Question

A researcher was attempting to quantify the amount of ddt (dichlorodiphenyltrichloroethane) in spinach using gas chromatography mass spectrometry (gcms). first attempts using external calibration proved difficult, as reproducibility and external standard agreement were poor. to overcome these problems, the researcher used the internal standard calibration method with chloroform as the internal standard. to begin, the researcher analyzed a sample containing 6.44 mg/l ddt standard and 1.41 mg/l chloroform as the internal standard, which produced peak areas of 3979 and 9257 for the ddt and chloroform, respectively.

a. determine the response factor (f).

Answer 1

Given data

Conc. of standard ddt = 6.44mg/l

Conc. of Internal standard chloroform = 1.41mg/l

Peak of standard ddt = 3979

Peak of internal standard chloroform = 9257

Required

Response factor (RF) = ?

Solution

As we know that

Response factor (RF) = Peak area/sample amount

So RF for standard ddt

RF = 3979/6.44 = 617.85 (answer)

RF for internal standard chloroform

RF = 9257/ 1.41= 6565.24 (answer)