Determination of vitamin K 1 using square wave adsorptive stripping voltammetry at solid glassy carbon electrode

Electrochemical biosensor based on NAD(P)H-dependent quinone reductase for rapid and efficient detection of vitamin K3

Vitamin K refers to a group of vitamins that play an important role in blood coagulation and regulation of bone and vascular metabolism. However, vitamin K3 may give severe side effects in animal and humans when improperly added to food and feed due to its toxicity. Here, an electrochemical biosensor, based on the YaiB NADPH-dependent quinone reductase from Lactococcus lactis (YaiB), was developed to achieve rapid and redox probe-free detection of vitamin K3. First, the ability of the carbon electrode to distinguish between 1,4-benzoquinone and hydroquinone was demonstrated. Then, we engineered YaiB to work as a bioreceptor immobilized at the electrode and its sensitivity and specificity to reduce vitamin K3 were demonstrated. Finally, to demonstrate the practical potential of the biosensor, we tested it directly in spiked milk samples, achieving 15-minute quantification of the vitamin K3. The limit of detection was 0.87 µM and 4.1 µM in buffer and milk, respectively.

Different Aspects of the Voltammetric Detection of Vitamins: A Review

Vitamins comprise a group of organic chemical compounds that contribute significantly to the normal functioning of living organisms. Although they are biosynthesized in living organisms, some are also obtained from the diet to meet the needs of organisms, which is why they are characterized as essential chemical compounds. The lack, or low concentrations, of vitamins in the human body causes the development of metabolic dysfunctions, and for this reason their daily intake with food or as supplements, as well as the control of their levels, are necessary. The determination of vitamins is mainly accomplished by using analytical methods, such as chromatographic, spectroscopic, and spectrometric methods, while studies are carried out to develop new and faster methodologies and techniques for their analysis such as electroanalytical methods, the most common of which are voltammetry methods. In this work, a study is reported that was carried out on the determination of vitamins using both electroanalytical techniques, the common significant of which is the voltammetry technique that has been developed in recent years. Specifically, the present review presents a detailed bibliographic survey including, but not limited to, both electrode surfaces that have been modified with nanomaterials and serve as (bio)sensors as well as electrochemical detectors applied in the determination of vitamins.

Processes and Interactions Impacting the Stability and Compatibility of Vitamin K and Gold Nanoparticles

This study provides evidence on the stability of vitamin K1 (VK) in the form of phytomenadione, in the absence and presence of a therapeutic preparation, as the gold nanoparticles (AuNPs), under the effect of sodium halide ions. The degradation susceptibility of the two compounds was assessed individually and in mixtures by cyclic voltammetry and electrolysis at a constant current density assisted by UV-Vis spectrophotometry. Their interactions with the halide ions differently impact on the electrochemical processes as follows: (i) the fluoride ions weakly affects the VK/AuNP stability and compatibility; (ii) the presence of chloride ions leads to VK/AuNP stability, for a short time and restrictive compatibility; (iii) bromide ions induce instability and incompatibility of the VK/AuNP system; (iv) spontaneous interactions between VK/AuNPs and iodide ions take place, consequently defining as an unstable and incompatible system.

Recent Techniques in Nutrient Analysis for Food Composition Database

Food composition database (FCD) provides the nutritional composition of foods. Reliable and up-to date FCD is important in many aspects of nutrition, dietetics, health, food science, biodiversity, plant breeding, food industry, trade and food regulation. FCD has been used extensively in nutrition labelling, nutritional analysis, research, regulation, national food and nutrition policy. The choice of method for the analysis of samples for FCD often depends on detection capability, along with ease of use, speed of analysis and low cost. Sample preparation is the most critical stage in analytical method development. Samples can be prepared using numerous techniques; however it should be applicable for a wide range of analytes and sample matrices. There are quite a number of significant improvements on sample preparation techniques in various food matrices for specific analytes highlighted in the literatures. Improvements on the technology used for the analysis of samples by specific instrumentation could provide an alternative to the analyst to choose for their laboratory requirement. This review provides the reader with an overview of recent techniques that can be used for sample preparation and instrumentation for food analysis which can provide wide options to the analysts in providing data to their FCD.

Determination of Vitamins K1, K2 MK-4, MK-7, MK-9 and D3 in Pharmaceutical Products and Dietary Supplements by TLC-Densitometry

Vitamin K is a group of lipophilic molecules. Forms of vitamin K play an essential role in the activation of specific proteins involved in blood clotting cascade or bone metabolism. Another molecule belonging to the fat-soluble vitamins group that also plays an important role in calcium metabolism is vitamin D3. The dietary supplements containing vitamins K and D3 are one of the most frequently consumed by patients. The objective of this work was to develop a simple, fast and sensitive thin-layer chromatography (TLC)-densitometric procedure for the simultaneous quantitative analysis of vitamins K and D3 in pharmaceutical products and dietary supplements. The analysis of vitamins was performed on the silica gel RP-18 F₂₅₄s plates with methanol-ethanol-isopropanol in a volume ratio of 15:1:4 as a mobile phase. The densitometric measurements were made at 254 nm. The method was validated by checking the specificity, linearity, precision, recovery, limit of detection, limit of quantification and robustness in accordance with International Conference on Harmonization (ICH) guidelines. The method was shown to be specific, accurate (recoveries were from 95.78 to 104.96%), linear over the tested range (correlation coefficient, exceeding 0.99), and precise (precision and intermediate precision RSD below 2.70% for all analytes). The satisfactory results of the validation of the method indicate that it can be used in the quality control of dietary supplements and pharmaceutical products containing vitamins K and D3.

Simultaneous Determination of Vitamin E and Vitamin K in Food Supplements Using Adsorptive Stripping Square-Wave Voltammetry at Glassy Carbon Electrode

A new voltammetric method for the simultaneous determination of vitamin E and vitamin K present in different types of commercially available food supplements has been developed. This electroanalytical method is based on the ex situ adsorptive accumulation of these biologically active compounds onto the surface of a solid glassy carbon electrode (GCE) with subsequent electrochemical detection by square-wave adsorptive stripping voltammetry in 0.01-mol L−1 HNO3 containing 0.1-mol L−1 KCl at pH 2.08. Due to reversible electrochemical reactions of phylloquinone, a subsequent voltammetric detection of both vitamins in anodic mode can be performed. Since individual forms of vitamins E and K usually exhibit nearly identical electrochemical behavior, it is therefore impossible to distinguish individual forms (quinones and tocopherols) and determine their molar concentrations in this way. Thus, the values of vitamin content were expressed as mass equivalent of phylloquinone and α-tocopherol as they are the most biologically active forms. Despite the high sensitivity, relatively short linear ranges were obtained due to the interaction (competition) of both vitamins during adsorption onto the freshly polished surface of the GCE from a 50% aqueous–acetonitrile mixture. The obtained results showed that the voltammetric approach is a very simple and low-cost analytical method that can be used in analyses of food supplements.