🎨 Synthetic Food Dyes (HPLC)

Food Chemistry NMKL 130

Overview

STATUS (as of 06.11.2026). Until now this method cited the standard PN-EN 12878 — a standard on pigments for colouring building materials based on cement or lime, not a method for testing food. In the accreditation scopes of laboratories in Poland the determination of colours in food by HPLC does not cite any standard — laboratories perform it according to their own test procedures (techniques: HPLC with a diode-array detector, LC-MS/MS). The description is based on the NMKL 130 method “Colours, synthetic, water-soluble. Liquid chromatographic determination in foods” (Nordic Committee on Food Analysis, 1989; publisher’s summary — the full text is not free) and on EU regulations.

SCOPE (NMKL 130). Qualitative and quantitative determination of water-soluble synthetic colours in most types of food, at concentrations higher than 5 mg/l. In the collaborative study results for a fatty food (fish roe) were unsatisfactory for all colours, so applicability to high-fat foods is uncertain. A positive result must be confirmed by another method, e.g. thin-layer chromatography (NMKL 114).

PRINCIPLE (NMKL 130). Solid samples are dissolved in hot water or the colours are extracted with a methanol-ammonia mixture; fatty samples are defatted with petroleum ether, and some require prior breakdown of the matrix with papain. Extracts are purified on polyamide, liquid samples also on a sample preparation cartridge. The colours are separated on a reversed-phase C18 column with an eluent containing an ion-pairing reagent and determined at 480 and 546 nm; all colours except quinoline yellow are determined in one run, quinoline yellow is detected e.g. at 416 nm.

REGULATIONS. Regulation (EC) No 1333/2008 on food additives determines which colours may be used, in which foods and in what amounts (Union list, Annex II). Article 24 and Annex V: food containing sunset yellow (E 110), quinoline yellow (E 104), azorubine/carmoisine (E 122), allura red (E 129), tartrazine (E 102) or ponceau 4R (E 124) bears the additional information “name or E number of the colour(s): may have an adverse effect on activity and attention in children” — except colours used for health marking and other marking of meat products and for decorative colouring or stamping of eggshells.

WHAT WE DO NOT GIVE HERE. The eluent composition, gradient, column dimensions, volumes and masses in sample preparation or precision data — they are in the full text of NMKL 130, which we do not have. We do not give limits of detection or quantification — they depend on the laboratory procedure and the matrix. Fat-soluble dyes (e.g. Sudan dyes, not permitted in food) require a different method and are not covered by this description. We do not copy the maximum permitted levels of individual colours in food categories — they are in Annex II of Regulation (EC) No 1333/2008 as amended.

Method principle

Water-soluble colours are brought into solution (hot water or extraction with a methanol-ammonia mixture), purified on polyamide and separated by HPLC on a reversed-phase C18 column with an eluent containing an ion-pairing reagent. Detection in the visible range (480 and 546 nm, quinoline yellow for example 416 nm) and comparison with standards allow the colours to be identified and determined; a positive result is confirmed by a second method, for example thin-layer chromatography.

Applications

• Checking that food contains only colours permitted in the given category and in permitted amounts (Regulation (EC) No 1333/2008, Annex II)
• Verification of the labelling of food with the colours E 110, E 104, E 122, E 129, E 102 and E 124 — additional information on the effect on activity and attention in children (Article 24 and Annex V)
• Beverages, confectionery and other food with water-soluble colours, at concentrations higher than 5 mg/l (NMKL 130)

Key parameters

Standard

Standard number

NMKL 130:1989

Title (PL)

Barwniki syntetyczne rozpuszczalne w wodzie — oznaczanie w żywności metodą chromatografii cieczowej (tłumaczenie robocze)

Title (EN)

Colours, synthetic, water-soluble — Liquid chromatographic determination in foods

Step-by-step procedure

1. Sample preparation

   Solid samples: dissolution in hot water or extraction with a methanol-ammonia mixture; fatty samples — defatting with petroleum ether; where needed — breakdown of the matrix with papain.

2. Clean-up

   The extract is purified on polyamide; liquid samples may be cleaned up on a sample preparation cartridge.

3. Chromatographic separation

   HPLC on a reversed-phase C18 column, eluent with an ion-pairing reagent.

4. Detection and identification

   Measurement at 480 and 546 nm; quinoline yellow in a separate run (e.g. 416 nm); identification by comparison with standards.

5. Quantitative determination

   From calibration with colour standards; the method is applicable at concentrations higher than 5 mg/l.

6. Confirmation

   Each positive result is confirmed by another method, e.g. thin-layer chromatography (NMKL 114).

7. Assessment

   Comparison with the conditions of use of colours in Annex II to Regulation (EC) No 1333/2008 and check of the information of Annex V on the label.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Methanol, petroleum ether and ammonia — according to the safety data sheets (flammable, toxic or corrosive substances)

Frequently asked questions