INFICON Explorer Portable Gas Chromatograph - Manual (Page 323)

Explorer Operator Manual
321
Detector response drift will manifest itself as an effect that typically occurs over a
longer time period than adsorption and which is not as compound specific as
adsorption. Also, it is not affected by the frequency of sampling, unlike adsorption
phenomena. Calibration is recommended when the detector response has changed by
greater than 10%.
The table below provides a recommended maximum operating time before
calibration is necessary. The instrument must be calibrated when
Explorer is
turned on and should be calibrated at the indicated interval thereafter. We
recommend that you perform the calibration under similar temperature and
humidity conditions as that of the sample.
The calibration information in the table, and the discussion which follows, are
applicable only for measurement of dry, pure, sample gases containing the target
compounds at approximately calibration concentrations.
Compound TLV
(ppm)
Precision
% RSD from Mean *
Calibration
Interval**(Hrs)
MTBE 10 0.5@5ppm 8
TAME 0.5 1.6@5ppm 8
Ethanol 0.5 1.2@20ppm 8
Benzene 10 [email protected] 8
Toluene 50 0.8@10ppm 8
Methanol 200 5.0@96ppm 8
Ethylbenzene 750 0.5@10ppm 8
m-Xylene 200 0.5@10ppm 8
o-Xylene 100 0.5@10ppm 8
* Based on five consecutive samples
** Interval between calibrations for <10% change in accuracy
assuming Explorer is calibrated once immediately after a 20 minute
warm up period.
Table 1 Precision and Calibration Data for Assay 2 Compounds