Calibration is accomplished using a single n-alkane vapor standard. A library of retention times of known chemicals indexed to the n-alkane response (Kovats indices) allows for machine independent measurement and compound identification. Chemical Analysis (Chromatography) The time derivative of the sen¬sor spectrum (Figure 3) yields the spectrum

552 and concentration as 415 ppm The zNose® system response is linear over a wide range of vapor concentrations. This is clearly shown by the N-point responses obtained from a series of 1-liter tedlar bags injected with increasing amounts of ethanol as shown in Figure 11. Detector Sensitivity vs

lower limit of detectable compounds which can be analyzed by the zNose. Sensitivity is determined by the loop trap’s ability to concentrate ethanol from air samples and the ability of the SAW sensor to condense and detect it as it elutes from the GC column. To

super heated steam when passes through the column and strikes the surface of the SAW detector. Often this destroys the electrodes on the surface of the crystal and the detector must be replaced. To prevent high concentrations of water vapor and particles from entering the instrument an inert

using a side-ported sample needle and PTFE filter attached to the inlet of the zNose? as shown in Figure 14. The concentration of ethanol in headspace vapors from water at room temperature is very low because ethanol is very soluble in water. Heating the water sample using a

optimize the trapping efficiency of the loop trap system temperatures are necessarily low. Maximum SAW sensitivity is achieved by using a crystal temperature of 10oC or 0oC. A valve temperature of 70oC and an inlet temperature of 50oC are recommended. Because the loop trap contains only 1

552 and concentration as 415 ppm The zNose® system response is linear over a wide range of vapor concentrations. This is clearly shown by the N-point responses obtained from a series of 1-liter tedlar bags injected with increasing amounts of ethanol as shown in Figure 11. Detector Sensitivity vs

and 10oC detector temperatures, 7-replicate measurements at 100 and 13-ppm ethanol concentrations yield MDLs of 14.1 and 5.2 ppm respectively as shown in Figure 13. . Detection of Ethanol in Water Headspace vapors from water standards (20 mL water in a 40 mL vial) were sampled directly