Assignment:
A gun shot residue containing barium and lead is analysed using atomic absorption. Residue from sample collected in Glasgow and Inverurie are also available
Glasgow gun shot residue (n-20) Ba (o.12+/-0,005%), Pb (5.2+/-2.0%)
Inverurir (n=5) Ba (0.22+/-0,001%), Pb (7.2+/- 1.0%)
(a) Describe the necessary parts of an atomic absorption spetrometer.
(b) Analysis of the unknown residue yields the following data.
Ba+2 [mg/L] Absorbance Pb [mg/L] Absorbance
0.0 0.000 0.0 0.00
0.1 0.101 2.0 0.10
0.2 0.216 4.0 0.21
0.3 0.308 6.0 0.29
0.4 0.392 8.0 0.40
0.5 0.474 10 0.49
The residue was measured 3 times and gave absorbances and standard deviations of 0.4+/-0.1 for Ba and 0.25+/- 0.05 for Pb
What were the concentrations of both elements in the residue if 10mg were dissolved in 100mL solution?
(c) Which statistical test is needed to identify the precision and which one identifies the differences in the mean?
Provide complete and step by step solution for the question and show calculations and use formulas.