Dear all,

I would like to talk to someone who has experience with both manual and automated calibration of the analyzer GC955 SYNSPEC. We use the device to measure benzene in the ambient air. Would anyone find have experienced and help me answer my questions?

Currently, I provide calibration manualy via SAMPLE PORT situated on switching box. For this reason, the calibration apparatus has included exhaust between SAMPLE PORT and apparatus. I use undiluted standard bottles with specific concentration benzene: 1ppb, 5ppb, 10ppb.

The problem is that, after measuring all concentration levels and calculating the calibration curve, the values of the measured standards are low eg. 1ppb is only 0,65pbb, 5pbb is only 4,45bbp, 10ppb is 9,65ppb or lower. I provide calculating calibration curve via FIXED BASE POIN. How do you calibrate other users, what type of calibration apparatus use for calibration? What is your experience with the calibration result?

My next question would be about measuring ZERO. What are the typical values for this parameter? Is normally when I use zero gass from bottle ( synthetically air) that I measure, for example, 500 units of peak area, is it OK?

Many thanks

Have a nice day