The chromatogram shows total ions of eight herbicides and five degradation products in 1.0 nanogram per microliter standard solution (USGS Open-File Report 00-385).
Chromatography Analysis
After extraction, a small volume of the extract is injected into either the GC (1 - 10 microliters) or HPLC (5 - 20 microliters) (see Fifield and Haines, 2000 Ch. 5). The result is a chromatogram (see figure) that shows peaks for different analytes.
- Distinct, sharp peaks are desireable and if a mixture of analytes is being measured, clear separation between peaks is also desirable.
- To determine the amount of an analyte, the area under each peak is compared to areas corresponding to the points in the calibration curve. Peak area integration is usually performed with computer software integrated with the instrument.