ARCHIVED REPORTS_XR0012713 - Laserfiche WebLink

Home Browse Search

i The Photovac IOSSO is a portable, programmable, integrating gas chromatograph with a photoionization detector (PID) . The PID is a non-destructive flow--through detector that uses high energy ultraviolet radiation as its ionization source. The high energy radiation ionizes Compounds, generating an energy increase in the detector which appears as an electrical signal, Treasured in volts. The instrument is calibrated with standards consisting of 10 ppm benzene and 10 ppm toluene in air. For the reading of each standard, the instrument stores the known -,oncentration and the volt-second (V-sec) response to it. The HNU 421 is a laboratory-size, temperature-programmable gas chromatograph equipped with a flame ionization detector (FID) . The hydrogen-air flame ionizes compounds, generating an energy increase in the detector, which appears as an electrical signal. ' The instrument is operated isothermally at 600C and the capillary column flow rate is 10 ml/min. These conditions ensure peak retention time stability and prevent contaminant build-up within the column. The instrument is calibrated with standards k consisting of known concentrations of benzene, toluene, xylenes, and ethylbenzene in air. For the reading of each standard, the instrument stores the known concentration and the V--sec response to it in a Shimadzu C-R3A integrator. The ratio for the standard, V-sec:ppm, is then used to quantify the concentrations � of identifiable vapors in field samples according to their V-sec values. Theconcentrations of unidentified compounds are calculated in a similar manner. Although petroleum hydrocarbons produce variable -- -- instrumental responses,-.the--assumption may be:made that all of -- 1 - - the:hydrocarbon constituents haveresponse-to-concent ration ; ratios approximately equivalent to that of benzene and that all quantifications may be based .on the ratio for benzene. In the i a. table of results, the column entitled "Peaks Prior to Benzene" represents the.sum of the responses in V--sec for :all peaks eluting prior to benzene, proportioned.to the calibrated V-sec EXXON9:89L g c s� .