Method For Simultaneous Quantification Research Articles

New approach to rifampicin stability and first-line anti-tubercular drug pharmacokinetics by UPLC-MS/MS

Successful tuberculosis (TB) therapy requires achieving sufficient exposure to multiple drugs. Limited stability of several first-line anti-TB drugs might compromise reliable therapeutic drug monitoring (TDM). We developed and validated a sensitive and selective UPLC-MS/MS method for simultaneous quantification of isoniazid (INH), pyrazinamide (PZA), rifampicin (RIF), its metabolite 25-desacetylrifampicin and degradation products: rifampicin quinone and 3-formyl-rifampicin. Analysis was completed from a very small plasma volume (20 µL) using only protein precipitation with methanol. Chromatographic separation was achieved on a Kinetex Polar C18 column (2.6 µm; 150 × 3 mm) with a mobile phase consisting of 5 mM ammonium acetate and acetonitrile, both containing 0.1 % formic acid, in gradient elution. The analytes were detected using a positive ionization mode by multiple reaction monitoring. The LLOQ for RIF and its degradation products was 0.1 µg/mL, 0.05 µg/mL for INH, and 0.2 µg/mL for PZA. The method was validated based on the FDA guidance. The application of the method was confirmed in the analysis of RIF, INH, and PZA, as well as RIF metabolism/degradation products in plasma samples of patients with TB. Based on the detailed stability study of the analyzed compounds at various storage conditions, we proposed recommendations for handling the plasma and serum samples in TDM and other pharmacokinetic studies.

Development and Validation of a Method for Simultaneous Quantification of Dihydroquercetin and Secoisolariciresinol

Development and Validation of a Method for Simultaneous Quantification of Dihydroquercetin and Secoisolariciresinol

Validated LC-MS/MS method for simultaneous quantification of KRASG12C inhibitor sotorasib and its major circulating metabolite (M24) in mouse matrices and its application in a mouse pharmacokinetic study

We have successfully developed and validated a bioanalytical assay using liquid chromatography tandem mass spectrometry to simultaneously quantify the first approved KRASG12C inhibitor sotorasib and its major circulating metabolite (M24) in various mouse matrices. M24 was synthesized in-house via low-pH hydrolysis. We utilized a fast and efficient protein precipitation method in a 96-well plate format to extract both analytes from biological matrices. Erlotinib was selected as the internal standard in this assay. Gradient elution using methanol and 0.1 % formic acid in water (v/v) was applied on an Acquity UPLC BEH C18 column to separate all analytes. Sotorasib, M24, and erlotinib were detected with a triple quadrupole mass spectrometer in positive electrospray ionization in multiple reaction monitoring mode. During the validation and sample quantification, a linear calibration range was observed for both sotorasib and M24 in a range of 4 – 4000 nM and 1 – 1000 nM, respectively. The %bias and %CV (both intra- and inter-day) for all tested levels in all investigated matrices were lower than 15 % as required by the guidelines. Sotorasib had a rather short room temperature stability in mouse plasma for up to 8 h compared to M24 which was stable up to 16 h at room temperature. This method has been successfully applied to measure sotorasib and M24 in several mouse matrices from three different mouse strains. We can conclude that the plasma exposure of sotorasib in mice is limited via human CYP3A4- and mouse Cyp3a-mediated metabolism of sotorasib into M24.

Stability Indicating Assay Method Development and Validation by RP-UPLC with PDA detector for Simultaneous Estimation of Glycopyrrolate and Neostigmine in Pharmaceutical dosage form

The presented research aimed to create a simple, precise, and accurate isocratic reversed-phase stability indicating Ultra Performance Liquid Chromatography (UPLC) method for simultaneous quantification of Glycopyrrolate and Neostigmine in bulk and injectable dosage form. On a Symmetry-C18(150mm X 4.6mm, 3.5m) column, isocratic separation was accomplished. The mobile phase is composed of acetonitrile and 1% orthophosphoric acid buffer (70:30 v/v) flowing at a rate of 1ml/min, with detection at 255nm utilising a photo-diode array detector. To apply stress conditions, the drug was treated to acid degradation, alkali degradation, peroxide degradation, photolysis, and heat. Specificity, precision, linearity, accuracy robustness, and solution stability were all validated. Glycopyrrolate and Neostigmine showed linearity in the range of 1-15mg mL-1 and 5-75mg mL-1, respectively. Glycopyrrolate accuracy was from 98.9 to 100.2 percent, whereas Neostigmine accuracy ranged from 98.4 to 100.2 percent. The detection of Glycopyrrolate and Neostigmine test does not interfere with degradation products produced as a result of stress studies, hence this method is regarded as stability-indicating.

A simple high-performance liquid chromatographic assay for concurrent quantification of lumefantrine and efavirenz in human plasma from malaria–HIV co-infected individuals

BackgroundAs per current treatment guidelines, artemether-lumefantrine and efavirenz-based antiretroviral therapy are recommended drugs for falciparum malaria and human immunodeficiency virus (HIV) infections, respectively. A liquid chromatography-ultraviolet detection method for simultaneous quantification of lumefantrine and efavirenz was developed and validated for efficacy and pharmacokinetic clinical studies. Lumefantrine and efavirenz were separated using a 100 × 4.6 mm × 3 µm Fortis C18 chromatographic column, and a multistep gradient mobile phase. Calibration curves were obtained with a series of standard solutions containing known concentrations of the chemical reference of both analytes prepared concomitantly in drug-free plasma. The assay was validated within the calibration ranges of 78.125–20,000 ng/mL for lumefantrine and 187.15–24,000 ng/mL for efavirenz. Stability assessment was carried out with or without heating the quality control sample to 58 °C for 45 min. The method was employed to measure the plasma concentrations of lumefantrine and efavirenz in a study conducted among malaria-HIV co-infected patients.ResultLumefantrine and efavirenz were well separated from each other and from the biological matrix. The method demonstrated a good recovery of 72.64% for lumefantrine and 117.17% for efavirenz. The intra- and inter-day accuracy presented as 95.36–105.14% for lumefantrine and 104.11–115% for efavirenz and precision ranged from 1.15 to 6.45% for lumefantrine and 0.43 to 13.12 for efavirenz, were within ± 15% at the three quality control levels. The analytes from both quality control lots and samples collected from HIV-malaria co-infected individuals were found to be stable post-deactivation of infectious virus by heating to 58 °C for 45 min.ConclusionThe assay is accurate, precise and shown to simultaneously measure the lumefantrine and EFV in human plasma.

The first RP-UHPLC method for simultaneous quantification of abiraterone acetate, its four degradants, and six specified process impurities and correct identification of all analytes based on molecular weight

This article describes the first simple, fast, time-saving, and cost-effective UHPLC method that was developed and validated for simultaneous quantification of abiraterone acetate, its four degradation products, and six specified process impurities in bulk and tablet form. Moreover, when coupled with a mass spectrometer detector, the proposed method provides additional advantages for confirmation of peak and correct identification based on molecular weight. The eleven peaks were separated on a Water Acquity BEH C18, (150 mm length, 2.1 mm internal diameter, 1.7 µm particle size) column maintained at a 50.0 °C temperature. Using 0.05% formic acid in 10 mM ammonium formate, acetonitrile, and methanol as mobile phases in gradient elution at a flow rate of 0.40 mL/min. provides excellent separation at 260 nm. The linearity curves of all analytes showed promising results with a correlation coefficient of 0.999 with a lower limit of detection and quantification. A forced degradation study on solid abiraterone acetate proved its specificity with improvements and significance. This proposed method provides improved separation with a lower flow rate, which offers faster analysis, reduces wastage and cost, and specifies the greener advantages compared to reported methods. The outcome of the specificity, linearity, precision, and trueness as per ICH guidelines proved that the proposed method is fast, time-saving, and cost-effective for the intended purpose.

Development and validation of simultaneous quantification method for gemcitabine and betulinic acid: augmenting industrial application.

Combinatorial treatment utilizing a nucleoside analogue gemcitabine (GEM), with a characteristic pentacyclic triterpenoid betulinic acid (BET), has exhibited empowering adequacy in the therapy of cancer. It lessens the advancement of collagen and upgrades the saturation of tumour medicines. With the advancement in nanotechnology, the co-loaded formulation urges for a validated method of estimation. The purposed work entails a robust, simple, and economical analytical method for the simultaneous estimation of GEM and BET through RP-HPLC. Orthophosphoric acid (0.1%)-acetonitrile was considered as the mobile phase for the detection of GEM and BET at 248nm and 210nm with retention times of 5min and 13min, respectively. The method was further validated as per the regulatory guidelines with all the parameters found within the limit. The developed method with adequate resolution and quantification was found to be linear, accurate, precise, robust, and stable with an intra- and inter-day variability of less than 2%. The method was found specific for GEM and BET with no matrix interference of drug-spiked FBS samples. To demonstrate the applicability of the developed method, a nano-formulation containing GEM and BET was prepared and assessed for various parameters including encapsulation efficiency, loading efficiency, drug release, and drug stability. The method developed can be a possible tool for the simultaneous quantification of GEM-BET in analytical and biological samples.

A HPLC method for simultaneous quantification of chlorhexidine and thymol using Box-Behnken design for robustness of the method assessment

The antimicrobial chlorhexidine is considered the gold standard in dentistry. Thymol is a phenol found in the essential oils of various plant species and also stands out for its antimicrobial potential. Synergistic effects can be promoted by applying these two active pharmaceutical ingredients together in technological products, for example in controlled release microparticles. The objective of this work was to develop and validate an analytical methodology applying a Box-Behnken experimental design and using High Performance Liquid Chromatography capable of quantifying chlorhexidine and thymol simultaneously in a matrix including pharmaceutical excipients. After optimization, the mobile phase consisted of methanol and 0.03 M monobasic sodium phosphate buffer (60:40), with 0.4% triethylamine and octylsilane as the applied stationary phase. The method proved selective, even in the presence of chlorhexidine and thymol degradation products. For chlorhexidine, the method was linear from 4.8 to 19.2 µg/mL, and for thymol from 8.0 to 32.0 µg/mL. Accuracy was close to 100%, and the precision assessment yielded coefficient variation values of <5%. Being based on the Box-Behnken design, the method was robust and therefore validated for assisting in quality control processes involving these active pharmaceutical ingredients.

Bioanalytical RP-HPLC Method for Simultaneous Quantification of Rivaroxaban and Ticagrelor in Spiked Human Plasma: Validation and Stability

For the effective assessment of preclinical, biopharmaceutical and clinical pharmacological investigations, selective and sensitive analytical methods for the quantitative evaluation of drugs and their metabolites (analytes) are essential. Using Rilpivirine as an internal standard (IS), a simple, fast, sensitive, precise and accurate high performance liquid chromatographic method for simultaneous determination of Rivaroxaban and Ticagrelor in human plasma was developed. The analytes were extracted using a direct protein precipitation method with acetonitrile from 500μL aliquots of human plasma. The content of the drugs was assessed using a mobile phase consisting of acetonitrile and 0.1% orthophosphoric acid buffer in a 40:60 v/v ratio and with a flow rate of 1.0ml/min, and an injection volume of 10μL. A Kromasil C18 (250×4.6mm; 5µm) analytical column was used for chromatographic separation and the effluents were monitored at 265nm using a photo diode array (PDA) detector.Rivaroxaban, Ticagrelor and Rilpivirine had retention times of 4.716min, 6.396min and 5.405 min, respectively. Rivaroxaban was shown to be linear at concentrations ranging from 0.018µg/mL - 1.80µg/mL, whereas Ticagrelor was found to be linear between 0.020µg/Ml - 2.00µg/mL. The method was validated according to US-FDA guidelines, and the findings satisfied the acceptance criteria. It was successfully used to determine Rivaroxaban and Ticagrelor in human plasma at the same time and this method is applicable for the pre-clinical and clinical estimation of drugs in biological fluids.

Validation of an LC-MS/MS method for simultaneous quantification of abiraterone, enzalutamide and darolutamide in human plasma

Currently, several oral androgen receptor signalling inhibitors are available for the treatment of advanced prostate cancer. Quantification of plasma concentrations of these drugs is highly relevant for various purposes, such as Therapeutic Drug Monitoring (TDM) in oncology. Here, we report a liquid chromatography/tandem mass spectrometric (LC–MS/MS) method for the simultaneous quantification of abiraterone, enzalutamide, and darolutamide. The validation was performed according to the requirements of the U.S. Food and Drug Administration and European Medicine Agency. We also demonstrate the clinical applicability of the quantification of enzalutamide and darolutamide in patients with metastatic castration-resistant prostate cancer.

A New Stability-Indicating RP-HPLC Method for Simultaneous Quantification of Diacerein and Aceclofenac in Novel Nanoemulgel Formulation and Commercial Tablet Dosage Form in the Presence of their Major Degradation Products Using DoE Approach.

The present study aimed to develop a simple, robust, sensitive and effective stability-indicating reversed-phase high-performance liquid chromatography method for simultaneous quantification of diacerein (DCN) and aceclofenac (ACE) in novel nanoemulgel formulation and commercial tablets in the presence of their main degradation product: rhein (RH) and diclofenac sodium (DLS), respectively. A fractional factorial design was used to screen the crucial independent factors, whereas a central composite design was used for the optimization of the chromatographic conditions. The separation was carried out on Phenomenex C18 column (5μm, 250 × 4.6mm), using a mobile phase consisting of phosphate buffer pH3 (0.1% v/v orthophosphoric acid) and acetonitrile (40:60v/v) at a flow rate of 1mL/min with detection at 264nm. The analytes were exposed to a variety of stress conditions, including heat, alkali, acid, oxidation, photochemical, humidity and hydrolysis. DCN, ACE, RH and DLS were found to have retention times of 4.32 ± 0.15, 5.77 ± 0.07, 8.28 ± 0.20 and 9.10 ± 0.18min, respectively. The percent recovery for all four analytes was found to be between 98 and 102, and the procedure was discovered to be linear in the range of 0.1-64μg/mL with R2 value > 0.999. The established method was validated as per ICH guidelines and successfully used to assay DCN and ACE in their combined marketed tablet dosage form and developed nanoemulgel formulation.

Determination of Pinoresinol 4-O-beta-D-glucopyranoside and Vladinol F as Markers in Pandanus tonkinensis Fruits by High Performance Liquid Chromatography

According to the traditional know-how, the Northern wild pineapple (Pandanus tonkinensis) has been used efficiently as a major component of oriental remedies for liver protection. Based on the experimentally found chemical composition of Pandanus tonkinensis and their obtained biological activities in terms of the hepatoprotection purpose, two structure-elucidated compounds pinoresinol 4-O-beta-D-glucopyranoside and vladinol F were selected as potential markers for this medical plant. This paper is aiming to present the validation of proposed HPLC method for simultaneous quantification of the both pinoresinol 4-O-beta-D-glucopyranoside and vladinol F in the fruits of Pandanus tonkinensis with the following conditions: using RP-C18 (250 mm × 4.6 mm; 5 μm) column, detection wavelength measured at 228 nm, the mobile phases consisting of acetonitrile and 0.1% acetic acid in gradient mode with a flow rate of 1mL/min and injection volume was 10 mL. Method validation showed a high specificity, linear calibration ranging from 25.5 to 76.4 mg/ml (r= 0.9991) and from 26.0 to 77.9 mg/ml (r= 0.9987) for two markers, respectively. Besides, a good repeatability and intermediate precisions (RSD &lt; 2%), a reliable accuracy (recovery efficiency between 99.4 and 101.5%, RSD &lt; 1.73%) as well as the obtained limits of quantification in values of 2.55 m/g and 2.60 mg/g for the two mentioned markers were received. Using the above validated method, the content of two markers - pinoresinol 4-O-beta-D-glucopyranoside and vladinol F in Pandanus tonkinensis fruits collected from different locations (Thanh Hoa, Hoa Binh, Thai Nguyen) had been determined falling in the range of 0.0250 - 0.0435 mg/g and 0.0243 - 0.0371 mg/g, respectively.&#x0D; Keywords: pinoresinol 4-O-beta-D-glucopyranoside, vladinol F, markers, Pandanus tonkinensis, HPLC

Discovery of two new isoforms of the human DUT gene

In human cells two dUTPase isoforms have been described: one nuclear (DUT-N) and one mitochondrial (DUT-M), with cognate localization signals. In contrast, here we identified two additional isoforms; DUT-3 without any localization signal and DUT-4 with the same nuclear localization signal as DUT-N. Based on an RT-qPCR method for simultaneous isoform-specific quantification we analysed the relative expression patterns in 20 human cell lines of highly different origins. We found that the DUT-N isoform is expressed by far at the highest level, followed by the DUT-M and the DUT-3 isoform. A strong correlation between expression levels of DUT-M and DUT-3 suggests that these two isoforms may share the same promoter. We analysed the effect of serum starvation on the expression of dUTPase isoforms compared to non-treated cells and found that the mRNA levels of DUT-N decreased in A-549 and MDA-MB-231 cells, but not in HeLa cells. Surprisingly, upon serum starvation DUT-M and DUT-3 showed a significant increase in the expression, while the expression level of the DUT-4 isoform did not show any changes. Taken together our results indicate that the cellular dUTPase supply may also be provided in the cytoplasm and starvation stress induced expression changes are cell line dependent.

A simple and sensitive HPLC method for simultaneous quantification of macrocyclic spermidine alkaloids in root, stem and leaf of Tripterygium wilfordii

AbstractThere has been a lively interest on macrocyclic polyamine alkaloids due to their remarkable pharmacological activities such as anti-tumor, anti-inflammatory, anti-Alzheimer's disease and anti-parasitic. Tripterygium wilfordii is a widely used traditional Chinese medicine, which is abundant in alkaloids including macrocyclic polyamine alkaloids. However, there are rarely studies on macrocyclic spermidine alkaloids of T. wilfordii so far. In this article, we use three known macrocyclic spermidine alkaloids celafurine, celabenzine and celacinnine, and successfully develop a simple and sensitive HPLC method for simultaneous quantification of macrocyclic spermidine alkaloids in root, stem and leaf of T. wilfordii.

Simple and fast quantification of cannabinoids in animal feeds by liquid chromatography-tandem mass spectrometry.

There is growing interest in using hemp materials as animal feed ingredients, which may raise safety concerns because of the potential transfer of active cannabinoids to the resultant products of animal origin. Hence, the detection and identification of cannabinoids in feeds would be useful. We developed a simple, fast, and sensitive method for simultaneous quantification of 4 major cannabinoids in animal feeds by liquid chromatography-tandem mass spectrometry (LC-MS/MS). We used a simple solvent extraction and dilution approach to extract cannabinoids from the feed matrix. We validated the method in 2 types of cattle feeds with acceptable intra-day and inter-day accuracy (87.5-116%) and precision (< 15%). The limit of detection was 0.05 µg/g, and the limit of quantification was 0.1 µg/g. Furthermore, the method was able to identify and quantify cannabinoids in cattle feeds mixed with hempseed cake as well as in several different hempseed materials, demonstrating its potential in veterinary laboratory applications.

A high-throughput LC-MS/MS method for simultaneous determination of direct oral anticoagulants in human plasma.

Direct oral anticoagulants are widely used in many indications to prevent thromboembolic events. Routine therapeutic monitoring is not required; however, there is increasing evidence suggesting the benefit of plasma level measurement in some situations. In addition, laboratory monitoring might help improve patient and drug non-compliance and thus individualize therapy. In the present study, we developed a sensitive and high throughput ultra-high-performance liquid chromatography-tandem mass spectrometry method for simultaneous quantification of apixaban, dabigatran, edoxaban and rivaroxaban in human plasma. A one-step extraction procedure in 96-well formate for phospholipid and protein removal was used for sample pre-treatment, and analytes were separated using gradient elution over 4.2 min. Analytes were detected on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode. The method was validated according to the European Medicine Agency guideline for the selectivity, linearity and lower limit of detection, precision and accuracy, matrix effects, extraction recovery, carryover, dilution integrity and stability over a concentration range of 3.0-1000 ng/mL for all analytes. The validated method was applied to real clinical samples of patients treated with one of the drugs. Therefore, we can conclude that our method is suitable for therapeutic drug monitoring of direct oral anticoagulants. This article is protected by copyright. All rights reserved.

Fast and Sensitive Method for Simultaneous Quantification of Meropenem and Vaborbactam in Human Plasma Microsamples by Liquid Chromatography-Tandem Mass Spectrometry for Therapeutic Drug Monitoring.

Meropenem (MRP)-Vaborbactam (VBR) is a novel beta-lactam/beta-lactamase inhibitor used for the management of difficult-to-treat Gram-negative infections. Among critically ill patients, MRP-VBR shows remarkable inter-individual variability in pharmacokinetic behavior, thus justifying the implementation of therapeutic drug monitoring (TDM) for improving real-time management in different challenging scenarios. In this study, we developed and validated a fast and sensitive Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method for the simultaneous quantification of MRP and VBR in human plasma microsamples of 3 microliters. The analysis required only a single-step sample preparation and was performed by means of a fast chromatographic run of 4 min, followed by positive electrospray ionization and detection on a high-sensitivity triple quadrupole tandem mass spectrometer operated in multiple reaction monitoring modes. The straightforward analytical procedure was successfully validated, based on the EMA guidelines, in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, the limit of quantification, and stability. The novel method was successfully applied for simultaneously measuring MRP and VBR concentrations in more than 42 plasma samples collected from critically ill patients affected by carbapenem-resistant Gram-negative bacteria infections.

Simultaneous voltammetric determination of 7-methyl-guanine and 5-methyl-cytosine using a cathodically pre-treated boron-doped diamond electrode

Given the importance of identifying the presence of biomarkers of human diseases in DNA samples, the main objective of this work was to investigate, for the first time, the electro-catalytic oxidation of 7-methyl-guanine (7-mGua) and 5-methyl-cytosine (5-mCyt) on a boron doped diamond electrode pre-treated cathodically (red-BDDE), using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The anodic peak potentials of 7-mGua and 5-mCyt by DPV were at E = 1.04 V and E = 1.37 V at pH = 4.5, indicating excellent peak separation of approximately 330 mV between species. Using DPV, experimental conditions such as supporting electrolyte, pH and influence of interferents were also investigated to develop a sensitive and selective method for individual and simultaneous quantification of these biomarkers. The analytical curves for the simultaneous quantification of 7-mGua and 5-mCyt in the acid medium (pH = 4.5) were: concentration range of 0.50–5.00 μmol L−1 (r = 0.999), detection limit of 0.27 μmol L−1 for 7-mGua; from 3.00 to 25.00 μmol L−1 (r = 0.998), with a detection limit of 1.69 μmol L−1 for 5-mCyt. A new DP voltammetric method for the simultaneous detection and quantification of biomarkers 7-mGua and 5-mCyt using a red-BDDE is proposed.

Optimisation of harvesting time and drying techniques for higher sennosides in Cassia angustifolia Vahl. by RP-HPLC

The commercially important leaves and pods of senna (Cassia angustifolia Vahl.), have many medicinal uses, including laxative properties due to active compounds such as sennoside A (SA) and sennoside B (SB). The content of secondary metabolites in the plant depends on harvesting time (HT), plant parts, and post-harvest techniques, apart from soil and climate conditions. In the present report, a simple, efficient and improved Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method for simultaneous quantification of sennosides (SA and SB) in different parts of C. angustifolia, harvested at 15 days short growth intervals was developed and used to optimise HT and drying techniques through monitoring the active compound content. An ideal HT for optimum content of sennosides in the leaf was observed at 90 days after sowing (DAS) (1.13%) and in pods at 105 DAS (1.4%). From the studies, the order of sennoside content range in different parts was: pods (1.21–1.4%) > leaves (0.25–1.19%) > whole plant (0.17–0.80%) > stem (0.16–0.74%) > root (0.06–0.14%) > flower (0.03–0.04%). These studies suggest that the discarded stems can also be considered for commercial exploitation. Further, different drying techniques revealed that on oven drying of leaves at 50 °C and 60 °C, more than 70% moisture loss within 6.4 h; in the p°ds, more than 77% moisture loss within 10 h was recorded. Shade drying and oven drying at 40 °C removed moisture, from leaves and pods, not more than 69% and 64%, respectively, even after 52 h. The RP-HPLC results showed that the leaves dried in the oven at 50 °C and pods dried at 40 °C possessed the highest sennosides content (1.28% and 3.21%, respectively). Sennoside content increased tremendously by 61.2% in the pods and 16.3% in the leaves when oven-dried at 40 °C and 50 °C, respectively, compared with shade drying. The present optimisation studies revealed that senna leaves harvested during 90–105 DAS and dried in the oven at 50 °C, pods harvested at 105 DAS and dried at 40 °C produced higher content of sennosides.

Development of HPLC-CAD method for simultaneous quantification of nine related substances in ursodeoxycholic acid and identification of two unknown impurities by HPLC-Q-TOF-MS

Ursodeoxycholic acid has gained increasing attention due to its recent discovery of the preventive effect on SARS-CoV-2 infection. Ursodeoxycholic acid has been included in various pharmacopoeias as an old drug, and the latest European Pharmacopoeia lists nine potential related substances (impurities A∼I). However, existing methods in pharmacopoeias and literature can only quantify up to five of these impurities simultaneously, and the sensitivity is inadequate, as the impurities are isomers or cholic acid analogues lacking chromophores. Herein, a novel gradient RP-HPLC method coupled to charged aerosol detection (CAD) was developed and validated for the simultaneous separation and quantification of the nine impurities in ursodeoxycholic acid. The method proved sensitive and allowed the quantification of the impurities as low as 0.02 %. Relative correction factors of the nine impurities were all within the range of 0.8–1.2 in the gradient mode by optimizing chromatographic conditions and CAD parameters. In addition, this RP-HPLC method is fully compatible with LC-MS due to the volatile additives and high percentage of the organic phase, which can be directly used for the identification of impurities. The newly developed HPLC-CAD method was successfully applied to commercial bulk drug samples, and two unknown impurities were identified by HPLC-Q-TOF-MS. The effect of CAD parameters on the linearity and correction factors was also discussed in this study. Overall, the established HPLC-CAD method can improve the methods in current pharmacopoeias and literature and contributes to understanding the impurity profile for process improvement.