Tie internal standard method of analysis was employed in GC for the determinatio
ID: 1004124 • Letter: T
Question
Tie internal standard method of analysis was employed in GC for the determination of TCDD in river water. An analog of TCDD was used as an internal standard. The responses were 55 and 34 for the standard and the internal standard respectively. The internal standard procedure was as follows: 1.0 mg of internal standard was added to 2.0 mg of standard to a volume of 10.0 L. The internal standard was added to the unknown and the response was 29 for the unknown and 25 for the internal standard. Find the concentration (in ppm) of the unknown? (ppm - mg/L)Explanation / Answer
Step 1: relative response facrot RRF = 55/34 = 1.62
Step 2: C(unknown) = 1/RRF * C(internal standard) * R(unknown)/R(internal std)
= 1/1.62* 1* 29/25 = 0.716 mg/10 = 0.0716 mg/l