BROWN FK-棕色FK

BROWN FK Prepared at the 30th JECFA (1986), published in FNP 37 (1986) and in FNP 52 (1992). Metals and arsenic specifications revised at the 59th JECFA (2002). No ADI was allocated at the 30th (JECFA 1986) SYNONYMS CI Food Brown 1; INS No. 154 DEFINITION A mixture of six mono-, bis- and trisazo colours (see ‘Chemical names’ below) and subsidiary colouring matters together with water, sodium chloride and/or sodium sulfate as the principal uncoloured components. This product as manufactured, and to which these specifications apply, is often diluted with sodium chloride to a total colouring matters content of about 50% to meet the needs of users. Chemical names A mixture of I Sodium 4-(2,4-diaminophenylazo) benzenesulfonate II Sodium 4-(4,6-diamino-m-tolylazo) benzenesulfonate III Disodium 4,4'-(4,6-diamino-1,3-phenylenebisazo)- di(benzenesulfonate) IV Disodium 4,4'-(2,4-diamino-1,3-phenylenebisazo)- di(benzenesulfonate) V Disodium 4,4'-(2,4-diamino-5-methyl-1,3-phenylene- bisazo)di(benzene- sulfonate) VI Trisodium 4,4',4''-(2,4-diaminobenzene-1,3,5- trisazo)tri-(benzene- sulfonate) C.A.S. number 8062-14-4 Chemical formula I C12H11N4NaO3S II C13H13N4NaO3S III C18H14N6Na2O6S2 IV C18H14N6Na2O6S2 V C19H16N6Na2O6S2 VI C24H17N8Na3O9S3 Structural formula I II III IV V VI Formula weight I 314.30 II 328.33 III 520.46 IV 520.46 V 534.47 VI 726.59 Assay Not less than 70% total colouring matters. Of the total colouring matters present the proportions of the components shall not exceed: I 26% II 17% III 17% IV 16% V 20% VI 16% DESCRIPTION Red-brown powder or granules FUNCTIONAL USES Colour CHARACTERISTICS IDENTIFICATION Solubility (Vol. 4) Soluble in water; sparingly soluble in ethanol Identification of colouring matters (Vol. 4) Passes test PURITY Loss on drying at 135o (Vol. 4) Not more than 30% together with chloride and sulfate calculated as sodium salts Water insoluble matter (Vol. 4) Not more than 0.2% Lead (Vol. 4) Not more than 2 mg/kg Determine using an atomic absorption technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the method described in Volume 4, “Instrumental Methods.” Subsidiary colouring matters Not more than 3.5% See description under METHOD OF ASSAY Organic compounds other than colouring matters Not more than - 0.7% of 4-aminobenzene-1-sulfonic acid - 0.35% of - m-phenylenediamine and 4-methyl-m-phenylenediamine See description under TESTS Unsulfonated primary aromatic amines (Vol. 4) Not more than 0.007% calculated as aniline (other than m-phenylene diamine and 4-methyl-m-phenylene diamine) Ether extractable matter (Vol. 4) Not more than 0.2% TESTS Organic compounds other Use liquid chromatography (see Volume 4) under the following conditions: than colouring matters Detector: A UV HPLC detector recording absorbances at 254 nm Column: 250 x 4 mm Li Chromosorb RP8, 7 µm Solvent system A: 0.075 M sodium acetate solution adjusted to pH 6.0 using glacial acetic acid. B: A:methanol (2:3) Flow rate: 1 ml/min Gradient: 0 min: 100% (A), 0% (B) 15 min: 0% (A), 100% (B) 20 min: 0% (A), 100% (B) 25 min: 100% (A), 0% (B) METHOD OF ASSAY Determination of the amount of component colouring matters and subsidiary colouring matters. Apparatus - Glass tank capable of holding 20 cm x 20 cm glass TLC plates. - Micrometer syringe capable of delivering 0.10 ml with a tolerance of ± 0.002 ml - Spectrophotometer Reagents: All of recognized analytical grade - Chromatography solvent: A mixture of 4 parts phenol and 1 part water by volume - Diethyl ether - Kieselgel G - Extraction solvent: Mix 100 ml 10% sodium carbonate solution with 500 ml methanol and dilute to 1 L with water Procedure Prepare a 20 x 20 cm TLC plate with a 0.5 mm thick coating of Kieselgel G. Using the micrometer syringe apply a solution containing 0.4 mg Brown FK as evenly as possible in an area near the bottom of the plate. Develop the chromatogram in the phenol/water mixture allowing the solvent to ascend the full height of the plate; then remove it from the tank and allow it to dry. The diagram shows a typical Brown FK chromatogram with the bands numerically identified. Remove each band from the plate and transfer it to a small beaker. The subsidiary colouring matters are located in the area between bands I and V. Remove this area of Kieselgel G. Transfer it to a beaker and wash it with a small quantity of ether to remove the phenol. Allow the residual ether to evaporate. Add 10 ml of extraction solvent to each beaker and swirl to extract the colour. Filter through a small filter paper and measure the absorbance versus extraction solvent in 10 mm cells at the wavelength of maximum absorption. Calculate the concentration of each component colouring matter and of the subsidiary colouring matters using the absorptivity figures given in the table below. Component Wavelength(nm) Absorptivity I 453 55.1 II 464 59.6 III 355 88.2 IV 412 70.5 V 448 60.3 VI 410 59.7 Subsidiary Colouring Matters 425 74.2 Calculation of (i) Total colouring matters content (ii) Percentages of component colours (iii) Percentage of subsidiary colours Note: Component colours are expressed as percentages of the total colouring matters present, i.e. as percentages of the sum of component colours and subsidiary colours. Subsidiary colours are expressed for the purposes of the specification limit as a percentage of the sample. Let the absorptivities of the component colours be a1, a2....a6. and the absorbances of the extracts of the component colours be A1, A2...... A6. Let the Absorptivity of the subsidiary colours be a7 and the absorbance of the extract of the subsidiary colours be A7. The weight (in mg) of component colour I in the 10 ml extract is calculated from the expression: In a similar manner calculate the weights (W2, W3.......W7) of the remaining component colours and the subsidiary colours. (i) Total colouring matters content (%) = (ii) The percentage of component colour 1 = In a similar manner calculate the percentages of the other component colours. (iii) The percentage of subsidiary colours = BROWN FK SYNONYMS DEFINITION Chemical names C.A.S. number Chemical formula Structural formula Formula weight Assay DESCRIPTION FUNCTIONAL USES CHARACTERISTICS IDENTIFICATION Solubility (Vol. 4) Identification of colouring matters (Vol. 4) PURITY Loss on drying at 135o (Vol. 4) Water insoluble matter (Vol. 4) Lead (Vol. 4) Subsidiary colouring matters Organic compounds other than colouring matters Unsulfonated primary aromatic amines (Vol. 4) Ether extractable matter (Vol. 4) TESTS Organic compounds other than colouring matters METHOD OF ASSAY Apparatus Reagents: Procedure