Recovery in Headspace GC

[kalyanaraman]

I am facing problem of recovery of the residual solvents spiked with the sample at low level for a drug whereas I find the recovery of about 80-85% when spiked at specification level of the solvents. Can somebody suggest me how to approach this problem?

[dcobice]

hi, what about your matrix? GC conditions? and tell me what kind of volatiles compounds are spiked? are you on the EPA oe USP?

Thanks!

[kalyanaraman]

Hi,

The matrix is a bulk drug buffered with sodium carbonate. Of the various solvents the problem is only with the recovey of methanol. All other solvents are perfectly getting recovered.

[chromatographer1]

It is difficult to trouble shoot with so little information.

methanol is fairly volatile but hydrophilic compared to many other solvents. Adding salts to an aqueous sample does not always improve recovery as much as may be desired.

Reducing sample size can improve recovery of methanol and other hydrophilic analytes.

Methanol also can be adsorbed to active sites in your system. (flatter response)

One more problem is that it can be difficult to plug focus if your injection volume is large. (flatter response)

Sorry I cannot be of more assistance.

[kalyanaraman]

Thank you chromatographer1. Your suggestions helped us a lot. The problem got solved by reducing the sample size.