The determination of vitamins in Food Supplements

Transcription

1 The determination of vitamins in Food Supplements

2 Food Supplements Directive Food Supplements are defined by : EC Directive 2002/46/EC (as amended) on the approximation of the laws of the Member States relating to Food Supplements and The Food Supplements Regulations 2003

3 Food Supplements Directive For the purposes of this Directive: (a) "food supplements" means foodstuffs the purpose of which is to supplement the normal diet and which are concentrated sources of nutrients or other substances with a nutritional or physiological effect, alone or in combination, marketed in dose form, namely forms such as capsules, pastilles, tablets, pills and other similar forms, sachets of powder, ampoules of liquids, drop dispensing bottles, and other similar forms of liquids and powders designed to be taken in measured small unit quantities; (b) "nutrients" means the following substances: (i) vitamins, (ii) minerals.

4 Which vitamins are allowed? VITAMIN B - thiamin hydrochloride, thiamin mononitrate VITAMIN B2 - riboflavin, riboflavin 5'-phosphate, sodium NIACIN - nicotinic acid, nicotinamide PANTOTHENIC ACID - D-pantothenate, calcium, D-pantothenate, sodium, dexpanthenol (D+ Panthenol) VITAMIN B6 - pyridoxine hydrochloride, pyridoxine 5'- phosphate FOLIC ACID - pteroylmonoglutamic acid NOTE: EC Directive (but NOT UK regulation) amended to FOLATE and adds calcium-l-methylfolate VITAMIN B2 - cyanocobalamin, hydroxocobalamin BIOTIN -D-biotin VITAMIN C - L-ascorbic acid, sodium-l-ascorbate, calcium-lascorbate, potassium-l-ascorbate, L-ascorbyl 6-palmitate

5 Which vitamins are allowed? Shedule of the Directive contains a positive list of vitamins which may be used & prescribes the units in which they should be expressed. Shedule 2 prescribes the forms of vitamins which may be used. VITAMIN A - Retinol, Retinyl acetate,retinyl Palmitate, Beta-carotene µg RE VITAMIN D Cholecalciferol, Ergocalciferol µg VITAMIN E - D-alpha-tocopherol, DL-alpha-tocopherol, D-alpha-tocopheryl mg ATE acetate, DL-alpha-tocopheryl acetate, D-alpha-tocopheryl acid succinate VITAMIN K - Phylloquinone (phytomenadione) µg

6 Vitamin E Eight isomers exist: α, β, γ, δ Tocopherols and α, β, γ, δ Tocotrienols Eight stereoisomers exist for the tocopherols Synthetic forms: All-racemic α Tocopherol (dl α Tocopherol) Natural form: RRR -α-tocopherol (d-α Tocopherol) Semi-synthetic: RRR-α-tocopherol formed by hydrolysis & methylation of natural tocopherol esters

7 Biological activity Biological activity of Tocopherol isomers Relative Activity: α 00%, β 40-50%, γ 0%, δ -3% Tocotrienols : α 20-30%, β 4-5%, γ & δ <% Biological activity of alpha tocopherol:(iu)/mg Natural RRR (d) - a -Tocopherol.49 RRR (d) - a -Tocopherol acetate.36 Synthetic All racemic (dl) -a-tocopherol acetate.00 All racemic (dl) - a Tocopherol.0 Activity is dependant on the assay/pharmacological attribute tested. In human serum/plasma Natural tocopherol activity is 2 x synthetic tocopherol

8 Activity Nomenclature International Units (IU) Activity of Vitamin E based on the rat fetal absorption test IU = mg of all-racemic alpha tocopherol acetate. AlphaTocopherol equivalent α-te or ATE National Research Council definition of Vitamin E in terms of naturally occuring alpha tocopherol. ATE = mg of RRR alpha tocopherol The Food Supplements directive requires ATE to be used.

9 Biological activity Vitamer mg IU/mg ATE/mg ATE mg IU mg RRR α Tocopherol RRR α Tocopherol acetate RRR α tocopherol succinate All rac α Tocopherol All rac α Tocopherol acetate All rac α tocopherol succinate

10 Vitamin A activity Quantity of Source Material µgall-trans-retinol ( µg RAE) (synonym: vitamin A) µgof all-trans-retinyl acetate (synonym: vitamin A acetate) µgall-trans-retinyl palmitate (synonym: vitamin A palmitate) µgsupplemental all-trans-beta-carotene (synonym: beta-carotene) i.e. as an isolate µgdietary all-trans-beta-carotene (synonym: beta-carotene) i.e. in plant (e.g. carrot powder), algal, or bacterial matrices µgsupplemental all-trans-alpha-carotene or all-trans-beta-cryptaxanthin (synonyms: alphacarotene and beta-cryptaxanthin) i.e. as isolates µgdietary all-trans-alpha-carotene or all-trans-beta-cryptaxanthin (synonyms: alpha-carotene and beta-cryptaxanthin) i.ein citrus fruit powder) Vitamin A Activity (in International Units) 3.33 IU 2.9 IU.82 IU.67 IU 0.28 IU 0.83 IU 0.4 IU Retinol Activity Equivalent ( µg RAE): = µg all-trans-retinol = 2 µg supplemental all-trans-beta-carotene = 2 µg dietary all-trans-beta-carotene = 24 µg dietary all-trans-alpha-carotene or all-trans-beta-cryptaxanthin

11 Types of food supplements Tablets Swallowable Coated Uncoated Chewable Effervescent Capsules Hard-gel Soft-gel Oil fillled Paste filled Gelatin Non-gelatin Liquids Oils Syrups Emulsions

12 Analytical problems Physical formulation coatings, gels, oil, granulation Chemical formulation Effect of excipients and additives, other vitamins, minerals. Potential for absorption onto capsule shell. Stability, lability Calculation errors, expression errors Overages Different extraction methods Different analytical methods Tolerances

13 Source of methods. USP/ BP methods 2. CEN/ISO - Mainly food methods at present. Supplements added to remit of CEN Vitamins working group. 3. Published literature 4. Industry methods

14 Choice of method. Before analysis: Single or multiple vitamin? What are the supplement ingredients? What is the target vitamin concentration? What form of vitamin is present? Is the form of vitamin important? How is result to be reported? (w/w, per tablet, wt/vol) Is it likely that overages have been used? How old is the sample? Should whole capsules or fill only be examined? What sample weight is required? Should tablets be ground?

15 Extraction Are all vitamins stable under the extraction conditions? Are minerals present? Is fill lipid or water soluble? Are the target analytes oil or water soluble Matrix interactions

16 Analysis Vitamin Forms Individual vitamers or total content Isomers Stability Detection method Recovery, Uncertainty etc

17 FSA study of Methods for the determination of food supplements To provide guidance in the selection of methods for the determination of food supplements To validate a method for the determination of b-group vitamins in Food Supplements To validate a method for the determination of oil-soluble vitamins in Food Supplements.

18 B,B2, Niacin, B6 & Ca Pantothenate Extraction: Whole capsules and whole/ground tablets Citric acid containing EDTA and Tween C for 0mins Ultrasonicate for 20mins

19 Analytical Method HPLC Lichrocart, Superspher 60RP (Merck) Gradient elution A: Phosphate buffer,containing Sodium heptane sulfonate, ph 3. B: Acetonitrile/Phosphate buffer (60/40) UV-Diode Array Detection B, B2, B3, B2-260 nm B6-290 nm 275 nm for all? Ca Pantothenate nm

20 Water Soluble vitamins Chromatogram of B vitamins Luna C8(2) Modified H2O/MeoH gradient Diode Array detection

21 Chromatogram of a multivitamin Tablet

22 Collaborative Trial Five test materials as blind duplicates. Tablets and soft-gel capsules with & without minerals Range of concentrations Target Analytes : Thiamine, Riboflavin, Niacinamide, B6, Ca Pantothenate. 6 laboratories Mainly PA labs HPLC conditions recommended but not mandatory

23 Bias Comparison of study means with claim/input values Thiamin Riboflavin mg/tablet A B C D E mg/tablet A B C D E Sample Sample Study mean Claim Input Study mean Claim Input Niacin Vitamin B6 mg/tablet mg/tablet A B C D E A B C D E Sample Sample Study mean Claim Input Study mean Claim Input

24 Collaborative trial results Repeatability Horrat Values Sample Thiamin Niacin Vitamin B6 Riboflavin Ca Pantothenate A B Ho r C D E Reproducibility Horrat Values Sample Thiamin Niacin Vitamin B6 Riboflavin Ca Pantothenate A B HO R C D E

25 Other B Vitamins Folic acid Determined by HPLC after neutral/alkaline extraction or Microbiological assay Biotin HPLC at 200nm for premixes after alkaline extraction or Microbiological assay Vitamin B2 HPLC in premixes. Too low in finished products for HPLC. Microbiological assay. Vitamin C Titrimetry (DCIP), Fluorimetry (OPD), HPLC after acid extraction as AA (DTT) & UV 245 or as DHAA (OPD derivatisation)

26 A, D & E in supplements Samples saponified to convert esters to corresponding alcohols. Vitamins extracted using organic solvents A & E quantified directly D requires HPLC clean-up before analytical HPLC.

27 Analysis ZORBAX ODS, 250 x 4.5 mm Flowrate: ml/min Mobile Phase: Acetonitrile / Dichloromethane / Methanol 70/20/0 Detector: Diode Array: Vit D-265nm, Vit A 325nm, Vit E 292nm Prep-LC (D only) Partisil 5 PAC, 250 x 4mm Mobile Phase: Hexane / Propan-2-ol 99/ Detector: UV 265

28 Oil Soluble vitamins Chromatogram Mixed Standard Zorbax ODS MeCN/DCM/MeOH

29 Vitamin A - Retinol Chromatograms for Vitamins A, D & E in Multivitamin & Mineral soft-gel capsule with CLO. Vitamin E α -Tocopherol Vitamin D

30 Collab trial Thirteen participants (Largely PA labs) Six test samples of Tablets and capsules as blind duplicates Range of concentrations Analytes: Vitamin A (ATR) Vitamin E (Alpha tocopherol) Vitamin D

31 Bias Comparison with claimed values Method Performance Characteristic Coated Multivitamin and Mineral Tablet Chewable Multivitamin Tablet with Iron and Calcium Chewable Multivitamin and Mineral Tablet Multivitamin Soft-Gel Capsule with Cod Liver Oil Multivitamin and Mineral Soft-Gel Capsule with Cod Liver Oil Multivitamin Tablet (Sample A) (Sample B) (Sample C) (Sample D) (Sample E) (Sample F) Vitamin A Claim Vitamin D ? 4.6 Claim D2 5.0 Vitamin E Claim

32 Collaborative trial results Vitamin A Method Performance Characteristic Coated Multivitamin and Mineral Tablet Chewable Multivitamin Tablet with Iron and Calcium Chewable Multivitamin and Mineral Tablet Multivitamin Soft-Gel Capsule with Cod Liver Oil Multivitamin and Mineral Soft-Gel Capsule with Cod Liver Oil Multivitamin Tablet (Sample A) (Sample B) (Sample C) (Sample D) (Sample E) (Sample F) n outliers n mean r s r RSD r Ho r R s R RSD R HoR

33 Collaborative trial results Method Performance Characteristic Coated Multivitamin and Mineral Tablet Vitamin D Chewable Multivitamin Tablet with Iron and Calcium Chewable Multivitamin and Mineral Tablet Multivitamin Soft-Gel Capsule with Cod Liver Oil Multivitamin Tablet (Sample A) (Sample B) (Sample C) (Sample D) (Sample F) n 9 0 outliers 2 2 n mean r s r RSD r Ho r R s R RSD R Ho R

34 Collaborative trial results Vitamin E Method Performance Characteristic Coated Multivitamin and Mineral Tablet Chewable Multivitamin Tablet with Iron and Calcium Chewable Multivitamin and Mineral Tablet Multivitamin Soft-Gel Capsule with Cod Liver Oil Multivitamin and Mineral Soft-Gel Capsule with Cod Liver Oil Multivitamin Tablet (Sample A) (Sample B) (Sample C) (Sample D) (Sample E) (Sample F) n outliers n mean r s r RSD r Ho r R s R RSD R Ho R

35 Conclusion Vitamin analysis can be easy but often isn t. Consider all available information Consider output required Staff should be trained and experienced Examine results critically Consultation before formal action?