air measurements take less than 15 seconds and can be repeated at one minute intervals.

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

compared and indexed. As an example, a response midway between C10 and C11 would have a retention time index of 1050. Properties of Ethanol Physical properties of ethanol are shown in Figure 5. Although it is relatively volatile it also is very soluble in water which accounts for the low

compounds are injected into the helium gas. The organic compounds pass through a capillary column with different velocities and thus individual chemicals exit the column at characteristic times. As they exit the column they are detected and quantified by a solid state de¬tector. An internal high-speed

two-zone (top and bottom) vial heater can greatly increase headspace concentration. For example a 300-ppm water standard at 40oC had a response of 284 counts or 104 ppmv. Increasing the water temperature to 65oC increased the response to 957 (353 ppmv), an increase of more than 300%.

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