Question

There is a solution mixed caffeine and methanol . Using HPLC, we have to know the concentration of caffeine.

1.What kind of detector i use and why?

2. What kind of column i use and why?

Answer 1

1. the kind detector used to know the concentration of coffeine in a mixed solution of caffeine and methanol is variable wavelength UV detector.The reason for selecting this type of detector is that,the best sensitivity of caffeine is at a wavelength of 282nm.The output from the detector goes to the computer,which is used to give us the peaks.The computer process the data and gives us the retention times,peak areas.

2.the column to be used for the analysis of caffeine in caffeine+methanol solution is bonded phase c-18 column.The reason for selecting this column is,caffeine is a polar organic molecule and it is water soluble,it also has a amino acid group in it which can be protonated by addition of acid.so, this can be seperated by bonded phase c-18 column using an acis methanol-water mobile phase.