LABGUIDE
Determination of lead in paint by atomic absorption
Equipment:
AA spectrophotometer, Dri-block heater, Bottle-top
dispensette, Oven set at 130°C.
Apparatus:
100ml vol. flasks,
boiling tubes, grad pipettes 1,2,5 ml; funnels, funnel racks, filter paper, mortar and pestle,
analytical sieves 90 to 100um.
Sample:
Paint scrapings
(0.20g, for det. of Pb only)
Solutions preparations:
1. 100ppm standards - dilute the 1000ppm 1 in 10.
ie 10mls in 100ml vol. = 100ppm.
Sample preparation:
1. Dry sample in oven at 130°C for 10 to 12 hrs.
2. Cool, grind sample, sift through 100um sieve, and weigh out in
triplicate the req. amt.
3. Predigest sample with 10mls conc. HNO3 overnight.
4. Digest on dri-block heater at 130°C for 1 to 2
5. Filter through Watman filter paper #542 into 100ml vol. flask and make
up to mark with distilled water.
Analytical notes:
1. Make up a mixed standard.
2. Dilution is 1 in 20.
3. Possible range of standards required: Low range stds. and High range
stds.
(1) 0.5, 1.0, 2.0, 4.0, 8.0 ppm.
(2) 0.25, 0.5, 1.0, 1.5, 2.0 ppm.
(3) 0.125, 0.25, 0.50, 1.0, 2.0 ppm.
(4) 2.5, 5.0, 10, 20, 30, 40 ppm.
(5) 5, 10, 20, 40, 60 ppm.
Operation of Instrument:
Follow user
guide or get help from Technician or demonstrator.
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