Ultra-performance Liquid Chromatography-diode Array Detection Research Articles

A comprehensive quality evaluation for Huangqi Guizhi Wuwu decoction by integrating UPLC-DAD/MS chemical profile and pharmacodynamics combined with chemometric analysis

Ethnopharmacological relevanceHuangqi Guizhi Wuwu Decoction (HGWD), a classical Chinese formula originally recorded in Jin Kui Yao Lue, was used for the treatment of human “blood impediment” (a type of “Bi” syndrome). In clinical practice, HGWD has been applied to treat rheumatoid arthritis (RA). Aim of the studyThe characterization of chemical markers reflecting both efficacy and chemical characteristics is of great significance for TCM quality control. With the anti-RA effects of HGWD as an example, the aim of this study was to develop a comprehensive strategy combining the overall chemical profile and biological activity data to identify chemical markers. Materials and methodsFirst, an ultra-performance liquid chromatography-diode array detector (UPLC-DAD) fingerprint was established and validated to evaluate the holistic quality of HGWD of different origins. Characteristic markers associated with HGWD from different geographical origins were screened by a combination of UPLC-DAD fingerprint and chemometrics methods. Second, the chemical profiles of the 15 batches of HGWD samples were characterized by UPLC coupled tohybrid linear ion trap-Orbitrap mass spectrometry (UPLC-HRMS). The in vitro anti-RA activities of the 15 HGWD samples were then evaluated. Third, spectrum-effect relationship analysis was performed to identify bioactive compounds that could potentially be used as quality markers. Finally, a UPLC-triple quadrupole tandem mass spectrometry approach was optimized and established for quantitative analysis of the characteristic and quality markers in 15 batches of HGWD. ResultsIn total, 30 common peaks were assigned in the UPLC-DAD fingerprint. Nine peaks were recognized and considered characteristic markers: protocatechuic acid, coumarin, cinnamic acid, oxypaeoniflorin, paeoniflorin, calycosin, formononetin, catechin, and albiflorin. Furthermore, ninety-five common compounds were identified in the UPLC-HRMS chemical profile. The pharmacological analysis indicated that the anti-RA activities of the 15 HGWD samples were vastly different. The spectrum-effect relationship analysis revealed 30 potential bioactive constituents positively correlated with anti-RA activity. Among them, five compounds with relative amounts >1%, paeoniflorin, astragaloside IV, hexahydrocurcumin, formononetin and calycosin-7-glucoside, were selected as quality markers, and their activity was verified in LPS-induced RAW264.7 macrophages. Finally, the above 12 representative components were simultaneously quantified in the 15 batches of HGWD samples. ConclusionCombining a holistic chemical profile with representative component evaluation, this systematic strategy could be a reliable and effective method to improve quality evaluations of HGWD.

Comprehensive characterization of flavonoid derivatives in young leaves of core-collected soybean (Glycine max L.) cultivars based on high-resolution mass spectrometry

Most previous studies have been focused on isoflavone profile with biological activities from soybean seed and its related products. However, in the present study, eighty-three flavonoid derivatives (55 flavonols, 9 flavones and 19 isoflavones) were comprehensively identified and quantified from young leaves of 21 core-collected soybean cultivars based on ultra-performance liquid chromatography-diode array detector with quadrupole time of flight/mass spectrometry (UPLC-DAD-QToF/MS). Among total flavonoids from soybean leaves (SLs), the abundant flavonols (83.6%) were primarily composed of di- and tri- glycosides combined to the aglycones (K, kaempferol; Q, quercetin; I, isorhamnetin). Particularly, K-rich SLs (yellow coated seed), Nongrim 51 (breeding line) and YJ208-1 (landrace) contained mainly kaempferol 3-O-(2″-O-glucosyl-6″-O-rhamnosyl)galactoside and 3-O-(2″,6″-di-O-rhamnosyl)galactoside, and were expected to be superior cultivars by their higher flavonoids. Besides, the new tri-I-glycosides (soyanins I–V) were presented as predominant components in Junyeorikong (landrace, black). Thus, this study suggest that the SLs can be considered as valuable edible resources due to their rich flavonoids. Also, these detailed profiles will support breeding of superior varieties with excellent biological activities as well as relationship with seed anthocyanins production, and contribute to perform metabolomics approach to investigate the changes of SLs flavonols during the leaf growth and fermentation in further research.

Determination of Nitrofuran Metabolites in Fish by Ultraperformance Liquid Chromatography-Photodiode Array Detection with Thermostatic Ultrasound-Assisted Derivatization.

Nitrofuran (NF) is a class of broad-spectrum antibiotics that are used illegally in animal feeding. NF and its metabolites have proven to pose potential risk to human health. To address the current analytical needs to quantify low levels of NF metabolites in animal foods, a sensitive method was developed for simultaneous detection of four NF metabolites in fish products by an ultraperformance liquid chromatography-diode array detector (UPLC-DAD). With 2-nitrobenzaldehyde (2-NBA) as the derivatizing reagent, the metabolites were hydrolyzed and derivatized under the assistance of thermostatic ultrasound. Compared with the current detection methods, the time of the derivatization reaction has been shortened from 16 to 2 h. The relative coefficient of four NF metabolite derivatives reached more than 0.998, with excellent linear relationship. The limits of detection (LODs) and limits of quantification (LOQs) of six repeated determinations reached 0.25–0.33 and 0.80–1.10 μg/kg, respectively. For all four NF metabolites, the limit of detection of the method was below the minimum required performance limit (MRPL) of 1.0 μg/kg, which makes it compatible with the EU requirements. The recoveries ranging from 89.8 to 101.9% with relative standard deviation below 6.5% were obtained for all of the NF metabolites. What’s more, this method was successfully applied for the determination of four NF metabolites in the fish products. As a promising approach, this method could also be extended for the quantitation of NF metabolites in aquaculture and poultry products.

Anthocyanin Accumulation in the Leaves of the Purple Sweet Potato (Ipomoea batatas L.) Cultivars.

Sweet potato anthocyanins are water-soluble pigments with many physiological functions. Previous research on anthocyanin accumulation in sweet potato has focused on the roots, but the accumulation progress in the leaves is still unclear. Two purple sweet potato cultivars (Fushu No. 23 and Fushu No. 317) with large quantities of anthocyanin in the leaves were investigated. Anthocyanin composition and content were assessed with ultra-performance liquid chromatography diode-array detection (UPLC-DAD) and ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS), and the expressions of genes were detected by qRT-PCR. The two cultivars contained nine cyanidin anthocyanins and nine peonidin anthocyanins with an acylation modification. The acylation modification of anthocyanins in sweet potato leaves primarily included caffeoyl, p-coumaryl, feruloyl, and p-hydroxy benzoyl. We identified three anthocyanin compounds in sweet potato leaves for the first time: cyanidin 3-p-coumarylsophoroside-5-glucoside, peonidin 3-p-coumarylsophoroside-5-glucoside, and cyanidin 3-caffeoyl-p-coumarylsophoroside-5-glucoside. The anthocyanidin biosynthesis downstream structural genes DFR4, F3H1, anthocyanin synthase (ANS), and UDP-glucose flavonoid 3-O-glucosyltransferase (UFGT3), as well as the transcription factor MYB1, were found to be vital regulatory genes during the accumulation of anthocyanins in sweet potato leaves. The composition of anthocyanins (nine cyanidin-based anthocyanins and nine peonidin-based anthocyanins) in all sweet potato leaves were the same, but the quantity of anthocyanins in leaves of sweet potato varied by cultivar and differed from anthocyanin levels in the roots of sweet potatoes. The anthocyanidin biosynthesis structural genes and transcription factor together regulated and controlled the anthocyandin biosynthesis in sweet potato leaves.

Simultaneous quantification and identification of Amaryllidaceae alkaloids in Narcissus tazetta by ultra performance liquid chromatography-diode array detector-electrospray ionisation tandem mass spectrometry

Narcissus tazetta is used traditionally for treatment of sores, wounds, skin diseases, cancer in different parts of world. Present study focus on the analysis of amaryllidaceae alkaloids in this plant using an ultra-performance liquid chromatography-diode array detection method. The method was developed for simultaneous quantification of eight Amaryllidaceae alkaloids i.e. pseudolycorine (1), lycorine (2), galanthamine (3), 8-O-demethylhomolycorine (4), N-methylhaemanthidine chloride (5), homolycorine (6), narciclasine (7) and zefbetaine (8) in Narcissus tazetta. The method was validated using a BEH C18 column with linear gradient. Standard calibration curve for the analytes showed good linearity ( r2≥0.999). The method was validated for intra-day (RSDs<0.91%) and inter-day (RSDs<0.65%) precisions and accuracy (recovery 92.2–112.5%). The developed method was successively applied for studying the variation of alkaloids in different parts of Narcissus tazetta, i.e. bulbs, roots, flowers, flower stalks and leaves. The study showed a significant variation of these alkaloids in different parts of the plant. Among the alkaloids under investigation, pseudolycorine had highest content in all the parts. Furthermore, application of the developed method to the identification of phytocomponents allowed the identification of sixteen alkaloids.

RETRACTED: Organometallic cerium oxide nanostructures acted as nanofertilizer during callogenesis and organogenesis of recalcitrant plant Berberis lycium Royle

Abstract We report organometallic cerium oxide nanostructures (OM-CeO2-NS) mediated in vitro callus induction and direct shoot regeneration of medicinally important and recalcitrant plant (Berberis lycium Royle). To achieve greater biocompatibility, Hypericum scabrum flower extract was used during the green synthesis process. Ultra-performance Liquid Chromatography-Diode Array Detector (UPLC-DAD) coupled with Mass spectrometry (MS) was employed to detect the potential secondary metabolites in H. scabrum flower extract which acted as reducing as well as the surface stabilizing agents for tailoring the morphology of OM-CeO2-NS. High resolution Transmission Electron Microscopy (Hr-TEM) and Atomic Force Microscopy (AFM) examination of the prepared OM-CeO2-NS revealed homogenous morphology with an average size of 38 ± 5 nm. Moreover, Fourier Transform Infrared (FT-IR) spectroscopy examination and X-ray Diffraction (XRD) technique also confirm organometallic chemistry of prepared CeO2-NS. Interestingly, nutritive behaviour of OM-CeO2-NS was observed in B. lycium tissue culturing primarily due to the extremely small size and organometallic nature. The results reveal that callus induction is enhanced to 90% with low concentration of OM-CeO2-NS (4 mg/L) and direct shoot regeneration is improved to 79% with increased concentration of 20 mg/L. The current study concludes that OM-CeO2-NS can be used as nanofertilizer in tissue culturing of the recalcitrant plant species.

Geographical Discrimination in Curcuminoids Content of Turmeric Assessed by Rapid UPLC-DAD Validated Analytical Method.

A fast and reliable ultra-performance liquid chromatography-diode array detection method was developed and validated for the quantitative assessment of turmeric extracts from different geographical locations. Acclaim RSLC PolarAdvantage II column (2.2 μm, 2.1 × 100 mm) was used to analyze individual curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin) from turmeric samples. The detection was done on ultraviolet absorbance at 425 nm and the column temperature was maintained at 45 °C. A mobile phase consisting of acetonitrile and water was found to be suitable for separation, at a flow rate of 1 mL/min with linear gradient elution. Linearity, specificity, precision, recovery and robustness were measured to validate the method and instrument. Under the described conditions, curcuminoids were collected within one minute. The calibration curve of each curcuminoid showed good linearity (correlation coefficient > 0.999). The relative standard deviations (RSD) of intra-day, inter-day precision and repeatability were less than 0.73%, 2.47% and 2.47%, respectively. In the recovery test, the accuracy ranged from 98.54%-103.91% with RSD values of less than 2.79%. The developed method was used for quantification of individual curcuminoids of turmeric samples. Analysis of turmeric samples from Nepal and South Korea revealed that curcuminoid content was related to geographical location. Turmeric cultivated in warmer climates were found to have higher curcumionoid content than turmeric samples from cooler climates, the southern part of Nepal was found to have two times higher content of curcuminoids than turmeric from the north.

Qualitative identification of impurities and principal component quantitative analysis of zearalanone on purity certified reference material

A liquid chromatography method was established for the determination of zearalanone (ZAN) raw material. The qualitative analysis of ZAN and its trace impurities was performed by ultra performance liquid chromatography-diode array detector (UPLC-DAD) and ultra performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS), and the response factors of each impurity were calculated. The three main organic impurities in the ZAN raw material were identified as β -zearalanol, α -zearalanol and a dehydration product of zearalanol with relative response factors of 0.5352, 0.8594 and 0.6973, respectively. The main component of the ZAN raw material was determined by the calibration factor normalization method. The purity of zearalanone was determined to be 99.6% with a standard deviation of 0.01%. This method can provide a technical support for the development of ZAN standard materials.

Stability Study and Identification of Degradation Products of Caffeoylgluconic Acid Derivatives from Fructus Euodiae.

Caffeoylgluconic acid derivatives are characteristic constituents isolated from the aqueous extract of Fructus Euodiae. In this research focusing on caffeoylgluconic acid derivatives, trans-caffeoyl-6-O-d-gluconic acid (CGA), trans-caffeoyl-6-O-d-gluconic acid methyl ester (CGA-ME), and trans-caffeoyl-6-O-d-glucono-γ-lactone (CGA-LT), a systematic study of stability was performed under different temperatures and pH levels by ultra performance liquid chromatography-diode array detector (UPLC-DAD) and ultra performance liquid chromatography-diode array detector/electrospray ionization-quadrupole-time of flight mass spectrometry (UPLC-DAD/ESI-Q-TOF MS). From the concentration–time curves and sensitivity index (SeI), it was found that compared to CGA, which is inert to the variation of temperature and pH in the tested range, CGA-ME and CGA-LT were more sensitive, with stabilities more likely to be influenced by temperature. Considering the stability index (StI), the integrated stability of CGA was the best, and that of CGA-ME was the worst. In terms of the quasi-molecular and fragment ions of the tested compounds, the degradation products were identified or tentatively characterized, which could shed light on the degradation pathways. CGA-ME and CGA-LT were easily converted to CGA by hydrolytic reaction, all of which were susceptible to the formation of isomers. This study elucidated the degradation mechanism of caffeoylgluconic acid derivatives, contributing to better guidance on manufacturing and controlling the quality of drugs.

Identification Markers of Adulteration in Korean Red Ginseng (Panax Ginseng) Products Using High-Performance Liquid Chromatography (HPLC) and Liquid Chromatography–Mass Spectrometry (LC-MS)

ABSTRACTThe commercial products of Panax ginseng have increasing market demand and high prices due to the pharmacological activities. To obtain high profits, P. ginseng may be adulterated with lower priced morphologically similar species such as Platycodon grandiflorum, Codonopsis lanceolata, and Pueraria lobata. This study was designed to validate accurate methods for the analysis of adulteration in P. ginseng products. High-performance liquid chromatography (HPLC) and ultraperformance liquid chromatography–diode array detector–electrospray ionization–ion trap–time of flight–mass spectrometry (UPLC–DAD–ESI-IT-TOF-MS) were validated to analyze the raw plant materials, self-prepared formulations, and commercial products of P. ginseng, C. lanceolata, P. grandiflorum, and P. lobata. The developed analytical methods were confirmed by quality assurance parameters such as linearity, sensitivity, precision, and accuracy. Lobetyolin and ononin were identified as marker compounds by HPLC and confirmed by accurate mass measurement with ESI-IT-TOF-MS. HPLC analysis of self-prepared formulations indicated that by increasing the ratio of C. lanceolata, P. grandiflorum, and P. lobata in P. ginseng extracts, the peak area is increased at the same retention time. The limits of detection and quantification for lobetyolin and ononin were 0.098 and 0.171, and 0.108 and 0.726 mg/kg, respectively. Furthermore, the intraday precision (<1.0%) measurements confirmed that the developed analytical methods fulfill the required criteria for characterization of these products. The results demonstrated that the developed liquid chromatographic and mass spectrometric methods accurately characterized adulteration in P. ginseng commercial products.

Identification and characterization of matrix components in spinach during QuEChERS sample preparation for pesticide residue analysis by LC-ESI-MS/MS, GC-MS and UPLC-DAD.

In this article matrix components in spinach were investigated in detail. The samples were prepared using two QuEChERS (quick, easy, cheap, effective, rugged and safe) methods, AOAC and CEN. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS), gas chromatography-mass spectrometry (GC-MS) and ultra performance liquid chromatography-diode array detector (UPLC-DAD), were applied for component identification. The strategies of identification by LC-ESI-MS/MS include accurate mass spectra of the parent ion, comparison with previous literature data and investigation of the mass spectral decomposition pattern. Overall, fourteen components were identified by LC-ESI-MS/MS in each methods of AOAC and CEN, which were phytosteroids, flavonoids, fatty acids and fatty acid amides. Fifty components using AOAC method and fifty-seven components using CEN method were identified in GC-MS by comparing mass data with the National Institute of Standards and Technology (NIST, U.S.) database. The results indicate that the major components of the matrix are terpenoids, fatty acids and fatty acid esters. Moreover, three pigments (neoxanthin, violaxanthin and lutein) in the AOAC method and eight pigments (neoxanthin, violaxanthin, zeaxanthin, lutein, chlorophyll a, chlorophyll b, pheophytin a and beta-carotene) in the CEN method that gave a characteristics peak at 440nm were identified by the UPLC-DAD. According to the sample preparation condition using different amounts of graphitized carbon black (GCB) in this study, the AOAC method had higher matrix component removal efficiency than the CEN method. A better understanding of matrix components would increase the current knowledge for improvement of existing QuEChERS methodology, as well as contribute to new method developments.

Anti-oxidative and anti-inflammatory activities of devil's club (Oplopanax horridus) leaves.

This study aimed to investigate the anti-oxidative properties of the ethanolic extracts of the devil's club (Oplopanax horridus) leaves, stems, and roots. Furthermore, the anti-inflammatory activity of the leaf extract was analyzed. The leaf extract had higher total phenolic and flavonoid contents and anti-oxidative activity (radical scavenging, reducing power, and inhibition of lipid oxidation) than the root and stem extracts. The leaf extract also had anti-inflammatory effects. It significantly reduced lipopolysaccharide (LPS)-induced nitric oxide (NO; 71.0% at 50 μg/mL), tumor necrosis factor (TNF)-α (87.6% at 100 μg/mL), and interleukin (IL)-6 (36.2% at 100 μg/mL) production in murine RAW 264.7 macrophages. Furthermore, LPS-induced inducible nitric oxide synthase (iNOS) expression was decreased by the leaf extract (IC50=24.4 μg/mL). The ultra performance liquid chromatography-diode array detector (UPLC-DAD) analysis showed that the leaf extract contained gallic acid, protocatechuic acid, chlorogenic acid, and maltol. These findings suggest that the leaf extract could be utilized as a functional food material because of its anti-oxidative and anti-inflammatory activities.

Simultaneous quantification and identification of flavonoids, lignans, coumarin and amides in leaves of Zanthoxylum armatum using UPLC-DAD-ESI-QTOF–MS/MS

The current study presents isolation and characterization of twelve compounds including catechin (1), isovitexin (2), hesperidin (3), psoralin (4), eudesmin (5), kobusin (6), fargesin (7), sesamin (8), asarinin (9), planispine-A (10), α-sanshool (11) and vitexin (12), from the leaves of Zanthoxylum armatum. Further, two rapid and simple ultra performance liquid chromatography-diode array detection (UPLC-DAD) methods were developed for the simultaneous quantitative determination of isolated compounds from Z. armatum leaves. These analytical methods were validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). The LOD and LOQ were in the range of 0.06–0.21μg/mL and 0.19–0.69μg/mL, respectively. The validated method was linear (R2≥0.9906), precise in terms of peak area (intra-day RSDs <3.8% and inter-day RSDs <2.7%), and accurate (109.6–92.5%). This is the first report on the isolation and quantification of 1, 2, 4 and 12 in Z. armatum and 3 in Zanthoxylum genus. The methods: were successfully applied to assess the quality of samples collected from different locations of Himachal Pradesh during summer and winter season. The results demonstrated that flavonoids and furofuran lignans were the major constituents in Z. armatum leaves. The developed methods: were further applied for tandem electrospray ionization-mass spectrometry (UPLC-DAD-ESI-MS/MS) and total eighteen compounds were identified including phenolic acid, flavonoids, furofuran lignans, coumarin and isobutyl amides.

Long-term stability of ketamine hydrochloride 50mg/ml injection in 3ml syringes.

Ketamine hydrochloride (Ketalar(®)) injection is often used as a general anesthetic agent. It is particularly suited to short-term interventions. It can also be used as an inducer of anesthesia before the administration of other anesthetic agents. The aim of this study was to evaluate the stability of ketamine hydrochloride in 3ml polypropylene syringes after storage for up to 180days at room temperature. Syringes containing ketamine hydrochloride (50mg/ml) were prepared and stored at room temperature (25°C) for 180days. The concentrations were measured by validated ultra-performance liquid chromatography-diode array detection at 0, 7, 14, 28, 60, 84, 112, 140 and 180days. A degradation test was performed to evaluate the specificity of the analysis. At each time point, the pH, color and visible particles of each solution were also assessed. Degradation tests proved no interfering peaks with ketamine. All solutions were physically stable during the storage. The lower confidence limit of the concentration for these solutions remains superior to 90% of the initial concentration at this date as recommended by the Food and Drug Administration (FDA) until 180days (100%±2%). Solutions of ketamine (50mg/ml) were chemically stable for 180days in polypropylene syringes with storage at room temperature and could be prepared in advance by a centralized intravenous admixture service.

UPLC-PDA quantification of chemical constituents of two different varieties (golden and royal) of apple leaves and their antioxidant activity.

Malus domestica is the most widely cultivated fruit tree and is well known for its therapeutic value. Apple leaves are known to contain phenolic compounds but the nature of these has not been explored to the same extent as in apple fruit. A simple, rapid and sensitive ultra-performance liquid chromatography-diode array detection (UPLC-DAD) quantification method has been developed. Total polyphenol and flavonoid contents, as well as the antioxidant activity of golden and royal apple leaves were evaluated. Four compounds, namely rutin, 3-hydroxyphloridzin, phloridzin and quercetin-3-O-arabinoside were identified by UPLC. The separation was achieved in less than 7 min. Total polyphenol and flavonoid contents were found to be slightly higher in apple golden variety than royal variety. The IC50 values determined by the DPPH assay were 49.94 µg mL(-1) for golden apple leaves and 43.89 µg mL(-1) for royal apple leaves. IC50 values determined by the ABTS assay were 47.10 and 66.53 µg mL(-1) for golden and royal apple leaves, respectively. Antioxidant activity was determined as 24.45 and 21.15 mg ascorbic acid g(-1) for golden and royal apple leaves, respectively, by using the FRAP assay. This study showed that apple leaves (both varieties) contain considerable amounts of polyphenols and flavonoids and are also a promising source of phloridzin.

UPLC-DAD determination of taxodione content in hairy roots ofSalvia austriacaJacq.

Taxodione is the abietane diterpenoid, which has been earlier reported to show cytotoxic, antitumor, antibacterial, and antioxidant properties. This compound has been isolated from a genetically transformed root culture of Salvia austriaca. However, no method for taxodione quantification is yet available. A validated ultra-performance liquid chromatography-diode array detector (UPLC-DAD) method was developed for the quantification of taxodione in a hexane extract taken from genetically transformed roots of S. austriaca. The developed UPLC-DAD method demonstrated good linearity in the range 10–500 μg mL−1 (r2 = 0.99988), high precision (relative standard deviation (RSD) <1.42%), and good repeatability (RSD <1.84%). The limits of detection and quantification of taxodione were found to be 0.48 ng and 1.60 ng, respectively. The recovery of taxodione ranged between 90.4 and 113.1%, and the RSD was less than 2.5%.The developed UPLC-DAD method was then used to determine the content of taxodione in various hairy root lines and changes in amount of the compound during the 50-day growth cycle of the culture. The content of taxodione in hairy root cultures of S. austriaca ranged from 0.29 to 1.12 mg g−1 dry weight depending on root line and stage of growth.

Investigation of the Rotational Isomerism of Quinapril and Quinaprilat by UPLC–DAD and Elucidation of the Conformational Equilibrium by NMR

Quinapril and quinaprilat are two angiotensin-converting enzyme inhibitors (ACEIs) characterized by a peak broadening and splitting when they were analyzed by ultra-performance liquid chromatography (UPLC). This phenomenon is due to the existence of the two isomers cis and trans around the amide band. In order to confirm the existence of the two conformers and allow identification of the predominant form, NMR studies of quinapril, involving 1H, 13C, 1H-1HCOSY, Impact-HMBC, JMOD, HSQC, and ROESY have been conducted in this work. The analyses allowed us to identify the predominant form of quinapril; the conformer trans is the predominant form (75 %). In addition, this study highlights the important benefits of UPLC to separate quinapril and quinaprilat isomers due to its high resolving power. The effect of various operating conditions on the retention peak, namely, splitting and band broadening of quinaprilat and quinapril, has been qualitatively examined in this study. Several practical experimental conditions have been tested, allowing both the elution of the two ACEIs as single peaks, while keeping at the same time an acceptable separation. The effect of various factors on the conformational s-cis–s-trans equilibrium of quinapril and quinaprilat, namely, the composition of the mobile phase, column temperature, flow rate, pH, and type and amount of organic modifier was investigated by UPLC–DAD (diode array detector) with a BEH C18 column (100 mm, 2.1 mm internal diameter × 1.7 µm particle diameter). Several deconvolution models were used to model overlapped peaks and to determine resolution. Results obtained showed that a mobile phase consisting of ammonium buffer (10 mM; pH 8) and acetonitrile allows the separation of the quinapril and quinaprilat conformers. Maximum resolution was obtained for a composition of mobile phase (55/45) and (65/35) (ammonium buffer/acetonitrile, v/v) for quinapril and quinaprilat, respectively at 45°C and flow rates of 0.4 and 0.5 mL min–1.

The Effect of Different Cold Storage Conditions on the Compositions of Extra Virgin Olive Oil

AbstractStorage conditions can affect the stability and quality of extra virgin olive oil (EVOO). While many studies have reported the influence of high temperature and light exposure during storage, little is known on the influence of the cold storage. The aim of this study was to evaluate the effect of different storage conditions (25, 4.5 and −27 °C) on the various compositions of EVOO and to determine if cold storage will prolong shelf‐life by retarding hydrolysis and oxidation. The changes of quality indices (FFA, PV, and UV) and natural antioxidants such as α‐tocopherol and phenolic compounds were evaluated periodically during storage. The characterization and quantification of phenolics were achieved by ultra‐performance liquid chromatography—diode array detector (UPLC‐DAD). In addition, 1, 2‐diacylglycerols (DAGs), pyropheophytin A (PPP) were measured to indicate thermal degradation during storage.

Quantitative and structural analysis of amides and lignans in Zanthoxylum armatum by UPLC-DAD-ESI-QTOF–MS/MS

A rapid and simple ultra performance liquid chromatography-diode array detection (UPLC-DAD) method has been developed for the simultaneous quantification of four biologically important furofuran lignans, asarinin, sesamin, fargesin and kobusin, and an amide, armatamide in Zanthoxylum armatum within 7min. The separation was carried out on a BEH C18 column (2.1mm×100mm, 1.7μm particle size) with 0.05% formic acid aqueous solution and acetonitrile as mobile phase under gradient conditions at 25°C. The method was validated and found to be linear (R2≥0.9997), precise in terms of peak areas (intra-day RSDs≤0.62% and inter-day RSDs≤2.95%) and accurate (95.6–104.0%). The developed method was applied to the quality assessment of different parts (leaves, bark and seeds) of Z. armatum including locational variation of leaves samples. Significant variation in the amount of amides and furofuran lignans was observed. Tandem electrospray ionization–mass spectrometry (UPLC-DAD-ESI–MS/MS) of samples led to the identification of sixteen compounds in the category of amides and furofuran lignans.

Quantitative Assessment of Traditional Oriental Herbal Formulation Samhwangsasim-tang Using UPLC Technique

A specific and reliable ultra-performance liquid chromatography-diode array detection method has been developed and validated for the quantitative assessment of a traditional Oriental herbal formulation, Samhwangsasim-tang (SST). A Halo reversed-phase amide column (2.7 µm, 4.6 × 150 mm) was used to separate marker compounds; detection was conducted by ultraviolet absorbance at 250 nm. The column temperature was maintained at 45°C. A mobile phase consisting of acetonitrile (A) and 0.1% trifluoroacetic acid in water (B) was found to be suitable for the separation, at a flow rate of 1.8 mL/min with gradient elution. Linearity, specificity, precision and recovery were calculated to validate the method and instrumentation. Under the described conditions, all marker compounds (rhaponticin, berberine, palmatine, baicalin, baicalein and wogonin) were collected within 25 min. All calibration curves of components showed good linearity (correlation coefficient > 0.9996). The limit of detection and limit of quantification ranged from 0.08-3.05 and 0.23-8.12 µg/mL, respectively. The relative standard deviation (RSD) and repeatability values of intra-day and inter-day precision were less than 2.30, 2.99 and 1.82%, respectively. In the recovery test, the accuracy ranged from 97.56-103.30% with RSD values less than 2.63%. The developed method was simple, specific, sensitive, accurate, precise and reproducible for the quantification of the active chemical constituents of SST. The simultaneous analysis of the contents of marker compounds in different SST samples prepared by different extraction procedures and different commercial products was successfully evaluated.