of column flux, commonly referred to as a chromatogram. The chromatogram response (Figure 4) of n-alkane vapors (C6 to C14) pro¬vides a set of reference reten¬tion times. Graphi¬cally defined re¬gions, shown as red bands, pro¬vide a method dependent reference time base against which subsequent chemical responses can be

70oC valve, and 50oC inlet. Each data point is the average of three triplicate measurements. The averaged data points and linear response factor (counts/ppm) for each case is shown as insets in the figure. Summary Detecting ethanol in air and water is fast and easy

70oC. Detecting Ethanol in Ambient Air To calibrate the instrument for detecting ethanol in air, standard vapors are first created by injecting known amounts of ethanol into a known volume of air in a tedlar bag. For example injecting 1 ?L of pure ethanol into 1000 mL of air will produce

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

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

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