70 Model 5380 PFPD Operator’s Manual
Rev. 3.1
Figure 5.8. Chromatogram of the OI Analytical Test Standard (Sulfur Mode)
Thimet
Chorpyrifos
Diazinon
6. For each peak resulting from the chromatographic output, measure the peak
height and width at half height (or width at quarter height for sulfur in stan-
dard, nonsquare root mode). Calculate detectivity for each analyte and deter-
mine if the detectivity and/or selectivity is sufficient for the intended applica-
tion. (See Appendix A for calculation of detectivity for sulfur and phosphorus.)
Figures 5.8 and 5.9 provide a chromatographic example of a standard test for sulfur
run by OI Analytical. The following specifications were used to obtain this output.
• Carrier gas is helium and the flow rate is 1.2 mL/min
• Column specifications are: HP-5 5% phenyl methyl siloxane, 30.0 m length,
0.32 mm diameter, and 0.25 µm film thickness
• Temperatures settings are:
Splitless isothermal injector set at 250°C
GC oven is programmed as follows:
Initial temperature set to 60°C, held for 0.50 min
Increased 25°C/min to 180°C
Increased at 8°C/min to 260°C
Increased at 25°C/min to 300°C, held for 2.00 min
PFPD temperature set at 200°C
The test standard contains 500 pg/µL thimet, 1,200 pg/µL diazinon, and
1,500 pg/µL chorpyrifos. Figure 5.8 shows a chromatogram of the quadratic
response output for sulfur, which was obtained using the conditions described
above. Figure 5.10 shows the sulfur emissions captured in WinPulse for each of the
three peaks. It should be noted that the emission response seen in WinPulse will
vary according to the analyte concentration. This example deals with generally high
concentration analytes. Emissions from low concentration analytes may not be
readily observable on the WinPulse screen unless the range and attenuation settings
are decreased in the Board/Channel Parameters screen of WinPulse.
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