CRITIQUE OF SOME CONVENTIONAL EVALUATION METHODS AND A CONTINUOUS FLOW, STEADY-STATE BLENDER FOR EVALUATION OF GAS CHROMATOGRAPHY DETECTOR LINEARITY

Conventional detector evaluation methods suffer various drawbacks which are thoroughly discussed. A new method using a steady-state flowing gas of known solute concentration is presented. The steady-state method eliminates adsorption problems and unequivocally determines detector linearity on an absolute basis. The technique presented employs a constant temperature saturator and a series of calibrated flowmeters to make blends of clean helium and solute-saturated helium. The lower range of concentration which was normally used was approximately 10-9 gram/sec; the upper limit is set by the solute saturation pressure at approximately 10-4 gram/sec. The accuracy is ±5%. Several late model flame ionization detectors were evaluated. Some showed reasonable linear response up to 10-5 gram/sec., while others were grossly nonlinear over the entire range. © 1969, American Chemical Society. All rights reserved.