Question

A researcher was attempting to quantify the amount of dichlorodiphenyltrichloroethane (DDT) in spinach with gas chromatography using a chloroform internal standard. To begin, the researcher examined a sample containing 9.65 mg/L DDT standard and 2.40 mg/L chloroform as the internal standard, producing peak areas of 3589 and 6209, respectively.

Then, the researcher collected 6.53 g of spinach, homogenized the sample, and extracted the DDT using an established method (assume 100% extraction), producing a 3.24 ml volume of unknown sample. The researcher then prepared a sample that contained 1.00 ml of the unknown sample and 1.50 ml of 12.90 mg/L chloroform, which was diluted to a final volume of 25.00 ml. The sample was analyzed using GCMS, producing peak areas of 8017 and 13637 for the DDT in the unknown and the chloroform, respectively.

Calculate the DDT concentration in the spinach sample. Express the final answer as milligrams of DDT per gram of spinach.

concentration of DDT:

Answer 1