The method illustrated is suitable for routine quantitative and qualitative analyses of PGRs in vegetable samples.

Determination of seven fluorescent whitening agents in flour by high performance liquid chromatography-triple quadrupole mass spectrometry

Determination of seven fluorescent whitening agents in flour by high performance liquid chromatography-triple quadrupole mass spectrometry

Simultaneous rapid determination of 12 microcystins and one nodularin in water by direct injection-ultra performance liquid chromatography-triple quadrupole mass spectrometry

A rapid method was developed for the simultaneous determination of 12 microcystins (MCs) and one nodularin (NOD) in water by direct injection-ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). The water samples were first diluted with equal volume of methanol, and then filtered through polyether sulfone (PES) syringe filter. The filtrates were directly injected into the UPLC system. The separation of the analytes was carried out on an ACQUITY UPLC BEH 300 C18 column (100 mm×2.1 mm, 1.7 μm) with gradient elution using mobile phases of acetonitrile containing 0.1% (v/v) formic acid and 0.2% (v/v) formic acid aqueous solution. The 12 microcystins and one nodularin were detected by positive electrospray ionization in the multiple reaction monitoring (MRM) mode, and quantified by standard solvent external standard method. The limits of detection were 0.03-0.1 μg/L and the limits of quantification were 0.1-0.3 μg/L. The recoveries were in the range of 79.5%-123% with the relative standard deviations ranging from 1.0% to 20% (n=6). The method is simple, sensitive and accurate, and has been successfully applied to the detection of the 13 kinds of algae toxins in water.

Rapid determination of benzo[a]pyrene in foods by ultra performance liquid chromatography-triple quadrupole mass spectrometry with atmospheric pressure chemical ionization

A method for the determination of benzo[a]pyrene in foods was developed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) based on isotope dilution and molecularly imprinted solid-phase extraction (MIP-SPE). The target analyte in samples was extracted with n-hexane after spiked with benzo[a]pyrene-d12, and purified using MIP-SPE to eliminate most of the coextracts. The separation of benzo[a]pyrene was carried out on an XBridge BEH C18 column with gradient elution of methanol and water. An atmospheric pressure chemical ionization (APCI) interface was used as the ion source and the analysis was performed in the multiple reaction monitoring (MRM) mode. Benzo[a]pyrene levels in the range of 0.07-50 μg/kg were measured accurately by this method, and the limit of quantification (LOQ) was 0.07 μg/kg. The average recoveries were between 86% and 104% with the relative standard deviations within 2.3%-14%. The method was sensitive and accurate, and it has been successfully applied to the measurement of benzo[a]pyrene in food samples.

Determination of 34 illegally adulterated weight loss compounds in foods by ultra high performance liquid chromatography- triple quadrupole mass spectrometry

An analytical method was developed for the determination of 34 illegally adulterated weight loss compounds in foods and dietary supplements by ultra high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-MS/MS). A Waters CORTECS T3 column (100 mm×2.1 mm, 2.7 μm) was used with 0.1% (v/v) formic acid aqueous solution-acetonitrile containing 0.1% (v/v) formic acid as mobile phases by gradient elution. The compounds were detected by electrospray ion source in positive or negative mode with multiple reaction monitoring (MRM) mode. The calibration curves showed good linearity in the range of 0.5-10 μg/L for 29 compounds such as sibutramine, and in the range of 2.5-50 μg/L for five compounds such as chlorothiazide. The correlation coefficients (r) of the standard calibration curves for the 34 analytes were all greater than 0.99. The recoveries of the 29 compounds at spiked levels of 5, 10 and 20 μg/kg were in the range of 49.2%-136.2%, and the RSDs were 0.7%-15.0% (n=6). The recoveries of the five compounds at spiked levels of 25, 50 and 100 μg/kg were in the range of 51.5%-130.9%, and the RSDs were 0.8%-14.0% (n=6). The limits of detection (LODs) and limits of quantification (LOQs) were 5 μg/kg and 10 μg/kg for the 29 compounds, 25 μg/kg and 50 μg/kg for the five compounds, respectively. The method was successfully applied to the analysis of actual samples, and 12 compounds were checked out, which combated the illegal adulteration behavior effectively.

Phytohormone Profiling During Tuber Development of Chinese Yam by Ultra-high performance Liquid Chromatography–Triple Quadrupole Tandem Mass Spectrometry

Changes in agronomic characters and the profile of various endogenous phytohormones during tuber development were studied in Dioscorea opposite (Chinese yam) cv. Guihuai 16. Tuber development exhibited a sigmoidal growth pattern according to the changes in tuber agronomic characters. The growth cycle of yam tuber could be divided into three stages: initiation stage, enlargement stage, and maturation stage. Moreover, the enlargement stage could be separated into three phases—slow growth phase, rapid growth phase, and late growth phase. Endogenous changes in phytohormones were associated with developmental changes in the tubers. The pulses of bioactive gibberellins (such as GA3 and GA4) were measured in tubers. The highest contents of GA3 and GA4 were reached 90 days after field planting, corresponding to the beginning of the rapid growth phase of tuber enlargement. Changes in trans-zeatin (tZ), jasmonic acid (JA), indole-3-acetic acid (IAA), and abscisic acid (ABA) levels were also observed, and seemed to be related to tuber enlargement at different phases. Continuous increases in JA and tZ contents accompanied tuber enlargement. Transient pulses of both IAA and ABA contents were also observed at the start of tuber rapid growth. Additionally, a second peak level of IAA was detected at the tuber maturation stage. These results suggest GAs play a key role at the beginning of the tuber rapid growth stage, and there is a close relationship between whole tuber enlargement and the contents of JA and tZ. Moreover, it is suggested that IAA and ABA also may be linked to the beginning of tuber rapid growth, and IAA also seems to be correlated to late tuber maturation.

High-sensitivity detection of biogenic amines with multiple reaction monitoring in fish based on benzoyl chloride derivatization

In this study an efficient and sensitive method for biogenic amines detection was established by combining rapid extraction and derivatization with multiple reaction monitoring (MRM) based on ultra high performance liquid chromatography-triple quadrupole mass spectrometry. Bead-beating disruption and extraction using 5-sulfosalicylic acid not only improved the extraction efficiency but also was environmentally friendly. Benzoyl chloride derivatization could obtain stable biogenic amine derivatives with a shorter reaction time. By combining with MRM detection mode, higher detection sensitivity for biogenic amines could be achieved. The method showed a good linearity with linear range of 3–4 orders of magnitude and regression coefficients ranging from 0.9966 to 0.9999. The limit of detection and limit of quantitation could even reach lower pg/mL level. Satisfactory recovery was obtained from 74.9% to 119.3%. And the derivatives were stable within 48h at 4°C. The method established was used to determine content of biogenic amines in different fishes at different storage conditions. The results indicated that this method was suitable for analysis of biogenic amines.

13C-assisted Ultra-High Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry Method for Precise Determination of Intracellular Metabolites in Pichia pastoris

Abstract The yeast Pichia pastoris is an effective host for recombinant protein production and the recombinant protein production level is tightly related to the concentrations of intracellular metabolites. The intracellular metabolites have the features of wide range of types, distinct variation in physical and chemical properties, rapid turning-over and low concentration, so it is difficult to quantify their concentrations precisely. In this study, we tried to make it possible by combining ultra-high performance liquid chromatography-triple quadrupole mass spectrometry method and 13 C isotope labeling techniques. 64 metabolites including organic acids, sugar phosphate, nucleoside substance, amino acid were successfully separated by UPLC with three kinds of chromatographic column. The appropriate and unique ion pairs and collision voltages were found after the mass spectrometry condition optimization. By using the U 13 C metabolites as internal standards collected from the cells growing on U 13 C-glucose as sole carbon source, the standard curves of 53 metabolites was established. The results showed that this method had a high accuracy. The correlation coefficients were above 0.99. The method also had a good reproducibility, and the influence of experimental and equipment operating condition was very small. Reliable and accurate determination of the concentrations of intracellular metabolites in Pichia pastoris was obtained. The works lays the foundation for comprehensive regulation mechanism research and efficient recombinant protein production in Pichia pastoris .

Cleaning Up Vegetable Samples Using a Modified “QuEChERS” Procedure for the Determination of 17 Plant Growth Regulator Residues by Ultra High Performance Liquid Chromatography–Triple Quadrupole Linear Ion Trap Mass Spectrometry

A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample pretreatment method coupled with ultra high performance liquid chromatography–triple quadrupole linear ion trap mass spectrometry (UHPLC-QTrap-MS/MS) was developed for simultaneous determination of 17 plant growth regulator (PGR) residues in vegetables. Generik ChlorF (GCF) was used as one of the adsorbents in modified QuEChERS procedure, which can selectively remove the chlorophyll of acetonitrile extract without causing the losses of PGRs that have planar structure. To achieve the optimum performance toward the target analytes, extraction solvent, the type of adsorbent, and the amount of the adsorbent were investigated. Under the optimized conditions, good linearities with correlation coefficients (γ) higher than 0.9954 were obtained. The new method provided sufficient sensitivity as reflected by the values of limit of detection (LOD) and limit of quantification (LOQ). The LOD varied between 0.01 and 0.70 μg/kg and the LOQ varied between 0.04 and 2.32 μg/kg. Acceptable recoveries ranging from 78.5 to 116.8 % with the relative standard deviations (RSDs) of 0.9–11.9 % were achieved. The evaluated method provided reliable screening, quantification, and identification of 17 PGRs in vegetables.

Determination of ginkgolic acids in the ginkgo biloba extract and its preparations by ultra high performance liquid chromatography-triple quadrupole mass spectrometry

An analytical method was developed for the determination of ginkgolic acids in ginkgo biloba extract and its preparations by ultra high performance liquid chromatography-triple quadrupole mass spectrometry. A chromatographic column, Agilent Poroshell 120 EC-C18 (50 mm x 3. 0 mm, 2.7 µm), was used with methanol-l% acetic acid (90 :10, v/v) as the mobile phase. The ginkgo acids were detected by electrospray ionization mass spectrometry in negative mode with multiple reaction monitoring (MRM) mode. Ginkgo acids C13:0, C15:1 and C17:1 possessed good linear correlations in the mass concentration range from 2 to 200 µg/L, with the correlation coefficients more than 0. 999. The mean recoveries at the spiked levels of 5, 20 and 100 µg/L were in the range of 86. 3%-114. 3%, and the RSDs were 0. 5%-13. 6%. The limits of detection and quantification were 0. 003-0. 08 µg/g and 0. 01-0. 19 µg/g, respectively. The method was successfully applied to the analysis of actual samples.

A New Fluorinated Surfactant Contaminant in Biota: Perfluorobutane Sulfonamide in Several Fish Species.

Environmental contamination and regulation of longer-chain perfluoroalkyl substances (PFASs) such as perfluorooctanesulfonate (PFOS) has given rise to the increased use of shorter-chain PFASs as alternatives in new products, although confirmation of their presence in the environment remains limited. In this study, the PFAS alternative, perfluoro-1-butane-sulfonamide (FBSA), was identified for the first time in biota in homogenate samples of fish by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-ToF-MS) and quantified by ultra high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-QQQ-MS/MS). In one flounder (Platichthys flesus) muscle sample from the Western Scheldt, The Netherlands, FBSA concentration was at 80.12 ng/g wet weight (w.w.) and was exceeded only by PFOS. FBSA was also detected in 32 out of 33 samples of freshwater fish collected (2009-2010) from water bodies across Canada. In lake trout (Salvelinus namaycush) from northern Canada (e.g., Lake Kusawa (Yukon Territory), Great Bear Lake (Northwest Territories and in the Arctic), and Lake Athabasca (northern Alberta)), the concentrations of FBSA ranged from below method detection limit (<0.01 ng/g w.w) to 0.44 ng/g w.w. and were much lower than those reported for lake trout from the more urbanized and industrialized Laurentian Great Lakes sites (3.17 ± 1.53 ng/g w.w.). In three species of fish purchased from a supermarket in Ottawa (ON, Canada), FBSA concentrations were the lowest of all fish and ranged from < MLOD to 0.29 ng/g w.w. and 0.03 to 0.76 ng/g w.w. in muscle and liver, respectively. FBSA is a bioaccumulative contaminant in fish in Canada and possibly in The Netherlands. It is likely sourced from new alternative perfluorobutane-based products, as well as other shorter chain perfluoroalkyl-based products.

The roles of carboxylesterase and CYP isozymes on the in vitro metabolism of T-2 toxin.

BackgroundT-2 toxin poses a great threat to human health because it has the highest toxicity of the currently known trichothecene mycotoxins. To understand the in vivo toxicity and transformation mechanism of T-2 toxin, we investigated the role of one kind of principal phase I drug-metabolizing enzymes (cytochrome P450 [CYP450] enzymes) on the metabolism of T-2 toxin, which are crucial to the metabolism of endogenous substances and xenobiotics. We also investigated carboxylesterase, which also plays an important role in the metabolism of toxic substances.MethodsA chemical inhibition method and a recombinant method were employed to investigate the metabolism of the T-2 toxin by the CYP450 enzymes, and a chemical inhibition method was used to study carboxylesterase metabolism. Samples incubated with human liver microsomes were analyzed by high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC- QqQ MS) after a simple pretreatment.ResultsIn the presence of a carboxylesterase inhibitor, only 20 % T-2 toxin was metabolized. When CYP enzyme inhibitors and a carboxylesterase inhibitor were both present, only 3 % of the T-2 toxin was metabolized. The contributions of the CYP450 enzyme family to T-2 toxin metabolism followed the descending order CYP3A4, CYP2E1, CYP1A2, CYP2B6 or CYP2D6 or CYP2C19.ConclusionCarboxylesterase and CYP450 enzymes are of great importance in T-2 toxin metabolism, in which carboxylesterase is predominant and CYP450 has a subordinate role. CYP3A4 is the principal member of the CYP450 enzyme family responsible for T-2 toxin metabolism. The primary metabolite produced by carboxylesterase is HT-2, and the main metabolite produced by CYP 3A4 is 3′-OH T-2. The different metabolites show different toxicities. Our results will provide useful data concerning the toxic mechanism, the safety evaluation, and the health risk assessment of T-2 toxin.

Targeted metabolomic analysis reveals the association between the postprandial change in palmitic acid, branched-chain amino acids and insulin resistance in young obese subjects

Obesity is the result of a positive energy balance and often leads to difficulties in maintaining normal postprandial metabolism. The changes in postprandial metabolites after an oral glucose tolerance test (OGTT) in young obese Chinese men are unclear. In this work, the aim is to investigate the complex metabolic alterations in obesity provoked by an OGTT using targeted metabolomics. We used gas chromatography–mass spectrometry and ultra high performance liquid chromatography–triple quadrupole mass spectrometry to analyze serum fatty acids, amino acids and biogenic amines profiles from 15 control and 15 obese subjects at 0, 30, 60, 90 and 120min during an OGTT. Metabolite profiles from 30 obese subjects as independent samples were detected in order to validate the change of metabolites. There were the decreased levels of fatty acid, amino acids and biogenic amines after OGTT in obesity. At 120min, percent change of 20 metabolites in obesity has statistical significance when comparing with the controls. The obese parameters was positively associated with changes in arginine and histidine (P<0.05) and the postprandial change in palmitic acid (PA), branched-chain amino acids (BCAAs) and phenylalanine between 1 and 120min were positively associated with fasting insulin and HOMA-IR (all P<0.05) in the obese group. The postprandial metabolite of PA and BCAAs may play important role in the development and onset of insulin resistance in obesity. Our findings offer new insights in the complex physiological regulation of the metabolism during an OGTT in obesity.

Simultaneous determination of 22 typical pharmaceuticals and personal care products in environmental water using ultra performance liquid chromatography- triple quadrupole mass spectrometry

An analytical method for simultaneous determination of 22 typical pharmaceuticals and personal care products (PPCPs) in environmental water samples was developed by ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). An Oasis HLB solid phase extraction cartridge, methanol as washing solution, water containing 0. 1% formic acid-methanol (7:3, v/v) as the mobile phases were selected for sample pretreatment and chromatographic separation. Based on the optimized sample pretreatment procedures and separation condition, the target recoveries ranged from 73% to 125% in water with the relative standard deviations ( RSDs) from 8.8% to 17.5%, and the linear ranges were from 2 to 2 000 µg/L with correlation coefficients (R2) not less than 0.997. The method can be applied to simultaneous determination of the 22 typical PPCPs in environmental water samples because of its low detection limits and high recoveries. It can provide support and help for the related research on water environmental risk assessment and control of the micro-organic pollutants.

Determination of Cotinine, 3′-Hydroxycotinine, and Their Glucuronides in Urine by Ultra-high Performance Liquid Chromatography

The measurement of the primary nicotine metabolites, cotinine and trans-3′-hydroxycotinine, is a useful biomarker of nicotine exposure and metabolism genetics for smoking cessation research. Herein is described an ultra-high performance liquid chromatography–tandem mass spectrometry method for the determination of these primary nicotine metabolites in urine. Urine samples were diluted one hundred-fold with water and introduced into an ultra-high performance liquid chromatography triple quadrupole mass spectrometer using positive ion electrospray ionization with multiple reaction monitoring. Levels of urinary nicotine metabolites: cotinine, trans-3′-hydroxycotinine, and their respective glucuronides were determined directly using deuterated internal standards and compared with indirect determination by enzymatic hydrolysis. The assay was applied to a community sample of smokers’ urine (n = 280). The assay demonstrated satisfactory performance (relative standard deviation of 1.6–6.5 percent at the 1000 nanograms per milliliter level and >98 percent recovery) suitable for application to smoking studies with a run time less than five minutes. The mean (min-max) levels of cotinine and cotinine-glucuronide were 968 (31-3831) and 976 (9-5607) nanograms per milliliter. The mean (min-max) levels of trans-3′-hydroxycotinine and trans-3′-hydroxycotinine-glucuronide were 3529 (13-21337) and 722 (0-4633) nanograms per milliliter. Direct determination of glucuronide metabolites was superior to indirect measurement using enzymatic hydrolysis, where there was evidence of loss of metabolites during sample preparation. A sensitive and selective ultra-high performance liquid chromatography–tandem mass spectrometry assay was successfully developed for the determination of cotinine, trans-3′-hydroxycotinine, and their glucuronides in urine. The rapid and simple sample preparation makes this assay suitable for high throughput studies involving nicotine metabolism phenotype for both cytochrome P450 2A6 and uridine 5′-diphospho-glucuronosyltransferase, smoking prevalence, and cessation studies.

Multi-residue method for the analysis of pharmaceuticals and some of their metabolites in bivalves

A fast, simple and robust method has been developed for the simultaneous determination of 23 pharmaceuticals (including some major metabolites) in bivalve mollusks. The analytes belong to eight different therapeutic groups: antibiotics, psychiatric drugs, analgesics/anti-inflammatories, tranquilizer, calcium channel blockers, diuretic, and prostatic hyperplasia. The method is based on pressurized liquid extraction (PLE) followed by solid phase extraction clean-up (SPE), and ultra performance liquid chromatography–triple quadrupole mass spectrometry (UHPL–MS/MS) for the identification and quantification of the target analytes. It has been developed and validated in three different species of bivalves: Crassostrea gigas (Pacific oyster), Mytilus galloprovincialis (Mediterranean mussel), and Chamelea gallina (striped venus clam). The majority of the compounds were extracted with a recovery between 40 and 115%. The developed analytical method allowed the determination of the compounds in the lower ng/g concentration levels. The relative standard deviation was under 12% for the intra-day and 20% inter-day analyses, respectively. Finally, the method was applied to oyster, clam and mussel samples collected from the Ebro delta, Spain. The most ubiquitous compounds detected were the psychiatric drug venlanfaxine and the antibiotic azithromycin, with the highest concentrations found in mussel (2.7ng/g dw) and oyster (3.0ng/g dw), respectively. To the best of our knowledge, this is the first time that azithromycin has been reported in environmental samples of marine biota.

Simultaneous quantification of chrysophanol and physcion in rat plasma by ultra fast liquid chromatography-tandem mass spectrometry and application of the technique to comparative pharmacokinetic studies of Radix et Rhei Rhizoma extract alone and Dahuang Fuzi Decoction.

Most herbal medicines are prescribed in combination based on the theory of TCM to obtain synergistic effects or diminish the possible adverse reactions. Compatibility refers to the combination of two or more herbs based on the clinical settings and the properties of herbs. Chrysophanol and physcion are the main effective compounds in Radix et Rhizoma Rhei and Dahuang Fuzi Decoction which is the combination of Radix et Rhizoma Rhei, Radix Aconiti Lateralis Praeparata and Radix et Rhizoma Asari. However, chrysophanol and physcion are difficult to detect in vivo because of their low concentration and interference from endogenous compounds. The aim of this study is to develop a rapid, specific and sensitive ultra high performance liquid chromatography-triple quadrupole tandem mass method to simultaneously quantify chrysophanol and physcion in rat plasma, in order to better understand the pharmacokinetics and compatibility mechanism of Dahuang Fuzi Decoction for the first time. Multiple reaction monitoring (MRM) mode was applied for the quantitation at [M-H](-)m/z 253.0→m/z 225.1 for chrysophanol, [M-H](-) for m/z 283.1→m/z 240.0 physcion and [M-H](-)m/z 239.0→m/z 211.0 for IS. The analytes were separated on an Agilent Eclipse plus C18 column (100mm×2.1mm, 1.8μm) column within a total running time of 6.5min using a mixture of 3mM ammonium acetate in water and methanol (95:5, v/v) with a time program flow gradient according to the "plus gradient chromatography" theory. The inclusion of the ammonium acetate in the UFLC mobile phase dramatically improved the detection limit of the tested compounds and decreased the interference by matrix effects, which have been referred to as "LC-electrolyte effects". Finally, we demonstrated the application of a validated method in a comparative pharmacokinetic study of rats receiving an oral dose of Dahuang Fuzi Decoction or Radix et Rhei Rhizoma, the monarch drug in the prescription. Pharmacokinetic parameters showed significant difference between the two groups. The achieved comparative pharmacokinetic results were helpful to clarify the combination mechanism of Dahuang Fuzi Decoction.

Sensitive Determination of Panaxadiol Using Rhodamine B as Sensitizing Derivatization Reagent by Ultrahigh Performance Liquid Chromatography Triple Quadrupole Mass Spectrometry

Commercial Rhodamine B was first reported as a derivatization reagent labeling hydroxyl compound for mass spectrometry sensitization. In virtue of the strategy of ultrasonic-assisted dispersive liquid-liquid microextraction (UA-DLLME) combined with Rhodamine B derivatization, a new method of ultrahigh performance liquid chromatography triple quadrupole mass spectrometry (UHPLC-MS/MS) was developed for the sensitive determination of Panaxadiol (PD). UA-DLLME and derivatization conditions were investigated. PD in cosmetics and ginseng was extracted by UA-DLLME (150 mu L chloroform as extraction solvent, 500 mu L ethanol as disperser solvent, 3 min). Using Rhodamine B as precolumn derivatization reagent, the stable derivative of PD was obtained in acetonitrile at 70 degrees C for 30 min under microwave radiation (800 W) with the catalyst of N, N'-carbonyldiimidazole (CDI) and 4-dimethylaminopyridine (DMAP). And then the PD derivative was separated and detected within 3 min by multiple reaction monitoring (MRM) mode of UHPLC-MS/MS. The LOD was 4.0 ng L-1, and the LOQ was 15.0 ng L-1. This method had perfect linearity, precision and recovery results, and showed obvious advantages such as sensitivity and low matrix effect in comparison with the previously reported methods.

Using pollen grains as novel hydrophilic solid-phase extraction sorbents for the simultaneous determination of 16 plant growth regulators

In this article, pollen grains were for the first time used as a hydrophilic solid-phase extraction (HILIC-SPE) sorbent for the determination of 16 plant growth regulators (PGRs) in fruits and vegetables. Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM) and nitrogen sorption porosimetry (NSP) were used to investigate the chemical structure and the surface properties of the pollen grains. Pollen grains exhibited an excellent adsorption capacity for some polar compounds due to their particular functional groups. Several parameters influencing extraction performance were investigated. A green and simple HILIC-SPE-method using pollen grain cartridge for purification of fruit and vegetable extractions, followed by ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) was established. Good linear relationships were obtained for 16 PGRs with correlation coefficients (R) above 0.9980. The limits of detection (LODs) of 16 PGRs in cucumber were in the range of 0.01–1.10μg·kg−1. Reproducibility of the method was evaluated by intra-day and inter-day precisions with relative standard deviations (RSDs), which were less than 14.4%. We successfully applied this methodology to analyze 16 PGRs in 8 different kinds of fruits and vegetables. The recoveries from samples spiked with 16 PGRs were from 80.5% to 119.2%, with relative standard deviations less than 15.0%.