Vitamin E - Revision history

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Figure 1. Structures of tocopherols. ?-tocopherol: C₂₉H₅₀O₂, Mw = 430,71 g/mol. The group vitamin E includes eight compounds that hav..."

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Created page with " Figure 1. Structures of tocopherols. ?-tocopherol: C29H50O2, Mw = 430,71 g/mol. The group vitamin E includes eight compounds that hav..."

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Figure 1. Structures of tocopherols.

?-tocopherol: C29H50O2, Mw = 430,71 g/mol.

The group vitamin E includes eight compounds that have similar biological activity as ?-tocopherol. These compounds are ?-, ?-, ?- and ?-tocopherols and the corresponding tocotrienols. The measurement of vitamin E is carried out by determination of tocopherols, and vitamin E activity can be calculated taking the activity of each tocopherol into account.

Note:

USDA Food Composition Database for Standard Reference, Release 25 defines vitamin E as ?-tocopherol only ) . This definition has been adopted by many European food databases.

Synonyms for vitamin E:

* tocopherol, ephanyl

[https://metrofood-wiki.foodcase-services.com/index.php?title=Summary+-+vitamin+E Summary]

-----

=== Golden standard ===

* [http://www.cen.eu/cen/Sectors/TechnicalCommitteesWorkshops/CENTechnicalCommittees/Pages/Standards.aspx?param=6256&title=CEN/TC%20275 EN 12822:2000]Foodstuffs - Determination of vitamin E by high performance liquid chromatography - Measurement of ?-, ?-, ?- and ?-tocopherols.
** draft prEN 12822:2012

=== Method indicator ===

* ''Name''
* ''Code''

=== Scope ===

The European Standard EN 12822 describes a method for the determination of vitamin E in foodstuffs by high performance liquid chromatography (HPLC). Vitamin E content is determined by measurement of ?-, ?-, ?- and ?-tocopherols.

=== Principle ===

Sample treatments usually include saponification and extraction. ?-, ?-, ?- and ?-tocopherols are determined by HPLC using fluorometric detection. Also photometric detection (UV-range) can be used but fluorometric detection is preferred.

=== Key steps ===

==== General ====

* The sample treatments described below are meant for other samples than oil and fat samples (low water content) containing unesterified tocopherols.
* For oil and fat samples with unesterified tocopherols, the following pretreatments are used:
** n-hexane is added to dissolve the test portion.
** Solution is diluted prior to chromatography.
** Only normal phase chromatography should be used for determination of tocopherols in these oil and fat samples.

==== Saponification ====

* The sample is homogenised prior to saponification.
* Ethanol or methanol, water, an antioxidant and an aqueous potassium hydroxide are added.
* Saponification includes heat treatment.
** 80-100 °C, 15-40 min

==== Extraction ====

* The ratio of alcohol to water should be 1:1 before extraction to avoid emulsions.
* Extraction is carried out using suitable solvent.
** Recovery should be checked to exclude the possibility of losses.
* The extract is washed with water.
* Solvent is evaporated and sample is redissolved using e.g. mobile phase.

==== HPLC ====

* Liquid chromatographic system consisting of a pump, an injector, a fluorescence detector (excitation wavelength 295 nm and emission wavelength 330 nm) and data evaluation system.
** Also UV detector (292 nm) may be used.
* Normal phase column: particle size 5 µm (silica phase), diameter e.g. 4,0-4,6 mm, length 100-250 mm.
* Mobile phase: e.g. 3 % 1,4-dioxane in n-hexane.
* Also other chromatographic systems can be used if equivalent results are guaranteed.
** Reverse phase columns can be used to quantify ?- and ?-tocopherols, but ?- and ?-tocopherols cannot be separated.
* The performance criteria is the baseline separation of the analytes from interferences.

==== Identification and detection ====

* Tocopherols are detected fluorometrically (excitation wavelength 295 nm and emission wavelength 330 nm) or using UV detector (292 nm).
* Identification of tocopherols is done by the comparison of the retention time obtained with the standard test solution to that of the sample test solution.
** Identification can also be done by adding a small amount of the appropriate standard solution to the sample test solution.

==== Quantification and calculations ====

* External standard method is used for quantification.
** Peak areas or peak heights of the samples are compared to the corresponding values for the standard substances.
* The linearity of the calibration must be checked.
* The mass fraction of ?-, ?-, ?- or ?-tocopherol is calculated and result is reported as mg/100 g of the sample.
* For calculation of vitamin E content, biological activities must be taken into account.

 

-----

=== Remarks ===

* The purity of standard substances can vary, thus it is necessary to check the concentration of calibration solution spectrometrically.
* Unnecessary exposure to light must be avoided during analysis.
* Alternative HPLC conditions are described in the Standard.
* Oldet methods
** colorimetric
*** gives a total tocopherol content
*** forming complexes unstable
** GLC

=== Criteria for analytical performance and analytical quality control ===

* Greenfield and Southgate discuss the criteria for analytical performance and quality of analytical data in their book.
** [ftp://ftp.fao.org/docrep/fao/008/y4705e/y4705e00.pdf Greenfield H, Southgate DAT. 2003. Food composition data ? production, management and use. Elsevier Applied Science, London, UK.]

* [https://metrofood-wiki.foodcase-services.com/index.php?title=Precision+data+-+vitamin+E link to precision data]

=== Certified Reference Materials/Standard Reference Material ===

* [https://metrofood-wiki.foodcase-services.com/index.php?title=Reference+materials+-+vitamin+E link to detailed data]

=== Proficiency testing schemes ===

Here are listed some completed, on-going and/or upcoming proficiency testing schemes concerning vitamin E:

[http://otis.jtlnet.com/%7Eproficie/proficiencytesting.com.au/documents/651.pdf PTA - Proficiency Testing Australia: Report No. 651, Food Proficiency Testing Program, Round 31 - Vitamins]

[http://www.dla-lvu.de/english/DLA%20Programm%202012%20english.html DLA - Dienstleistung Lebensmittel Analytik GbR: 32/2012 Food Supplement I: Vitamins A, D3, E, K1 and beta-Carotin]

[http://www.dgfett.de/lvu/ DGF - Deutsche Gesellschaft für Fettwissenschaft]

Some upcoming proficiency testing schemes can be found in the [http://www.eptis.bam.de/en/index.htm EPTIS database].

=== Other methods available ===

* [http://methods.aaccnet.org/summaries/86-06-01.aspx AACC 86-06.01] Analysis of Vitamins A and E by High-Performance Liquid Chromatography
* AOAC 948.26 ?-Tocopheryl acetate (supplemental) in foods and feeds
** colorimetric
* [http://www.aoac.org/omarev1/971_30.pdf AOAC 971.30]?-Tocopherol and ?-tocopheryl acetate in foods and feeds
** colorimetric
* [http://www.aoac.org/omarev1/975_43.pdf AOAC 975.43]Identification of RRR- or all-rac-alpha-tocopherol in drugs and food or feed supplements
** polarimetric
* AOAC 988.14 Tocopherol isomers in mixed tocopherols concentrate (FCC, USP, AOAC method)
** gas chromatographic
* [http://www.aoac.org/omarev1/989_09.pdf AOAC 989.09]?-Tocopheryl acetate in supplemental vitamin E concentrates
** gas chromatographic
* AOAC 992.03 Vitamin E activity (all-rac-?-tocopherol) in milk-based infant formula
** liquid chromatographic

=== Literature ===

* see separate child page below

== EuroFIR assistance to this method/guidelines ==

-----

@@ Line 2: / Line 2: @@
 <br /> Figure 1. Structures of tocopherols.
-?-tocopherol: C<sub>29</sub>H<sub>50</sub>O<sub>2</sub>, Mw = 430,71 g/mol.
+α-tocopherol: C<sub>29</sub>H<sub>50</sub>O<sub>2</sub>, Mw = 430,71 g/mol.
 The group vitamin E includes eight compounds that have similar biological activity as ?-tocopherol. These compounds are ?-, ?-, ?- and ?-tocopherols and the corresponding tocotrienols. The measurement of vitamin E is carried out by determination of tocopherols, and vitamin E activity can be calculated taking the activity of each tocopherol into account.

← Older revision		Revision as of 07:53, 21 November 2017
Line 1:		Line 1:
		+	[[File:tocopherols.jpg]]
	<br /> Figure 1. Structures of tocopherols.		<br /> Figure 1. Structures of tocopherols.

← Older revision	Revision as of 13:33, 9 May 2019
(No difference)

← Older revision	Revision as of 12:35, 8 January 2018
(No difference)

@@ Line 105: / Line 105: @@
 * Greenfield and Southgate discuss the criteria for analytical performance and quality of analytical data in their book.
-** [ftp://ftp.fao.org/docrep/fao/008/y4705e/y4705e00.pdf Greenfield H, Southgate DAT. 2003. Food composition data ? production, management and use. Elsevier Applied Science, London, UK.]
+** [ftp://ftp.fao.org/docrep/fao/008/y4705e/y4705e00.pdf Greenfield H, Southgate DAT. 2003. Food composition data - production, management and use. Elsevier Applied Science, London, UK.]
 * [https://metrofood-wiki.foodcase-services.com/index.php?title=Precision+data+-+vitamin+E link to precision data]
@@ Line 128: / Line 128: @@
 * [http://methods.aaccnet.org/summaries/86-06-01.aspx AACC 86-06.01] Analysis of Vitamins A and E by High-Performance Liquid Chromatography
-* AOAC 948.26 ?-Tocopheryl acetate (supplemental) in foods and feeds
+* AOAC 948.26 α-Tocopheryl acetate (supplemental) in foods and feeds
 ** colorimetric
-* [http://www.aoac.org/omarev1/971_30.pdf AOAC 971.30]?-Tocopherol and ?-tocopheryl acetate in foods and feeds
+* [http://www.aoac.org/omarev1/971_30.pdf AOAC 971.30]α-Tocopherol and α-tocopheryl acetate in foods and feeds
 ** colorimetric
 * [http://www.aoac.org/omarev1/975_43.pdf AOAC 975.43]Identification of RRR- or all-rac-alpha-tocopherol in drugs and food or feed supplements
@@ Line 136: / Line 136: @@
 * AOAC 988.14 Tocopherol isomers in mixed tocopherols concentrate (FCC, USP, AOAC method)
 ** gas chromatographic
-* [http://www.aoac.org/omarev1/989_09.pdf AOAC 989.09]?-Tocopheryl acetate in supplemental vitamin E concentrates
+* [http://www.aoac.org/omarev1/989_09.pdf AOAC 989.09]α-Tocopheryl acetate in supplemental vitamin E concentrates
 ** gas chromatographic
-* AOAC 992.03 Vitamin E activity (all-rac-?-tocopherol) in milk-based infant formula
+* AOAC 992.03 Vitamin E activity (all-rac-α-tocopherol) in milk-based infant formula
 ** liquid chromatographic

@@ Line 4: / Line 4: @@
 α-tocopherol: C<sub>29</sub>H<sub>50</sub>O<sub>2</sub>, Mw = 430,71 g/mol.
-The group vitamin E includes eight compounds that have similar biological activity as ?-tocopherol. These compounds are ?-, ?-, ?- and ?-tocopherols and the corresponding tocotrienols. The measurement of vitamin E is carried out by determination of tocopherols, and vitamin E activity can be calculated taking the activity of each tocopherol into account.
+The group vitamin E includes eight compounds that have similar biological activity as α-tocopherol. These compounds are α-, β-, γ- and δ-tocopherols and the corresponding tocotrienols. The measurement of vitamin E is carried out by determination of tocopherols, and vitamin E activity can be calculated taking the activity of each tocopherol into account.
 Note:
-USDA Food Composition Database for Standard Reference, Release 25 defines vitamin E as ?-tocopherol only ) . This definition has been adopted by many European food databases.
+USDA Food Composition Database for Standard Reference, Release 25 defines vitamin E as α-tocopherol only ) . This definition has been adopted by many European food databases.
 Synonyms for vitamin E:
@@ Line 21: / Line 21: @@
 === Golden standard ===
-* [http://www.cen.eu/cen/Sectors/TechnicalCommitteesWorkshops/CENTechnicalCommittees/Pages/Standards.aspx?param=6256&title=CEN/TC%20275 EN 12822:2000]Foodstuffs - Determination of vitamin E by high performance liquid chromatography - Measurement of ?-, ?-, ?- and ?-tocopherols.
+* [http://www.cen.eu/cen/Sectors/TechnicalCommitteesWorkshops/CENTechnicalCommittees/Pages/Standards.aspx?param=6256&title=CEN/TC%20275 EN 12822:2000]Foodstuffs - Determination of vitamin E by high performance liquid chromatography - Measurement of α-, β-, γ- and δ-tocopherols.
 ** draft prEN 12822:2012
@@ Line 31: / Line 31: @@
 === Scope ===
-The European Standard EN 12822 describes a method for the determination of vitamin E in foodstuffs by high performance liquid chromatography (HPLC). Vitamin E content is determined by measurement of ?-, ?-, ?- and ?-tocopherols.
+The European Standard EN 12822 describes a method for the determination of vitamin E in foodstuffs by high performance liquid chromatography (HPLC). Vitamin E content is determined by measurement of α-, β-, γ- and δ-tocopherols.
 === Principle ===
-Sample treatments usually include saponification and extraction. ?-, ?-, ?- and ?-tocopherols are determined by HPLC using fluorometric detection. Also photometric detection (UV-range) can be used but fluorometric detection is preferred.
+Sample treatments usually include saponification and extraction.  α-, β-, γ- and δ-tocopherols are determined by HPLC using fluorometric detection. Also photometric detection (UV-range) can be used but fluorometric detection is preferred.
 === Key steps ===
@@ Line 69: / Line 69: @@
 * Mobile phase: e.g. 3 % 1,4-dioxane in n-hexane.
 * Also other chromatographic systems can be used if equivalent results are guaranteed.
-** Reverse phase columns can be used to quantify ?- and ?-tocopherols, but ?- and ?-tocopherols cannot be separated.
+** Reverse phase columns can be used to quantify α- and δ-tocopherols, but β- and γ-tocopherols cannot be separated.
 * The performance criteria is the baseline separation of the analytes from interferences.
@@ Line 83: / Line 83: @@
 ** Peak areas or peak heights of the samples are compared to the corresponding values for the standard substances.
 * The linearity of the calibration must be checked.
-* The mass fraction of ?-, ?-, ?- or ?-tocopherol is calculated and result is reported as mg/100 g of the sample.
+* The mass fraction of α-, β-, γ- or δ-tocopherol is calculated and result is reported as mg/100 g of the sample.
 * For calculation of vitamin E content, biological activities must be taken into account.