Procedure for Lead in Paint (16 CFR Part 1303)

Sample Preparation :

For Wet Paint , spread onto a clean glass plate a thin layer and allow to dry inside a conventional oven. When dry , scrape out the paint and cut into small pieces.

For paint coated on product , remove coating from item using a stainless steel razor blade or by using acetone or any suitable solvents.

Digestion & Analysis :

Weigh dried sample into a beaker.

Add conc. HNO3 to the sample.

Place beaker on a hot plate and cover with watch glass.

Heat to evaporate until a small amount is left. ( Make sure sample do not boil and sample is not allowed to go dry or evaporate completely.

Remove from hot plate and allow to cool.

Add 6N Nitric Acid then place beaker again on hot plate.

Continue heating making sure digestion is complete ( this is when sample becomes light in color or it does not change with continued heating.)

Heat to evaporate until about 10 ml of digestate remains.

Remove from hot plate and allow to cool. Wash insides of beaker and watch glass with water.

Filter the digestate using Whatman Filter paper to remove any insoluble material ( Since this could clog the nebulizer )

Transfer filtrate with rinsings to a volumetric flask.

Run the Lead standard solutions in the AAS and measure the linear regression (LR). Atleast 3 different concentrations of the standard must be measured.

Read the Lead content of each sample in the Atomic Absorption Spectrophotometer.

Calculate concentration of Lead in sample using Linear Regression.

Procedure for EN 71 Part 3 : Migration of Certain Elements

Weigh about 100mg of sample in a beaker.

Add Hydrochloric acid solution to the sample and mix. ( Volume of acid used must be 50 times the mass of the sample. Ex. 100mg of sample + 5ml of acid).

Shake for 1 minute at 37oC to make sure complete mixing.

Adjust pH to about 1 – 1.5 using Hydrochloric acid solution added dropwise.

Cover mixture to protect from light.

Place the mixture on a shaker or agitator.

Filter mixture by using a membrane filter ( Ex. whatman filter paper ).

Place filtrate on test tubes ready for AAS reading.

Read absorbances of atleast 3 the standard solutions for each of the 8 elements.

Read also absorbances of samples and blank on a Spectrophotometer at appropriate wavelength using 1 cm cuvette. Note that each of the eight (8) elements require different wavelengths.

Prepare calibration curve from absorbance readings of standard solutions against their corresponding concentrations.

Calculate the soluble Antimony, Arsenic, Barium, Cadmium, Chromium, Lead, Mercury & Selenium contents using Linear regression.

Related Posts :
EN 71 Part 3 ( Testing Procedure )
Lead in Paint (16 CFR CPSC Part 1303)
Lead Content in Water
US EPA 3060A – Hexavalent Chromium Testing Method & Procedure
IEC 62321 – Hexavalent Chromium Testing Method & Procedure