Question

Cobalt was used as an internal standard to analyze a sample of titanium with atomic absorption spectroscopy. A mixture was prepared by combining a 4.00 mL Ti solution of unknown concentration with 3.50 mL of a 12.3 μg/mL solution of Co. The atomic absorbances were measured as 0.103 and 0.212 for Ti and Co, respectively. As a reference, a standard mixture containing 2.20 μg Co/mL and 2.48 μg Ti/mL was prepared and measured to have a signal-to-signal ratio of 1.79 Ti: 1.00 Co. Determine the concentration (moles/L) of titanium in the original unknown solution.