Selective Liquid Chromatography Research Articles

Pharmacokinetics of the material basis compounds of Tianshu capsule in treating migraine

Ethnopharmacological relevanceTianshu capsule (TSC) is a traditional Chinese medicine (TCM) preparation and has significant clinical effect on migraine. The composition characteristics of TSC formula are worth exploring for the treatment of migraine. Aim of the studyIdentify the compounds in vivo after oral administration of TSC, Gastrodin (GAS), ferulic acid, senkyunolide G and senkyunolide I in the blood of healthy and migraine rats were used as representative compounds for time-dependent processes investigation. And we focus on explaining the characteristics of TSC treatment on migraine from a pharmacokinetic perspective. Materials and methodsIn this study, Ultra-high performance liquid chromatography with Orbitrap tandem mass spectrometry (UPLC-Orbitrap-MS/MS) system were used to detect the compounds in rat plasma and brain after oral administration of TSC. A sensitive, selective and reliable ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-TQ-MS/MS) system method was established for the simultaneous quantitative analysis of multi-components and evaluate the pharmacokinetic behavior of four main compounds. ResultsA total of 46 compounds were significantly identified in vivo of rat, including 35 compounds in plasma, 7 compounds only in brain and 4 compounds both in plasma and brain. The quantitative method has been confirmed to be feasible for multi-components content determination, pharmacokinetic parameters indicated that the four compounds absorbed into blood rapidly, and senkyunolide I also cross the blood-brain barrier (BBB) quickly into brain. GAS has relatively high concentrations in plasma, and the parameters AUC0-t, CLz/F displayed significant differences between the normal and migraine rats. And the AUC0-t and Cmax of GAS and ferulic acid exhibited dose-dependent way. Conclusionswe added compounds for the pharmacokinetic study of TSC, providing powerful help for clinical medication in the treatment of migraine.

Simultaneous Determination of Methotrexate and 7-Hydroxy-Methotrexate by UHPLC-MS3 Assay Coupled With Multiple Stage Fragmentation to Enhance Sensitivity.

A selective ultra-high performance liquid chromatography tandem mass spectrometry cubed (UHPLC/MS3) assay for simultaneous determination of methotrexate (MTX) and 7-hydroxy-methotrexate (7-OH-MTX) in human plasma was developed and validated. After protein precipitation with methanol, chromatographic separation of MTX, MTX-d3, and 7-OH-MTX was performed on a Waters AcQuity UPLC-BEH column (2.1×50mm I.D., 1.7µm) with gradient elution. MRM3 transition was used for the detection of MTX (m/z 455.2→308.0→175.1) and 7-OH-MTX (m/z 471.3→191.0→148.1). The linear range of UHPLC/MS3 assay for the determination of MTX and 7-OH-MTX was 0.5-300ng/mL (R2≥0.99) and 5-1500ng/mL (R2≥0.99), respectively. The enhanced selectivity and sensitivity are the novelties of the developed UHPLC/MS3 assay. The analytical method was successfully applied to simultaneous determination of MTX and its major metabolite 7-OH-MTX in real human plasma samples.

Development and Validation of Selective and Sensitive Liquid Chromatography - Tandem Mass Spectroscopy (UHPLC-MS/MS) Method for Bioanalysis of Remogliflozin in Rat Plasma

Remogliflozin is an inhibitor of sodium-glucose cotransporter 2 inhibitors (SGLT-2) protein and plays an important role in the treatment and management of type-2 diabetes mellitus. In this study, a selective isocratic method was developed and validated using liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the determination of remogliflozin in rat plasma. Acetonitrile with formic acid was used as a precipitating agent. Chromatographic separation was achieved by using X select CSH Fluorophenyl (150 mm x 4.6 mm, 3.5 µm) column and 0.1% formic acid in milli-Q water (20%) and acetonitrile (80%), v/v as a mobile phase for isocratic elution method. Flow rate and injection volume were maintained at 0.7 mL/min and 10 µL, respectively. The validated method was linear in the range of 15– 2009 ng/mL with the lower limit of quantification (LLOQ) of 18 ng/mL. Also, the method was precise with a % CV less than 5.75 and accuracy within ±10% of nominal concentration. The method is accurate, simple, precise, and suitable for its application in further bioequivalence and pharmacokinetic studies.

Evaluation of Microbial Phospholipase and Lipase Activity Through the Chromatographic Analysis of Crude, Degummed, and Transesterified Soybean Oil for Biodiesel Production.

The present study aimed at synthesizing fatty acid methyl esters in a combined enzymatic method by applying degumming and transesterification of soybean oil. A soluble lipase from Serratia sp. W3 and a recombinant phosphatidylcholine-preferring phospholipase C (PC-PLC) from Bacillus thuringiensis were used in a consecutive manner for phosphorus removal and conversion into methyl esters. By applying 1% of recombinant PC-PLC almost 83% of phosphorus was removed (final content of 21.01mg/kg). Moreover, a sensitive and selective high-performance liquid chromatography method coupled to tandem mass spectrometry was applied to obtain a comprehensive lipid profile for the simultaneous evaluation of phospholipids removal and diacylglycerol (DAG) increase. A significant increase for all the monitored DAG species, up to 138.42%, was observed by using the enzymatic degumming, in comparison to the crude sample, resulting in an increased oil yield. Serratia sp. W3 lipase was identified as a suitable biocatalyst for biodiesel production, converting efficiently the acylglycerols. The results regarding the physical-chemical characteristics show that the cetane level, density and pour point of the obtained biodiesel are close to current regulation requirements. These findings highlight the potential of a two-step process implementation, based on the combination of lipase and phospholipase, as a suitable alternative for biodiesel production.

Development and Validation of an LC-MS/MS Assay for the Quantitation of MO-OH-Nap Tropolone in Mouse Plasma: Application to In Vitro and In Vivo Pharmacokinetic Studies.

A rapid, selective, and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of MO-OH-Nap tropolone (MO-OH-Nap) in mouse plasma. MO-OH-Nap is an α-substituted tropolone with anti-proliferative properties in various cancer cell lines. Detection and separation of analytes was achieved on an ACE Excel C18 (1.7 µm, 100 × 2.1 mm, MAC-MOD Analytical, Chadds Ford, PA, USA) column with mobile phase consisting of 0.05% trifluoroacetic acid in water (mobile phase A) and 0.05% trifluoroacetic acid in acetonitrile (mobile phase B), with an isocratic elution of 15:85% (A:B) at a total flow rate of 0.25 mL/min. The LC-MS/MS system was operated at unit resolution in multiple reaction monitoring (MRM) mode, using precursor ion > product ion combination of 249.10 > 202.15 m/z for MO-OH-Nap and 305.10 > 215.05 m/z for the internal standard (IS), BA-SM-OM. The MS/MS response was linear over a concentration range of 1 to 500 ng/mL with a correlation coefficient (r2) of ≥0.987. The within- and between-batch precision (%RSD) and accuracy (%Bias) were within acceptable limits. The validated method was successfully applied to determine MO-OH-Nap metabolic stability, plasma protein binding, and bio-distribution studies of MO-OH-Nap in CD-1 mice.

Development and validation of an LC-MS/MS method for simultaneous quantification of eight drugs in plasma and brain: Application in a pharmacokinetic study in mice

A selective and sensitive liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) method was developed and validated for simultaneous quantitation of a cassette of 8 drugs, including docetaxel, erlotinib, loperamide, riluzole, vemurafenib, verapamil, elacridar and tariquidar. Stable isotopically labeled compounds were available for use as internal standards for all compounds, except for tariquidar for which we used elacridar-d4. Sample pre-treatment involved liquid–liquid extraction using tert-butyl-methyl ether as this resulted in good recovery and low ion suppression. Chromatographic separation was achieved using a Zorbax Extend C18 analytical column and a linear gradient from 20 % to 95 % methanol in 0.1 % (v/v) formic acid in water. MS/MS detection using multiple reaction monitoring was done in positive ionization mode. We validated this assay for human and mouse plasma and mouse brain homogenates. The calibration curves were linear over a range 1–200 nM for each drug in the mix, except for tariquidar probably due to the lack of a stable isotope labeled analog. The intra-day and inter-day accuracies were within the 85–115 % range for all compounds at low, medium and high concentrations in the three different matrices. Similarly, the precision for all compounds at three different concentration levels ranged below 15 %, with the exception of tariquidar in mouse plasma and brain homogenate and riluzole in brain homogenate. Pilot studies have confirmed that the method is suitable for the analysis of mouse plasma samples and brain homogenates following cassette dosing of this mixture in mice.

Construction of chiral crown ethers in robust covalent organic frameworks for electrochromatographic enantioseparation

ABSTRACT Capillary electrochromatography (CEC) is a rapidly emerging separation technique that merges the high separation efficiency of capillary electrophoresis with the exceptional selectivity of liquid chromatography. However, it remains a synthetic challenge to design functional chiral stationary phases (CSPs) with high chemical stability against acid and base in CEC enantioseparation. Here we demonstrate that incorporating chiral crown ethers into stable covalent organic frameworks (COFs) enables efficient and stable separations of racemates by CEC. This facilitates the crafting of two three-dimensional (3D) chiral COFs by polycondensation of a chiral 1,1'-binaphyl-20-crown-6-derived dialdehyde and tetraamines with diisopropyl substituents. Both feature an 11-fold interpenetrated diamond framework, characterized by tubular open channels decorated with chiral crown ethers serving as enantioselective recognition and binding sites. These frameworks demonstrate excellent stability in water, acid and base, thanks to the presence of bulky isopropyl groups that shield the dynamic imine linkages. Moreover, the precisely defined COF channels enhanced the accessibility of the enclosed crown ethers to the analytes while providing strong protection against harsh environments, rendering them suitable for CSPs in CEC separations. They can effectively separate some important enantiomers, including ketones, epoxides and alkaline substances, when utilized as coatings on chiral columns, particularly facilitating the chiral separation of drugs. This study advances the application of COFs in electrochromatographic separations, expanding the scope of porous materials design and engineering to create COFs with targeted enantioselective properties.

Detailed comparison of in-house developed and commercially available heart-cutting and selective comprehensive two-dimensional liquid chromatography systems

Recently, two-dimensional liquid chromatography (2D-LC) has become a popular approach to analyze complex samples. This is partly due to the introduction of commercial 2D-LC systems. In the past, 2D-LC was carried out on in-house developed setups, typically consisting of several switching valves and sample loops as the interface between the two dimensions. Commercial systems usually offer different 2D-LC modes in combination with specialized software to operate the instrument and analyze the data. This makes them highly user-friendly, however, at an increased cost compared to in-house developed setups. This study aims to make a comparison between an in-house developed 2D-LC setup and a commercially available 2D-LC instrument. The comparison is made based on experimental differences, in addition to more general differences, including cost price, flexibility, and ease of operation. Special attention is also paid to the different strategies to deal with the mobile phase incompatibility between the highly orthogonal separation mechanisms considered in this work: hydrophilic interaction liquid chromatography (HILIC) and reversed-phase LC (RPLC). For the commercial 2D-LC instrument, this is done using active solvent modulation (ASM), a valve-based approach allowing the on-line dilution of the effluent eluting from the first dimension column before transfer to the second dimension (2D) column. For the in-house developed setup, a combination of restriction capillaries and a trap column is used. Using a sample of 28 compounds with a large polarity range, peak shapes and recoveries of the 2D-chromatograms are compared for both setups. For early eluting compounds, the selective comprehensive approach, currently only possible on the commercial 2D-LC instrument, results in the best peak shapes and recoveries, however, at the cost of an increased analysis time. In general, depending on the analytical goal (single heart-cut versus full-comprehensive 2D-LC), an in-house developed system can be satisfactory for the analysis of specific target compounds/samples. For more complex problems, it can be interesting to use a more specialized commercial 2D-LC instrument. Overall, this comparison study provides advice for analytical scientists, who are considering to use 2D-LC, on the type of equipment to consider, depending on the needs of their particular applications.

Simple HPLC-UV Method for Therapeutic Drug Monitoring of 12 Antiepileptic Drugs and Their Main Metabolites in Human Plasma

The objective of the present report was to develop and validate a simple, selective, and reproducible high-performance liquid chromatography method with UV detection suitable for routine therapeutic drug monitoring of the most commonly used antiepileptic drugs and some of their metabolites. Simple precipitation of plasma proteins with acetonitrile was used for sample preparation. 10,11-dihydrocarbamazepine was used as an internal standard. Chromatographic separation of the analytes was achieved by gradient elution on a Phenyl–Hexyl column at 40 °C, using methanol and potassium phosphate buffer (25 mM; pH 5.1) as a mobile phase. The method was validated according to the FDA guidelines for bioanalytical method validation. It showed to be selective, accurate, precise, and linear over the concentration ranges of 1–50 mg/L for phenobarbital, phenytoin, levetiracetam, rufinamide, zonisamide, and lacosamide; 0.5–50 mg/L for lamotrigine, primidone, carbamazepine and 10-monohydroxycarbazepine; 0.2–10 mg/L for carbamazepine metabolites: 10,11-trans-dihydroxy-10,11-dihydrocarbamazepine and carbamazepine-10,11-epoxide; 0.1–10 mg/L for oxcarbazepine; 2–100 mg/L for felbamate and 3–150 mg/L for ethosuximide. The suitability of the validated method for routine therapeutic drug monitoring was confirmed by quantification of the analytes in plasma samples from patients with epilepsy on combination antiepileptic therapy.

Identification of the absorbed constituents and metabolites of Huangqi Guizhi Wuwu decoction by ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

Huangqi Guizhi Wuwu decoction (HGWWD) is a widely used traditional Chinese medicine (TCM) preparation for the treatment of ischemic stroke and diabetes peripheral neuropathy. However, the material basis for the efficacy of HGWWD remains unclear. In this study, a rapid, sensitive and selective ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) method was developed to separate and identify the absorbed components and metabolites of HGWWD in rat plasma after oral administration for the first time. By comparing the retention time, high-resolution mass spectrometry primary and secondary mass spectrometry data of blank plasma and drug-containing plasma, a total of 42 constituents, including 24 prototype compounds and 18 metabolites, were identified or tentatively characterized. The results indicated that monoterpenes, flavonoids, organic acids, amino acids, gingerols and alkaloids were main prototype compounds in rat plasma, and flavonoid-related metabolites, organic acid-related metabolites and gingerol-related metabolites were major metabolites. It is concluded the developed UHPLC-Q-TOF-MS method with high sensitivity and resolution is suitable for identifying and characterizing the absorbed components and metabolites of HGWWD, and the results will provide important data for further study on the relationship between the chemical constituents and pharmacological activities of HGWWD.

Development and Validation of RP-HPLC Method for the Estimation of Linezolid from Bulk and Formulations

A new, simple, rapid, selective, precise and accurate isocratic reverse-phase high-performance liquid Chromatography assay method has been developed to estimate Linezolid in tablet formulations. The separation was achieved using column Inert sustain C18 (250×4.6mm, 5µ) in the mobile phase consisting of methanol: 1% Acetic acid (50:50 v/v). The flow rate was 0.80mL/min-1, and the separated Linezolid was detected using a UV detector at 249nm. Column temperature 45°C and sample temperature ambient and injection volume 20µL. The retention time of Linezolid was noted to be 7.3min. The method was validated as per ICH guidelines. The proposed method was found to be accurate, reproducible, and consistent.

DEVELOPMENT OF QUANTITATIVE METHOD OF TULOBUTEROL HYDROCHLORIDE IN RAT PLASMA: VALIDATION AND APPLICATION TO PRECLINICAL PHARMACOKINETICS

Objective: A robust, simple, accurate, rapid, and selective bioanalytical high-performance liquid chromatography (HPLC) method was established and validated to determine the tulobuterol hydrochloride in rat plasma. Methods: The protein precipitation method deproteinated analyte from rat plasma using acetone. The analysis of tulobuterol hydrochloride from rat plasma was accomplished using a mobile phase comprising of methanol: potassium dihydrogen orthophosphate buffer (0.05M; pH 4.0) in 90:10 (v/v) ratio run at 1.0 ml/min flow rate. Separation was carried on BDS hypersil C18 column (4.6 mm × 250 mm; 5 µ) at ambient temperature employing a 996 photodiode array (PDA) detector at 228 nm. Results: The linearity model was exhibited from 100-500 ng/ml with a good correlation of 0.999. Tulobuterol hydrochloride was efficiently separated at a retention time of 7.281 min. The percent recovery rate was between 100.21-100.46 %. The accuracy, precision, robustness, and ruggedness study showed relative standard deviation (%RSD) was within 2% (acceptable limit), and that revealed the method was efficient, precise, reliable, and reproducible. Conclusion: A simple, accurate, suitable method to quantitate tulobuterol hydrochloride in rat plasma was established using HPLC employed with a PDA detector that overcomes the increased cost for analysis. The developed method was successfully validated in rat plasma.

Variable fragmentation and ionization of amyloid-beta epimers and isomers.

While the existence of D-amino acids in peptides and proteins has recently been accepted in higher forms of life, their roles and importance are yet to be understood. The lack of analytical methods present for such epimeric and/or isomeric analyses often limits developments in the field. Studies have shown the elevated presence of epimeric and isomeric modifications to amyloid-beta (Aβ) peptides extracted from Alzheimer's disease patients. These modifications most frequently occur through aspartic acid and serine residues. Because such peptides are indistinguishable by mass alone, selective liquid chromatography tandem mass spectrometry analysis is required to differentiate such peptides. Herein, we examine MS/MS of tryptic fragments of Aβ peptides containing D-Asp, L-iso-Asp, D-iso-Asp, and/or D-Ser modifications. Peptide ionizability and fragmentation are explored through selected reaction monitoring, selected ion monitoring, and product ion scan. The results show the variability of ionization and fragmentation for many "identical mass peptides" and how these differences can affect the analysis of isomeric and epimeric peptides.

Highly selective and sensitive high performance liquid chromatography method for determination of fumonisins from feed samples with MIL-101 based dispersed micro-solid-phase extraction and precolumn fluorescence derivatization

A selective and rapid high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method for determining fumonisins was established and validated, which based on dispersed microsolid-phase extraction (D-μ-SPE) and precolumn derivatization. The MIL-101 was prepared as sorbents to selectively enrich two fumonisins from feed samples. The obtained extracts were labeled by a novel derivatization reagent 2,5-dioxopyrrolidin-1-yl 4-(1-methyl-1H-phenanthro[9,10-d]imidazol-2-yl)benzoate (MPIBA-Su). There was no fluorescence from fumonisins itself, while their derivatives exhibited considerable fluorescence with a maximum excitation at λex 255 nm and a maximum emission at λem 457 nm. Key factors affecting extraction efficiency and derivatization efficiency were fully optimized. Excellent linearity was achieved with correlation coefficients > 0.9935 under optimal conditions. The detection limits (LODs) were between 2.4 and 3.5 ng·mL−1, and the quantitation limits (LOQs) were between 8.1 and 11.7 ng·mL−1. With recoveries in the range of 83.8% − 94.3%, the established method has successfully been applied to the quantitative analysis of fumonisins in feed samples.

A validated method for detection of cannflavins in hemp extracts

A selective and sensitive liquid chromatography mass spectrometry assay was developed for the detection of cannflavin A, B, and C in hemp extract specimens. A deuterated analog cannabidiol-D3 was used as the internal standard and the isocratic method used a mobile phase consisting of acetonitrile and water with 0.1 % formic acid [83:17]. Detection was carried out by electrospray positive ionization in single-ion monitoring mode through a C-18 analytical column. The assay (total run time <20 min) had excellent linearity and a lower limit of quantification of 0.5 μg/mL and a limit of detection of 0.25 μg/mL with a 10 μL injection. The method possessed suitable measures of stability, sensitivity, and selectivity for detecting cannflavins in several specimen types. The method was successfully applied to the analysis of samples of cannflavin release from prototype topical formulations.

Selectivity optimization in liquid chromatography via stationary phase tuning.

In striving for the best possible separation, the selectivity of stationary phases as an optimization parameter is often underestimated although there are many ways to influence this powerful tool. This review serves to provide an insight into the various ways of adapting the selectivity of a separation in liquid chromatography. Approaches via temperature and flow rate tuning are discussed as a basis followed by focusing on the stationary phase as the superior optimization parameter. Highly selective stationary phases hereby provide an advantage for groups of similar analytes. For more complex mixtures, separations can be improved using mixed-mode technologies where different retention mechanisms are combined. Serial coupling, mixed-bed columns, and stationary phase optimized selectivity liquid chromatography provide solutions to various degrees. Finally, the advantages of stationary phase tuning over adaption of mobile phase and/or temperature are presented in terms of optimum application range.

Polybutylene terephthalate-based stationary phase for ion-pair-free reversed-phase liquid chromatography of small interfering RNA. Part 2: Use for selective comprehensive two-dimensional liquid chromatography

With the increasing numbers of nucleic acid-based pharmaceuticals like antisense oligonucleotides (ASO), small interfering ribonucleic acid (siRNA) entering the market, research facilities, pharmaceutical industries and also regulatory authorities have been looking for efficient analytical methods for these synthetic oligonucleotides (ON). Besides of conventional one-dimensional (1D) reversed-phase liquid chromatography with or without ion-pairing (IP-RP-LC, RP-LC), hydrophilic liquid chromatography (HILIC) and mixed-mode chromatography (MMC), two-dimensional (2D) approaches combining two orthogonal chromatographic techniques also become more relevant due to the high structural complexity of oligonucleotides. Recently, we tested a polybutylene terephthalate(PBT)-based stationary phase under ion-pairing free RP mode for the liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) analysis of siRNA (Patisiran). In this study, retention profile and chromatographic orthogonality, respectively, were compared to other LC-modes like HILIC, IP-RPLC, another ion-pair free cholesterol-bonded RPLC and MMC considering their normalized retention times. Finally, because of higher orthogonality, the ion-pairing free PBT-bonded RPLC as first dimension (1D) was hyphenated with HILIC in the second dimension (2D) in a selective comprehensive 2D-LC setup leading to an enhanced resolution for peak purity evaluation of the main ON entities.

LC-MS/MS method for the quantitation of a dual PI3K/BRD4 inhibitor SF2523 in mouse plasma: Application to plasma protein binding and metabolism studies.

A sensitive and selective liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of dual PI3K/BRD4 inhibitor SF2523 in mouse plasma. The analysis was performed on a UPLC system connected to a Shimadzu 8060 mass spectrometer by electrospray ionization in positive multiple reaction monitoring mode. Chromatographic separation was carried out on an ACE Excel C18 column with a gradient elution containing 0.1% formic acid and methanol as the mobile phase. The linearity was conducted in the concentration range 0.1-500 ng/ml for SF2523 in 100 μl of plasma. The inter- and intra-batch precision (RSD) were both lower than 13.5%, with the accuracy (percentage bias) ranging from -10.03 to 11.56%. The validated method was successfully applied to plasma protein binding and in vitro metabolism studies. SF2523 was highly bound to mouse plasma proteins (>95% bound). Utilizing mouse S9 fractions, a total of seven phase I and II metabolites were identified with hydroxylation found to be the major metabolic pathway. Metabolite identification included analysis of retention behaviors, molecular weight changes and MS/MS fragment patterns of SF2523 and the metabolites. This newly developed and validated method allows the rapid and easy determination of the SF2523 concentration with high sensitivity in a low sample volume and can be applied to future pre-clinical studies.

A validated LC–MS/MS method for clinical pharmacokinetics and presumptive phase II metabolic pathways following oral administration of Andrographis paniculata extract

Andrographis paniculata, a medicinal plant in Thailand national list of essential medicines, has been proposed for treatment of patients with mild to moderate coronavirus disease 2019. This study aims to develop a highly selective and sensitive liquid chromatography triple quadrupole tandem mass spectrometry method for quantitative determination of major diterpenoids in plasma and urine with application in pharmacokinetics. Chromatographic separation was performed on C18 column using a gradient mobile phase of water and acetonitrile. Mass spectrometry was analyzed using multiple reaction monitoring with negative ionization mode. This validated analytical method was very sensitive, less time consuming in analysis, and allowed the reliability and reproducibility on its application. The clinical pharmacokinetics was evaluated after single oral administration of A. paniculata extract (calculated as 60 mg of andrographolide). The disposition kinetics demonstrated that major diterpenoids could enter into systemic circulation, but they are mostly biotransformed (phase II) into conjugated glucuronide and sulfate metabolites. These metabolites are predominantly found in plasma and then extremely eliminated, in part through urinary excretion. The successful application of this analytical method supports its suitable uses in further clinical benefits after oral administration of A. paniculata.

Multi-class determination of pharmaceuticals as emerging contaminants in wastewater from Eastern Province, Saudi Arabia using eco-friendly SPE-UHPLC-MS/MS: Occurrence, removal and environmental risk assessment

Occurrence of pharmaceuticals in wastewater, which might be released to different water environments causing contamination might lead to health hazards. Therefore, sensitive, selective and reliable analytical methods are required to monitor pharmaceuticals in such complex environmental matrix. In this work, an eco-friendly, sensitive, robust and selective ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) method was developed to simultaneously identify and quantify multiple classes of pharmaceuticals in influent and effluent wastewater samples in Eastern Province, Saudi Arabia using solid phase extraction (SPE) for sample preparation. The extraction conditions were optimized to achieve the best extraction efficiencies and achieved recoveries of 70.4 – 112.2% and 74.0 – 107.8% in influent (IWW) and effluent wastewater (EWW) samples, respectively. The optimized method had satisfactory precision represented as %RSD lower than 13.04%. Limits of detection were 0.06 – 16.0 and 0.07 – 13.23 ng L-1 for IWW and EWW, respectively. The developed method was successfully employed for the analysis of 32 pharmaceuticals in wastewater. The greenness profile was assessed using two assessment tools; Analytical Eco-scale and AGREE metric. Caffeine and Ciprofloxacin were the most frequent and highest concentration in influent wastewater with concentration range 23,600 – 37,602 ng L-1 and 1,684 –3,585 ng L-1, respectively. Average effluent concentrations range was from below method quantification limit to 1,241 ng L-1 (ciprofloxacin). Removal efficiency ranged from - 3.1% (trimethoprim) to 99% (caffeine). Environmental risk assessment was calculated using risk quotient approach for each individual analyte and for the mixture. The results revealed 4 and 6 compounds with high and medium risk, respectively. This work provides new insights into the occurrence, removal and ecotoxicological risk of pharmaceuticals from wastewater in Eastern Province, Saudi Arabia. It emphasizes the importance of monitoring these compounds as an input for future mitigation actions.