Ultra-performance Liquid Chromatography-electrospray Ionization Mass Research Articles

Lipidomic profile changes of yellow-feathered chicken meat during thermal processing based on UPLC-ESI-MS approach

In this work, ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESI-MS) was applied to compare the lipidomics profile of chicken breast meat heated to various temperatures. A total of 445 lipids including phospholipids, diacylglycerols, triacylglycerols, glycoglycerolipids, and sphingolipids were detected in chicken muscle. Significant decreases in a list of characteristic unsaturated phospholipid species including phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol were identified after heating, suggesting the occurrence of lipid oxidation, while significant increases in characteristic lysophospholipid species were found with increasing heating temperature, which were mainly derived from hydrolysis of phospholipids. Moreover, ether phospholipid and neutral lipid species exhibited remarkable changes during the heating process, and monoalk(en)yl diacylglycerol was first identified in chicken meat. The findings could contribute to the improved understanding of key lipids and biochemical reactions engaged in the heating of meat products.

UPLC-ESI/MS analysis of disinfection by-products (perchlorate, bromate, nitrate, nitrite and sulfite) in micro-filtered drinking water obtained from spring, well and tap water (desalinated) sources

ObjectivesIn the current study, an analytical technique has been optimized for the analysis of disinfection by-products (perchlorate (ClO4−), bromate (BrO3−), nitrate (NO3−), nitrite and sulfite (SO32–) in drinking water obtained from spring, well and tap water (desalinated) sources. MethodsThe ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESI/MS) conditions have been optimized for oxyhalides ClO4− (isotopes, 37ClO4− and 35ClO4−) and BrO3− (isotopes, 81BrO3− and 79BrO3−), and inorganic anions NO3−, NO2− and SO32–. Separation was achieved by BEH C18 column with methanol (75%) and water (24.99%, HCOOH 0.01%) mobile phase at flow rate 0.2 mL/min. ResultsThe analysis was carried out in <1 min with excellent coefficient of determination, (R2 > 0.995–0.999), limit of detection (0.016–0.043 µg/L), limit of quantification (0.051–0.104 µg/L) and precision (repeatability, 1.54–2.28% and reproducibility, 3.13–4.08%) in terms of RSD%. The method was successfully applied, and the amounts of 35ClO4− (5.33–22.64 µg/L), 81BrO3− (7.52–16.73 µg/L), NO3− (5.42–12.14 mg/L), NO2− (1.08–4.37 mg/L) and SO32– (6.84–32.45 mg/L) were identified in spring water, whereas well and tap water contained 35ClO4− (4.20–21.33 µg/L), 81BrO3− (8.05–15.13 µg/L), NO3− (1.27–16.11 mg/L), NO2− (0.43–10.77 mg/L) and SO32– (7.14–36.10 mg/L), and 35ClO4− (0.89–7.37 µg/L), 81BrO3− (5.15–14.68 µg/L), NO3− (1.12–6.33 mg/L), NO2− (0.67–3.95 mg/L) and SO32– (5.40–23.26 mg/L), respectively. ConclusionsThe levels of 35ClO4−, 81BrO3−, NO3−, NO2− and SO32– were found beyond the maximum contaminant levels and drinking water equivalent levels regulated by the Environmental Protection Agency, respectively. The outcomes also revealed that comparatively tap water produced lower levels of these contaminants especially in the cities with low population densities. In addition, the geographical site would be helpful to categorize the tap water samples.

Supercritical CO2 fluid extraction of flavonoid compounds from Xinjiang jujube (Ziziphus jujuba Mill.) leaves and associated biological activities and flavonoid compositions

In this study, the supercritical CO2 fluid extraction (SFE−CO2) conditions for obtaining the maximum flavonoid yield from Xinjiang jujube leaves (XJL) were optimized using response surface methodology (RSM). Box-Behnken design (BBD) was applied to evaluate the effects of four variables on flavonoid yield. The optimal conditions were a temperature of 52.52 °C, a pressure of 27.12 MPa, a time of 113.42 min, and a cosolvent flow rate of 0.44 mL/min. The flavonoid yield under the optimal conditions was 29.052 ± 0.38 mg/g. The major flavonoid profiles in the extracts were further analyzed using ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESI-MS). Eight flavonoid compounds were identified and quantified in each extract, and all of these compounds were kaempferol and quercetin glycosides. Compared with conventional Soxhlet extraction (CSE) and ultrasound-assisted extraction (UAE) extracts, the SFE−CO2 extracts had higher concentrations of total flavonoids and stronger antioxidant and antiproliferative activities. Therefore, SFE−CO2 is an alternative to CSE and UAE for obtaining flavonoid compounds from XJL at high concentrations and with strong bioactivity.

Evaluating iopamidol degradation performance and potential dual-wavelength synergy by UV-LED irradiation and UV-LED/chlorine treatment

This study revealed the iopamidol degradation performance and the synergistic effect of dual-wavelength ultraviolet light-emitting diodes (UV-LEDs). It was found that the dual-wavelength irradiation (265 and 280 nm) can promote iopamidol degradation during both UV-LED alone and UV-LED/chlorine processes (p < 0.05). The effects of key experimental parameters including pH, chlorine dosage and water matrix during UV-LED/chlorine process were evaluated. Peak degradation rate was observed at pH 7.0 due to the combined effects of the quantum yield of aquatic chlorine photolysis (Φchlorine) and absorptivity of chlorine. The destruction pathways of iopamidol in the UV-LED/chlorine process were proposed by Ultra Performance Liquid Chromatography-Electrospray Ionization-mass spectrometry. Additionally, an opposite trend of iodinated trihalomethane (I-THM) formation during subsequent chlorination between Milli-Q and real waters with prolonging irradiation time was observed, while other detected disinfection by-product (DBP) formation showed the same variation in Milli-Q and real waters. The UV-LED/chlorine treatment using dual-wavelength can enhance iopamidol degradation significantly, but it also promoted I-THM formation in real water, indicating the need for evaluating DBPs before the application of UV-LED/chlorine process in drinking water treatment.

Antioxidant Capacity and UPLC-PDA ESI-MS Phenolic Profile of Stevia rebaudiana Dry Powder Extracts Obtained by Ultrasound Assisted Extraction

Stevia leaves, which are commonly used as a natural sweetener in food products, have increased in importance for antioxidant delivery due to their high content of phenolic compounds. In this study, the influence of the drying process on stevia leaves, with regards to phenolic content and antioxidant activity during drying kinetics 40 °C for 7 h, was studied. The effect of solvent concentration and extraction time using a 32 factorial design on total phenol content (TPC), and on antioxidant activity of extracts obtained from dried stevia leaves, by ultrasound assisted extraction (UAE) as alternative method was evaluated. Steviol glycosides contents were also evaluated by a conventional and UAE method. Phenols identification, quantification and purification were performed by Ultra Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (UPLC-ESI-MS), Ultra Performance Liquid Chromatography-Photodiode Array (UPLC-PDA) and advanced automated flash purification, respectively. Drying time affected the moisture content of stevia leaves. A constant weight was reached after six hours of drying, and higher antioxidant activity was observed, while the highest TPC was obtained after seven hours of drying. The highest TPC (91.57 ± 8.8 mg GAE/g dw) and antioxidant activity (603.24 ± 3.5 μmol TE/g dw) in UAE method was obtained when ethanol 50% at 5 min was used. Steviol glycosides extracted by UAE were recorded with a content of 93.18 ± 1.36 mg/g dw and 98.97 ± 1.75 mg/g dw for stevioside and rebaudioside A respectively. Six phenolic compounds including four phenolic acids and two flavonoids were identified and quantified by UPLC-PDA, and confirmed by ESI-MS reporting its fragmentation pattern. Diosmin and chlorogenic acid were the most abundant compounds with values of 2032.36 μg/mL and 434.95 μg/mL respectively. As a novelty we found that the antioxidant activity evaluated in partially purified fractions suggested that biological activity might be attributed to the synergistic effect of the six phenols present in the stevia leaves extract. In addition to its sweeting properties, stevia leaves constitute a potential source of polyphenolic compounds, with antioxidant activity that could be used as a food additive.

Profiling of ginsenosides in the two medicinal Panax herbs based on ultra-performance liquid chromatography-electrospray ionization-mass spectrometry.

As the king of herb plants, ginseng has been used for nearly 5000 years in medicines in Asia and recently in the West. Ginsenosides, the main active constituents in Panax herbs, have prominent immunoregulatory effects. Although extensively studied in the roots, ginsenosides have not been studied with regard to their profiles and natural variations in the leaf, stem, petiole, lateral root, and main roots during development or among species. In this study, a sensitive ultra-performance liquid chromatography-electrospray ionization–mass spectrometry method with a shorter chromatographic running time was developed and validated for simultaneous quantification of ten ginsenosides. Comparing ginsenoside contents in various parts during different developmental stages revealed part-specific accumulation of most ginsenosides. Further investigation indicated that Rg3 accumulated at significantly higher levels in the petiole of P. ginseng than in that of P. quinquefolius. The relative ratio of ginsenoside Rb2 to Rb1 appears to be a candidate metabolic marker for identifying the ginseng cultivar within a diverse collection of ginseng accessions. In addition, the PCA showed that aboveground parts differed significantly between species and can be considered as species-specific markers rather than roots. This comprehensive survey, providing reliable, affordable and adequate scientific evidence, could be used to differentiate two species and discriminate ginseng cultivar ages.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-3427-3) contains supplementary material, which is available to authorized users.

Plasma free amino acid profile changes in hepatocellular carcinoma patients

Objective The aim of this study was to investigate plasma amino acid profile as a possible diagnostic/prognostic method in patients with hepatocellular carcinoma. Background Many previous reports have shown that metabolism is notably altered in cancer cells. Thus, various methods for cancer diagnosis and prognosis have been developed based on metabolite analysis. Among whole metabolites, amino acids were proposed as suitable candidates for focused metabolomics as they are either ingested or synthesized endogenously and they play an essential physiological role both as basic metabolites and metabolic regulators. Patients and methods This study included 71 hepatocellular carcinoma patients (60 male and 11 female) and 30 chronic hepatitis C virus patients (20 male and 10 female) in addition to 30 healthy controls (25 male and 5 female). Laboratory investigations including complete blood picture, liver function tests, serum α-fetoprotein, hepatitis viral markers (HBsAg and anti-HCVAb) were carried out for all participants. Amino acid assay was carried out using ultra performance liquid chromatography–electrospray ionization-mass spectrometry. Results The study showed a statistically significant increase in methionine, tyrosine, ornithine, citrulline, glycine, phenylalanine, alanine, glutamate, proline, and arginine and a decrease in valine, aspartate, leucine/isoleucine, branched tyrosine ratio (BTR), and Fischer's ratio in hepatocellular carcinoma compared with the control group. Moreover, the study indicated that there was a statistically significant correlation between BTR and platelets, alanine transaminase, albumin, bilirubin, and α-fetoprotein and significant differences in BTR among Child-Pugh A, B, and C. Conclusion Our results suggested that the plasma free amino acid profile is considered valuable for diagnosis and nutritional care in cancer patients. Furthermore, BTR reflects the pathological liver background with a high degree of correlation with other liver functional markers.

Distinguishing commercially grown Ganoderma lucidum from Ganoderma lingzhi from Europe and East Asia on the basis of morphology, molecular phylogeny, and triterpenic acid profiles

In China and other countries of East Asia, so-called Ling-zhi or Reishi mushrooms are used in traditional medicine since several centuries. Although the common practice to apply the originally European name ‘Ganoderma lucidum’ to these fungi has been questioned by several taxonomists, this is still generally done in recent publications and with commercially cultivated strains. In the present study, two commercially sold strains of ‘G. lucidum’, M9720 and M9724 from the company Mycelia bvba (Belgium), are compared for their fruiting body (basidiocarp) morphology combined with molecular phylogenetic analyses, and for their secondary metabolite profile employing an ultra-performance liquid chromatography–electrospray ionization mass spectrometry (UPLC–ESIMS) in combination with a high resolution electrospray ionization mass spectrometry (HR-ESI-MS). According to basidiocarp morphology, the strain M9720 was identified as G. lucidum s.str. whereas M9724 was determined as Ganoderma lingzhi. In molecular phylogenetic analyses, the M9720 ITS and beta-tubulin sequences grouped with sequences of G. lucidum s.str. from Europe whereas those from M9724 clustered with sequences of G. lingzhi from East Asia. We show that an ethanol extract of ground basidiocarps from G. lucidum (M9720) contains much less triterpenic acids than found in the extract of G. lingzhi (M9724). The high amount of triterpenic acids accounts for the bitter taste of the basidiocarps of G. lingzhi (M9724) and of its ethanol extract. Apparently, triterpenic acids of G. lucidum s.str. are analyzed here for the first time. These results demonstrate the importance of taxonomy for commercial use of fungi.

Development and characterization of a nanodendritic silver-based solid-phase extraction sorbent for selective enrichment of endocrine-disrupting chemicals in water and milk samples

In this study, 4-[4-phenylazo-phenoxy] butyl-1-thiol (AzSH) functionalized nanodendritic silver (AzS@AgNDs) materials were prepared as a solid-phase extraction (SPE) sorbent for the selective extraction of estrogens. AzS@AgNDs possess an extremely large surface-to-volume ratio and a small average particle size. The performance of the material was evaluated by selective enrichment of hexestrol, diethylstilbestrol, dienestrol and bisphenol A in water and milk samples followed by rapid ultra-performance liquid chromatography–electrospray ionization mass spectrometry (UPLC–ESI–MS) analyses. The results exhibited that AzS@AgNDs had excellent adsorption capability for the targeted estrogens. The limits of detection of the four estrogens ranged from 0.1 to 5.0 pg/mL. The recoveries of the estrogens spiked into tap water were over the range of 83.6–105.3% with relative standard deviations of 2.8–6.0%. The results indicated the capability of this method for the rapid determination of estrogens in milk and other environmental water samples. In addition, this method would be useful for the determination of human exposure and health risk assessments trace level of endocrine-disrupting compounds (EDCs) in drinking water.

Degradation of iohexol by UV/chlorine process and formation of iodinated trihalomethanes during post-chlorination

Degradation kinetics of iohexol by UV/chlorine advanced oxidation process (AOP) and the formation of iodinated trihalomethanes (I-THMs) during post-chlorination were investigated in this study. Iohexol, a commonly detected iodinated contrast media in water, can be effectively removed during UV/chlorine process with pseudo-first-order reaction kinetics due to the combination of UV photolysis and oxidation of hydroxyl radicals. The second-order rate constant between iohexol and hydroxyl radicals was determined as 3.8×109M−1s−1 by competition kinetic experiment. Five intermediates were identified by ultra performance liquid chromatography–electrospray ionization-mass spectrometry analysis and degradation pathways of iohexol during UV/chlorine were proposed. Effects of chlorine dose, pH and bromide concentration on iohexol degradation and I-THM formation during post-chlorination were also studied. The results showed that iohexol degradation was accelerated with the increase of chlorine concentration as well as the decrease of pH and bromide concentration. On the other hand, I-THM formation from post-chlorination of UV/chlorine treated iohexol favored relatively low chlorine doses, high bromide concentrations at circumneutral conditions. Raw water experiments showed that I-THM formation after post-chlorination of UV/chlorine-treated iohexol was lower compared to that from UV irradiation, indicating that UV/chlorine is superior to UV alone in controlling I-THM formation.

Solid-phase extraction of PFOA and PFOS from surface waters on functionalized multiwalled carbon nanotubes followed by UPLC–ESI-MS

This is the first report on the analytical application of multiwalled carbon nanotubes (MWCNTs) as solid-phase extraction (SPE) sorbents for determination in surface waters, at the nanograms per litre level, of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), the two predominant contaminants among the perfluorinated compounds detected. After the preconcentration step, the quantification was achieved by ultraperformance liquid chromatography-electrospray ionization mass spectrometry. To increase the extraction efficiency towards these amphiphilic compounds, MWCNTs were derivatized with amino-terminated alkyl chains, thus producing a mixed-mode material (MWCNT-R-NH2) combining hydrophobic affinity and anion-exchange properties. Experiments with distilled, tap and river water (pH 3) spiked at different concentrations (10, 15, 30, 100, 200 and 500 ng L(-1)) provided absolute recoveries in the range 71-102% (n = 3, relative standard deviations less than 10%). Analytes were eluted in a single fraction with 6 mL methanol (3 × 10(-4) M NaOH). The within-laboratory reproducibility of the MWCNT-R-NH2 SPE sorbent was evaluated with raw river water, and relative standard deviations less than 15% were obtained (n = 4). Preconcentration factors up to 125 (500-mL sample) made it possible to quantify PFOA and PFOS at low nanograms per litre levels in naturally contaminated river water. The method quantification limits of 10 ng L(-1) for PFOA and 15 ng L(-1) for PFOS were well below the advisory levels for drinking and surface waters. Comparison with non-derivatized MWCNTs highlighted the role of functionalization in improving the adsorption affinity towards these contaminants. MWCNT-R-NH2 maintained their extraction capability for at least eight repeated adsorption/desorption cycles.

Enhancement of anti-inflammatory activity of Aloe vera adventitious root extracts through the alteration of primary and secondary metabolites via salicylic acid elicitation.

Aloe vera (Asphodeloideae) is a medicinal plant in which useful secondary metabolites are plentiful. Among the representative secondary metabolites of Aloe vera are the anthraquinones including aloe emodin and chrysophanol, which are tricyclic aromatic quinones synthesized via a plant-specific type III polyketide biosynthesis pathway. However, it is not yet clear which cellular responses can induce the pathway, leading to production of tricyclic aromatic quinones. In this study, we examined the effect of endogenous elicitors on the type III polyketide biosynthesis pathway and identified the metabolic changes induced in elicitor-treated Aloe vera adventitious roots. Salicylic acid, methyl jasmonate, and ethephon were used to treat Aloe vera adventitious roots cultured on MS liquid media with 0.3 mg/L IBA for 35 days. Aloe emodin and chrysophanol were remarkably increased by the SA treatment, more than 10–11 and 5–13 fold as compared with untreated control, respectively. Ultra-performance liquid chromatography-electrospray ionization mass spectrometry analysis identified a total of 37 SA-induced compounds, including aloe emodin and chrysophanol, and 3 of the compounds were tentatively identified as tricyclic aromatic quinones. Transcript accumulation analysis of polyketide synthase genes and gas chromatography mass spectrometry showed that these secondary metabolic changes resulted from increased expression of octaketide synthase genes and decreases in malonyl-CoA, which is the precursor for the tricyclic aromatic quinone biosynthesis pathway. In addition, anti-inflammatory activity was enhanced in extracts of SA-treated adventitious roots. Our results suggest that SA has an important role in activation of the plant specific-type III polyketide biosynthetic pathway, and therefore that the efficacy of Aloe vera as medicinal agent can be improved through SA treatment.

Measurement of salivary metabolite biomarkers for early monitoring of oral cancer with ultra performance liquid chromatography–mass spectrometry

This study aimed to set-up an ultra performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS) method for the determination of salivary L-phenylalanine and L-leucine for early diagnosis of oral squamous cell carcinoma (OSCC). In addition, the diagnostic accuracy for both biomarkers was established by using receiver operating characteristic (ROC) analysis. Mean recoveries of l-phenylalanine and L-leucine ranged from 88.9 to 108.6% were obtained. Intra- and inter-day precision for both amino acids was less than 7%, with acceptable accuracy. Linear regression coefficients of both biomarkers were greater than 0.99. The diagnostic accuracy for both biomarkers was established by analyzing 60 samples from apparently healthy individuals and 30 samples from OSCC patients. Both potential biomarkers demonstrated significant differences in concentrations in distinguishing OSCC from control (P<0.05). As a single biomarker, L-leucine might have better predictive power in OSCC with T1-2 (early stage of OSCC including stage I and II), and L-phenylalanine might be used for screening and diagnosis of OSCC with T3-4 (advanced stage of OSCC including stage III and IV). The combination of L-phenylalanine and L-leucine will improve the sensitivity (92.3%) and specificity (91.7%) for early diagnosis of OSCC. The possibility of salivary metabolite biomarkers for OSCC diagnosis is successfully demonstrated in this study. This developed method shows advantages with non-invasive, simple, reliable, and also provides lower detection limits and excellent precision and accuracy. These non-invasive salivary biomarkers may lead to a simple clinical tool for the early diagnosis of OSCC.

Rapid sensitive validated UPLC–MS method for determination of venlafaxine and its metabolite in rat plasma: Application to pharmacokinetic study

A new ultra-performance liquid chromatography–electrospray ionization mass spectrometry (UPLC–MS/ESI) method for simultaneous determination of venlafaxine (VEN) and its metabolite O-desmethylvenlafaxine (ODV) in rat plasma has been developed and validated using Venlafaxine d6 as the internal standard. The compounds and internal standard were extracted from plasma by solid phase extraction. The UPLC separation of the analytes was performed on ACQUITY UPLC® BEH Shield RP18 (1.7µm, 100mm×2.1mm) column, using isocratic elution with mobile phase constituted of water (containing 2mM ammonium acetate): acetonitrile (20:80, v/v) at a flow rate of 0.3mL/min. All of the analytes were eluted within 1.5min. The compounds were ionized in the electrospray ionization (ESI) ion source of the mass spectrometer, operating in multiple reaction monitoring (MRM) and positive ion mode. The precursor to product ion transitions monitored for VEN, ODV and Venlafaxine d6 were m/z 278.3→121.08, 264.2→107.1 and 284.4→121.0, respectively. The developed and validated method was used for the pharmacokinetic study of VEN in rats.

Structural analysis of A-type or B-type highly polymeric proanthocyanidins by thiolytic degradation and the implication in their inhibitory effects on pancreatic lipase

Compared with oligomeric proanthocyanidins, highly polymeric proanthocyanidins have more difficulty to analyze the molecular sizes and the mode of interflavan linkages of flavan-3-ol units through doubly linked A-type bonds and single B-type bonds. Recently, we have shown that seed shells of the Japanese horse chestnut contain highly polymeric proanthocyanidins as dominant polyphenolics that can be separated into two fractions according to the difference in the molecular sizes. Here, we tried to perform the structural characterization of them in terms of the molecular sizes and the proportions of A-type linkages relative to B-type linkages. The results were compared with those of the corresponding preparations with variations in the sizes from fruits of blueberry and cranberry. Gel permeation chromatography revealed that the molecular sizes of them were higher in the order of blueberry > cranberry > seed shells of the Japanese horse chestnut when they are compared between the respective fractions. For the analysis of terminal and extension units of those proanthocyanidins, the isolated fractions were subjected to the thiolytic cleavage of the B-type linkages using 1-dodecanethiol, and the resulting degradation products were identified by ultra-performance liquid chromatography electrospray-ionization mass spectrometry (UPLC-ESI/MS). These analyses provided fast and good resolution of the degradation products and revealed higher proportions of A-type linkages compared with B-type linkages in the both isolated fractions in the order of the seed shells > cranberry > blueberry. Moreover, the isolated fractions with higher molecular sizes and those more abundant in the proportions of A-type linkages were found to be more effective in the inhibition of pancreatic lipase activity. The results suggest that higher molecular sizes and more abundance of A-type bonds in polymeric proanthocyanidins are promising key factors for the attenuation of lipid digestion as dietary supplements.

Voluntary wheel running exercise and dietary lactose concomitantly reduce proportion of secondary bile acids in rat feces

According to epidemiologic studies, a negative correlation exists between exercise amount and subsequent cancer development risk in the large intestine. The proportion of secondary bile acids (SBA) in the large intestine is related to subsequent risk for colorectal carcinogenesis. The aim of this study was to investigate the effects of voluntary wheel running exercise and dietary intervention on bile acid (BA) metabolism in the large intestine. Wistar/ST rats (6 wk old) were divided into two groups, exercise and sedentary, after acclimation. Four days after the animals were assigned to a group, rats in each group were fed diets supplemented with different carbohydrate sources including dextrin, sucrose, and lactose. The wheel running period was 4 wk in the exercise group, whereas rats in the sedentary group remained in individual cages during this period. BA composition in collected feces was analyzed with ultraperformance liquid chromatography-electrospray ionization mass spectrometry. We found that wheel running exercise decreased plasma concentrations of cholesterol, triglyceride, and free fatty acids. These decreases were accompanied by a reduction in the proportion of SBA to primary BA (PBA) in feces; however, daily excretion of BA was comparable regardless of wheel running exercise. In addition, ingestion of lactose decreased the SBA-to-PBA ratio and suppressed production of hyodeoxycholic acid in feces. In conclusion, voluntary wheel running exercise, in combination with dietary intervention, could independently reduce the SBA-to-PBA ratio within the large intestine without changing BA excretion. These changes may contribute to the prevention of colorectal carcinogenesis.

Simultaneous determination of senecionine, adonifoline and their metabolites in rat serum by UPLC–ESIMS and its application in pharmacokinetic studies

A rapid, selective and sensitive ultra-performance liquid chromatography–electrospray ionization mass spectrometry (UPLC–ESIMS) method was firstly developed and validated for the simultaneous determination of two hepatotoxic pyrrolizidine alkaloids (HPAs), senecionine (SEN), adonifoline (ADO), and their N-oxides (SENNOX and ADONOX), the main metabolites in rat serum. The whole analysis was achieved within 4.5 min by gradient elution on an ACQUITY UPLC BEH C18 column (50 mm × 2.1 mm, i.d. 1.7 μm) following a solid phase extraction for serum samples. Good linearity was achieved using weighted (1/ x 2) least squares linear regression over a 1600-fold dynamic range for SEN and ADO (LLOQ was about 0.006 μg/ml) and 800-fold dynamic range for SENNOX and ADONOX (LLOQ was about 0.012 μg/ml). The R.S.D. of intra- and inter-day precision was below 4.91% and 11.15% respectively, while the R.E. of accuracy was within 4.52%, 6.81%, 2.69%, and 7.12% for SEN, SENNOX, ADO, and ADONOX, respectively. The developed method was successfully applied to the in vivo pharmacokinetic study in rats after intravenous administration of SEN and ADO.

Rapid detection of ketamine and norketamine in rat hair using micropulverized extraction and ultra‐performance liquid chromatography–electrospray ionization mass spectrometry

A new method for the rapid and simultaneous detection of ketamine and its major metabolite, norketamine, in rat hair has been developed by combining micropulverized extraction and ultraperformance liquid chromatography-electrospray ionization mass spectrometry. By using reversed-phase UPLC, ketamine and norketamine were well separated within 2 min. Using ketamine-dosed rat hair, the conditions for micropulverized extraction were optimized, and the limits of detection and quantification of the developed method were found to be 1.7 and 5.7 pg/mg hair for ketamine, respectively. The precisions achieved with this method were slightly better than that obtained with conventional acidic methanol extraction method. Using this proposed method, analysis of the washed rat hair could be completed within 16-17 min. This method is expected to be applied for the analysis of the hair samples of not only rats but also ketamine abusers.

Determination of 13 Free Fatty Acids in Pheretima Using Ultra-Performance LC-ESI-MS

A simple and rapid ultra-performance liquid chromatography-electrospray ionization mass spectrometry method for the simultaneous determination of thirteen free fatty acids (FFAs) in Pheretima has been developed and validated. Measurements for each FFA were linear over a wide range (0.05–3.95 μg mL−1) with good correlation coefficients (>0.99). The limit of detection and limit of quantification for all the fatty acids were below 26 and 78 ng mL−1, respectively. The intra- and inter-assay precision and accuracy for the thirteen FFAs fell well within the predefined limits of acceptability. Satisfactory recoveries were in the range of 96–103%.

Determination of quinapril and quinaprilat in human plasma by ultraperformance liquid chromatography–electrospray ionization mass spectrometry

A novel, specific and sensitive ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination of quinapril and its active metabolite quinaprilat in human plasma. The method involves a simple, one-step extraction procedure coupled with an Acquity UPLC BEH C(18 )column (100 x 2.1 mm, i.d., 1.7 microm) with isocratic elution at a flow-rate of 0.2 mL/min and lisinopril as the internal standard. Detection was performed on a triple-quadrupole tandem mass spectrometer in multiple reaction monitoring mode via electrospray ionization. Using 250 microL plasma, the methods were validated over the concentration range 5.010-500.374 ng/mL for quinapril and 10.012-1000 ng/mL for quinaprilat, with a lower limit of quantification of 5.010 ng/mL for quinapril and 10.012 ng/mL for quinaprilat. The intra- and inter-day precision and accuracy were within 10.0%. The recovery was 85.8, 62.6 and 61.3% for quinapril, quinaprilat and lisinopril, respectively. Total run time was 3.0 min only.