A sample of gasoline was run through the GC yielding several peaks indicating the components that made up the gasoline mixture. Uncertain of the amount of benzene in the gas, a pair of students taking instrumental analysis does an experiment using internal standards. Their results are as follows:
Standard solution of 10ppm of benzene and 10ppm toluene yield relative signals(Curve areas) of 1350:960.
They then add 5 ml of a 20 ppm toluene to 5 ml of the unknown solution and relative signals of 1240:1100.
What is the concentration in ppm of the benzene?