Need help with extraction/seperation scheme. I am currently doing research into
ID: 893476 • Letter: N
Question
Need help with extraction/seperation scheme.
I am currently doing research into extracting the active ingredients in a Benadryl Allergy Medication containing Acetaminophen, Diphenhydramine, and Pseudophedrine HCl. I also want to quantify these ingredients as well to establish a % recovery. The pKa'a of the ingredients are 9.38, 8.98, and 9.22 respectively. I was originally thinking about doing a liquid-liquid extraction but the similar pKa's make this method hard. I was also thinking about TLC to separate them based on polarities but I'm not sure what solvent to use. I was thinking a mixture of MeOH(10%-15%?) in DCM. Another method I can try is solid phase extraction. If you guys have any suggestions to the procedure of my proposed methods or any other new methods I can try I would greatly appreciate it. Any input is helpful. Thanks.
Explanation / Answer
I think TLC is a good choice to try out always. First try with silica gel TLC and elute the mixture in DCM. Since all the three compounds polarity are much higher you may not get favourable result straight away. Then slowly increase the polarity of eluting solvent MeOH with 5%, 10%, 15%, etc., If you find the three compounds getting separated well, then you can use Column chromatography with little lesser polarity. Try to pack the column little lengthier so that the chances of getting the compounds separated is high.