Analytical Chem istry - DePauw University

660 Analytical Chemistry 2.01.04 1.77 10 72.24 3.88 10 73.15 5.61 10 79.25 1.64 10 8What is the %w/w Pb in a sample of brass that gives an emission intensityof 9.25 10 4 ?The analysis for Ni uses an internal standard. Results for a typical calibrationare show in the following table.% w/w Ni emission intensity ratio0.000 0.002670.0140 0.001540.0330 0.003120.130 0.1200.280 0.2460.280 0.2470.560 0.5331.30 1.204.82 4.44What is the %w/w Ni in a sample for which the ratio of emission intensityis 1.10 10 –3 ?39. Yan and colleagues developed a method for the analysis of iron basedits formation of a fluorescent metal–ligand complex with the ligand5-(4-methylphenylazo)-8-aminoquinoline. 33 In the presence of the surfactantcetyltrimethyl ammonium bromide the analysis is carried outusing an excitation wavelength of 316 nm with emission monitored at528 nm. Standardization with external standards gives the followingcalibration curve.I f=− 003 . + 1.594×mg FeL3+A 0.5113-g sample of dry dog food was ashed to remove organic materials,and the residue dissolved in a small amount of HCl and diluted tovolume in a 50-mL volumetric flask. Analysis of the resulting solutiongave a fluorescent emission intensity of 5.72. Determine the mg Fe/Lin the sample of dog food.40. A solution of 5.00 10 –5 M 1,3-dihydroxynaphthelene in 2 M NaOHhas a fluorescence intensity of 4.85 at a wavelength of 459 nm. What33 Yan, G.; Shi, G.; Liu, Y. Anal. Chim. Acta 1992, 264, 121–124.