Simultaneous determination of water-soluble vitamins in selected food matrices by liquid chromatography/electrospray ionization tandem mass spectrometry

A stability-indicating HPLC assay of ten different vitamins in a food supplement: Appraisal of the method's greenness, whiteness, and blueness

Due to their susceptibility to degradation, vitamin levels in food formulations may differ from those found in the finished product. Vitamin levels can be impacted by processing and storage. In this work, the ingredients of Strong B50 ® film-coated tablets were estimated simultaneously using simple efficient stability indicating HPLC method. Strong B50 ® film-coated tablets contain thiamine (VB1), riboflavin (VB2), calcium pantothenate (VB5), pyridoxine (VB6), vitamin C (VC), folic acid (FA), biotin (BT), inositol (IS), niacin (NC), para-aminobenzoic acid (PB), cyanocobalamine (B12), choline bitartarate, and iron gluconate. Hypersil BDS C18 column was used for achieving reasonable separation. Mobile phases (A) and (B) were utilized, the mobile phase (A) consisted of 0.015 M Hexane sulfonic acid sodium salt + 0.1 % Triethylamine and orthophosphoric acid was used to adjust the pH to (2.9) while (B) system consisted of acetonitrile. Validation of the method was assessed using International Conference of Harmonization (ICH) parameters, where linearity, accuracy, selectivity, and robustness of the method were investigated. Correlations were above 0.99, accuracy results ranged from 97.6 to 102.8 % and limits for detection and quantitation (LOD and LOQ) values were determined for each vitamin in μg/mL except for FA and BT in ng/mL. LOD values were between 0.006 and 15.08 μg/mL while LOQ values ranged from 0.031 to 49.77 μg/mL. Stability studies were conducted under stressed conditions and degradation percentages were computed. Where, VB5, VB6, FA and PB, VC, and NC were the most degradable vitamins. Whiteness evaluation using the modern RGB 12 algorithm compared our method and the old reported one by Sasaki et al., 2020. The comparison favored our newly developed method in terms of analytical performance, practical applicability and greenness. Besides, AGREE and GAPI soft wares were used to assess the greenness of the method. It was clear that the results of colored pictograms confirm low hazardous impact and that the new method is greener with AGREE score of 0.66. Furthermore, the functionality and applicability of the novel HPLC approach were concluded via the Blue Applicability Grade Index (BAGI) tool with a final score of 82.5.

Development of chromatographic methods to determine multivitamins formulation depending on their solubility and polarity: comparative study using three greenness assessment tools

High performance liquid chromatography is one of the techniques of choice for the separation and quantitative determination of drugs in mixture form. Ipriflavone, ascorbic acid, pyridoxine, vitamin D3, and lysine are formulated together as an adjuvant combination in osteoporosis. In this work, we developed and validated two complementary high performance liquid chromatographic methods to determine the five compounds in their pharmaceutical dosage form. The first method (method A) was capable of determining ipriflavone, ascorbic acid, pyridoxine, and vitamin D3 in their bulk and combined pharmaceutical formulation. The method is based on Liquid Chromatographic separation with UV detection at 254 nm using Agilent Eclipse XDB-C18 column with a mobile phase consisting of 25 mM ammonium acetate buffer (pH 4.2): methanol in gradient mode. Due to the high polarity of lysine, it was difficult to achieve satisfactory retention on reversed phase columns. So, we separated it on a strong cation exchange column (Exsil 100 SCX) without derivatization with a mobile phase consisting of 10 mM sodium dihydrogen phosphate and 200 mM sodium chloride (pH 6) with UV detection at 210 nm (method B). Validation of the proposed methods was performed according to ICH guidelines Q2(R1). The proposed methods proved to be valid for selective analysis of the stated drugs in their bulk and combined pharmaceutical formulation. Greenness assessment of the developed methods was evaluated using three assessment tools: ESA, GAPI and the most recently developed tool AGREE, showing a satisfactory comprehensive guide of the greenness of the developed methods.

A robust method for simultaneous determination of eight B vitamins in human serum by liquid chromatography tandem mass spectrometry

The level of vitamin B group in human serum is an important index of human health. Among B vitamins, cyanocobalamin in serum is unstable and its content is extremely low. Rapid and simultaneous detection of multiple B vitamins including cyanocobalamin is a challenge. Herein, we have developed a rapid and stable method that can realize the determination of thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin simultaneously in 6 min. The method was established based on protein precipitation with methanol and then chromatographic separation was achieved using Waters acquity ultra-high-performance liquid chromatography high strength silica T3 column, which was stable and sensitive especially for cyanocobalamin. Limit of quantification, precision, trueness, and matrix effect were validated according to the European Medicines Agency and United States Food and Drug guidelines and Clinical and Laboratory Standards Institute guidelines on bioanalytical method. The limit of quantification for thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin was 0.4, 0.4, 0.8, 2.0, 0.4, 0.1, 0.4, and 0.04 ng/mL separately, respectively. Intra- and interday precisions were 1.1%-12.4% and 2.0%-13.5%, respectively. The relative errors were between 0.3% and 13.3%, and the matrix effects were between 2.6% and 10.4%.

Novel role of folate (vitamin B9) released by fermenting bacteria under Human Intestine like environment

The anaerobic region of the gastrointestinal (GI) tract has been replicated in the anaerobic chamber of a microbial fuel cell (MFC). Electroactive biomolecules released by the facultative anaerobes (Providencia rettgeri) under anoxic conditions have been studied for their potential role for redox balance. MALDI study reveals the presence of vitamin B9 (folate), 6-methylpterin, para-aminobenzoic acid (PABA) and pteroic acid called pterin pool. ATR-FTIR studies further confirm the presence of the aromatic ring and side chains of folate, 6-methylpterin and PABA groups. The photoluminescence spectra of the pool exhibit the maximum emission at 420, 425, 440, and 445 nm when excited by 310, 325, 350, and 365 nm wavelengths (day 20 sample) highlighting the presence of tunable bands. The cyclic voltammetric studies indicate the active participation of pterin pool molecules in the transfer of electrons with redox potentials at - 0.2 V and - 0.4 V for p-aminobenzoate and pterin groups, respectively. In addition, it is observed that under prolonged conditions of continuous oxidative stress (> 20 days), quinonoid tetrahydrofolate is formed, leading to temporary storage of charge. The results of the present study may potentially be useful in designing effective therapeutic strategies for the management of various GI diseases by promoting or blocking folate receptors.

The importance, prevalence and determination of vitamins B6 and B12 in food matrices: A review

Vitamins are a vast group of fundamental organic compounds, which are not produced by the human body but are essential for the living organisms' good health. Vitamins B6 and B12 belong to the same group of hydrophilic vitamins. Structurally unrelated, they share the same purpose as essential components for normal cellular operation, growth and development. Vitamin B6 is an enzymatic co-factor that is vital for countless biochemical reactions, and is also important in sugar and fatty acid metabolization. It encompasses three natural and inter-convertible pyridine-derivatives: pyridoxine, pyridoxal and pyridoxamine. Vitamin B12 is a cobalt organometallic complex also indispensable in numerous human physiological functions. It has four bioactive forms: cyanocobalamin, methylcobalamin, hydroxocobalamin and 5'-deoxyadenosylcobalamin, and only a few prokaryotes have the ability to biosynthesize cobalamin. This work reviews the significant aspects of vitamins B6 and B12: their vital roles, consequences of deficit; food sources; and methods of determination and respective matrices, with heavy emphasis on chromatographic techniques developed within the last two decades.

A Novel Two-Dimensional Liquid Chromatography Combined with Ultraviolet Detection Method for Quantitative Determination of Pyridoxal 5'-Phosphate, 4-Pyridoxine Acid and Pyridoxal in Animal Plasma

Vitamin B₆ is an indispensable micronutrient in organisms and is widely distributed in blood, tissues, and organs. Changes in the content and ratio of vitamin B6 can affect the entire physiological condition of the body, so it becomes particularly important to reveal the relationship between changes in its content and disease by monitoring vitamin B6 levels in the organism. In this study, a two-dimensional liquid chromatography-UV detector (2D-LC-UV) was used to establish a method for the simultaneous detection of PLP, PA, and PL for the first time. First, PLP, PA, and PL were extracted with plasma: 0.6 M TCA: ultrapure water = 1:2:3 (v/v/v) and then derivatized. Enrichment and preliminary separation were performed on a one-dimensional column and automatically entered into a two-dimensional column for further separation. This method exhibited good selectivity, and the correlation coefficients for the analyte calibration curves were >0.99. The detection limits for PLP, PA, and PL were 0.1, 0.2, and 4 nmol/L, respectively. The results showed that the system has high loading capacity, excellent resolution, and a good peak shape. This method is expected to provide applicability for the determination of PLP, PA, and PL in pharmacological, pharmaceutical, and clinical research.

Simultaneous analysis of water-soluble and fat-soluble vitamins through RP-HPLC/DAD in food supplements and brewer's yeast

The current study is focused on investigation and quantitation of seven commercially available on the Bulgarian market food supplements, containing multivitamin mixtures of water-soluble and fat-soluble vitamins. In addition, a second fermentation brewer's yeast is also analyzed. The analytical procedures are performed on a RP-HPLC/DAD using Purospher STAR C18 (Merck Millipore, Germany) 5 μm, 25 × 0.46 cm column, conditioned at 25 °C in a column oven. Dionex UltiMate 3000 high performance liquid chromatograph was carried out in diode array detector, set up at 270 nm for water-soluble vitamins, except for vitamin B₅, where 210 nm was applied as analytical wavelength. The fat-soluble vitamins were detected at 325 nm and 265 nm for vitamin A and vitamin E, respectively. Two general methods were developed where Method 1 was based on gradient elution and Method 2 was based on isocratic elution. Both methods identified stated by the manufacturer labeled amounts. The developed methods are applicable for routine analysis of vitamin contents both in multivitamin preparations and in brewer's yeast from secondary fermentation.

Determination of selected water-soluble vitamins (thiamine, riboflavin, nicotinamide and pyridoxine) from a food matrix using hydrophilic interaction liquid chromatography coupled with mass spectroscopy

Water-soluble vitamins are essential dietary components with a multitude of important functions that require quantification from food sources to characterise the nutritional status of food. In this study, we have developed a hydrophilic interaction chromatography (HILIC) based method coupled to single-quadrupole mass spectrometry (MS) for the analysis of selected water-soluble vitamins. Due to their involvement in energy release from macronutrients, the quantification of thiamine (B₁), riboflavin (B₂), nicotinamide (B₃) and pyridoxine (B₆) offers significant value in food analysis. A commercially available vegetable soup was selected as the food matrix for this study and utilised to develop an efficient extraction procedure for the vitamins of interest. Vitamins were extracted using meta-phosphoric acid coupled with a reducing agent, DL-dithiothreitol (DTT) to produce the parent compound. The extracted vitamins were then analysed using an LC-MS system with electrospray - atmospheric pressure ionization (ES-API) source, operated in positive single ion monitoring (SIM) mode. The MS provided good linearity within the investigated range from 5 to 400 ng/mL with coefficient of determination (r²) ranging from 0.98 to 0.99. Retention times (0.65-9.04 min) were reproducible and no coelution between vitamins was observed. Limit of detection (LOD) varied from 2.4 to 9.0 ng/mL and limit of quantification (LOQ) was from 8 to 30 ng/mL, comparable to previously published studies. The extraction method provided good intra-day (%CV 1.56-6.56) and inter-day precision (%CV 8.07-10.97). Standard injections were used as part of quality control measures and provided excellent reproducibility (%CV 0.9-3.4). The overall runtime of this method was 19 min, including column reconditioning. Using this method, the quantity of thiamine (67 ± 7 ng/g), riboflavin (423 ± 39 ng/g), nicotinamide (856 ± 77 ng/g) and pyridoxine (133 ± 11 ng/g) was determined from a complex food matrix. In conclusion, we have developed a rapid and reliable, HILIC-single quad MS method utilising SIM for the low-level quantification of four B vitamins in a vegetable soup matrix in under 20 min. This method has shown excellent linearity, intra- and inter-day reproducibility and is directly applicable to other plant-based food matrices.

Development of Simple Analytical Method for B-Group Vitamins in Nutritional Products: Enzymatic Digestion and UPLC-MS/MS Quantification

A method for the simultaneous determination of seven B-group vitamers including thiamine, riboflavin, nicotinamide, niacin, pyridoxine, pyridoxal, and pyridoxamine in nutritional products by using enzymatic digestion followed by LC-MS/MS quantification was studied. The LC-MS/MS conditions such as MS transitions, mobile phase programs, and ammonium formate buffer concentrations, and sample treatment procedures (e.g., concentrations of buffer solution, digestion temperature, and digestion time) were investigated. The analytical method performance was evaluated by multiple criteria such as selectivity, linearity, detection and quantification limits, repeatability, reproducibility, and recovery by using real sample matrices. The validated method was successfully applied to analyze vitamin B concentrations in different nutritional products like ultra-heat-treated milk, powdered milk, and nutritional powder. Vitamin B concentrations varied over a wide range from lower than detection limits to about 9000 µg/100 g, depending on vitamin groups, compound forms, and sample types. The measured concentrations of B-group vitamins in our samples were generally in good agreement with values of label claims.

Development of a LC-MS/MS method using stable isotope dilution for the quantification of individual B6 vitamers in fruits, vegetables, and cereals

Vitamin B₆ comprises an important set of molecules tightly interwoven with the human amino acid, fatty acid, and carbohydrate metabolism. Analytical methods striving for the quantification of individual B₆ vitamers so far mostly rely on methods based on HPLC in combination with fluorescence detection, but their application encounters multiple difficulties due to the chemical divergence of the single vitamers. The present study describes the development of a method based on LC-MS/MS and stable isotope dilution assay (SIDA) for the simultaneous quantification of five vitamers (PN, PL, PM, PMP, and PNG) of the B₆ group in food samples. [¹³C₃]-PN, [¹³C₃]-PL, and [¹³C₆]-PNG were applied as internal standards for the analysis of PN, PL, and PNG. PM and PMP were quantified via matrix-matched calibration referring to [¹³C₃]-PN. The developed method was validated using starch matrix. The limits of detection and quantification ranged from 0.0028 to 0.02 mg/kg and from 0.0085 to 0.059 mg/kg, respectively, for all analytes. Calculated recoveries varied from 92 to 111%. Intra-injection precisions ranged from 0 to 9%, inter-day precisions from 4 to 10%, and intra-day precisions from 4 to 10%. A total of 14 plant-based food samples including fruits, vegetables, and cereals were examined for their content of vitamin B₆ using the validated method. Furthermore, the first quantitation of PNG without enzymatic steps or divergent internal standards was undertaken utilizing LC-MS/MS and SIDA.

Rapid Method for the Determination of Thiamine and Pantothenic Acid in Infant Formula and Milk-Based Nutritional Products by Liquid Chromatography‒Tandem Mass Spectrometry

Background

Thiamine and pantothenic acid play a critical role in numerous metabolic reactions and are typically supplemented in infant and adult nutritional formulas as thiamine chloride hydrochloride and calcium pantothenate salts.

Objective

A rapid compliance method for the analysis of thiamine and pantothenic acid applicable to infant formula and milk-based nutritional products is described.

Method

Proteins are removed by centrifugal ultrafiltration, followed by analysis by reversed-phase liquid chromatography‒tandem mass spectrometry (LC-MS/MS), with quantitation accomplished by internal standard technique.

Results

The method was shown to be accurate, with acceptable recovery (thiamine, 99.3–101.1%; pantothenic acid, 99.2–108.6%). A certified reference material (NIST 1849a), showed no statistical bias (α = 0.05) for thiamine (P = 0.64); although a statistically significant bias (P < 0.01) for pantothenic acid was found, the nominal bias was only 4.7% (mean = 7.1 mg/hg; certified value = 6.8 mg/hg). A comparison of results by LC-MS/MS and current methods showed negligible bias (mean bias: thiamine, 0.01 mg/hg; pantothenic acid, 0.17 mg/hg) and no statistical significance (α = 0.05; thiamine, P = 0.399; pantothenic acid, P = 0.058). Acceptable precision was demonstrated with a repeatability of 7.2% repeatability relative standard deviation (RSDr) (HorRat: 0.6) and an intermediate precision of 7.0% RSD for thiamine, and a repeatability of 5.7% RSDr (HorRat: 0.5) and an intermediate precision of 6.1% RSD for pantothenic acid.

Conclusions

This rapid method is intended for use in high-throughput laboratories as part of routine product compliance release testing of thiamine and pantothenic acid in manufactured infant and milk-based nutritional products.

The First Comprehensive LC-MS/MS Method Allowing Dissection of the Thiamine Pathway in Plants

Arabidopsis thaliana serves as a model plant for genetic research, including vitamin research. When aiming at engineering the thiamine (vitamin B1) pathway in plants, the availability of tools that allow the quantitative determination of different intermediates in the biosynthesis pathway is of pivotal importance. This is a challenge, given the nature of the compounds and the minute quantities of genetically engineered material that may be available for analysis. Here, we report on the first LC-MS/MS method for the simultaneous quantification of thiamine, its mono- and diphosphate derivatives and its precursors 4-methyl-5-(2-hydroxyethyl) thiazole (HET) and 4-amino-2-methyl-5-hydroxymethylpyrimidine (HMP). This method was optimized and validated for the quantitative determination of these analytes in Arabidopsis thaliana. All analytes were chromatographically separated within less than 2.5 min during an 8 min run. No unacceptable interferences were found. The method was fully validated based on international guidelines. Accuracy (%bias) and total imprecision (%CV) were within preset acceptance criteria for all analytes in both QC and real samples. All analytes were stable in extracted samples when stored for 48 h at 4 °C (autosampler stability) and when reanalyzed after storage at -80 °C and -20 °C for 2 weeks (freeze/thaw stability). We demonstrated the start material should be stored at -80 °C to ensure stability of all analytes during short- and long-term storage (up to 3 months). The validity and applicability of the developed procedure was demonstrated via its successful application on Arabidopsis lines, genetically engineered to enhance thiamine content.

Comprehensive and quantitative profiling of B vitamins and related compounds in the mammalian liver

•

A validated method for quantification of 13 B vitamins and four related compounds in sheep liver.

•

Limits of detection for the majority of analytes were within the range of 0.4–3.2 pmol/g.

•

Simple sample extraction procedure with high throughput.

•

Successfully applied to profile 1C major forms in 266 sheep liver samples.

•

Potential for dietary and genetic studies in metabolic health and epigenetic gene regulation.

A method for the simultaneous quantification of B vitamins and related amines in one-carbon (1C) metabolism would benefit the study of diet and genetic/epigenetic regulation of mammalian development and health. We present a validated method for the simultaneous quantitative analysis of 13 B vitamers and four related 1C-pathway amine intermediates in liver using hydrophilic interaction chromatography (HILIC) coupled to electrospray ionization tandem mass spectrometry. Frozen sheep liver samples (50 mg) were homogenized in cold 50% acetonitrile containing 1% acetic acid with the addition of two isotope labelled internal standards. Hot acid hydrolysis was applied to release the protein-bound forms. The separation of 17 analytes was achieved using a pHILIC column with a total run time of 13 min. Detection was achieved in electrospray positive ionisation mode. Limits of detection for the majority of analytes were within the range of 0.4–3.2 pmol/g. The method was applied to 266 sheep liver samples and revealed that adenosylcobalamin, methylcobalamin, pyridoxic acid, flavin adenine dinucleotide and thiamine were the major forms of the B vitamers present with pyridoxal 5′-phosphate and thiamine pyrophosphate being detected at lower concentrations. Trimethylglycine and methylglycine were the predominant 1C-related amines measured. As anticipated, the B vitamin status of individuals varied considerably, reflecting dietary and genetic variation in our chosen outbred model species. This method offers a simple sample extraction procedure and provides comprehensive coverage of B vitamins coupled with good sensitivity and reliability.

Structural characterization, immune regulation and antioxidant activity of a new heteropolysaccharide from Cantharellus cibarius Fr

A new heteropolysaccharide was extracted and purified from the fruiting bodies of Cantharellus cibarius Fr. The Cantharellus cibarius Fr. polysaccharide (CC-1) had a molecular weight of 61,056 kDa and was mainly formed of the glucose and xylose at ratio of 5:1. Structure identification of CC-1 was analysed by a combined application of total hydrolysis, high performance liquid chromatography (HPLC), methylation analysis, gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectra and nuclear magnetic resonance (NMR) spectroscopy. The experimental results showed that CC-1 had a backbone of 1,4-linked-β-D-glucose which branched at O-6 and the branches were mainly composed of 6→1)-α-D-xylopyranose residue. CC-1 exhibited significant in vitro antioxidant effect and proliferation effect of immune cells. The activity study showed CC-1 has ability to clear the ABTS⁺ free radical and DPPH⁻ free radical in a certain range of concentration. The proliferation activity of the immune cells showed that the proliferation effect on B cells was very significant (P<0.001) in the concentration of 0.625–80 mg/ml; and the effect of T cell proliferation was also very significant (P<0.001) in the concentration of 5–20 mg/ml. The result of this study introduced Cantharellus cibarius Fr. as a possible valuable source in exhibiting unique immunoregulatory and antioxidant properties.

Impact of Conventional and Integrated Management Systems on the Water-Soluble Vitamin Content in Potatoes, Field Beans, and Cereals

The reduction of the environmental footprint of crop production without compromising crop yield and their nutritional value is a key goal for improving the sustainability of agriculture. In 2009, the Balruddery Farm Platform was established at The James Hutton Institute as a long-term experimental platform for cross-disciplinary research of crops using two agricultural ecosystems. Crops representative of UK agriculture were grown under conventional and integrated management systems and analyzed for their water-soluble vitamin content. Integrated management, when compared with the conventional system, had only minor effects on water-soluble vitamin content, where significantly higher differences were seen for the conventional management practice on the levels of thiamine in field beans (p < 0.01), Spring barley (p < 0.05), and Winter wheat (p < 0.05), and for nicotinic acid in Spring barley (p < 0.05). However, for all crops, variety and year differences were of greater importance. These results indicate that the integrated management system described in this study does not significantly affect the water-soluble vitamin content of the crops analyzed here.

Phytochemical Profiles of New Red-Fleshed Apple Varieties Compared with Traditional and New White-Fleshed Varieties

This study is an exhaustive chemical characterization of the phenolic compounds, triterpenes, and organic and ascorbic acids in red-fleshed apple varieties obtained by different breeding programs and using five traditional and new white-fleshed apple cultivars as reference. To carry out these analyses, solid-liquid extraction (SLE) and ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) were used. The results showed that the red-fleshed apples contained, in either the flesh or peel, higher amounts of phenolic acids (chlorogenic acid), anthocyanins (cyanidin-3-O-galactoside), dihydrochalcones (phloretin xylosyl glucoside), and organic acids (malic acid) but a lower amount of flavan-3-ols than the white-fleshed apples. These quantitative differences could be related to an up-regulation of anthocyanins, dihydrochalcones, and malic acid and a down-regulation of flavan-3-ols (anthocyanin precursors) in both the flesh and peel of the red-fleshed apple varieties. The reported results should be considered preliminary because the complete phytochemical characterization of the red-fleshed apple cultivars will be extended to consecutive harvest seasons.

Vitamin C: the known and the unknown and Goldilocks

Vitamin C (Ascorbic Acid), the antiscorbutic vitamin, cannot be synthesized by humans and other primates, and has to be obtained from diet. Ascorbic acid is an electron donor and acts as a cofactor for fifteen mammalian enzymes. Two sodium-dependent transporters are specific for ascorbic acid, and its oxidation product dehydroascorbic acid is transported by glucose transporters. Ascorbic acid is differentially accumulated by most tissues and body fluids. Plasma and tissue vitamin C concentrations are dependent on amount consumed, bioavailability, renal excretion, and utilization. To be biologically meaningful or to be clinically relevant, in vitro and in vivo studies of vitamin C actions have to take into account physiologic concentrations of the vitamin. In this paper, we review vitamin C physiology; the many phenomena involving vitamin C where new knowledge has accrued or where understanding remains limited; raise questions about the vitamin that remain to be answered; and explore lines of investigations that are likely to be fruitful.

Simultaneous quantification of 21 water soluble vitamin circulating forms in human plasma by liquid chromatography-mass spectrometry

This manuscript reports a validated analytical approach for the quantification of 21 water soluble vitamins and their main circulating forms in human plasma. Isotope dilution-based sample preparation consisted of protein precipitation using acidic methanol enriched with stable isotope labelled internal standards. Separation was achieved by reversed-phase liquid chromatography and detection performed by tandem mass spectrometry in positive electrospray ionization mode. Instrumental lower limits of detection and quantification reached <0.1-10nM and 0.2-25nM, respectively. Commercially available pooled human plasma was used to build matrix-matched calibration curves ranging 2-500, 5-1250, 20-5000 or 150-37500nM depending on the analyte. The overall performance of the method was considered adequate, with 2.8-20.9% and 5.2-20.0% intra and inter-day precision, respectively and averaged accuracy reaching 91-108%. Recovery experiments were also performed and reached in average 82%. This analytical approach was then applied for the quantification of circulating water soluble vitamins in human plasma single donor samples. The present report provides a sensitive and reliable approach for the quantification of water soluble vitamins and main circulating forms in human plasma. In the future, the application of this analytical approach will give more confidence to provide a comprehensive assessment of water soluble vitamins nutritional status and bioavailability studies in humans.

Simultaneous Determination of Underivatized Vitamin B1 and B6 in Whole Blood by Reversed Phase Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry

Background

Vitamin B1 (thiamine-diphosphate) and B6 (pyridoxal-5’phosphate) are micronutrients. Analysis of these micronutrients is important to diagnose potential deficiency which often occurs in elderly people due to malnutrition, in severe alcoholism and in gastrointestinal compromise due to bypass surgery or disease. Existing High Performance Liquid Chromatography (HPLC) based methods include the need for derivatization and long analysis time. We developed an Ultra High Performance Liquid Chromatography Tandem Mass spectrometry (UHPLC-MS/MS) assay with internal standards for simultaneous measurement of underivatized thiamine-diphosphate and pyridoxal-5’phosphate without use of ion pairing reagent.

Methods

Whole blood, deproteinized with perchloric acid, containing deuterium labelled internal standards thiamine-diphosphate(thiazole-methyl-D₃) and pyridoxal-5’phosphate(methyl-D₃), was analyzed by UHPLC-MS/MS. The method was validated for imprecision, linearity, recovery and limit of quantification. Alternate (quantitative) method comparisons of the new versus currently used routine HPLC methods were established with Deming regression.

Results

Thiamine-diphosphate and pyridoxal-5’phosphate were measured within 2.5 minutes instrumental run time. Limits of detection were 2.8 nmol/L and 7.8 nmol/L for thiamine-diphosphate and pyridoxal-5’phosphate respectively. Limit of quantification was 9.4 nmol/L for thiamine-diphosphate and 25.9 nmol/L for pyridoxal-5’phosphate. The total imprecision ranged from 3.5–7.7% for thiamine-diphosphate (44–157 nmol/L) and 6.0–10.4% for pyridoxal-5’phosphate (30–130 nmol/L). Extraction recoveries were 101–102% ± 2.5% (thiamine-diphosphate) and 98–100% ± 5% (pyridoxal-5’phosphate). Deming regression yielded slopes of 0.926 and 0.990 in patient samples (n = 282) and national proficiency testing samples (n = 12) respectively, intercepts of +3.5 and +3 for thiamine-diphosphate (n = 282 and n = 12) and slopes of 1.04 and 0.84, intercepts of -2.9 and +20 for pyridoxal-5’phosphate (n = 376 and n = 12).

Conclusion

The described UHPLC-MS/MS method allows simultaneous determination of underivatized thiamine-diphosphate and pyridoxal-5’phosphate in whole blood without intensive sample preparation.

Development of a LC-MS/MS method for the simultaneous screening of seven water-soluble vitamins in processing semi-coarse wheat flour products

Wheat is the second largest crop cultivated around the world and constitutes a major part of the daily diet in Europe. It is therefore important to determine the content of micronutrient in wheat and wheat-based food products to define the contribution of wheat-based foods to the nutrition of the consumers. The aim of the present work was to develop a simple and rapid method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of seven water-soluble vitamins in various wheat-based food materials. The vitamins present in the test material were separated in less than 15 min by using a reverse-phase C18 column, and analyzed by positive ion electrospray selected reaction monitoring MS/MS. The MS response for all the vitamins was linear over the working range (0.05 to 9 μg/mL) with correlation coefficients ranging between 0.991 and 1. Limits of quantification in the different food materials ranged from 0.09 to 3.5 μg/g. Intra-day and inter-day precision were found satisfactory. The developed method was applied for the simultaneous analysis of the water-soluble vitamin natural content of different semi-coarse wheat flours and in their corresponding baking products.

Liquid chromatography with isotope-dilution mass spectrometry for determination of water-soluble vitamins in foods

Vitamins are essential for improving and maintaining human health, and the main source of vitamins is the diet. Measurement of the quantities of water-soluble vitamins in common food materials is important to understand the impact of vitamin intake on human health, and also to provide necessary information for regulators to determine adequate intakes. Liquid chromatography (LC) and mass spectrometry (MS) based methods for water-soluble vitamin analysis are abundant in the literature, but most focus on only fortified foods or dietary supplements or allow determination of only a single vitamin. In this work, a method based on LC/MS and LC/MS/MS has been developed to allow simultaneous quantitation of eight water-soluble vitamins, including multiple forms of vitamins B3 and B6, in a variety of fortified and unfortified food-matrix Standard Reference Materials (SRMs). Optimization of extraction of unbound vitamin forms and confirmation using data from external laboratories ensured accuracy in the assigned values, and addition of stable isotope labeled internal standards for each of the vitamins allowed for increased precision.

Determination of four forms of vitamin B12 and other B vitamins in seawater by liquid chromatography/tandem mass spectrometry

RATIONALE

Vitamin B(12) is an essential nutrient for more than half of surveyed marine algae species, but methods for directly measuring this important cofactor in seawater are limited. Current mass spectrometry methods do not quantify all forms of B(12), potentially missing a significant portion of the B(12) pool.

METHODS

We present a method to measure vitamins B(1), B(2), B(6), B(7) and four forms of B(12) dissolved in seawater. The method entails solid-phase extraction, separation by ultra-performance liquid chromatography, and detection by triple-quadrupole tandem mass spectrometry using stable-isotope-labeled internal standards. We demonstrated the use of this method in the environment by analyzing B(12) concentrations at different depths in the Hood Canal, part of the Puget Sound estuarine system in Washington State.

RESULTS

Recovery of vitamin B(12) forms during the preconcentration steps was >71% and the limits of detection were <0.275 pM in seawater. Standard addition calibration curves in three different seawater matrices were used to determine analytical response and to quantify samples from the environment. Hydroxocobalamin was the main form of B(12) in seawater at our field site.

CONCLUSIONS

We developed a method for quantifying four forms of B(12) in seawater by liquid chromatography/mass spectrometry with the option of simultaneous analysis of vitamins B(1), B(2), B(6), and B(7). We validated the method and demonstrated its application in the field.

Simultaneous determination of water-soluble vitamins in beverages and dietary supplements by LC-MS/MS

An LC-MS/MS method was developed for the simultaneous determination of 15 water-soluble vitamins that are widely used as additives in beverages and dietary supplements. This combined method involves the following simple pre-treatment procedures: dietary supplement samples were prepared by centrifugation and filtration after an extraction step, whereas beverage samples were diluted prior to injection. Chromatographic analysis in this method utilised a multi-mode ODS column, which provided reverse-phase, anion- and cation-exchange capacities, and therefore improved the retention of highly polar analytes such as water-soluble vitamins. Additionally, the multi-mode ODS column did not require adding ion pair reagents to the mobile phase. We optimised the chromatographic separation of 15 water-soluble vitamins by adjusting the mobile phase pH and the organic solvent. We also conducted an analysis of a NIST Standard Reference Material (SRM 3280 Multi-vitamin/Multi-element tablets) using this method to verify its accuracy. In addition, the method was applied to identify the vitamins in commercial beverages and dietary supplements. By comparing results with the label values and results obtained by official methods, it was concluded that the method could be used for quality control and to compose nutrition labels for vitamin-enriched products.

Nutritional profile of phytococktail from trans-Himalayan plants

We estimated the nutritive value, vitamin content, amino acid composition, fatty acid content, and mineral profile of a phytococktail comprising sea buckthorn (Hippophae rhamnoides), apricot (Prunus armeniaca), and roseroot (Rhodiola imbricata) from trans-Himalaya. The free vitamin forms in the phytococktail were determined by rapid resolution liquid chromatography/tandem mass spectrometry (RRLC-MS/MS). Vitamin E and B-complex vitamins were detected as the principle vitamins. Reversed-phase high performance liquid chromatography (RP-HPLC) with pre-column derivatization was used for identification and quantification of amino acids. Eight essential and eleven non-essential amino acids were quantified, and the content ranged between 76.33 and 9485.67 µg/g. Among the essential amino acids, L-methionine, L-phenylalanine, L-lysine, L-leucine, and L-histidine were found to be the dominant contributors. We also quantified the fatty acids in the phytococktail by using gas chromatography coupled with a flame ionization detector (GC-FID) with fatty acid methyl esters (FAMEs) derivatization. The analysis revealed the presence of 4 major fatty acids contributing to the total lipid content. Palmitic acid was found to be the rich source of saturated fatty acid (SFA) and constituted ∼31% of the total lipid content. Among the unsaturated fatty acids (UFAs), palmitoleic acid (43.47%), oleic acid (20.89%), and linoleic acid (4.31%) were prominent. The mineral profiling was carried out by inductively coupled plasma optical emission spectrometer (ICP-OES), and it was found to contain a number of important dietary mineral elements. The harsh climatic conditions, difficult terrain, and logistic constraints at high altitude regions of Indian trans-Himalayan cold desert lead to the scarcity of fresh fruits and vegetables. Therefore, the source of multiple vitamins, essential amino acids, fatty acids, and dietary minerals from the phytococktail would provide great health benefit in the stressful environment and could be used as a high value nutritional supplement.

Rapid quantitation of ascorbic and folic acids in SRM 3280 multivitamin/multielement tablets using flow-injection tandem mass spectrometry

RATIONALE

Ascorbic acid (AA) and folic acid (FA) are water-soluble vitamins and are usually fortified in food and dietary supplements. For the safety of human health, proper intake of these vitamins is recommended. Improvement in the analysis time required for the quantitative determination of these vitamins in food and nutritional formulations is desired.

METHODS

A simple and fast (~5 min) in-tube sample preparation was performed, independently for FA and AA, by mixing extraction solvent with a powdered sample aliquot followed by agitation, centrifugation, and filtration to recover an extract for analysis. Quantitative detection was achieved by flow-injection (1 μL injection volume) electrospray ionization tandem mass spectrometry (ESI-MS/MS) in negative ion mode using the method of standard addition.

RESULTS

The method of standard addition was employed for the quantitative estimation of each vitamin in a sample extract. At least 2 spiked and 1 non-spiked sample extract were injected in triplicate for each quantitative analysis. Given an injection-to-injection interval of approximately 2 min, about 18 min was required to complete the quantitative estimation of each vitamin. The concentration values obtained for the respective vitamins in the standard reference material (SRM) 3280 using this approach were within the statistical range of the certified values provided in the NIST Certificate of Analysis. The estimated limit of detections of FA and AA were 13 and 5.9 ng/g, respectively.

CONCLUSIONS

Flow-injection ESI-MS/MS was successfully applied for the rapid quantitation of FA and AA in SRM 3280 multivitamin/multielement tablets. Published 2012. This article is a US Government work and is in the public domain in the USA.

Evaluation of flow-injection tandem mass spectrometry for rapid and high-throughput quantitative determination of B vitamins in nutritional supplements

The use of flow-injection electrospray ionization tandem mass spectrometry for rapid and high-throughput mass spectral analysis of selected B vitamins, viz., B1, B2, B3, B5, and B6, in nutritional formulations was demonstrated. A simple and rapid (~5 min) in-tube sample preparation was performed. Automated flow injection introduced 1 μL of the extracts directly into the mass spectrometer ion source without chromatographic separation. Sample-to-sample analysis time was 60 s. Quantitative capabilities of the flow-injection analysis were tested using the method of standard additions and SRM 3280. The quantity determined for each B vitamin in SRM 3280 was within the statistical range provided for the respective certified values. This approach was also applied to two different commercial vitamin supplement tablets and proved to be successful in the quantification of the selected B vitamins, as evidenced by an agreement with the label values and the results obtained using isotope dilution liquid chromatography/mass spectrometry.

Sequential determination of fat- and water-soluble vitamins in green leafy vegetables during storage

The simultaneous analysis of fat- and water-soluble vitamins from foods is a difficult task considering the wide range of chemical structures involved. In this work, a new procedure based on a sequential extraction and analysis of both types of vitamins is presented. The procedure couples several simple extraction steps to LC-MS/MS and LC-DAD in order to quantify the free vitamins contents in fresh-cut vegetables before and after a 10-days storage period. The developed method allows the correct quantification of vitamins C, B(1), B(2), B(3), B(5), B(6), B(9), E and provitamin A in ready-to-eat green leafy vegetable products including green lettuce, ruby red lettuce, watercress, swiss chard, lamb's lettuce, spearmint, spinach, wild rocket, pea leaves, mizuna, garden cress and red mustard. Using this optimized methodology, low LOQs were attained for the analyzed vitamins in less than 100 min, including extraction and vitamin analysis using 2 optimized procedures; good repeatability and linearity was achieved for all vitamins studied, while recoveries ranged from 83% to 105%. The most abundant free vitamins found in leafy vegetable products were vitamin C, provitamin A and vitamin E. The richest sample on vitamin C and provitamin A was pea leaves (154 mg/g fresh weight and 14.4 mg/100g fresh weight, respectively), whereas lamb's lettuce was the vegetable with the highest content on vitamin E (3.1 mg/100 g fresh weight). Generally, some losses of vitamins were detected after storage, although the behavior of each vitamin varied strongly among samples.

Application of CZE Method in Routine Analysis for Determination of B-Complex Vitamins in Pharmaceutical and Veterinary Preparations

A competitive CZE method for quality control analysis of multivitamin preparations and veterinary products containing B-group vitamins was developed. Vitamins of interest are thiamine hydrochloride (B(1)), thiamine monophosphate chloride (B(1a)), riboflavine (B(2)), riboflavine-5'monophosphate (B(2a)), nicotinamide (B(3)), d-pantothenic acid calcium salt (B(5)), pyridoxine hydrochloride (B(6)), folic acid (B(9)), and 4-aminobenzoic acid (B(10)). These analytes were separated optimizing the experimental conditions in 20 mM tetraborate buffer pH = 9.2 as a BGE (background electrolyte), on a Beckman P/ACE System MDQ instrument, using uncoated fused silica capillary. The effective capillary length was of 49.5 cm, I.D. = 50 μm, the applied voltage 20 kV and the temperature 25°C. Detection was performed by a diode array detector at 214 nm for all vitamins except B(5) (190 nm) and B(2a) (260 nm). Separation time was about 9 min. After experimental conditions optimization, the proposed method was validated. Precision of migration time and corrected peak area, linearity range, LOD and LOQ, accuracy (recovery), robustness, and ruggedness were evaluated for each analyte demonstrating the good reliability of the method. Analyses of the pharmaceutical real samples were performed and confirmed the versatility of this method.

A novel HPLC method for the concurrent analysis and quantitation of seven water-soluble vitamins in biological fluids (plasma and urine): a validation study and application

An HPLC method was developed and validated for the concurrent detection and quantitation of seven water-soluble vitamins (C, B₁, B₂, B₅, B₆, B₉, B₁₂) in biological matrices (plasma and urine). Separation was achieved at 30°C on a reversed-phase C18-A column using combined isocratic and linear gradient elution with a mobile phase consisting of 0.01% TFA aqueous and 100% methanol. Total run time was 35 minutes. Detection was performed with diode array set at 280 nm. Each vitamin was quantitatively determined at its maximum wavelength. Spectral comparison was used for peak identification in real samples (24 plasma and urine samples from abstinent alcohol-dependent males). Interday and intraday precision were <4% and <7%, respectively, for all vitamins. Recovery percentages ranged from 93% to 100%.

Structural analysis of organometallic compounds with soft ionization mass spectrometry

The analysis of organometallic compounds with mass spectrometry has some special features in comparison with organic and bioorganic compounds. The first step is the choice of a suitable ionization technique, where the electrospray ionization is certainly the best possibility for most classes of organometallic compounds and metal complexes. Some ionization mechanisms of organometallic compounds are comparable to organic molecules, such as protonation/deprotonation, and adduct formation with sodium or potassium ions; however, in many cases, different mechanisms and their combinations complicate the spectra interpretation. Organometallics frequently undergo various types of adduct and polymerization reactions that result in significantly higher masses observed in the spectra in comparison to molecular weights of studied compounds. Metal elements typically have more natural isotopes than common organic elements, which cause characteristic wide distributions of isotopic peaks; for example, tin has ten natural isotopes. The isotopic pattern can be used for the identification of the type and number of metal elements in particular ions. The ionization and fragmentation behavior also depend on the type of metal atom; therefore, our discussion of mass spectra interpretation is divided according to the different type of organometallic compounds. Among various types of mass spectrometers available on the market, trap-based analyzers (linear or spherical ion-traps, Orbitrap) are suitable to study complex fragmentation pathways of organometallic ions and their adducts, whereas high-resolution and high-mass accuracy analyzers (time-of-flight-based analyzers, or Fourier transform-based analyzers-Orbitrap or ion cyclotron resonance mass spectrometers) provide accurate masses applicable for the determination of the elemental composition of individual ions.