We have Shimadzu GC-14A
I did not zero the base line before my sample analysis.
I have run lot of samples like that
Can I take that data into consideration

Thank you very much for your valauble information

would recommend not to use

but if all your samples are in the same buffer, the results maybe used after subtract buffer (blank exp)

You can run your GC without adjusting the zero, but be careful.

1. Your GC detector has a maximum output. If, for example, the maximum is 1000 mV, and your baseline rises to 900 mV (a very bad situation), any peak that is larger than 100 mV will cause the detector to reach its maximum value, and your results will not be accurate. Smaller peaks will not be affected, but you may find that your baseline has more noise. If you baseline drifts up a small amount (100 mV), this should not cause any problems.
2. The results will only be accurate if your integration program corrects for the baseline change. Most modern systems will do this.