How The unknown concentration can be determined

1. from the standard curve by drawing a horizontal line on the graph parallel to the x-axis and through the point on the y-axis which corresponds to the absorbance. 2. This line will intersect the standard curve; at this intersection, a vertical line is dropped to the x-axis and the concentration read from the x-axis. 3. Two factors are important in determining unknown or relative concentrations. 4. The absorption maximum should be used, and absorbance rather than percent transmittance should be plotted because absorbance is directly proportional to concentration and transmittance is not.