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Experiments Overview

Atomic absorption - Determination of Pb in paints

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Equipment:
AA spectrophotometer, Dri-block heater, Bottle-top dispensette, Oven set at 130°C.

Apparatus:
100ml vol. flasks, boiling tubes, funnels, funnel racks, filter paper, mortar and pestle, 1ml, 2ml, and 5ml grad. pipettes.

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.
6. Diluyion is 1 : 50.

Analytical notes:

1. Make up a mixed standard.
2. 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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