Reversed-phase Ultra-high Performance Liquid Chromatography Research Articles

A Novel RP-UHPLC-MS/MS Approach for the Determination of Tryptophan Metabolites Derivatized with 2-Bromo-4'-Nitroacetophenone.

Many biologically active metabolites of the essential amino acid L-tryptophan (Trp) are associated with different neurodegenerative diseases and neurological disorders. Precise and reliable methods for their determination are needed. Variability in their physicochemical properties makes the analytical process challenging. In this case, chemical modification of analyte derivatization could come into play. Here, we introduce a novel fast reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) coupled with tandem mass spectrometry (MS/MS) method for the determination of Trp and its ten metabolites in human plasma samples after derivatization with 2-bromo-4'-nitroacetophenone (BNAP). The derivatization procedure was optimized in terms of incubation time, temperature, concentration, and volume of the derivatization reagent. Method development comprises a choice of a suitable stationary phase, mobile phase composition, and gradient elution optimization. The developed method was validated according to the ICH guidelines. Results of all validation parameters were within the acceptance criteria of the guideline, i.e., intra- and inter-day precision (expressed as relative standard deviation; RSD) were in the range of 0.5-8.2% and 2.3-7.4%, accuracy was in the range of 93.3-109.7% and 94.7-110.1%, limits of detection (LODs) were in the range of 0.15-9.43 ng/mL, coefficients of determination (R2) were higher than 0.9906, and carryovers were, in all cases, less than 8.8%. The practicability of the method was evaluated using the blue applicability grade index (BAGI) with a score of 65. Finally, the developed method was used for the analysis of Alzheimer's disease and healthy control plasma to prove its applicability. Statistical analysis revealed significant changes in picolinic acid (PA), anthranilic acid (AA), 5 hydroxyindole-3-acetic acid (5-OH IAA), and quinolinic acid (QA) concentration levels. This could serve as the basis for future studies that will be conducted with a large cohort of patients.

Innovative Reversed-Phase Chromatography Platform Approach for the Fast and Accurate Characterization of Membrane Vesicles' Protein Patterns.

Outer membrane vesicles (OMVs) have been widely explored to develop vaccine candidates for bacterial pathogens due to their ability to combine adjuvant properties with immunogenic activity. OMV expresses a variety of proteins and carbohydrate antigens on their surfaces. For this reason, there is an analytical need to thoroughly characterize the species expressed at their surface: we here present a simple and accurate reversed-phase ultrahigh-performance liquid chromatography (RP-UPLC) method developed according to quality by design principles. This work provides an analytical alternative to the classical sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) characterization. The higher selectivity and sensitivity of the RP-UHPLC assay allow for the identification of additional protein species with respect to SDS-PAGE and facilitate its precise relative abundance quantification. According to validation results, the assay showed high accuracy, linearity, precision, repeatability, and a limit of quantification of 1% for less abundant proteins. This performance paves the way for improved production campaign consistency while also being analytically simple (no sample pretreatment required), making it suitable for routine quality control testing. In addition, the applicability of the assay to a wider range of vesicle classes (GMMA) was demonstrated.

Integration of ion-mobility high-resolution liquid chromatography/mass spectrometry-based untargeted metabolomics and desorption electrospray ionization-mass spectrometry imaging to unveil the ginsenosides variation induced by steaming for Panax ginseng, P. quinquefolius and P. notoginseng

The raw and steamed products of ginseng exhibit different efficacy, and elucidation of the underlying chemical transformation is significant for their rational application and quality control. This work was designed to holistically depict the chemical variation of Panax ginseng (PG), P. quinquefolius (PQ), and P. notoginseng (PN) induced by the steaming, and to unveil the steaming-associated markers diagnostic for differentiating between the raw and processed products, following a three-step strategy: 1) systematic ginsenosides characterization by hybrid scan (namely HDDIDDA) available on the Vion™ ion mobility-quadrupole time-of-flight mass spectrometer coupled with reversed-phase ultra-high performance liquid chromatography; 2) holistic depiction of the chemical variation and discovery of potential markers by the pattern recognition untargeted metabolomics analysis; and 3) construction of steaming-induced transformation network combined with desorption electrospray ionization-mass spectrometry imaging (DESI-MSI). Consequently, 542 ginsenosides were characterized from the raw and processed PG/PQ/PN. Steaming at 1–10 h could cause significant chemical variation, and separately 26, 28, and 18 potential markers were found for the steaming of PG, PQ, and PN. Steaming-induced transformation network mainly involved hydration of the malonyl group, hydrolysis of the glycosyl moiety, and dehydration at C-20. DESI-MSI further revealed spatial distribution of marker saponins in the cork layer, phloem, and xylem, and primarily confirmed the hydrolysis reactions occurring to ginseng steaming. Conclusively, the established strategy is practical to unveil the holistic ginsenosides variation of ginseng induced by the processing, which is useful in the quality control of both the herbal medicines and foods.

Mass Spectrometry-Based Metabolomics Multi-platform for Alzheimer's Disease Research.

The integration of complementary analytical platforms is nowadays the most common strategy for comprehensive metabolomics analysis of complex biological systems. In this chapter, we describe methods and tips for the application of a mass spectrometry multi-platform in Alzheimer's disease research, based on the combination of direct mass spectrometry and orthogonal hyphenated approaches, namely, reversed-phase ultrahigh-performance liquid chromatography and gas chromatography. These procedures have been optimized for the analysis of multiple biological samples from human patients and transgenic animal models, including blood serum, various brain regions (e.g., hippocampus, cortex, cerebellum, striatum, olfactory bulbs), and other peripheral organs (e.g., liver, kidney, spleen, thymus).

Study of nusinersen metabolites in cerebrospinal fluid of children with spinal muscular atrophy using ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry

The study aimed to analyze nusinersen metabolites in the cerebrospinal fluid samples using ion-pair reversed-phase ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Three different sample preparation methods were...

Comparison of nocturnal and diurnal metabolomes of rose flowers and leaves.

Roses are one of the most essential ornamental flowers and are commonly used in perfumery, cosmetics, and food. They are rich in bioactive compounds, which are of interest for therapeutic effects. The objective of this study was to understand the kinds of changes that occur between the nocturnal and diurnal metabolism of rose and to suggest hypotheses. Reversed-phase ultrahigh-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry or triple quadrupole mass spectrometry (TQ MS/MS) was used for nontargeted metabolomics and hormonal profiling respectively. For metabolite annotation, accurate mass spectra were compared with those in databases. The hormonal profile of flowers showed an increase in jasmonate at night, while that of leaves indicated an increase in the salicylic acid pathway. Nontargeted analyses of the flower revealed a switch in the plant's defense mechanisms from glycosylated metabolites during the day to acid metabolites at night. In leaves, a significant decrease in flavonoids was observed at night in favor of acid metabolism to maintain a level of protection. Moreover, it might be possible to place back some of the annotated molecules on the shikimate pathway. The influence of day and night on the metabolome of rose flowers and leaves has been clearly demonstrated. The hormonal modulations occurring during the night and at day are consistent with the plant circadian cycle. A proposed management of the sesquiterpenoid and triterpenoid biosynthetic pathway may explain these changes in the flower. In leaves, the metabolic differences may reflect night-time regulation in favor of the salicylic acid pathway.

Perioperative exposure to volatile organic compounds in neonates undergoing cardiac surgery

ObjectiveVolatile organic compounds (VOCs) are used in the sterilization and manufacture of medical equipment. These compounds have high vapor pressures with low water solubility and are emitted as gases from solids or liquids. They can be mutagenic, neurotoxic, genotoxic, and/or carcinogenic. Safe limits of exposure are not known for neonates. This study examined determinants of exposure in newborns undergoing cardiac surgery. MethodsTwenty metabolites of 16 VOCs (eg, xylene, cyanide, acrolein, acrylonitrile, N, N-dimethylformamide, 1,3-butadiene, styrene, and benzene) were measured as metabolites in daily urine samples collected from 10 neonates undergoing cardiac operations (n = 150 samples). Metabolites were quantified using reversed-phase ultra-high performance liquid chromatography and electrospray ionization tandem mass spectrometry. Repeated measures analysis of covariance was performed for each metabolite to examine associations with use of medical devices. ResultsAt least 3 metabolites were detected in every sample. The median number of metabolites detected in each sample was 14 (range, 3-15). In a model controlling for other factors, the use of extracorporeal membrane oxygenation was associated with significantly (P ≤ .05) greater metabolite levels of acrolein, acrylonitrile, ethylene oxide, propylene oxide, styrene, and ethylbenzene. Patients breathing ambient air had greater levels of metabolites of acrolein, xylene, N,N-dimethylformamide, methyl isocyanate, cyanide, 1,3-butadiene (all P ≤ .05). ConclusionsExposure to volatile organic compounds is pervasive in newborns undergoing cardiac surgery. Sources of exposure likely include medical devices and inhalation from the air in the intensive care unit. The contribution of VOC exposure during cardiac surgery in newborns to adverse outcomes warrants further evaluation.

UHPLC-MS/MS Method Development and Validation for the Genotoxic Impurities Trimethyl Phosphate and Triisopropyl Phosphate of Elagolix Sodium.

Elagolix sodium is a gonadotropin-releasing hormone (GnRH) receptor antagonist that inhibits endogenous GnRH signaling by competitively binding to GnRH receptors in the pituitary gland to treat moderate to severe pain associated with endometriosis. To keep the safety and quality of the drug, a fast quantitative method by reversed-phase ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry has been developed and validated for the identification, assay and estimation of potential genotoxic impurities trimethyl phosphate and triisopropyl phosphate in commercial batches of this active pharmaceutical ingredient in accordance with International Conference on Harmonization guidelines Q2 and M7. The method was validated by assessing specificity, sensitivity, linearity, the limit of quantification and detection, accuracy, precision and robustness for above analytes at a very low concentration, whose quantification and detection limits reached to 24 and 4.8pg/ml, respectively, and the total run time for a single injection was 6min.

Green Solid-Phase (Micro)Extraction of Andrographolides’ from Human Plasma Samples Followed by UHPLC-DAD-QqQ-MS/MS Analysis

Since inflammatory bowel disease is a progressive disease, optimal treatment early in the disease course is paramount. Still, the use of conventional drugs is accompanied by side effects. The herbal therapies for gastrointestinal disorders are traditionally widespread in Asia, while in Western countries have been adopted in recent years. Andrographis paniculata is a herbaceous plant used in anti-inflammatory treatment. To improve its clinical application, an analytical method with the potential to define a relationship between dose and plasma concentration of active ingredients is prerequisite. Considering the increasing demand for eco-friendly bioanalytical methods, our research aimed to implement new sample preparation technique microextraction by packed sorbent for extraction of marker compounds of A. paniculata from plasma. This green procedure using polymeric sorbent based on the poly (styrene-divinylbenzene) allowed miniaturization of sample volume (100 µL), decrease in consumption of solvents, and high recovery (92–98%). A highly selective and sensitive reversed-phase ultrahigh-performance liquid chromatography method has been developed and validated. The newest greenness assessment software AGREE calculator was used for evaluation of the method’s environmental performance. It suggests that our method conforms to the eco-friendly conditions (score 0.8). The sample preparation was identified as weak point of the bioanalytical methods which highlights the importance of microextraction.

Characterization of the Autoxidation of Terpenes at Elevated Temperature Using High-Resolution Mass Spectrometry: Formation of Ketohydroperoxides and Highly Oxidized Products from Limonene.

Low-temperature experiments on the oxidation of limonene-O2-N2 mixtures were conducted in a jet-stirred reactor (JSR) over a range of temperatures (520-800 K) under fuel-lean conditions (equivalence ratio φ = 0.5) with a short residence time (1.5 s) and a pressure of 1 bar. Collected samples of the reaction mixtures were analyzed by (i) online Fourier transform infrared spectroscopy (FTIR) and (ii) Orbitrap Q-Exactive high-resolution mass spectrometry after direct injection or chromatographic separation using reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) and soft ionization (with positive or negative heated electrospray ionization and atmospheric-pressure chemical ionization). H/D exchange using deuterated water (D2O) and a reaction with 2,4-dinitrophenylhydrazine (2,4-DNPH) were performed to probe the presence of OH, OOH, and C═O groups in the oxidized products. A broad range of oxidation products ranging from water to highly oxygenated products containing five and more O atoms were detected (C7H10O4,5, C8H12O2,4, C8H14O2,4, C9H12O, C9H14O1,3-5, C10H12O2, C10H14O1-9, C10H16O2-5, and C10H18O6). Mass spectrometry analyses were only qualitative, and quantification was performed with FTIR. The results are discussed in terms of reaction routes involving the initial formation of peroxy radicals, H atom transfer, and O2 addition sequences producing a large set of chemical products, including ketohydroperoxides and more oxygenated products. Carbonyl compounds derived from the Waddington oxidation mechanism on exo- and endo-double bonds (C═C) were observed in addition to their products of further oxidation. Products of the Korcek mechanism (carboxylic acids and carbonyls) were also detected.

Development of an ultra high performance liquid chromatography method for the separation and determination of nucleotides and nucleosides in extracts from infant milk formulas and human milk samples

Chromatographic methods developed to date allow the separation of nucleosides and nucleotides mixtures, but the resolution is not always complete, and analysis times are usually long. Therefore, this study aimed to develop a method for separating and determining these two groups of compounds in a short time and with good selectivity using the reversed-phase ultra-high performance liquid chromatography. The type of stationary phase and pH of the mobile phase had the most significant impact on the separation. The developed method allowed to separate and quantify a mixture of eleven compounds in 14 min. It was successfully applied to the analysis of milk extracts and appeared to be accurate, simple, and rapid. The LOQ values were in the 0.05–0.16 μg/ml range with high linearity (R2 higher than 0.998). The inter-day precision did not exceed 3.3 %, while Intra-day was in the range of 2.3–4.6 %. The procedure for extracting nucleosides and nucleotides from milk samples using protein precipitation and liquid-liquid extraction was reproducible, easy, and inexpensive, with analyte recovery between 69 % and 73 %.

Comprehensive and High-Throughput Method for Quantitative Fingerprinting of Phenolic Compounds.

Accurate, robust, and wide-coverage analytical tools are needed in polyphenol research to deal with the high physicochemical complexity of the secondary plant metabolome. In this chapter, a novel method based on reversed-phase ultrahigh-performance liquid chromatography coupled with a diode array detector and mass spectrometry is presented, which enables high-throughput, comprehensive, and quantitative fingerprinting of a broad spectrum of phenolic compounds and related metabolites in different food products. The simplicity, low-cost, and excellent analytical performance of this method would facilitate its implementation in food science for quality control and authenticity purposes.

Chemometrics of anisotropic lipophilicity of anticancer androstane derivatives determined by reversed-phase ultra high performance liquid chromatography with polar aprotic and protic modifiers

The research of the use of steroid compounds in the treatment of various types of cancer has a history of more than 50 years. Numerous steroid derivatives have expressed significant anticancer activity, however the thorough analysis of their physicochemical and toxicological properties is required prior to their clinical application. The present study is focused on the characterization of physicochemical properties of a series of previously synthesized new androstane derivatives (16E-hydroxyimino derivatives, D-homo lactones and D-seco dinitriles) with anticancer activity applying reversed-phase ultra high performance liquid chromatography (RP-UHPLC) system under isocratic conditions and chemometric tools, including in silico determination of their absorption, distribution, metabolism, excretion and toxicity (ADMET) properties. The chromatographic analysis was carried out applying two two-component and one ternary mobile phases with aprotic (acetonitrile) and protic (water and methanol) solvents. The conducted quantitative structure-retention relationship modeling resulted in two univariate and nine multivariate linear mathematical models that successfully correlate the retention parameters (logk) with descriptors of molecular polarity/lipophilicity (tPSA, REF, Average LogP, ClogP, ALOGP, LogS-SILICOS-IT, AClogS), descriptors that mainly depend on intermolecular interactions (BP, CP, CT, DE, HL) and ADMET descriptors (SWISSLogKpSP, GPCR, HIA, EI). The quality of the models was proved by the internal and external validation, while the robustness of the models was confirmed by Y-randomization test. Considering the established meaningful relationships between physicochemical/ADMET properties and retention parameters, the determined logk parameters of the analyzed series of steroid derivatives can be considered to be a biopharmaceutical property from the perspective of lipophilicity.

Comprehensive profiling of phytochemicals in the fruits of Gardenia jasminoides Ellis and its variety using liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry.

The fruits of Gardenia jasminoides Ellis are an important herb medicine in Traditional Chinese Medicine (TCM) and have been used for thousands of years for clearing away heat and toxic materials. It mainly contains iridoids, pigments, organic acids, and flavonoids. Although belonging to one species, it has two kinds of cultivars and one variety widely distributed and sold. This study aims to develop anintegratedandefficientanalytical strategy for comprehensive profiling of phytochemicals and clarify the differences in all three populations. Based on reversed-phase ultra-high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC/ESI-QTOFMS), an optimized analytical approach for comprehensive profiling of phytochemicals in the fruits of G. jasminoides was established in negative ionization mode. The holistic metabolites profiling was carried out on UHPLC/ESI-QTOFMS and data analysis program Progenesis QI, and a total of 80 metabolites were obtained and interpreted by chromatographic and tandem mass spectral data. The interpretation of metabolites comprises iridoids, pigments, organic acids, and flavonoids. Principal component analysis and partial least square-discriminant analysis were performed, and 19 main different components could be obtained to distinguish the three populations. Combined with non-targeted and targeted data analysis, the integrated strategy developed in this study was feasibly applied to discern differences in the profiles of the phytochemicals accumulating in the fruits of three populations of G. jasminoides.

Stress Degradation Studies and Development of a Validated RP-UHPLC Method of Ledipasvir

The intent of the research work was to develop and validate a simple, selective and precise reversed phase ultra-high performance liquid chromatography (RP-UHPLC) method for the determination of ledipasvir. A forced degradation study was performed as per International Conference on Harmonisation (ICH) guidelines Q1A (R2) and Q1B. Ledipasvir was found to be well separated from degradation products using an analytical C18 column (150 mm × 4.6 mm i.d., 5 μm particle size) with a ratio of mobile phase (75:25 v/v) consisting of methanol and 0.1% trifluoroacetic acid (TFA) kept at ambient temperature. The average retention time of ledipasvir was found 4.45 min at 254 nm wavelength with 1.6 mL/min isocratic flow rate and 10 µL injection volume. Linearity, accuracy, precision, sensitivity, robustness, and ruggedness were studied according to ICH guideline Q2 (R1) to validate the method. Then, this validated method was applied for forced degradation studies of ledipasvir. In conclusion, the developed method has been successfully used to study degradation behaviour of ledipasvir and may be useful to quantify the drug in different pharmaceutical dosage forms.

EXPLORATION OF STABILITY-INDICATING ASSAY UHPLC METHOD FOR SIMULTANEOUS ANALYSIS OF SITAGLIPTIN AND METFORMIN IN PURE MATERIAL AND PHARMACEUTICAL DOSAGE FORMS

The scientific novelty of designed work was to develop a specific and precise stability-indicating ultra high performance liquid chromatography (UHPLC) assay method for simultaneous quantification of Sitagliptin and Metforminin extendedrelease fixed dose combinations (FDCs). The reversed-phase UHPLC resolution was analyzed with the assistance of UPLC BEH C18 (150 mm 2.1 mm) with 1.7 µm particle size column at ambient temperature using a solvent system in a proportion of (90:10 % v/v) acetonitrile: potassium dihydrogen orthophosphate buffer; pH 3.0±0.2 was adjusted with 0.1 % ortho phosphoric acid (OPA), with flow rate of 0.4 mL/min of the solvent system. The analytes were supervised at 267 nm by employing photodiode array recognition. The retention times of Sitagliptin and Metformin were found to be1.903±0.01 and 1.301±0.022, respectively. The Sitagliptin and Metformin have confirmed the linearity ranges of 5- 30μg/mL, and 100-600 μg/mL respectively, with 0.9996 and 0.9996 determination coefficients. The UHPLC method was effectually validated concerning the accuracy, precision, sensitivity, robustness, ruggedness, selectivity, and specificity. Moreover, the anticipated UHPLC method's capability to analyze the Sitagliptin and Metformin with no obstruction from degradation products.

Solid-phase analytical derivatization as a tool for the quantification of steroid hormones in human urine with HPLC-Q-ToF detection

A possibility of application of solid-phase analytical derivatization (SPAD) for the quantification of seven steroid hormones (testosterone, dihydrotestosterone, cortisone, cortisol, progesterone, 11α-hydroxyprogesterone, and estrone) in human urine was evaluated. To prepare urine samples for instrumental analysis, SPAD with hydroxylamine was applied after enzymatic hydrolysis of the sample. To achieve high recovery values, extraction and derivatization conditions were optimized. Cartridges packed with end-capped octadecylsilyl silica sorbent provided optimum extraction of target analytes, while the reaction with hydroxylamine in the cartridge was found as a simple and efficient way for the chemical derivatization of steroids. The obtained derivatives were detected by using reversed-phase ultra-high performance liquid chromatography–quadrupole time-of-flight mass spectrometry. The proposed procedure was validated and applied to the analysis of real urine samples to prove the applicability of the proposed method for the routine analysis.

An ion mobility-enabled and high-efficiency hybrid scan approach in combination with ultra-high performance liquid chromatography enabling the comprehensive characterization of the multicomponents from Carthamus tinctorius

Liquid chromatography/mass spectrometry (LC/MS) is extensively applied for the untargeted/targeted analyses of the herbal components, utilizing data-dependent acquisition (DDA) or data-independent acquisition (DIA) to record the fragmentation information useful for the structural elucidation. A new trend recently has emerged by integrating DDA and DIA to render the hybrid scan, which, unfortunately, has rarely been reported. Herein, by using the Vion™ ion-mobility quadrupole time-of-flight mass spectrometer, a hybrid scan strategy (HDMSE-HDDDA) was presented and validated by the untargeted characterization of the multicomponents from Carthamus tinctorius (safflower), in combination with reversed-phase ultra-high performance liquid chromatography (RP-UHPLC). Good chromatographic separation was achieved on an HSS T3 column within 26 min, while HDMSE-MS/MS was used to acquire the collision-induced dissociation MS2 data in the negative mode. Automatic workflows (e.g., data correction, precursors/product ions matching, and peak annotation) were well established on UNIFI™ (incorporating an in-house library recording 261 known compounds) to process the obtained MS2 data. Compared with single DDA or DIA, the hybrid approach of HDMSE-HDDDA better balanced between the coverage and reliability, led to high-definition MS spectra, offered useful collision cross section (CCS) information, and showed satisfactory identification performance comparable to MSE. A total of 141 components (involving 41 quinochalcones, 66 flavanols/flavones, 11 flavanones, 6 organic acids, 1 polyacetylene, and 16 others) were characterized from safflower. Moreover, CCS prediction could assist isomers characterization, to some extent. Conclusively, this hybrid scan approach enables a dimension-enhanced MS data acquisition strategy providing the complementary structural information, which more suits the chemical characterization of complex samples.

Stability-Indicating UHPLC Method for the Determination of Desvenlafaxine: Application to Degradation Kinetics

This study was aimed to investigate the degradation behavior and physicochemical stability of desvenlafaxine using reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) system. The chromatogram was developed on Eclipse XDB-C8 column (150 x 4.6 mm, 5μm). The eluents were monitored through a photo diode array plus (PDA+) detector at 210 nm using an isocratic method with a flow rate of 1.5 ml/min. Mobile phase composition was 30:70 v/v mixture of 0.1 % trifluoroacetic acid (TFA) in water and methanol. Forced degradation studies were performed on drug substance of desvenlafaxine as per International Conference on Harmonization (ICH) prescribed stressed conditions (Q1A(R2) and Q1B) using hydrolytic (acidic, basic, and neutral), oxidative and photolytic methods. The drug substance was found highly labile to acidic (0.5 N hydrochloric acid, 18.65 % degradation in 2 hours at 70°C), basic (1.0 N sodium hydroxide, 11.01 % degradation in 12 hours at 70°C) and oxidative (3 % hydrogen peroxide, 17.05 % degradation in 2 hours at 50°C) stressed conditions, but a great resistance was observed towards dry heat (maximum degradation 0.27 % in 10 days from ambient to higher temperature, 80°C), moist heat (maximum degradation 0.25 % in 2 hours at 80°C and 75 % relative humidity) as well as in photolytic degradation (maximum degradation 0.23 % in 10 days at UV light of 315 - 400 nm). A pseudo-first order kinetic was followed in acidic, basic and peroxide degradation methods which paved a way to calculate the half-life of the drug substance desvenlafaxine under ICH mentioned stressed conditions. The results were also statistically analyzed and the % RSD values were compared with recommended guidelines. Dhaka Univ. J. Pharm. Sci. 20(2): 167-176, 2021 (December)

Multilayered solid phase extraction and ultra performance liquid chromatographic method for suspect screening of halogenated pharmaceuticals and photo-transformation products in freshwater - comparison between data-dependent and data-independent acquisition mass spectrometry

Since conventional biological wastewater treatments are not admittedly effective to convert pharmaceutical active compounds (PhACs) into nontoxic products, natural abiotic mechanisms such as solar photolysis arises as an important degradation process, especially for halogenated molecules. In the present work, photolysis simulation was carried out in-lab for precursors and their respective photo-transformation products (photo-TPs), which were analyzed through reversed-phase ultra-high performance liquid chromatography coupled to high resolution mass spectrometry (RP-UHPLCHRMS). An in-house library was created in order to provide reference information for target (precursors) and suspect screening (photo-TPs) analysis of freshwater samples from impacted aquatic environments. Strategies in the use of data-dependent acquisition (DDA) and data-independent acquisition (DIA), as well as the data processing software are discussed here for the identification of 6 PhACs and photo-TPs. Because no standards of photo-TPs were available, only the target compounds, i.e. sitagliptin (398 ± 2 ng L−1), iohexol (209 ± 5 ng L−1), lamotrigine (103 ± 10 ng L−1), losartan (43 ± 10 ng L−1), ofloxacin (28 ± 7 ng L−1), and sertraline (25 ± 7 ng L−1) could be quantified through multiple standard additions.