New LC-MS/MS method with single-step pretreatment analyzes fat-soluble vitamins in plasma and amniotic fluid

Association between fat-soluble vitamin co-exposure patterns and blood pressure in people with hypertension: a cross-sectional study

Background

Existing epidemiological studies investigated the association between a single vitamin and hypertension. However, the potential relationship between the level of circulating multivitamins and blood pressure has not been explored. We aimed to investigate the association between multiple fat-soluble vitamin levels and blood pressure.

Methods

A total of 2052 participants with essential hypertension were sampled nationwide. The plasma concentrations of fat-soluble vitamins (A, E, D, and K) were assessed using liquid chromatography coupled with the mass spectrometry method. Participants were categorized into different co-exposure patterns using the unsupervised K-means clustering method. The multiple linear regression model was used for subsequent analyses.

Results

Participants were classified into two co-exposure patterns of fat-soluble vitamins. The levels of vitamins were relatively low in pattern 1, compared to pattern 2. Participants in pattern 2 had no significantly different blood pressure levels compared to pattern 1. However, the plasma 25-hydroxyvitamin D3 (VD3) levels were negatively associated with SBP (logarithmic 10 transformed) (β = -0.002, 95% CI: -0.004, 0); participants in the fourth α-tocopherol quartile had mean SBP levels that were 1.02% (95% CI: 0.43, 1.61%) greater than those in the lowest quartile (p for trend <0.01). In addition, no significant relationships were found between plasma VA/VK concentrations and blood pressure.

Discussion

Although no significant association between fat-soluble vitamin co-exposure patterns and blood pressure was found, further analyses could imply that plasma α-tocopherol levels may offset the potential protective effect of plasma VD3 on blood pressure among hypertensive adults. This provided a novel perspective for exploring the joint effects of fat-soluble vitamins on blood pressure. Further studies are warranted to better understand the implications.

Quantitative Determination of a Series of Oxysterols by an Optimized LC-MS/MS Analysis in Different Tissue Types

Oxysterols, as metabolites of cholesterol, play a key role in cholesterol homeostasis, autophagosome formation, and regulation of immune responses. Disorders in oxysterol metabolism are closely related to the pathogenesis of neurodegenerative diseases. To systematically investigate the profound molecular regulatory mechanisms of neurodegenerative diseases, it is necessary to quantify oxysterols and their metabolites in central and peripheral biospecimens simultaneously and accurately. However, there are a lot of unsolved problems with the existing methods, such as the hindrance of applying a single method to different biological specimens or the challenge of simultaneous quantification due to differential groups on the ends of the oxysterol side chains. Herein, according to the physicochemical properties and structure of oxysterols, an optimized liquid chromatography-tandem mass spectrometry method for the quantification of oxysterols was established by optimizing the sample preparation process, chromatographic conditions, mobile phase pH, and solvent selection. Seven oxysterols were detected by this method, including 27-hydroxycholesterol, 7α-hydroxycholesterol, 7α,27-dihydroxycholesterol, 7-dehydrocholesterol, 7α-hydroxy-3-oxo-4-cholestenoic acid, 3-hydroxy-5-cholestenoic acid, and 24(S)-hydroxycholesterol. Non-derivatization extraction with methyl tert-butyl ether was used for different biospecimens, followed by simultaneous chromatographic separation of oxysterols on a phenyl hexyl column. By repeated validation, this method exhibited satisfactory linearity, precision, recovery, sensitivity, repeatability, and stability, and it was successfully applied to the detection of oxysterols in the plasma, cerebral cortex, and liver of mouse. In summary, our optimized method enables concurrent analysis and quantification of oxysterols and their metabolites in various biospecimens, presenting a broad range of applicability.

An HPLC-UV Method to Assess Human Plasma 25(OH)D3

The aim of this study was to validate an HPLC-UV method to assess vitamin D status by determining the linearity and precision of the 25-hydroxyvitamin D3 (25(OH)D3) calibration curve, the limits of detection, quantitation and robustness of the method, and its accuracy. A second stock solution of 25(OH)D3 was prepared (500 ng/mL), and working dilutions (5, 10, 20, 30, 40, and 50 ng/mL) were prepared for a calibration curve. The HPLC equipment had a UV-Vis diode-array detector and utilized an AcclaimTM 120 C18 column (5 µm, 4.6 × 250 mm) with a flow rate of 1.2 mL/min, a column temperature of 30 °C, and the standards and samples were maintained at 4 °C, with an injection volume of 100 µL. Detection of 25(OH)D3 was determined at 265 nm, with a retention time of 4.0 min. The validation was conducted according to the FDA Validation of Analytical Procedures: Guidance for Industry. Vitamin D was extracted from plasma samples using acetonitrile (ACN)-0.1% formic acid (2:1 v/v), and the percentage of recovery was calculated. The proposed method conditions gave excellent linearity (R2 = 0.9989) and the linearity coefficient was R2 > 0.99 for 25(OH)D3. The detection and quantification limits were 1.1703 ng/mL and 3.5462 ng/mL, respectively. Decreasing or increasing the reading temperature by 1 °C decreased the response units (AU) of vitamin D, 25(OH)D3. When the current flow rate decreased by 0.2 mL/min (1.0 mL/min), the retention time increased to 4.913 min, whereas an increase of 0.2 mL/min of the proposed flow rate (1.4 mL/min) decreased the retention time to 3.500 min. The percentage of recovery varied from 92.2% to 97.1%. The proposed method to quantify a vitamin D metabolite (25(OH)D3) in human plasma samples was reliable and validated.

Associations Between Vitamin K and Suicide Attempts in Patients with Depression: A Case-Control Study

Background

Hypovitaminosis K has been linked to depression and suicide, but epidemiological research is scarce. This study aimed to explore the association among vitamin K with depression and suicidal attempts.

Methods

This was a retrospective cross-sectional study involving 146 cases with a history of suicidal attempts and 149 subjects without a lifetime history of suicidal attempts. The levels of thyroid hormones, lipid profile, inflammatory cytokines, and vitamins were measured.

Results

Subjects who had suicidal attempts presented with a significant decrease in FT4, TC, vitamin D, and vitamin K but increased CRP levels. In these variables, vitamin K has a better diagnostic value for suicidal attempts in depressed patients, with a sensitivity of 0.842 and a specificity of 0.715. Correlation analysis suggested that vitamin K was significantly and positively related to FT4, TC, LDL, and sdLDL. Multivariate analysis showed that serum vitamin K level predicts suicidal attempts in depressive patients (OR = 0.614, P = 0.004, 95% CI 0.153-0.904). Moreover, a negative correlation between vitamin K and suicidal attempts was also noted for partial FT4, CRP, and vitamin D strata analysis.

Conclusion

Our study suggests that low vitamin K levels were correlated with suicidal attempts in patients with depression, indicating that vitamin K deficiency might be a biological risk factor for depression.

Accurate Clinical Detection of Vitamin D by Mass Spectrometry: A Review

Vitamin D deficiency is thought to be associated with a wide range of diseases, including diabetes, cancer, depression, neurodegenerative diseases, and cardiovascular and cerebrovascular diseases. This vitamin D deficiency is a global epidemic affecting both developing and developed countries and therefore qualitative and quantitative analysis of vitamin D in a clinical context is essential. Mass spectrometry has played an increasingly important role in the clinical analysis of vitamin D because of its accuracy, sensitivity, specificity, and the ability to detect multiple substances at the same time. Despite their many advantages, mass spectrometry-based methods are not without analytical challenges. Front-end and back-end challenges such as protein precipitation, analyte extraction, derivatization, mass spectrometer functionality, must be carefully considered to provide accurate and robust analysis of vitamin D through a well-designed approach with continuous control by internal and external quality control. Therefore, the aim of this review is to provide a comprehensive overview of the development of mass spectrometry methods for vitamin D accurate analysis, including emphasis on status markers, deleterious effects of biological matrices, derivatization reactions, effects of ionization sources, contribution of epimers, standardization of assays between laboratories.

Multiplatform untargeted metabolomics

Metabolomics samples like human urine or serum contain upwards of a few thousand metabolites, but individual analytical techniques can only characterize a few hundred metabolites at best. The uncertainty in metabolite identification commonly encountered in untargeted metabolomics adds to this low coverage problem. A multiplatform (multiple analytical techniques) approach can improve upon the number of metabolites reliably detected and correctly assigned. This can be further improved by applying synergistic sample preparation along with the use of combinatorial or sequential non-destructive and destructive techniques. Similarly, peak detection and metabolite identification strategies that employ multiple probabilistic approaches have led to better annotation decisions. Applying these techniques also addresses the issues of reproducibility found in single platform methods. Nevertheless, the analysis of large data sets from disparate analytical techniques presents unique challenges. While the general data processing workflow is similar across multiple platforms, many software packages are only fully capable of processing data types from a single analytical instrument. Traditional statistical methods such as principal component analysis were not designed to handle multiple, distinct data sets. Instead, multivariate analysis requires multiblock or other model types for understanding the contribution from multiple instruments. This review summarizes the advantages, limitations, and recent achievements of a multiplatform approach to untargeted metabolomics.

Multiplatform untargeted metabolomics

Metabolomics samples like human urine or serum contain upwards of a few thousand metabolites, but individual analytical techniques can only characterize a few hundred metabolites at best. The uncertainty in metabolite identification commonly encountered in untargeted metabolomics adds to this low coverage problem. A multiplatform (multiple analytical techniques) approach can improve upon the number of metabolites reliably detected and correctly assigned. This can be further improved by applying synergistic sample preparation along with the use of combinatorial or sequential non-destructive and destructive techniques. Similarly, peak detection and metabolite identification strategies that employ multiple probabilistic approaches have led to better annotation decisions. Applying these techniques also addresses the issues of reproducibility found in single platform methods. Nevertheless, the analysis of large data sets from disparate analytical techniques presents unique challenges. While the general data processing workflow is similar across multiple platforms, many software packages are only fully capable of processing data types from a single analytical instrument. Traditional statistical methods such as principal component analysis were not designed to handle multiple, distinct data sets. Instead, multivariate analysis requires multiblock or other model types for understanding the contribution from multiple instruments. This review summarizes the advantages, limitations, and recent achievements of a multiplatform approach to untargeted metabolomics.

Rapid LC-MS/MS detection of 25-hydroxyvitamin D in dried blood spots

BACKGROUND

The detection of 25-hydroxyvitamin D (25OHD) from dried blood spots (DBS) has been widely studied. However, the existing pretreatment methods suffer from limitations in terms of throughput (usually exceeding 2 h), complexity (involving liquid-liquid extraction or solid-phase extraction), and contamination (including multiple steps of organic solvent evaporation).

RESULTS

We first released 25OHD from DBS samples by 50% acetonitrile solution through ultrasonication. Subsequently, the cold-induced phase separation technique was introduced for in-situ concentration and purification. Afterward, the PTAD derivatization of 25OHD was performed directly, profiting from the high acetonitrile content in the concentrated solution. In the end, the resulting solution was submitted to LC-MS/MS for quantification. The established LC-MS/MS methodology possessed favorable analytical performance, possessing lower limit of quantification of 1 ng/mL pointing to plasma, accuracy of 86.8-110.1% and imprecision of 5.4-16.8%. Method comparison with plasma samples demonstrated that over 93% of the detections met the acceptance limit for cross-validation of ±20%.

SIGNIFICANCE AND NOVELTY

The novel sample preparation can be finished within 15 min and eliminated the traditional steps of extraction and organic solvent evaporation. Based on this high-throughput, reliable and applicable LC-MS/MS method, the detection of 25OHD in DBS samples can be better achieved for clinical patients and researchers with relevant demands.

The Mediation Role of Sleep Disturbances between Vitamin D and Depressive Symptoms: A Cross-Sectional Study

Depression and sleep disturbances are highly prevalent health problems that have been suggested to be associated with vitamin D deficiency. This study investigated whether sleep disturbances affect the association between vitamin D and depressive symptoms. A total of 425 patients with depression were included in this study. Spearman correlation coefficients were chosen to assess the relation between vitamin D concentrations and depressive symptomatology (according to the PHQ-9 and HAMD-17 scores). The GLM Mediation Model in the Medmod module for data analysis in Jamovi 2.2.5 was used to analyze the mediation models for sleep disturbances. Vitamin D concentrations were significantly correlated with PHQ-9 and HAMD-17 scale scores. In addition, item 3 was suggested to have a mediating effect between vitamin D and depressive symptoms in the mediating model of PHQ-9, and item 4 was suggested to have a mediating effect between vitamin D and depressive symptoms in the mediating model of HAMD-17. Sleep disturbances (especially difficulty falling asleep) are mediators between vitamin D and depressive symptoms, suggesting that increasing vitamin D levels at the right time to regulate sleep disturbances may improve depression symptoms, yet further research is necessary.

Evaluation of Vitamin D Status and the Analysis of Risk Factors of Vitamin D Deficiency in Twin Pregnancies

OBJECTIVE

Optimization of maternal vitamin D (VD) status has beneficial effects on pregnancies, but little is known about it of twin pregnancies (TP). Our aim was to promote the current understanding of VD status and its associated factors in TP.

METHODS

We performed liquid chromatography-tandem mass spectrometry to quantify 25-hydroxyvitamin D [25(OH)D] and used the enzyme-linked immunosorbent assay method to detect vitamin D binding protein (VDBP) in 218 singleton pregnancies (SP) and 236 TP.

RESULTS

Levels of 25(OH)D and VDBP were higher in TP than SP. The 25(OH)D, free 25(OH)D, C-3 epimer of 25-hydroxyvitamin D [epi-25(OH)D], and VDBP all increased with gestational progress. Age, body 
mass index, and hemoglobin level were associated with VD deficiency (VDD). Analysis of covariance demonstrated that the 25(OH)D and VDBP of TP and SP still showed differences after adjusting for the above associated factors.

CONCLUSION

Differences in VD status were found in SP and TP, suggesting that the assessment of VD status in TP should be treated with caution. High VDD prevalence is observed among pregnant Chinese women, and it is recommended to promote evaluation for VDD.

Liquid chromatography-tandem mass spectrometry in fat-soluble vitamin deficiency

Fat-soluble vitamins, including vitamins A, D, E, and K, are essential for maintaining normal body function and metabolism. Fat-soluble vitamin deficiency may lead to bone diseases, anemia, bleeding, xerophthalmia, etc. Early detection and timely interventions are significant for preventing vitamin deficiency-related diseases. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is developing into a potent instrument for the precise detection of fat-soluble vitamins due to its high sensitivity, high specificity, and high resolution.

The relationship between vitamin D levels in seasonal variations and Chinese patients with first-episode drug-naive depression

BACKGROUND

Vitamin D deficiency is highly prevalent worldwide and is associated with various diseases, including depression. Previous studies on vitamin D and depression have different conclusions.

OBJECTIVES

Our study aimed to examine the association between vitamin D levels in seasonal variation and depression.

METHODS

A total of 324 patients with first-episode depression aged 18-50 years were recruited for our study. Vitamin D levels were recorded, and PHQ-9 scale evaluation was performed in different seasons. Seasonal variations in vitamin D levels and depressive symptoms were examined.

RESULTS

The cohort comprised 77 males and 247 females. 98.1% of patients had insufficient or deficient vitamin D levels. The median vitamin D level was 12 ng/mL; 14.5 ng/mL in summer and 13 ng/mL in autumn, which was significantly higher than 9 ng/mL in spring, and the correlation between vitamin D level and PHQ-9 score was more significant in spring but not in summer and autumn.

LIMITATIONS

Our study used cross-sectional data and could not examine the causal relationship of the vitamin D level and depressive symptoms. There are also some possible influencing factors, such as the dietary habits, outdoor sports, and the use of sunscreen were not investigated.

CONCLUSION

Observational data showed that the vitamin D level of depression is lower than the normal (30 ng/mL), and it is closely related to depressive symptoms in spring. The seasonal variations in vitamin D levels might play a critical role in Chinese patients with first-episode depression.

A novel LC-MS/MS method for the simultaneous analysis of selected fat-soluble vitamins in serum obtained from pediatric patients with pneumonia

Several observational studies have reported associations between low levels of fat-soluble vitamins (A, D and E) and the incidence of pneumonia. Whether infection affects or negatively regulates serum vitamin levels remains controversial. Our aims were to develop and validate a simple-pretreatment and fast method to determine the serum levels of selected fat-soluble vitamins, namely vitamin A (retinol), vitamin D (25-OH-D₃, 25-OH-D₂, and 3-epi-25-OH-D₃), and vitamin E (α-tocopherol), in children suffering from pneumonia during the acute phase and after inflammatory marker recovery. The sample preparation procedure involving protein precipitation and filtration was finished in one step, and separation took 8 min per sample. The calibrations were linear, with R² > 0.99. Both the intra-run (n = 6) and inter-run (n = 3) precision (relative standard deviation, RSD%) values were below 14.61%. The spiked recoveries at 3 concentrations ranged from 80.97 to 111.91%. Accuracies were calibrated using both National Institute of Standards and Technology serum (NIST 968f) and external quality assurance (EQA) samples offered by the National Center of Clinical Laboratories of China, and the relative error (RE%) values ranged from -13.17% to 12.53%. Clinical sample analysis revealed that infection did alter the serum retinol concentration and it did not alter the 25-OH-D and α-tocopherol levels in young children with pneumonia.

Sample preparation techniques for extraction of vitamin D metabolites from non-conventional biological sample matrices prior to LC-MS/MS analysis

The determination of vitamin D metabolites as status marker or for diagnostic purposes is almost entirely conducted from blood serum or plasma. Other biological matrices, however, have also interested researchers, for two main reasons: (1) alternative matrices may allow non-invasive sampling, permit easier sample transfer and require less demanding storage conditions; and (2) the levels of vitamin D metabolites in other body compartments may further aid the understanding of vitamin D metabolism and function. Thus, the development of reliable and efficient sample preparation protocols for sample matrices other than serum/plasma, which will remove potential interferences and selectively extract the targeted metabolites, is of great importance. This review summarizes sample preparation methods for measurement of vitamin D metabolites using liquid chromatography-(tandem)mass spectrometry in more than ten different human tissues, including hair, saliva, adipose tissue, brain and others.

Development and Validation of a Liquid Chromatography Mass Spectrometry Method for Simultaneous Measurement of 25(OH)D3, epi-25(OH)D3, 25(OH)D2, Vitamin A, α-Tocopherol, and γ-Tocopherol

OBJECTIVES

Fat-soluble vitamins are measured to identify deficiencies that may lead to rickets, osteomalacia, night blindness, and reversible motor and sensory neuropathies. We present a rapid liquid chromatography-mass spectrometry (LC-MS/MS) method that simultaneously measures 25-hydroxyvitamin D3 (25[OH]D3), epi-25(OH)D3, 25(OH)D2, vitamin A, α-tocopherol, and γ-tocopherol.

METHODS

We mixed 100 µL serum with internal standard and extracted it by using supported liquid extraction plates. Reconstituted specimens were analyzed by LC-MS/MS with a 10-minute gradient.

RESULTS

The method was linear, covering physiological levels with r2 > 0.99, and the total precision was less than 15% at all quality control levels. The lower limit of the measuring intervals for 25(OH)D3, epi-25(OH)D3, 25(OH)D2, vitamin A, α-tocopherol, and γ-tocopherol were 4 ng/mL, 4 ng/mL, 4 ng/mL, 1 µg/dL, 0.2 µg/mL, and 0.2 µg/mL, respectively, with coefficient of variation of 20% or less. Recoveries were between 92% and 111% for National Institute of Standards and Technology reference materials and 81% and 122% for spike-recovery studies. Comparison studies for vitamin D total, vitamin A, and α-tocopherol demonstrated slopes between 1.04 and 1.11 and r2 between 0.94 and 0.96. Minimal matrix effect was observed for all analytes.

CONCLUSIONS

We developed and validated a rapid LC-MS/MS method for the simultaneous measurement of 25(OH)D3, epi-25(OH)D3, 25(OH)D2, vitamin A, α-tocopherol, and γ-tocopherol.

Influence of Tacrolimus on Serum Vitamin A Levels in Patients After Renal Transplantation

OBJECTIVE

Patients after renal transplantation exhibit high levels of vitamin A, which has been previously suspected to be related with immunosuppressive medication. However, this possibility has not yet been systematically studied.

MATERIALS AND METHODS

Altogether, 116 patients were included and divided into 2 groups based on serum creatinine levels. The mean values of vitamin A levels between the 2 groups were compared using the Student's t-test. The Pearson's correlation coefficient was calculated to assess the association between vitamin A and tacrolimus.

RESULTS

Elevated vitamin A levels were found in both groups, and patients with kidney dysfunction after transplantation showed higher levels of vitamin A than patients with recovered kidney function. Most important, we could not identify any significant correlations between vitamin A level and tacrolimus for both groups. After long-term and short-term monitoring for different patients, obvious individual differences emerged. Such results generally ruled out previous suspicions regarding causality between immunosuppressive medication (tacrolimus) and vitamin A elevation after renal transplantation.

CONCLUSION

Patients after renal transplantation showed higher serum vitamin A levels than people with a normal medical exam, even if their graft function was restored. The cause of this abnormality did not seem to be related with tacrolimus.

Absolute quantification of eleven A, D, E and K vitamers in human plasma using automated extraction and UHPLC-Orbitrap MS

Fat-Soluble Vitamers [FSV] deficiencies and hypervitaminosis are associated with lifestyle diseases such as cardiovascular disease, diabetes, and cancer. Quantification of FSV and their metabolites in plasma has proved to be one of the most demanding analytical chemistry challenges. Current FSV quantification methods are compromises between breadth of coverage and sensitivity across the physiological range. Here, we developed and validated a sensitive, robust, semi-automated method using liquid-liquid extraction coupled with LC-ESI-MS/MS to quantify 11 FSV across their physiological concentrations in plasma. The addition of Phree® phospholipid removal plates as the last step in the extraction process reduced matrix effects, improving precision, recoveries, and the method's final sensitivity. This method can detect and quantify: retinol, retinoic acid, retinyl palmitate, 25 hydroxyvitamin D₃ [25-OH-D₃], 1-α-25-dihydroxy-D_3, α-tocopherol, γ-tocopherol, α-tocotrienol, phylloquinone [K1], Menatetrenone [MK-4], and menaquinone-7 [MK-7].The Instrument Quantitation Limit [IQL]s for retinol (64.1 ng/mL), 25-OH-D₃ (10.2 ng/mL), and α-tocopherol (3000 ng/mL) can detect clinical deficiencies. Our automated method will assist in the understanding of the complex interaction between these compounds and their possible role in health and disease.

An Updated Comprehensive Review on Vitamin A and Carotenoids in Breast Cancer: Mechanisms, Genetics, Assessment, Current Evidence, and Future Clinical Implications

Vitamin A and carotenoids are fat-soluble micronutrients that play important role as powerful antioxidants modulating oxidative stress and cancer development. Breast cancer is the most common malignancy in women. As the risk of breast cancer is dependent on various lifestyle factors such as dietary modifications, there is increasing interest surrounding the anti-cancerous properties of vitamin A and carotenoids. Despite the suggested protective roles of vitamin A and carotenoids in breast cancer development, their clinical application for the prevention and treatment of breast cancer is limited. In this narrative review, we discuss the roles of vitamin A and carotenoids along with the evaluation method of vitamin A status. We also exhibit the association of genetic variations involved in metabolism of vitamin A and carotenoids with cancers and other diseases. We demonstrate the epidemiological evidence for the relationship of vitamin A and carotenoids with breast cancer risk, their effects on cancer mechanism, and the recent updates in clinical practice of vitamin A or carotenoids as a potential therapeutic agent against breast cancer. This review provides insight into the preventive and therapeutic roles of vitamin A and carotenoids in breast cancer development and progression.

Vitamin D: Current Challenges between the Laboratory and Clinical Practice

Vitamin D is a micronutrient with pleiotropic effects in humans. Due to sedentary lifestyles and increasing time spent indoors, a growing body of research is revealing that vitamin D deficiency is a global problem. Despite the routine measurement of vitamin D in clinical laboratories and many years of efforts, methods of vitamin D analysis have yet to be standardized and are burdened with significant difficulties. This review summarizes several key analytical and clinical challenges that accompany the current methods for measuring vitamin D. According to an external quality assessment, methods and laboratories still produce a high degree of variability. Structurally similar metabolites are a source of significant interference. Furthermore, there is still no consensus on the normal values of vitamin D in a healthy population. These and other problems discussed herein can be a source of inconsistency in the results of research studies.

Vitamin A Update: Forms, Sources, Kinetics, Detection, Function, Deficiency, Therapeutic Use and Toxicity

Vitamin A is a group of vital micronutrients widely present in the human diet. Animal-based products are a rich source of the retinyl ester form of the vitamin, while vegetables and fruits contain carotenoids, most of which are provitamin A. Vitamin A plays a key role in the correct functioning of multiple physiological functions. The human organism can metabolize natural forms of vitamin A and provitamin A into biologically active forms (retinol, retinal, retinoic acid), which interact with multiple molecular targets, including nuclear receptors, opsin in the retina and, according to the latest research, also some enzymes. In this review, we aim to provide a complex view on the present knowledge about vitamin A ranging from its sources through its physiological functions to consequences of its deficiency and metabolic fate up to possible pharmacological administration and potential toxicity. Current analytical methods used for its detection in real samples are included as well.

LC-MS/MS quantification of fat soluble vitamers - A systematic review

Fat soluble vitamers (FSV) are several biochemically diverse micronutrients essential for healthy development, growth, metabolism, and cell regulation. We cannot synthesize FSV completely or at the required concentrations. Deficiency or excess of FSV can result in many health problems. Plasma is the most accessible sample matrix for the quantification of FSV. However, due to its complexity and other analytical challenges (e.g., FSV sensitivity to light, oxygen, heat, pH, chemical heterogeneity, standard availability), developing a method for the simultaneous quantification of multiple FSV at physiological concentrations has been challenging. In this systematic review, we examine the parameters and criteria used in existing Liquid Chromatography with tandem Mass Spectrometry (LC-MS/MS) methods for FSV quantification to the extraction method, chromatographic resolution, matrix effects, and method validation as critical to a sensitive and robust method. We conclude that the final FSV method sensitivity is predominantly based on aforementioned criteria and future method development using LC-MS/MS will benefit from the application of this systematic review.

Application of Dried Blood Spot Cards combined with liquid chromatography-tandem mass spectrometry to determine eight fat-soluble micronutrients in human blood

The analysis of the fat-soluble vitamins A and E and lipid micronutrients in blood, such as carotenoids, is an important parameter to monitor the micronutrient status in humans. Although the potential of dried blood spot (DBS) cards, the use of this technique for blood sampling and subsequent analysis of these fat-soluble micronutrients has been poorly or not studied. An analytical method based on DBS cards (FTA® DMPK-A) combined with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) has been developed and validated for the determination of carotenoids (lutein, zeaxanthin, β-cryptoxanthin and β-carotene), tocopherols (α-tocopherol, γ-tocopherol and δ-tocopherol) and all-trans-retinol in human blood. Under optimum DBS card extraction conditions, the extraction recoveries of the studied compounds were higher than 72%, the sample matrix effect lower than 17%, and the detection limits at hundred nM concentration levels. The developed method was applied to the analysis of human blood, and the concentration ranges obtained fell within the expected ranges previously reported in healthy adults. Moreover, the influence of hematocrit effect was investigated in a range of 25-55% in order to compare the obtained results to those reported in the literature for the analysis of plasma samples. This method represents an improvement over current techniques reported in the literature due to the use of a non-invasive blood collection method, and moreover, this methodology was for the first time 1) validated for the analysis of all-trans-retinol, tocopherols and carotenoids, and 2) applied for the determination of tocopherols in human blood samples.

Effects of Atypical Antipsychotics on Neuroactive Vitamins in Patients With Schizophrenia

In schizophrenia, neuroactive vitamins A/D/E play vital neuroprotective roles in its pathophysiological processes. During medical treatment, atypical antipsychotics, including aripiprazole, amisulpride, olanzapine, and paliperidone, were widely used at present. However, their impact on vitamin metabolism in vivo remained unclear. In this study, we conducted a case-control research to investigate the impacts of antipsychotics on vitamin metabolism. Schizophrenic patients (n = 163), who were divided into 5 groups (aripiprazole group, amisulpride group, olanzapine group, paliperidone group, nonmedication group) according to their different medication patterns, and healthy controls (n = 75) were involved. The concentrations of vitamin A/D/E and antipsychotics were measured using liquid chromatography-tandem mass spectrometry methods. Compared with healthy controls, significantly lower vitamin D and E concentrations were found in the nonmedication group after covariance analysis adjusting for age, sex, albumin, bilirubin, triglyceride, and cholesterol. We found that aripiprazole could affect vitamin D concentrations in vivo, and a positive correlation between aripiprazole concentrations and vitamin D concentrations (r = 0.319, P = 0.025) was observed in aripiprazole group. Such result revealed the very first observation for the influence of atypical antipsychotics medication toward vitamin status in vivo. Our study showed that low concentrations of vitamin D and E in vivo could be associated with schizophrenia, suggesting that hypovitaminosis may lead to a vulnerability to schizophrenia. More importantly, aripiprazole may potentially benefit the patients through improving their vitamin D status in vivo.

UPLC-MS/MS method for determination of retinol and α-tocopherol in serum using a simple sample pretreatment and UniSpray as ionization technique to reduce matrix effects

Background

Our goal was to develop a simple, rapid and precise ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the determination of retinol and α-tocopherol in serum. Currently published LC-MS/MS methods either require complex extraction procedures (liquid-liquid or solid-phase) or do not meet desirable specifications for imprecision in serum (coefficient of variation [CV] <6.8% and 6.9%, respectively).

Methods

Sample preparation consisted of a simple protein precipitation with ethanol and acetonitrile. Stable isotope-labeled internal standards (IS) and a homemade calibration curve were used for quantification. The analysis was performed using an Acquity I-class Xevo TQ XS LC-MS/MS. Chromatographic runtime was 6.0 min using a reversed phase gradient elution. UniSpray (US) as an ionization technique was compared to electrospray ionization (ESI). Analytical validation included matrix effect, recovery and trueness compared to National Institute of Standards and Technology (NIST) standards and United Kingdom National External Quality Assessment Service (UK NEQAS) samples.

Results

Intra- and inter-run CVs were <4.9% for retinol and <1.7% for α-tocopherol, both complying with desirable specifications for imprecision. Bias compared to NIST standards was <3.1% for both compounds. The method was linear over the entire tested range. The lower limit of quantification (LLOQ) with US was lower than with ESI for both retinol (0.022 vs. 0.043 mg/L) and α-tocopherol (0.22 vs. 0.87 mg/L). Matrix effects were not significant (<15%) for retinol. However, for α-tocopherol matrix effects of on average 54.0% were noted using ESI, but not with US.

Conclusions

We developed a fast, precise and accurate UPLC-MS/MS method for the determination of retinol and α-tocopherol in human serum using a single-step sample pretreatment. Ionization using US eliminated the matrix effects for α-tocopherol.

Acylation derivatization based LC-MS analysis of 25-hydroxyvitamin D from finger-prick blood

Vitamin D metabolite analysis possessed significant clinical value for the pediatric department. However, invasive venipuncture sampling and high blood consumption inflicted much suffering on patients. For alleviation, we carried out a LC-MS method for 25-hydroxyvitamin D quantification in only 3 μl of plasma from the considerably less invasive finger-prick blood samples. To improve sensitivity, acylation on C3-hydroxyl (by isonicotinoyl chloride) rather than Diels-Alder adduction on s-cis-diene structure was for the very first time introduced into vitamin D metabolite derivatization. Compared with the existing derivatization approaches, this novel strategy not only prevented isomer interference, but also exhibited higher reacting throughput. For certification, the methodology was systematically validated and showed satisfying consistency with SRM927a. During clinical application, we found a convincing correlation between 25-hydroxyvitamin D and indirect/total bilirubin in jaundiced newborns. Such an observation indicated that vitamin D supplementation may help to achieve optimal outcomes in neonatal jaundice.