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

milliliter of vapor will form droplets within the sampling needle and loop trap. When the sample is transferred to the helium section and the trap rapidly heated to 250oC during injection, the water vaporizes and expands more than 1000X. This in turn creates a very high-pressure burst of

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

using the zNose? electronic nose or portable gas chromatograph. Even though ethanol is at the lower limit of detectable compounds, concentrations well into the low part-per-million range can be quantified with good precision and accuracy. Because ethanol is very soluble in water, headspace measurements are best

sensitivity to very volatile organic compounds (VVOC), a valve temperature of 70oC and an inlet temperature of 50oC works well. Although the column can be operated isothermally, better chromatography is achieved with at least a 1oC/second temperature ramping of the column. Sample times longer than 5 seconds are

using the zNose? electronic nose or portable gas chromatograph. Even though ethanol is at the lower limit of detectable compounds, concentrations well into the low part-per-million range can be quantified with good precision and accuracy. Because ethanol is very soluble in water, headspace measurements are best

performed with water samples elevated to at least 40oC. Use of a PTFE inlet filter is recommended to prevent water droplets from forming, entering the instrument, and possibly damaging the sensitive vapor detector. A summary chart of ethanol MDL amounts is shown in Table I. For good

dependent, allow the instrument to display air concentrations as ppmv values. As an example, the ethanol response using a 415 ppmv vapor standard is compared to that of n-alkane vapors (C6-C10) using a 1ps3a1b method in Figure 10. The system software correctly displays the Kovats index of ethanol as