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Testing facility for determination of free in-can formaldehyde according to VdL-Guideline 03

Posted Date:2025/11/18

5.Equipment and test facilities

5.1.Acetyl acetone method

(Determination of free in-can formaldehyde)

–Precision balance, resolution of at least 0.001 g

–Spectrophotometer, suitable for a wavelength of 412 nm

–Centrifuge, e.g. Suprafuge 22 model from Heraeus

–Polycarbonate centrifuge tubes with screw cap

–Centrisart® tubes, Sartorius brand, or similar product (as required)

–Graduated cylinder, 25 ml, with ground joint

–Suitable pipettes

–Suitable cuvettes

–Suitable volumetric flasks for calibration

–Single-use filters, e.g. 0.2 µm (as required)

–Single-use syringes

–Acetyl acetone reagent for a volume of 500 ml aqueous solution:

–75 g ammonium acetate p.a.

–1 ml acetylacetone (2,4-pentandione) p.a.

–1.5 ml acetic acid 100% p.a.

–Fill up to 500 ml with deionised water

–Deionised water

–Iodine solution, c(l₂) = 0.05 mol/l (equivalent to 12.69 g I₂/l)

–Sodium hydroxide solution, c(NaOH) = 1 mol/l (equivalent to 40.00 g NaOH/l)

–Hydrochloric acid, c(HCl) = 1 mol/l (equivalent to 36.46 g HCl/l)

–Starch solution, 1% soluble, acc. to Zulkowsky

–Sodium thiosulphate solution, c(Na₂S₂O₃) = 0.1 mol/l (equivalent to 15.81 g Na₂S₂O₃/l)

Note 1:

The acetyl acetone reagent is not stable. If kept at room temperature, it may be used for testing for no longer than 14 days.

Note 2:

Deionised water is susceptible to microbial contamination. Either use deionised water with a low level of microbial contamination (<100 CFU) or perform a test to confirm that potential microbial contamination of the deionised water shall not influence the measurement results. As a preservative, formaldehyde is potentially able to react with microbes.