Selective Liquid Chromatography Research Articles

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.

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.

A Simple and Sensitive LC-MS/MS for Quantitation of ICG in Rat Plasma: Application to a Pre-Clinical Pharmacokinetic Study

A selective, sensitive, and rapid liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of ICG in rat plasma. The chromatographic separation was achieved using an ACE excel C18 (3 µm, 50 × 3.0 mm) column, with a mobile phase composition of 0.1% formic acid and 0.1% formic acid in acetonitrile, using a gradient flow at a rate of 0.3 mL/min. The MS was operated at a unit resolution in the multiple reaction monitoring mode, using the precursor ion → product ion combinations of 753.3 → 330.2 m/z (ICG) and 747.45 → 717.50 (Cy7.5 amine) with a run time of 5 min. The assay was linear over a concentration range of 1–1000 ng/mL with a regression coefficient (r2) of 0.998 or better. The inter and intra-batch precision (% relative standard deviation, %RSD) was lower than 13.5%, with accuracy (%Bias) between −10.03% and 11.56%. The ICG was stable under laboratory storage and handling conditions. The validated method was successfully applied to preclinical pharmacokinetic (PK) studies of ICG at a dose of 0.39 mg/kg in rats. PK parameters suggested the highest plasma concentration within 2 min of intravenous dosing with restricted systemic distribution and rapid clearance.

Validation of the HPLC Analytical Method for the Determination of Chemical and Radiochemical Purity of Ga-68-DOTATATE.

Ga-68-DOTA-peptides targeting somatostatin receptors have been assessed as a valuable tool in neuroendocrine tumors imaging using positron emission tomography (PET). A new selective and sensitive high-pressure liquid chromatography (HPLC) method was developed for determining chemical and radiochemical purity of Ga-68-DOTATATE (PET) tracer. The identification of peaks was achieved on a symmetry C18 column 3 μm 120Å (3.0 mm × 150 mm spherical particles) using (A) water + 0.1% trifluoroacetic acid (TFA) and (B) acetonitrile + 0.1% TFA, as the mobile phases at a flow rate of 0.600 mL/min and monitored at 220 nm. The run time was 16 min. The method was validated to fulfill International Conference on Harmonization requirements and EDQM guidelines, and it included specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, and precision. The calibration curve was linear over the concentration range from 0.5 to 3 μg/ml, with a correlation coefficient (r2) equal to 0.999, average coefficient of variation (CV%) 2%, and average bias% did not deviate more than 5% for all concentrations. The LOD and LOQ for DOTATATE were 0.5 and 0.1 μg/mL, respectively. The method was considered precise, obtaining coefficients of variation between 0.22% and 0.52% for intraday and 0.20% and 0.61% for interday precision. Accuracy of method was confirmed with average bias% that did not deviate more than 5% for all concentrations. All results were acceptable and this confirmed that the method is suitable for its intended use in routine quality control of Ga-68-DOTATATE to guarantee the high quality of the finished product before release.

LC-MS/MS method for determination of r-RGD-hirudin in human plasma and its application in pharmacokinetic study

ObjectiveThis study aimed to develop a simple, sensitive, and selective Liquid chromatography with a Mass spectroscopic method for simultaneous quantification of a recombinant bifunctional hirudin (r-RGD-Hirudin, Bifunctional Hirudin, BFH) in human plasma and verify its effectiveness. MethodsThe analytes and the internal standards from human plasma were extracted using the solid-phase extraction technique. The reconstituted samples were chromatographed on Waters C18 column (BEH 50 × 2.1 mm, 1.7 μm) using a mixture of 0.1% formic acid/acetonitrile (85%/15%, v/v) with gradient elution as the initial mobile phase at a flow rate of 0.3 mL/min. ResultsThe effectiveness of the proposed method was verified over the concentration range of 10–2000 ng/mL for r-RGD-Hirudin. A linear calibration curve was obtained. The precision and accuracy of BFH in the intra- and inter-day runs fell within the range of ±15% at LQC, GMQC, MQC and HQC concentrations. The extraction recoveries and matrix effect at two quality control (QC) levels for BFH were confirmed to conform to the relevant requirement. ConclusionThe proposed method was successfully adapted to examine the pharmacokinetics of BFH in 40 Chinese healthy volunteers, respectively.

A novel RP-HPLC method development and validation for simultaneous quantification of gefitinib and resveratrol in polymeric hybrid lipid nanoparticles and glioma cells

Resveratrol and Gefitinib are adjunct therapies for various cancers; however, both have been limited by low solubility, low cellular uptake, and bioavailability issues. As a result, this research aimed to develop an accurate, precise, selective, and sensitive reverse-phase high-performance liquid chromatography (RP-HPLC) method to simultaneously determine both compounds in nanoformulation and Glioma cells. The phenomenex luna C8 column, a mobile phase (80: 20 ratios of acetonitrile: 200 mM ammonium acetate) with a flow rate of 1 mL. min−1, 40 ± 0.2 °C as a column temperature, and the injection volume was 20 μl were selected as optimized chromatographic conditions. Retention time (RT) of resveratrol (1.80 min) and gefitinib (2.56 min) were identified using an optimized analytical method and detected at 345 nm (isosbestic point). The approach was proven to be specific for resveratrol and gefitinib analysis in the existence of PHLNPs, precise (RSD 2 %), and accurate (>90 %). The simultaneous analytical method was successfully developed to identify percentage drug entrapment efficiency (% DEE), % drug loading (% DL) of resveratrol and gefitinib in PHLNPs, and secondary estimates of in-vitro drug release profile and percentage cellular uptake studies. The in-vitro results revealed that the developed analytical method could simultaneously detect and quantify these drugs in other nanoformulations and in-vivo studies.

Development and Validation of a Selective Reversed-phase High Performance Liquid Chromatography Method for the Quantification of 1 ALPHA -Hydroxy Vitamin D2 and its Impurities

A selective reversed-phase high-performance liquid chromatography (RP-HPLC) technique was developed for 1α-hydroxy vitamin D2 (Doxercalciferol) related substances analysis. The technique is proficient of eluting various impurities related to process and degradation. To separate both the vitamin D2 Analogs i.e., doxercalciferol and ergocalciferol. HPLC of Shimadzu, provided with autosampler, column oven, quaternary pump and UV detector, were used for development studies. The mobile phase used water and acetonitrile. The diluent used was methanol and detection was examined at wavelength 265 nm. The method is sensitive for doxercalciferol, ergocalciferol, impurity-A and impurity-B; the limit of detection (LoD), value is 0.01% and limit of quantitation (LoQ) value is 0.03%. Linearity of doxercalciferol and related impurities at various concentrations was performed and the obtained correlation coefficient for doxercalciferol is 0.995, ergocalciferol is 0.997, impurity-A is 0.990 and impurity-B is 0.993. The optimized method was validated and demonstrated that the technique is selective, precise, linear, sensitive and accurate. The method is simple, inexpensive and useful for routine testing of doxercalciferol API. In addition, the technique was effectively applied for the elution of both the vitamin D2 Analogs i.e., doxercalciferol and ergocalciferol. Further, the same method is applicable for the determination of assay for these two API’s and the same assay method was validated.

Development of a two-dimensional liquid chromatography-tandem mass-spectrometry method for the determination of vitamin D2 in mushrooms

Different foods, especially mushrooms, are a valuable source of vitamin D2. However, published concentrations in mushrooms show large variabilities. One reason for this is certainly the high biological variability caused by growth conditions, and another could also be found in the analytical methodology. Therefore, this study aimed to develop a sensitive and highly selective two-dimensional liquid chromatography mass spectrometry (LC–MS/MS) method for vitamin D2 analysis in mushrooms. After validation, the method was applied to four different mushroom species. The developed method with a one-step extraction procedure showed a limit of detection of 0.01 µg vitamin D2/g dry mass (DM), a limit of quantification of 0.05 µg vitamin D2/g DM, and recovery rates between 87.6 and 94.8%. The total run time including the re-equilibration of the columns for the next injection was 7.5 min. After adding increased concentrations of pure substance to Pleurotus ostreatus, Lentinula edodes, and brown and white button mushrooms the standard addition plot showed excellent correlation coefficients (R2) of > 0.9994. Mean vitamin D2 concentrations were observed at 0.122 ± 0.007, 0.074 ± 0.005, 0.099 ± 0.007, and 0.073 ± 0.005 µg/g DM. The coefficient of variation (CV) was between 5.1 and 7.6%. This well-optimized, sensitive LC–MS/MS method, with a fast and simple sample preparation and a short run time, can be applied to future studies especially in different mushroom species with variable growing conditions. This will improve our knowledge about the vitamin D2 content in mushrooms.Graphical abstract