Detection and quantification of vitamins in microliter volumes of biological samples by LC-MS for clinical screening

Rapid Determination of Water-Soluble Vitamins in Human Serum by Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry

Water-soluble vitamins play essential roles in normal body functions and metabolic activities. However, few methods have simultaneously measured all nine water-soluble vitamins in biological matrices. In this study, we developed a sensitive and accurate method for the simultaneous measurement of thiamine (B1), riboflavin (B2), nicotinamide (B3), pantothenic acid (B5), 4-pyridoxic acid (B6), biotin (B7), 5-methyltetrahydrofolic acid (B9), ascorbic acid (VC), and methylmalonic acid (MMA) in human serum. Samples were analyzed using ultrahigh-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) with Waters HSS T3 and BEH C18 columns, each measuring 2.1 × 50 mm with a particle size of 1.7 μm. The mass spectrometer was equipped with an electrospray ionization source, and optimized multiple reaction monitoring was employed to detect all compounds in positive ionization mode. The capillary voltage was set at 0.5 kV. Nitrogen was used as the desolvation gas, with a flow rate of 1000 L/h at 500 °C. Argon was used as the collision gas. The method's performance was validated according to the Clinical and Laboratory Standards Institute guidelines assessing linearity, limit of quantitation, precision, accuracy, carryover, matrix effects, recovery, and dilution. The results confirmed the successful validation of this method for water-soluble vitamins in serum. However, the presence of common endogenous interferences and the type of blood collection tube influenced the results for certain water-soluble vitamins. The results showed that this method was satisfactory, offering significant improvements in analytical performance, including shorter analysis time, higher sensitivity, and the requirement of a smaller sample volume.

Biological Properties of Vitamins of the B-Complex, Part 1: Vitamins B1, B2, B3, and B5

This review summarizes the current knowledge on essential vitamins B1, B2, B3, and B5. These B-complex vitamins must be taken from diet, with the exception of vitamin B3, that can also be synthetized from amino acid tryptophan. All of these vitamins are water soluble, which determines their main properties, namely: they are partly lost when food is washed or boiled since they migrate to the water; the requirement of membrane transporters for their permeation into the cells; and their safety since any excess is rapidly eliminated via the kidney. The therapeutic use of B-complex vitamins is mostly limited to hypovitaminoses or similar conditions, but, as they are generally very safe, they have also been examined in other pathological conditions. Nicotinic acid, a form of vitamin B3, is the only exception because it is a known hypolipidemic agent in gram doses. The article also sums up: (i) the current methods for detection of the vitamins of the B-complex in biological fluids; (ii) the food and other sources of these vitamins including the effect of common processing and storage methods on their content; and (iii) their physiological function.

Dilute-and-shoot-based direct nano-electrospray ionization tandem mass spectrometry as screening methodology for multivitamins in dietary supplement and human urine

INTRODUCTION

In recent years, analytical screening methods for simultaneous detection of multivitamins have gained substantial attention to ensure quality and public confidence in dietary supplements. Even so, few analytical methods have been proposed for simultaneous analysis of multivitamin constituents due to the large divergence in chemical characteristics.

OBJECTIVES

In the present study, the objective was to develop a simple and rapid direct nano-electrospray ionization-tandem mass spectrometry (DI-nano-ESI-MS/MS) method for targeted detection of water soluble vitamins, fat soluble vitamins, amino acids, royal jelly, ginkgo biloba, and ginseng in a dietary supplement. The applicability of dilute-and-shoot-based DI-nano-ESI-MS/MS to analyze the same tested compounds and their related metabolites in clinical samples was also examined.

METHODS

Intact urine mixed with the ionization solvent was loaded (4-μL aliquot) into a nanospray (NS) capillary of 1-μm tip diameter. The NS capillary was then fitted into an off-line ion source at a distance of 5 mm from MS aperture. The sample was directly injected by applying a voltage of 1.1 kV, producing a numerous of m/z peaks for analysis in mere minutes.

RESULTS

The DI-nano-ESI-MS/MS method successfully identified almost all dietary supplement components, as well as a plethora of component-related metabolites in clinical samples. In addition, a new merit of the proposed method for the detection of index marker and chemical contaminants as well as subspecies identification was investigated for further quality evaluation of the dietary supplement.

CONCLUSIONS

The previous findings illustrated that DI-nano-ESI-MS/MS approach can emerge as a powerful, high throughput, and promising analytical tool for screening and accurate detection of various pharmaceuticals and ingredient in dietary supplements as well as biological fluids.

Herbivory meets fungivory: insect herbivores feed on plant pathogenic fungi for their own benefit

Plants are regularly colonised by fungi and bacteria, but plant-inhabiting microbes are rarely considered in studies on plant-herbivore interactions. Here we show that young gypsy moth (Lymantria dispar) caterpillars prefer to feed on black poplar (Populus nigra) foliage infected by the rust fungus Melampsora larici-populina instead of uninfected control foliage, and selectively consume fungal spores. This consumption, also observed in a related lepidopteran species, is stimulated by the sugar alcohol mannitol, found in much higher concentration in fungal tissue and infected leaves than uninfected plant foliage. Gypsy moth larvae developed more rapidly on rust-infected leaves, which cannot be attributed to mannitol but rather to greater levels of total nitrogen, essential amino acids and B vitamins in fungal tissue and fungus-infected leaves. Herbivore consumption of fungi and other microbes may be much more widespread than commonly believed with important consequences for the ecology and evolution of plant-herbivore interactions.