Quantitative Analysis of Vitamins

Vitamins

... and vitamin-like substances

Vitamins are essential (life-giving and vital) nutritional elements as they undertake important functions in the human organism. Alongside the natural vitamins, synthetic vitamins are also added to foodstuffs during the production and processing stages.

Declaration of these vitamins in Switzerland depends on the product and is regulated in the “Ordinance of the Swiss Federal Department of Home Affairs via the Addition of Essential or Physiologically Useful Substances to Foodstuffs” from 23/11/2005 and in the “Ordinance of the Swiss Federal Department of Home Affairs over Special Foodstuffs” from 23/11/2005. 

Do you require content determination of vitamins performed by an accredited Swiss contract laboratory?
We will test all vitamins for you in accordance with the Swiss Book of Foodstuffs (Schweizer Lebensmittelbuch, SLMB), or from your internally developed methods - quickly, competently and reliably.

Would you like to know which points you should observe when contracting out your analyses? Do you know the differences for analysis that can result from the addition of the various vitamin derivatives?  

 

We will be happy to advise you.

Read on here for more information or contact us.


What are vitamins, provitamins and vitaminoids?

Sample preparation for the determination of vitamins in carrots
Sample preparation for the determination of vitamins in carrots

Vitamins are organic compounds that are required by the human organism for life-giving vital (essential) functions but cannot be produced, or can be produced but not in sufficient quantities by metabolism. Therefore, they must be taken in regularly as food, either as complete vitamins or as provitamins which can then be transformed into the corresponding vitamins. In contrast to the essential fatty acids and essential amino acids, vitamins serve neither as a body constituent nor as an energy supplier, instead they are involved primarily in catalytic functions (coenzymes) or controlling functions (hormone-like substances). Therefore, only very small amounts of vitamins are required for their physiological effects. A total of 13 substances posses these characteristics and they are divided into water-soluble and fat-soluble vitamins depending on their physical characteristics:

Water soluble vitamins   Fat soluble vitamins  
Vitamin B1 (thiamine) Vitamin A (retinol)
Vitamin B2 (riboflavin) Vitamin D2 (ergocalciferol)
Vitamin B5 (pantothenic acid) Vitamin D3 (cholecalciferol)
Vitamin B6 (pyridoxine) Vitamin E (alpha-Tocopherol)
Vitamin B12 (cyanocobalamin) Vitamin K1 (phylloquinone)
Vitamin Bc (folic acid) Vitamin K3 (menadione)
Vitamin C (ascorbic acid)  
Vitamin H (biotin)  
Vitamin PP (niacin, niacinamide)  

Vitaminoids

The simple definition of vitamins above should enable an unambiguous and doubt-free classification. Even nowadays however, active ingredients are still classified as vitamins even though they do not fulfil the definition of a vitamin, partly due to ignorance of their pharmacological characteristics, but also as a result of strategic marketing considerations. These so-called vitaminoids possess characteristics that are similar to vitamins and are contained in foodstuffs. In contract to vitamins however, they are also produced by the body. Some of these vitaminoids have been listed as examples in the following list:

 

  • L-carnitine and combined carnitine (acetyl-carnitine)
  • Inosit
  • Choline
  • Taurine
  • Ubichinon (coenzyme Q)

Provitamins

Provitamins however are still ineffective preliminary stages of vitamins and must first be transformed into vitamins in the organism for them to be of use to the body. Some examples of provitamins are the following compounds:

  • Beta-carotene (provitamin A)
  • Ergosterol (provitamin D2)

Why should the vitamin content of foodstuffs be analytically monitored?

Vitamins are added to many foodstuffs - here for example to cornflakes
Vitamins are added to many foodstuffs - here for example to cornflakes

Vitamins have an essential function in nutrition and as a result are added in a targeted manner during the foodstuff manufacturing and processing stages for technological, nutritional and physiological reasons, alongside the naturally occurring vitamins that are already present.

In the event of insufficient intake of vitamins, hypovitaminosis can occur (deficiencies such as scurvy occur with a lack of vitamin C or rickets with a lack of vitamin D), and in later stages avitaminosis (severe forms of deficiencies) appears that can lead to death.

But it is not only hypovitaminosis that is critical. A too high content, particularly of the fat-soluble vitamins, can also cause problems. After being absorbed from food, vitamins are stored in the fatty tissue of the body for a long period of time, that can lead to toxic effects (hypervitaminosis). Too high doses of soluble vitamins are less problematic because they are excreted from the body again quickly.

Statutory regulations on the maximum allowable dosage of vitamins

To avoid these signs of deficiency or overdose, there are legal regulations in relation to the vitamin content in foodstuffs. Hence, for example in Article 4 of the “Ordinance of the Swiss Federal Department of Home Affairs onr the Addition of Essential or Physiologically Beneficial Substances to Foodstuffs”, the maximum allowable dosage has been defined. For all vitamins apart from vitamins A and D, a daily dose of a maximum of three times the daily ration is allowed, to compensate for loss of vitamins during storage. For vitamin A, an overdose of max. 200 % of the recommended daily dosage is allowed and for vitamin D, a maximum of 150 % is acceptable. The respective recommended daily dose is defined in Appendix 1 of the same Ordinance. In addition to these, only compounds that are cited in Appendix 2 of the Ordinance are permitted to be added. For special foodstuffs, the “Ordinance of the Swiss Federal Department of Home Affairs over Special Foodstuffs” applies.

For quality control of the manufacturing process of foodstuffs and compliance with the legal regulations, reliable testing is therefore essential. By performing regular determination of the vitamin content, errors in production (for examples problems during the addition of vitamin mixtures) can be recognised early. By storing foodstuffs as part of a stability study, the composition of the products and their vitamin contents when the products reach the use-by date or best-before date can all also be investigated. As a result, a statement can be made as to whether the declared information about the product is still correct and if the guidelines have been adhered to.

Permitted vitamins and their recommended daily doses for adults
Substance Recommended daily dose for adults
Vitamins  
Vitamin A 800 ug
a-carotene (provitamin A) 4.8 mg
Vitamin D 5 ug
Vitamin E 12 mg
Vitamin C 80 mg
Vitamin K 75 ug
Vitamin B1 (Thiamine) 1.1 mg
Vitamin B2 (Riboflavin) 1.4 mg
Niacin (vitamin PP) 16 mg
Vitamin B6 1.4 mg
Folic acid/folacin 200 ug
Vitamin B12 2.5 ug
Biotin 50 mg
Pantothenic acid 6 mg

What should be considered when commissioning vitamin analyses in the sense of providing a rapid and representative handling of the order?

1.    Sample shipment

Vitamins can be destroyed by the influence of light, heat and atmospheric oxygen in varying measures. The following table gives an overview of the stability of various vitamins against external influences of this kind. As a result, for the analysis of light-sensitive vitamins such as vitamin C or provitamin A, it is recommended to send these vitamins in brown glass containers.

The destruction of vitamins
Sensitive to: Light Oxygen Water Heat pH value Irradiation
Water soluble vitamins  
B1 (Thiamine)  

 X

 X

X

 

X

B2 (Riboflavin)

 X

 X

 

X

   
B6 (Pyridoxine)

 X

 X

 

X

   
Niacin    

 X

     
B12 (Cobalamin)

 X

 X

 X

     
C (Ascorbic acid)

 X

 X

 X

X

 

 X

Folic acid        

 X

 
Fat soluble vitamins  
A (Retinol)

 X

 X

     

 X

D (Calciferol)

 X

 X

       
E (Tocopherol)

 X

 X

       
K (Phylloquinone)

 X

         

2. Microencapsulation of the Vitamins

As a result of the well-known loss of vitamins from external influences, protective microencapsulations are used, particularly in highly concentrated vitamin premixes that enter into the production of foodstuffs, to prevent losses during the production stage. These microencapsulations are extremely stable and have not been cracked during the vitamin routine analysis stage, which would have led to findings of vitamins being greatly lower than expected in the analysis. In such cases, a special additional sample homogenisation will be carried out using a ball mill, so this information is helpful for sample preparation in the laboratory.

3. Types of application for the vitamins used

Vitamins can be deployed as a variety of derivatives - important to know for the analysis
Vitamins can be deployed as a variety of derivatives - important to know for the analysis

It is important to know which vitamin has been added specifically during production as this has a direct influence over the analyses’ methods to be selected, the way that this method will be carried out, or the calculation of the result. Examples on this subject:

  • Different methods of analysis for vitamin K1 (Phylloquinone) and vitamin K3 (Menadione)
  • Different implementation of the analysis method for vitamin D2 (Ergocalciferol) and vitamin D3 (Cholecalciferol)
  • Different methods of analysis for vitamin C (ascorbic acid) and ascorbyl palmitate
  • Different methods of analysis for vitamin E (alpha-tocopherol) and the tocopherol spectrum (alpha, beta, gamma and delta-tocopherol)
  • Was the active form of the vitamin used (e.g. retinol) or was a derivative of the active vitamin form used (e.g. retinyl acetate)? Different calculations of results arise from this.

4. Reference Values of the Vitamins

It is helpful to have a reference value for the respective vitamins because this will influence the choice of method. For highly concentrated vitamin premixes, chemical methods such as HPLC-UV are the method of choice. For lower levels of vitamin concentrations in foodstuffs however, the more sensitive biological determinations using the growth of micro-organisms are the better choice. Furthermore, the data on reference values means that the appropriate level of sample dilution can be selected directly for the analytical test to lie within the linear range of the measurement technique. This means that subsequent analyses can be avoided and quicker order processing results. It is also important that the correct unit for the reference value,  e.g. IE or mg, is given.

Do you require additional information?

Please read the unabridged version in our technical article (see the right-hand column) or ask for advice from our customer services.


Our services in detail:

Vitamin analysis: Crystals of pure vitamin D3 under the microscope
Vitamin analysis: Crystals of pure vitamin D3 under the microscope
  • Consultation on vitamin analysis
  • Content determination of vitamins, vitaminoids and provitamins in foodstuffs
  • Stability testing of vitamin-containing products
  • Additional services are according to the directory of services or upon request

contact person

customer services for foodstuffs

Sascha Theobald Doctor of natural sciences (Dr. rer. nat.) Graduate in food chemistry

Tel. +41 58 434 42 00 service@ufag-laboratorien.ch

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