Chromatography Forum

Dear Friends
iam getting high response for Acetone in Clindamycin if i use DMSO as diluent and very less response if i use water as Diluent for sample preparation, But Acetone response is same in Standard ireespective of Diluent ( water or DMSO), the sample is failing if am using DMSO as diluent for sample preparation, I can not use water as diluent as the responses for Solvents from standard injections is not reproducible in headspace .The response of Acetone is almost 10 times in DMSO when compared to water from Sample. The solvents to be estimated in Clindamycin are Ethanol, Acetone, Chloroform and DMF. please suggest me how to solve this problem.

thanks

In order to get linear and reproducible results from headspace analysis you must use the same amount of the same diluent solvents in each vial at each concentration of sample or concentration of residual solvent. You must have the same amount of drug in each vial for samples and for standards.

For example if you are required to dilute the drug in DMSO:water at 9:1 then you must make all your samples in DMSO:water at 9:1.

The presence of the drug can change the partition of the residual solvents.

Don't forget to add the same amount of internal standard if you use one.

best wishes,

Rod

Just to be sure that you do not have a contaminant in the DMSO you need to run a blank of DMSO only.

Peter

Is it in the realm of possibility that is the sample is not 100% soluble in the water, and the DMSO is allowing more of the acetone to be released from the matrix?

This is assuming that all of the above suggestions do not provide an answer.