CHEM 140A Study Guide - Final Guide: High-Performance Liquid Chromatography, Iodate, Gas Chromatography

4 standards of toluene were analyzed using gas chromatography, the areas measured for each concentration are in the table below. Then the three samples A, B, and C of unknown concentration of toluene were analyzed and measured areas were 80, 120 and 160, respectively. What is the concentration of toluene in those samples? A mixture containing 12.8 mu M analyze (X) and 44.4 mu M of internal standard (IS) gave a chromatographic peak area of 306 for X and 511 for IS. A second solution containing an unknown quantity of X plus 55.5 mu M of IS had peak areas of 251 for X and 563 for IS. Find the concentration of X in the second solution. The following values were found for the palladium standard when an instrumental assay was employed. The instrument reading for a sample with unknown Pd was 56.0 units. Plot calibration curve and find the concentration of the sample.

Chloroform is an internal standard in the determination of the pesticide DDT in a polarographic analysis in which each compound is reduced at an electrode surface. A mixture containing 0.350 mM chloroform and 0.650 mM DDT gave signals of 12.5 mu A for chloroform and 9.64 mu A for DDT. An unknown solution (10.0 mL) containing DDT was placed in a 100-mL Volumetric flask and 9 55 mu L of chloroform (FM 119.39, density = 484 g/mL) were added. After dilution to the mark with solvent, polarographic signals of 19.8 mu A and 5.3 mu A were observed for the chloroform and DDT, respectively. Find the concentration of DDT (mM) in the unknown. Report the final answer to 3 significant figures.