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The measurement of Li in brine (salt water) is used by geochemists to help determine the
Chapter 20, Problem 20-D(choose chapter or problem)
The measurement of Li in brine (salt water) is used by geochemists to help determine the origin of this fluid in oil fields. Flame atomic emission and absorption of Li are subject to interference by scattering, ionization, and overlapping spectral emission from other elements. Atomic absorption analysis of replicate samples of a marine sediment gave results in the table. Sample and Li found Analytical Flame treatment (g/g) method type 1. None 25.1 standard curve air/C2H2 2. Dilute to 1/10 with H2O 64.8 standard curve air/C2H2 3. Dilute to 1/10 with H2O 82.5 standard addition air/C2H2 4. None 77.3 standard curve N2O/C2H2 5. Dilute to 1/10 with H2O 79.6 standard curve N2O/C2H2 6. Dilute to 1/10 with H2O 80.4 standard addition N2O/C2H2 SOURCE: B. Baraj, L. F. H. Niencheski, R. D. Trapaga, R. G. Frana, V. Cocoli, and D. Robinson, Interference in the Flame Atomic Absorption Determination of Li, Fresenius J. Anal. Chem. 1999, 364, 678. (a) Suggest a reason for the increasing apparent concentration of Li in samples 1 through 3. (b) Why do samples 4 through 6 give an almost constant result? (c) What value would you recommend for reporting the real concentration of Li in the sample?
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QUESTION:
The measurement of Li in brine (salt water) is used by geochemists to help determine the origin of this fluid in oil fields. Flame atomic emission and absorption of Li are subject to interference by scattering, ionization, and overlapping spectral emission from other elements. Atomic absorption analysis of replicate samples of a marine sediment gave results in the table. Sample and Li found Analytical Flame treatment (g/g) method type 1. None 25.1 standard curve air/C2H2 2. Dilute to 1/10 with H2O 64.8 standard curve air/C2H2 3. Dilute to 1/10 with H2O 82.5 standard addition air/C2H2 4. None 77.3 standard curve N2O/C2H2 5. Dilute to 1/10 with H2O 79.6 standard curve N2O/C2H2 6. Dilute to 1/10 with H2O 80.4 standard addition N2O/C2H2 SOURCE: B. Baraj, L. F. H. Niencheski, R. D. Trapaga, R. G. Frana, V. Cocoli, and D. Robinson, Interference in the Flame Atomic Absorption Determination of Li, Fresenius J. Anal. Chem. 1999, 364, 678. (a) Suggest a reason for the increasing apparent concentration of Li in samples 1 through 3. (b) Why do samples 4 through 6 give an almost constant result? (c) What value would you recommend for reporting the real concentration of Li in the sample?
ANSWER:Step 1 of 4
Sample 1 to 3 air-ethylene flame type is used and in sample 4-6 nitrous acid ethylene flame is used
