Answer these questions clearly and thoroughly. Be sure I cannot misunderstand yo

ID: 902478 • Letter: A

Question

Answer these questions clearly and thoroughly. Be sure I cannot misunderstand your answers. Go into as much detail as necessary so that there is no doubt I know what you are talking about In an attempt to develop an assay for content analysis of a very difficult mixture, four separate employees turn in content analysis reports on the company's product. The reports determine the concentration of compound A in the product based on some standards and samples run on HPLC. Their reports were based off the same data (below), yet they came up with different conclusions. Analyze the data and give your opinion on the experiment and what you think the actual concentration of compound A is and what you would do to improve the method. Also indicate what should be done with the employees.

Explanation / Answer

Observe peak number 9 in each table:

-the peak area is proportional to the concentration of the compound A.

-for the other peaks, the peak areas are relatively constant for the same peak number.

Peak 9 is A.

But observe also some abnormalities:

In the Table for 12.5 ppm standard :

-the area of peak 8 and 9 in 12.5 ppm Table are probably interchanged

- the area of peak 8 in sample table is probably 6395, not 16395

Conc.

6.25

12.5

100

Peak area

3842

8922

20644

37522

75154

Use Excel to do a plot and calculate:

Slope = 753.9

Intercept = 0.917

Area = 753.9 C + 0.917

C = (Area – 0.917) / 753.9

Csample = (7010 – 0.917) / 753.9 = 9.296

Employee 1 has provided a good answer. He has recognised the data error, has corrected it and has done a complete statistical treatment.

Employee 2 used the wrong value in 25 ppm Table to calculate

(25/7923) x 7010 = 22.12 ppm

Employee 3 and 4 probably don’t correctly identified the A peak position. Ask for an explanation.

Train and verify for a period of time the work of E2,E3 and E4.