Which of the following criteria meet the requirements to achieve and maintain an

Question

Which of the following criteria meet the requirements to achieve and maintain an adequate isocratic HPLC separation?

A researcher used HPLC to examine a bicomponent mixture containing 1.64 mg/L of compound A and 1.34 mg/L of compound B, which was added as an internal standard. This mixture produced peak areas for A and B of 10169 and 3223, respectively. Using the above information, determine the response factor (F). After establishing F, the researcher prepared a solution by combining 10.21 mg of B with 15.00 ml. of an unknown solution containing only A and then diluted it to a final volume of 50.00 mL. The sample was examined using HPLC and peak areas of 7576 and 8838 were observed for A and B, respectively. Determine the concentration of A (mg/mL) in the unknown solution.

Explanation / Answer

Response Factor (RF) = peak area/ concentration

A RF = 10169/1.64 = 6200.6

B RF = 3223/1.34 = 2405

10.21 mg of B in 50 mL is

10.21mg/0.05L = 204.2 mg/L

B RF is 8838/204.2 = 43.3

When B RF was 2405 then A RF was 6200.6

When B RF was 43.3 then A RF will be 111.6

A RF = area/concentration

111.6 = 7576/concentration

concentration is = 67.88 mg/L in 50 mL

so in the 15 mL unknown was (67.88/1000) x 50 = 3.39 mg was in 15 mL

so 3.39/15 = 0.226 mg/mL

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