Liquid Chromatography-tandem Quadrupole Mass Research Articles

Ultratrace analysis of per- and polyfluoroalkyl substances in drinking water using ice concentration linked with extractive stirrer and high performance liquid chromatography – tandem mass spectrometry

Detection of drinking water contaminants is vital to the protection of human health. One group of contaminants that have recently generated serious concerns over health risks are per- and polyfluoroalkyl substances (PFAS). These compounds are very bio-persistent, leading to their detection in all types of water sources, including drinking water. While analysis of drinking water for PFAS is important, it is currently arduous to detect ultratrace levels of these contaminants. Specifically, current ultratrace PFAS analysis methods are difficult, costly, require large sample volumes, and consume relatively large volumes of organic solvent. In the present work, an analytical method using Ice Concentration Linked with Extractive Stirrer (ICECLES) and high performance liquid chromatography—tandem quadrupole mass spectrometry (HPLC-MS/MS), was developed and validated to provide simple and ultratrace analysis of drinking water for 14 PFAS. The method featured a relatively low sample volume requirement (10 mL), automated extraction, minimal matrix effects, and minimal organic solvent use (i.e., the method requires only 50 µL of methanol per sample). The method produced a wide linear range of 0.5 to 500 ng/L, ultratrace limits of detection (0.05 to 0.3 ng/L), and good accuracy and precision (i.e., 87 to 108% accuracy and ≤19% relative standard deviation as a measure of precision). This method was tested on drinking water samples from across the United States and detected at least one PFAS compound in 52 of the 53 drinking water samples tested. Perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluoroheptanoic acid (PFHpA) were detected in 89, 96, and 77% of the samples tested with maximum concentrations of 268 ng/L for PFHxA, 213 ng/L for PFOA, and 75.7 ng/L for PFHpA. Additionally, perfluorononanoic acid, perfluorodecanoic acid, and perfluoroheptanoic acid were each detected in at least one drinking water sample at concentrations > 20 ng/L. The availability of the method presented here allows ultratrace detection of PFAS while circumventing many of the disadvantages of current methods.

Metonitazene in the United States-Forensic toxicology assessment of a potent new synthetic opioid using liquid chromatography mass spectrometry.

Metonitazene is considered a new psychoactive substance (NPS) and emerging potent synthetic opioid, causing increased public health concern beginning in 2020. Metonitazene joins a growing list of new synthetic opioids (NSOs) contributing to deaths among people who use drugs in the United States and other parts of the world. Metonitazene (a 2-benzylbenzimidazole analogue) first appeared in mid-2020 in the recreational drug supply and subsequently began proliferating in death investigation casework towards the end of 2020. Screening and metabolite discovery were performed by liquid chromatography quadrupole time-of-flight mass spectrometry. Quantitative confirmation was performed by liquid chromatography tandem quadrupole mass spectrometry. Metonitazene was confirmed in 20 authentic forensic postmortem cases with an average concentration in blood at 6.3 ± 7.5ng/ml (median: 3.8ng/ml, range: 0.5-33 ng/ml, n = 18) and in urine at 15 ± 13 ng/ml (median: 11 ng/ml, range: 0.6-46 ng/ml, n = 14). Metonitazene was the only opioid identified in 30% of cases but was also found in combination with fentanyl (55%) and NPS benzodiazepines, opioids, and hallucinogens (45%). Medical examiners included metonitazene as a drug responsible for the cause of death, and the manner of death was always ruled to be an accident. The metabolism of metonitazene was found to be similar to that of isotonitazene, a closely related analogue. Toxicology laboratories and death investigators should ensure that metonitazene is included in forensic testing protocols, all while remaining vigilant for subsequent NSOs to emerge.

Effects of Xian-Ling-Gu-Bao capsule on the gut microbiota in ovariectomized rats: Metabolism and modulation

Xian-Ling-Gu-Bao capsule (XLGB) has been proven to prevent and treat osteoporosis. However, as a long-term oral formula, XLGB's effects on the metabolic capacity, structure and function of gut microbiota have yet to be elucidated in ovariectomized (OVX) rats. Our objectives were to evaluate the capacity of gut microbiota for metabolizing XLGB ingredients and to assess the effect of this prescription on gut microbiota. Herein, an integrated analysis that combined ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and ultrahigh-performance liquid chromatography tandem triple quadrupole mass spectrometry (UPLC-TQD-MS) was conducted to determine the metabolic capacity of gut microbiota. The effects of XLGB on gut microbiota were explored by metagenomic sequencing in OVX rats. Fecal samples from each group were collected after intragastric administration for three months. In total, 64 biotransformation products were fully characterized with rat gut microbiota from the OVX group and the XLGB group. The deglycosylation reaction was the main biotransformation pathway in core structures in the group that was incubated with XLGB. Compared with the OVX group, different biotransformation products and pathways of the XLGB group after incubation for 2 h and 8 h were described. After three months of feeding with XLGB, the domesticated gut microbiota was conducive to the production of active absorbed components via deglycosylation, such as icaritin, psoralen and isopsoralen. Comparisons of the gut microbiota of the OVX and XLGB groups showed differences in the relative abundances of the two dominant bacterial divisions, namely, Firmicutes and Bacteroidetes. The proportion of Firmicutes was significantly lower and that of Bacteroidetes was significantly higher in the XLGB group. This result demonstrated that XLGB could provide a basis for the treatment of osteoporosis by regulating lipid and bile acid metabolism. In addition, the increase in Lactobacillus, Bacteroides and Prevotella could be an important factor that led to easier production of active absorbed aglycones in the XLGB group. Our observation provided further evidence of the importance of gut microbiota in the metabolism and potential activity of XLGB.

Quantification of major royal jelly proteins using ultra performance liquid chromatography tandem triple quadrupole mass spectrometry and application in honey authenticity

Major royal jelly proteins (MRJPs) have been used as endogenous biomarkers for honey authentication. However, no study on quantification of MRJPs in honey authentication was reported. In order to develop a new honey authenticity method based on quantitative analysis of MRJPs in honey, trypsin-digested peptides from MRJPs were examined by mass spectrometry (MS). Three peptides, YNGVPSSLNVISK, TLQMIAGMK, and LTVAGESFTVK were selected as specific markers for MRJP1, MRJP 2 and MRJP 3(MRJP1∼3), respectively. An ultra performance liquid chromatography-triple quadrupole MS (UPLC-TQMS) method used for quantification of MRJPs in honey was developed and validated. A database on the MRJP1∼3 contents of honey established by quantification of 70 authentic samples showed a potential application in honey authenticity identification. The analysis results of 10 commercial honey samples by UPLC-TQMS with reference to the MRJP1∼3 database of authentic honey were compared and confirmed by widely used isotope ratio mass spectrometry, a AOAC Official Method. In conclusion, the results showed our method, a proteomic-based UPLC-TQMS method, has a high accuracy, sensitivity and specificity for honey authenticity.

Pharmacokinetics and biotransformation investigation in beagle dog of active compounds from naoxintong capsule

Naoxintong Capsule (NXTC), a standardized herbal medicine, has been widely applied in treating cardiovascular and cerebrovascular diseases with remarkable efficacy. However, the efficacy contributing components of NXTC are unclear, and the in vivo absorption and metabolism processes of NXTC remain largely obscured. In this study, using beagle dog as model species, we have identified and tentatively characterized 25 prototype and 15 catabolites of NXTC in beagle dog plasma by ultra-fast liquid chromatography/quadrupole-time-of-flight tandem mass spectrometry (UFLC-Q-TOF-MS/MS). We have proposed the in vivo bio-transformation pathways of these absorbed constituents. In addition, for six crucial components, we have developed a quantitative method and conducted plasma pharmacokinetic study of these six components by rapid resolution liquid chromatography tandem triple quadrupole mass spectrometry (RRLC-QQQ-MS/MS). In conclude, our study provided comprehensive insights into the understanding of the plasma absorbed components profiling of NXTC as well as their in vivo transformation behaviors, which would be of great value for identifying efficacy contributing critical components as well as mechanism related investigations of NXTC in the future.

Enantioseparation and stereoselective dissipation of the novel chiral fungicide pydiflumetofen by ultra-high-performance liquid chromatography tandem mass spectrometry

Pydiflumetofen is a novel and efficient broad-spectrum chiral fungicide consisting of a pair of enantiomers. A simple and sensitive chiral analytical method was established to determine the enantiomers of this chiral fungicide in food and environmental samples by ultra-high-performance liquid chromatography tandem triple quadrupole mass spectrometry (UHPLC-MS/MS) using QuEChERS method coupled with octadecylsilane-dispersive solid-phase extraction (C18-dSPE) as extraction procedure. The specific optical rotation and the absolute configuration of the enantiomers were identified by polarimetry and electronic circular dichroism (ECD). The elution order of the pydiflumetofen enantiomers on Lux Cellulose-2 was S-(−)-pydiflumetofen and R-(+)-pydiflumetofen. The average recoveries of eleven matrices ranged from 71.3% to 107.4%. The intraday relative standard deviations (RSDs) were less than 11.8%, and the interday RSDs were less than 12.6% for the two enantiomers. Stereoselective dissipation in pakchoi and soil were observed: S-(−)-pydiflumetofen was degraded faster than R-(+)-pydiflumetofen in pakchoi, causing the enantiomer fraction (EF) of the enantiomers to change from 0.50 to 0.42 in 7 days. However, R-(+)-pydiflumetofen was degraded faster than S-(−)-pydiflumetofen in soil, causing the EF of the enantiomers to change from 0.49 to 0.52 in 21 days. This study provides a method for monitoring pydiflumetofen enantiomer residues, which is crucial for improving risk assessments and the development of chiral pesticides.

Simultaneous Quantitative Analysis of Multiple Biotransformation Products of Xian-Ling-Gu-Bao, a Traditional Chinese Medicine Prescription, with Rat Intestinal Microflora by Ultra-Performance Liquid Chromatography Tandem Triple Quadrupole Mass Spectrometry.

Xian-Ling-Gu-Bao (XLGB), a famous traditional Chinese medicine prescription consisted of six herbal medicines, was used for prevention and treatment of osteoporosis in China. As an oral formulation, the multiple components contained in XLGB were inevitably biotransformed by the intestinal microflora before absorption via the gastrointestinal tract. However, the dynamic profiles of biotransformation products of XLGB remain unknown. In this paper, a rapid and sensitive ultra-performance liquid chromatography tandem triple quadrupole mass spectrometry method was developed for the simultaneous quantitative analysis of multiple biotransformation products of XLGB with rat intestinal microflora. For 10 selected quantitative compounds, all calibration curves revealed good linearity (r2>0.99) within the sampling ranges considered. The whole intra- and inter-day precisions (as relative standard deviation) of all analytes were <13.5%, and the accuracies (as relative error) were in the range from -11.3 to 11.2%. The lower limits of quantification were 20, 10, 5, 20, 2, 2, 2, 5, 2 and 2ng/mL for sweroside, timosaponin BII, epimedin C, asperosaponin VI, psoralen, isobavachin, icariside II, timosaponin AIII, isobavachalcone and icaritin, respectively. The matrix effects, extraction recoveries and stabilities were all satisfactory. Meanwhile, dynamic profiles of 21 additional biotransformation products were also monitored by their area-time curves. The analytical method was successfully applied to describe dynamic profiles of 31 biotransformation products of XLGB and the recipes with removal of a definite composed herbal medicine (Anemarrhenae Rhizoma or Rehmanniae Radix).

Extraction Optimization of Six Alkaloids and Four Lignans in Zanthoxylum armatum by Orthogonal Design and Ultra-fast Liquid Chromatography–tandem Quadrupole Mass Spectrometry

Alkaloids and lignans in Zanthoxylum armatum display important biological activities, but the quanitification method of alkaloids has not been reported. In this study, an effective extraction method was developed through an orthogonal design, and ten compounds in roots, stems, branches and leaves of Zanthoxylum armatum were simultaneously quantified by ultra-fast liquid chromatography–tandem quadrupole mass spectrometry (UFLC–MS/MS). The roots, stems, branches and leaves of Z. armatum were ultrasonically extracted with methanol (solvent–to–sample ratio 100 : 1, v/w) for 10 min. An UFLC–MS/MS method was developed with a gradient UFLC mobile phase and triple quadruple tandem mass spectrometry with electrospray ionization in the positive ion mode. The method was validated for linearity, precision, repeatability and accuracy. The limits of detection and quantification were within 0.01–7.5 and 0.04–30 ng/mL, respectively. The root samples collected from Tian’e County were abundant in N-methylanhydrotetrahydroberberrubine A, escholidine perchlorate and pinoresinol monomethyl ether, eudesminthe.

Focus on photonics, spectrometry, and spectroscopy

Focus on photonics, spectrometry, and spectroscopy

Distribution of Psychotropic Drugs Into Lipoproteins.

The aim of this pilot study was to investigate whether psychotropic drugs frequently analyzed in a routine therapeutic drug monitoring laboratory bind to low-density lipoproteins/very-low-density lipoproteins (LDL/VLDL) in human serum. Drug concentrations in 20 serum sample pools containing one psychotropic drug each, and in the LDL/VLDL fractions extracted from the same samples, were measured by triple quadrupole liquid chromatography tandem mass spectrometry. The membrane permeability of the drugs was measured using a Parallel Artificial Membrane Permeability Assay. Of the 20 antidepressants, antipsychotics, and antiepileptics examined, 7 drugs were detected in both the pooled serum samples and in the LDL/VLDL fraction. Binding of drugs to LDL/VLDL significantly correlated with high octanol: water partition coefficient (logP), high degree of protein binding, and a low polar surface area. The drugs found in LDL/VLDL, with the exception of aripiprazole, were also characterized by high or intermediate membrane permeability. The present results indicate that psychotropic drugs with certain characteristics bind to LDL/VLDL in blood. This further implies that lipoproteins could play an important role in drug transport.

Dynamic Variations in Multiple Bioactive Constituents under Salt Stress Provide Insight into Quality Formation of Licorice.

The demand for licorice and its natural product derivatives in domestic and foreign market is considerably huge. The core production areas of licorice are covered with salinity and drought land in northwestern China. Studies have shown that suitable environmental stress can promote the accumulation of glycyrrhizin and liquiritin to improve its quality as medicinal materials. However, there are few reports on other bioactive constituents of licorice, not to mention their dynamic accumulation under stressed conditions. To explore the quality formation of licorice from the perspective of salt influence, a reliable method based on ultra-fast liquid chromatography tandem triple quadrupole mass spectrometry (UFLC–MS/MS) was established for simultaneous determination of sixteen bioactive constituents, including triterpenoids, flavonoids, chalcones and their glycosides. Physiological experiments were performed to investigate salt tolerance of licorice under different salinity treatments. The expressions of crucial genes (bAS and CHS), key enzymes of triterpenoid and flavonoid synthesis, were also tested by qRT-PCR. Our study found that 50 mM NaCl treatment (low stress) was the most favorable to promote the accumulation of bioactive constituents in the long term, without harming the plants. Flavonoid accumulation of non-stressed and low-stressed groups became different in the initial synthesis stage, and glycosyltransferases may have great influence on their downstream synthesis. Furthermore, bAS and CHS also showed higher levels in low-stressed licorice at harvest time. This work provides valuable information on dynamic variations in multiple bioactive constituents in licorice treated by salt and insight into its quality formation under stressed conditions.

Variation in Plant Morphology and Sinigrin Content in Ethiopian Mustard (Brassica carinata L.)

Ethiopian mustard (Brassica carinata) is mainly grown as a leafy vegetable and oilseed crop. Sinigrin is predominant glucosinolate in the leaves of Ethiopian mustard. It is hydrolyzed by enzyme myrosinase to produce bioactive product specifically allyl-isothiocyanates. Due to sinigrin content, Ethiopian mustard has a mild flavor and it is a healthy addition to human diet. However, sinigrin concentration depends on genotype. Understanding variations of plant morphology and sinigrin content may be the first step for crop improvement. According to the analyses of various plant characteristics among ninety nine Ethiopian mustard accessions, we found significant differences in plant height, chlorophyll content, and petiole length. In addition, sinigrin content was determined using ultra-performance liquid chromatography tandem quadrupole mass spectrometers/tunable ultraviolet detector (UPLC-TQS/TUV). We found a significant difference in sinigrin content among leaves of 94 Ethiopian mustard accessions. Except for petiole length, the sinigrin content was negatively correlated with leaf area, leaf width, number of primary branches, and plant height. This information will help Ethiopian mustard breeders in screening breeding lines for new accessions.

Quantitative analysis of pyrrolizidine alkaloids in Gynura procumbens by liquid chromatography–tandem quadrupole mass spectrometry after enrichment by PCX solid-phase extraction

ABSTRACTGynura procumbens is commonly consumed as a vegetable and has been approved as an ingredient for food and dietary supplements in China. However, Gynura species are known to contain toxic pyrrolizidine alkaloids (PAs) and the PA profiles in G. procumbens are not known. This study was to extract and enrich PA from G. procumbens or health care products using PCX solid-phase extraction (SPE) cartridges identify the main PAs in the herb and to develop an liquid chromatography–mass spectrometry (LC-MS/MS) method for assaying the PA contents in the plant and its derived products. Upon using multiple reaction monitoring (MRM) acquisition together with comparison to the characteristics of mass fragmentations and retention times of reference standards, 11 PAs were identified as the main PAs in the plant. After clean-up and enrichment with PCX solid-phase extraction (SPE) cartridges, which resulted in better PA recoveries than either C18 or SCX cartridges, the LC-MS/MS method was subjected to validation in terms of linearity, repeatability, limits of quantification (LOQ) and recovery. The validated method was applied to quantify PAs in 12 plant samples and 7 commercial finished products. The total amounts of targeted PAs were found to vary from 15.6 to 848 μg/kg in the herbs and from 9.9 μg/kg to 33.9 mg/kg in the commercial products. The present work was the first to demonstrate that G. procumbens contained PAs in the herb and its derived products and the PA contents might exceed the daily dose limits in food and herbal medicinal products proposed by the European Medicines Agency (i.e. 0.35 μg PA per day for 50 kg adult).

Prevalence of phycotoxin contamination in shellfish from the Northern Bering Sea and the Chukchi Sea

To understand phycotoxin contamination in shellfish in the sub-Arctic and Arctic areas, scanning for the presence of 13 hydrophilic and lipophilic toxin components each was by liquid chromatography tandem quadrupole mass spectrometry analysis in shellfish samples collected from the Northern Bering Sea and the Chukchi Sea in 2014. The results showed that shellfish collected in both areas werecontaminated to different extents. Saxitoxin (STX), decarbamoylsaxitoxin (dcSTX) and decarbamoylneosaxitoxin (dcNEO) were the most frequently detected hydrophilic components, with maximum concentrations of 90.1 μg/kg, 112.25 μg/kg and 23.09 μg/kg, respectively. Although gonyautoxins (GTXs) were only detected in 3 samples, they were the main contributors to overall toxicity of high-latitude samples, especially GTX1. For lipophilic toxins, spirolide-1 (SPX1) and yessotoxin (YTX) were present in all samples at low levels (< 7 μg/kg and < 50 μg/kg, respectively). Only 5 samples showed evidence of okadaic acid (OA) and dinophysistoxin-2 (DTX-2) at low concentrations, ranging from 0.42 μg/kg to 7.23 μg/kg and 3.03 μg/kg to 30.59 μg/kg, respectively. Notably, a high level of pectenotoxin-1 (PTX-1) at 467.40 μg/kg was found in the shellfish collected at the northernmost station, exceeding the safety regulation standard by nearly 3 times. For both lipophilic and hydrophilic toxins, contamination in shellfish in the sub-Arctic and the Arctic area may be much more widespread and severe than was previously thought. This study highlighted the need to monitor toxins in a wider variety of shellfish, especially economic or commercial species, and across a wider range of sub-Arctic and Arctic waters, as well as the potential sources of these toxins.

Comparison of Multiple Bioactive Constituents in the Flower and the Caulis of Lonicera japonica Based on UFLC-QTRAP-MS/MS Combined with Multivariate Statistical Analysis

Lonicerae japonicae flos (LJF) and Lonicerae japonicae caulis (LJC) are derived from different parts of Lonicera japonica Thunb. (Caprifoliaceae), and have been used as herbal remedies to treat various diseases for thousands of years with confirmed curative effects. However, little attention has been paid to illustrating the differences in efficacy from the perspective of phytochemistry. In the present study, a simultaneous determination of 47 bioactive constituents, including 12 organic acids, 12 flavonoids, six iridoids, 13 amino acids and four nucleosides in 44 batches of LJF and LJC samples from different habitats and commercial herbs was established based on ultra-fast liquid chromatography tandem triple quadrupole mass spectrometry (UFLC-QTRAP-MS/MS). Moreover, principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and t-test were then performed to classify and reveal the differential compositions of LJF and LJC according to the content of the tested constituents. The results demonstrated that the types and contents of chemical components (e.g., isochlorogenic acid A, chlorogenic acid, neochlorogenic acid, quinic acid, secologanic acid, luteoloside, loganin, secoxyloganin, morroniside and L-isoleucine) were significantly different, which may lead to the classification and the differences in efficacy of LJF and LJC. Our findings not only provide a basis for the comprehensive evaluation and intrinsic quality control of LJF and LJC, but also pave the way for discovering the material basis contributing to the different properties and efficacies of the two medicinal materials at the phytochemical level.

Widely targeted metabolome and transcriptome landscapes of Allium fistulosum\u2013A. cepa chromosome addition lines revealed a flavonoid hot spot on chromosome 5A

Here, we report a comprehensive analysis of the widely targeted metabolome and transcriptome profiles of Allium fistulosum L. (FF) with the single extra chromosome of shallot [A. cepa L. Aggregatum group (AA)] to clarify the novel gene functions in flavonoid biosynthesis. An exhaustive metabolome analysis was performed using the selected reaction monitoring mode of liquid chromatography–tandem quadrupole mass spectrometry, revealing a specific accumulation of quercetin, anthocyanin and flavone glucosides in AA and FF5A. The addition of chromosome 5A from the shallot to A. fistulosum induced flavonoid accumulation in the recipient species, which was associated with the upregulation of several genes including the dihydroflavonol 4-reductase, chalcone synthase, flavanone 3-hydroxylase, UDP-glucose flavonoid-3-O-glucosyltransferase, anthocyanin 5-aromatic acyltransferase-like, pleiotropic drug resistance-like ATP binding cassette transporter, and MYB14 transcriptional factor. Additionally, an open access Allium Transcript Database (Allium TDB, http://alliumtdb.kazusa.or.jp) was generated by using RNA-Seq data from different genetic stocks including the A. fistulosum–A. cepa monosomic addition lines. The functional genomic approach presented here provides an innovative means of targeting the gene responsible for flavonoid biosynthesis in A. cepa. The understanding of flavonoid compounds and biosynthesis-related genes would facilitate the development of noble Allium varieties with unique chemical constituents and, subsequently, improved plant stress tolerance and human health benefits.

Per- and polyfluorinated compounds in saleswomen's urine linked to indoor dust in clothing shops

This study aims to investigate the characteristics of typical per- and polyfluorinated compounds (PFCs) in indoor dust from clothing shops and urine sampled from saleswomen. A total of 58 indoor dust samples and 73 urine samples from saleswomen were collected from clothing shops in Shanghai, China. All samples were analyzed for PFCs using high-performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC-MS/MS). The mean PFC concentrations in indoor dust ranged from 0.42 (PFDA) to 5.04 ng g−1 (PFDoA). PFDoA and PFHxS were the most prominent PFCs, with median concentrations of 2.95 ng g−1 and 1.49 ng g−1, respectively. The median PFC concentrations in urine ranged from 10.15 (PFDS) to 666.1 ng l−1 (PFOA) and PFOA was the most abundant chemical with concentrations ranging from 207 to 907 ng l−1. A significant positive correlation was obtained between long-chain PFCs in dust and in urine (p < 0.01). Daily intake values of PFCs via dust ingestion were also calculated, and even under high-end exposure scenarios, the intake of PFOA (36.5 pg day−1) and PFOS (56.7 pg day−1) were well within the tolerable daily intake values. These results are important to both characterize PFC levels and estimate the saleswomen's exposure to PFCs from indoor dust.

Pharmacokinetics, Tissue Distribution, Metabolism, and Excretion of Naringin in Aged Rats.

Aging is an inevitable biological process characterized by the loss of functional capacity and associated with changes in all phases of pharmacokinetic processes. Naringin, a dietary flavanone glycoside, has been proved to be beneficial for the treatment of multiple age-associated chronic diseases. To date, the pharmacokinetic processes of naringin in aged individuals are still unknown. Thus, a rapid resolution liquid chromatography tandem triple quadrupole mass spectrometry (RRLC-QQQ-MS/MS) method was established for the determination of naringin and its metabolite naringenin in rat plasma, urine, feces, and tissue homogenate. The pharmacokinetic parameters were calculated and a higher exposure of naringin and naringenin were observed in aged rats. Naringin and naringenin were mostly distributed in gastrointestinal tract, liver, kidney, lung, and trachea. Furthermore, a total of 39 flavonoid metabolites (mainly glucuronides and sulfates) and 46 microbial-derived phenolic catabolites were screened with ultra-fast liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UFLC-Q-TOF-MS/MS). Naringenin, hippuric acid, and 3-(4’-hydroxyphenyl)propionic acid were predominated metabolites. This study systemically investigated the pharmacokinetics, tissue distribution, metabolism, and excretion of naringin in aged rats, revealing age- and gender-related changes in the in vivo behavior of naringin. These results would be helpful for the interpretation of pharmacokinetics and pharmacodynamics of naringin in aged population.

A Validated Ultra-Performance Liquid Chromatography Tandem Triple Quadrupole Mass Spectrometric Method for Fast Determination of Losartan in Rabbit Plasma.

A rapid UPLC-MS-MS method was developed and validated for determination of losartan in rabbit plasma. Protonated adducts of losartan and eprosartan (IS) were monitored in multiple reaction monitoring mode. Molecular masses of daughter species of losartan were m/z 423.19 > 207 and m/z 423.19 > 180; and of eprosartan were m/z 425.11 > 135 and m/z 425.11 > 107. Losartan from plasma samples was extracted by protein precipitation method. The mobile phase comprising water (0.1% formic acid) (A) and acetonitrile (0.1% formic acid) (B) was used in gradient mode. Analytes were eluted on Acquity UPLC®BEH C18 1.7 μm, 2.1 × 50 mm column. Sample run time was 3.0 min. The validation parameters: accuracy, precision and recovery were within recommended limits. Losartan as well as internal standard remains stable in benchtop stability study as well as in post-preparative stability study. Pharmacokinetic parameters such as Cmax (182.79 ± 23.80 ng/mL), Tmax (1.16 ± 0.28 h), AUC0-t (1188.57 ± 404.60 ng h/mL) and Kel (0.0954 ± 0.0140 h-1) of losartan were measured. Method was successfully applied for pharmacokinetic investigation in rabbits and can be used for losartan determination in plasma sample obtained from other animals.

Ultra-high-performance liquid chromatography with tandem mass spectrometry method for determination of four compounds in rat plasma after oral administration of Xanthii fructus and stir-fried Xanthii fructus extracts.

Xanthii fructus (XF), the fruit of Xanthium sibiricum Patr., is a traditional Chinese materia medica commonly used to treat allergic rhinitis and other rhinitis diseases. To uncover the mechanism of the stir-frying process and its effect on the pharmacokinetic behavior of active compounds in model rats, four active compounds-chlorogenic acid, 4-caffeoylquinic acid, 1,5-O-dicaffeoylquinic acid and apigenin-were selected based on previous spectrum-effect experiments. High performance liquid chromatography tandem triple quadrupole mass spectrometry (UPLC-QqQ-MS) technology, an accurate and feasible method, was applied to measure the concentration of these four compounds in rat plasma. This validated method can accurately measure the concentration of each compound at each sampling point of rat plasma. This validated method shows good linearity, extraction recoveries, matrix effects, intra- and inter-day precision and stabilities. Compared with the XF group, the maximum plasma concentration (Cmax ) value of 1,5-O-dicaffeoylquinic acid decreased remarkably (p < 0.05) after oral administration of stir-fried Xanthii fructus (SXF) extract, while the other compounds showed no significant difference. The mean residence time value of chlorogenic acid (p < 0.05) and 1,5-O-dicaffeoylquinic acid (p<0.01) after oral administration of SXF extraction demonstrated significant differences compared with the XF group, while the other two compounds showed no statistical difference, indicating that the stir-frying process prolonged the effect time and delayed the removal time of chlorogenic acid and 1,5-O-dicaffeoylquinic acid. The values of the area under the plasma concentration-time curve from zero to the last quantifiable time-point, the area under the plasma concentration-time curve from zero to infinity, the time to maximum concentration and the elimination half-life of four compounds in the SXF group showed no statistically significant difference from the XF group. From this data, we speculated that the stir-frying process can not only keep the absorption of 4-caffeoylquinic acid and apigenin, but also increase the effect time of chlorogenic acid and 1,5-O-dicaffeoylquinic acid, which could be the mechanism underlying the stir-frying process enhancing the effects of XF.