Review
Recent advances in vitamins analysis by capillary electrophoresis

https://doi.org/10.1016/j.jpba.2017.07.030Get rights and content

Highlights

  • Vitamin analysis by capillary electrophoresis reviewed from mid-2007 until mid-2017.

  • Overview of electrophoretic modes, detection and sample concentration approaches.

  • Table summary of pharmaceutical, dietary supplement and biological applications.

Abstract

Vitamins are essential molecules required for human metabolism such as energy production, immune system and cell formation. Accurate vitamin analysis is critical for disease diagnosis, nutrients assessment, as well as food and drug production. This review gives an overview of the recent developments in the use of capillary electrophoresis combined with different detection techniques for the analysis of vitamins. The period covers mid-2007 until mid-2017. Different separation modes are discussed for the analysis of water-soluble vitamins and fat-soluble vitamins. On-line sample concentration for sensitive analysis is also described. The applications include the analysis of pharmaceutical, dietary supplement and biological samples.

Introduction

As is well known, vitamins are a group of essential compounds for the development and normal growth, self-maintenance and functioning of the human and animal body. According to their solubility, they are classified into two main groups: water-soluble and fat-soluble vitamins. The group of water-soluble vitamins consists of eight vitamins collectively known as B-complex vitamins plus vitamin C (ascorbic acid) [1], [2], [3]. The fat-soluble vitamins include the vitamins A, D, E, K. These vitamins play specific and vital functions in metabolism, and their lack or excess can cause health problems. With the exception of vitamin D, the vitamins cannot be produced within the body and should be obtained from the diet or via pharmaceutical preparations. Therefore, health care products with vitamins are very common in modern food and pharmaceutical industry [4]. Some vitamins can also be used as biomarkers for certain diseases. For example, a deficiency of fat-soluble vitamins is typical for children with cystic fibrosis [5]. Therefore, a sensitive and reliable analysis of vitamins in different sample matrices is crucial for health care industry and disease control.

Internationally accepted conventional analytical methods for vitamins analysis mainly rely on microbiological assay and immunoassay. However, they are usually labor intensive and time consuming and mostly do not allow the simultaneous determination of multi-vitamins. Several analytical methods have been developed for the analysis of vitamins. HPLC is one of the most common techniques for separating vitamins in a variety of products due to its high selectivity and sensitivity [6], [7], [8]. However, this method usually requires a larger sample volume with much more solvent consumption. Nowadays, capillary electrophoresis (CE) as an alternative tool to HPLC offers unique advantages due to its short analysis time, low reagent cost, and minimal sample requirement [9]. The sensitivity could be a disadvantage for CE in the analysis of vitamins due to the short light path. Currently, various detection formats can be coupled directly to CE, including UV absorbance, laser-induced fluorescence (LIF), electrochemical (EC) and MS detection, which makes CE a powerful tool to meet different requirements [10]. The methods of vitamins analysis by CE have been covered in food, pharmaceutical and biological samples. Most of the developed methods based on CE-UV mainly concern the assessment of vitamins in pharmaceutical and food products due to the relatively high analyte concentration [11]. UV detection is also a good choice for simultaneous determination of several vitamins. However, the application of CE-UV was limited due to unsatisfactory detection sensitivity owing to its short light path and small sample volume, especially when biological samples are tested. To improve the detection sensitivity of CE, sensitive detectors and/or on-line preconcentration methods are usually applied in CE analysis [12].

LIF is an extremely sensitive detection method for CE, which is about 1000 times more sensitive than the traditional UV detector [13]. It is only suitable for analytes containing a fluorophore like riboflavin (vitamin B2). Chemiluminescence (CL) detection is considered one of the most sensitive detection schemes. Its convincing advantage over fluorescence detection is that it does not require a bulky light source. The CL detector is limited in its applicability by the lack of CL reactions for many compounds. Electrochemical detection coupled with CE has been getting more attention due to its high sensitivity and good selectivity to electroactive analytes such as ascorbic acid (vitamin C). With electrochemical detection however, the high separation voltage could interfere with the detection of the electrochemical signal, and the contamination of the electrode surface might also pose problems in the analysis of real samples. MS detectors have a higher sensitivity and selectivity with the added function of structural identification. However, this requires expensive instrumentation, and method development in CE-MS is restricted to the use of volatile buffers [14]. MEKC can also be coupled with MS by using volatile surfactants, as shown by Hernandez-Borges’s group [15].

In the meantime, various types of extraction to enrich the analytes in the sample are employed to increase the sensitivity of the method [16]. However, these methods are usually time consuming and may lead to the loss of analytes during sample preparation steps. On-line pre-concentration techniques do not have these disadvantages and can be successfully used for electrophoretic separation, immediately after a parameters optimization procedure [17]. Highly sensitive detectors could thus be combined with on-line pre-concentration techniques for highly sensitive analysis.

Water-soluble vitamins such as vitamins B or C can be easily charged and can be separated using capillary zone electrophoresis (CZE) [18]. Micellar electrokinetic chromatography (MEKC) was mostly used for simultaneous separations of several water-soluble vitamins due to the improved selectivity [19], [20].

Fat-soluble vitamins which are neutral and have poor water-solubility need to be separated by a chromatography-based method (MEEKC/CEC). On the other hand, the use of multiple separation modes is reported for the simultaneous separation of water and fat-soluble vitamins which have diverse properties.

This review, as a summary of vitamins analysis by CE, gives an overview of the recent developments and applications of CE combined with different detectors using various separation modes over the period from mid-2007 to mid-2017. The various types of samples in which vitamins have been determined, are listed in Table 1, together with the respective sample pretreatment, separation mode, buffer, detection type and obtained sensitivity.

A review regarding the application of capillary electrophoresis to the analysis of vitamins in food and beverages was presented by Trenerry [21].

Section snippets

Sample preparation

Sample pretreatment steps are very important for the analysis of vitamins. In cells and tissues, vitamins can easily form complexes with phosphate groups (thiamine mono-, di- and triphosphate, nicotinamide adenine dinucleotide phosphate, etc.). Moreover, free thiamine, nicotinamide and nicotinic acid are often bound to proteins, and therefore acid hydrolysis with heat treatment is sometimes required to liberate them to the free form. Several procedures have been presented for the extraction of

Fluorescence detection

The analysis of vitamins by fluorescence detection can be achieved by direct analysis for compounds with a natural fluorophore or through a derivatization method. Riboflavin (RF), commonly called vitamin B2, is a natural fluorophore. A new CE system with in-column optical fiber LIF detection was developed for the analysis of RF in beverage, green tea and urine samples. The optical fiber was inserted directly into the tail end of the capillary to avoid the light reflection and scattering from

Micellar electrokinetic chromatography

Micellar electrokinetic chromatography has been used to separate both ionic and neutral analytes which are difficult to separate by CZE. The presence of micelles of surfactants in the background electrolyte (BGE) acts as a “pseudostationary phase”, which leads to both hydrophobic and electrostatic interactions with solutes. Therefore, the MEKC technique is applicable to the separation of both water-soluble and fat-soluble vitamins.

UV detection is one of the most used detection techniques in

Conclusions

The challenge of vitamins analysis by CE is the sensitivity on the one hand, and multi-vitamins determination on the other hand. Sample preparation by SPE or LLE could be helpful for the extraction of low amounts of vitamins. Light protection and low temperature were used to ensure the stability of vitamins during sample pretreatment. High sensitivity of vitamins analysis could be achieved by fluorescence detection with sub nM detection limits, where the analysis was mainly applied to vitamin B2

Acknowledgement

Xu Wang and Kefeng Li contributed equally to this review. This work was supported by the Tianjin Natural Science Foundation (No. 16JCQNJC14400), Foundation of Science and Technology for oversea returnees of Tianjin and the Foundation (No. 2014M001) of Key Laboratory of Industrial Fermentation Microbiology of Ministry of Education and Tianjin Key Lab of Industrial Microbiology (Tianjin University of Science & Technology). X.W. was also supported by a talent grant from the Tianjin University of

References (73)

  • K.E. Johnston et al.

    Folate concentrations of fast foods measured by trienzyme extraction method

    Food Res. Int.

    (2002)
  • J. Arcot et al.

    Folate: methods of analysis

    Trends Food Sci. Technol.

    (2005)
  • L. Hu et al.

    Determination of riboflavin in urine and beverages by capillary electrophoresis with in-column optical fiber laser-induced fluorescence detection

    J. Chromatogr. B

    (2007)
  • T. Galeano-Díaz et al.

    Determination of tocopherols in vegetable oil samples by non-aqueous capillary electrophoresis (NACE) with fluorimetric detection

    J. Food Compos. Anal.

    (2012)
  • T. Wu et al.

    Determination of flavonoids and ascorbic acid in grapefruit peel and juice by capillary electrophoresis with electrochemical detection

    Food Chem.

    (2007)
  • X. Sun et al.

    Determination of ascorbic acid in individual rat hepatocyte by capillary electrophoresis with electrochemical detection

    J. Chromatogr. B

    (2008)
  • P. He et al.

    Measurement of ascorbic acid in single rat peritoneal mast cells using capillary electrophoresis with electrochemical detection

    J. Chromatogr. B

    (2010)
  • S. Dong et al.

    Simultaneous determination of sugars and ascorbic acid by capillary zone electrophoresis with amperometric detection at a carbon paste electrode modified with polyethylene glycol and Cu2O

    J. Chromatogr. A

    (2007)
  • B. Wu et al.

    Noble metal nanoparticles/carbon nanotubes nanohybrids: synthesis and applications

    Nano Today

    (2011)
  • X. Wang et al.

    Determination of ascorbic acid in individual liver cancer cells by capillary electrophoresis with a platinum nanoparticles modified electrode

    J. Electroanal. Chem.

    (2014)
  • S. Zhao et al.

    Microchip electrophoresis with chemiluminescence detection for assaying ascorbic acid and amino acids in single cells

    J. Chromatogr. A

    (2009)
  • S. Dziomba et al.

    Field-amplified sample stacking–sweeping of vitamins B determination in capillary electrophoresis

    J. Chromatogr. A

    (2012)
  • M. Navarro-Pascual-Ahuir et al.

    Determination of water-soluble vitamins in energy and sport drinks by micellar electrokinetic capillary chromatography

    Food Control

    (2016)
  • M. Bellini et al.

    Capillary electrophoretic separation of vitamins in sodium dodecyl sulfate containing buffers with lower aliphatic alcohols and n-hexane as organic modifiers

    J. Chromatogr. B

    (2000)
  • C. Yin et al.

    Rapid determination of water- and fat-soluble vitamins with microemulsion electrokinetic chromatography

    J. Chromatogr. A

    (2008)
  • S. Pedersen-Bjergaard et al.

    Selectivity in microemulsion electrokinetic chromatography

    J. Chromatogr. A

    (2000)
  • Analysis of Food Constituents

  • Analyzing Food for Nutrition Labeling and Hazardous Contaminants

  • The Nutrition Handbook for Food Processors

  • J. Wan

    Analyzing status and development of functional drinks in the world

    Food Ferment. Ind.

    (2007)
  • B. Wiedemann et al.

    Evaluation of body mass index percentiles for assessment of malnutrition in children with cystic fibrosis

    Eur. J. Clin. Nutr.

    (2007)
  • Carlos D. Garcia et al.

    Fundamental Concepts, Practical Applications, and Limitations of Capillary Electrophoresis and Microchip Capillary Electrophoresis

    (2013)
  • M. Castro-Puyana et al.

    CE methods for the determination of non-protein amino acids in foods

    Electrophoresis

    (2007)
  • R.H.F. Cheung et al.

    Investigation of folic acid stability in fortified instant noodles by use of capillary electrophoresis and reversed-phase high performance liquid chromatography

    J. Chromatogr. A

    (2008)
  • G. Hempel

    Strategies to improve the sensitivity in capillary electrophoresis for the analysis of drugs in biological fluids

    Electrophoresis

    (2000)
  • F.T. Han et al.

    Pteridine analysis in urine by capillary electrophoresis using laser-induced fluorescence detection

    Anal. Chem.

    (1999)
  • Cited by (44)

    • “Turn-on” fluorescence sensor for vitamin B1 based on cyanostilbene macrocycle

      2022, Dyes and Pigments
      Citation Excerpt :

      The development of rapid, simple and on-site detection for vitamin B1 is extremely anticipated. Up to now, some normal analytical methods had been developed for vitamin B1, such as high-performance liquid chromatography [6–11], capillary electrophoresis [12–17], and voltammetry [18]. The oxidized product (thiochrome) of vitamin B1 prepared by alkaline oxidation exhibited strong fluorescence, which also used for determining vitamin B1.

    • Green microemulsion electrokinetic chromatographic method for simultaneous determination of azelastine and budesonide

      2022, Sustainable Chemistry and Pharmacy
      Citation Excerpt :

      Capillary electrophoresis (CE) is a versatile advanced separation technique that is widely employed for separation and analysis of pharmaceutical compounds, food products, proteins, and vitamins (Dawod et al., 2017; Ibáñez et al., 2016; Wang et al., 2018; Zeid et al., 2016; Zhu and Scriba, 2018).

    View all citing articles on Scopus
    View full text