Hach Portable Spectrophotometer DR 2800 - Manual (Page 66)

66
Advanced Operations
Chemical form:
Enter the chemical formula used in the display to represent the
analysis parameter.
Use the alphanumeric keypad to enter the chemical form and press
Next to enter Calibration settings.
6.1.1.3 Calibration settings for single and multi wavelength mode
A method is calibrated by determining the absorbance values of
several standard solutions of known concentration.
There are three ways to create and store a calibration curve.
Instructions for each method follows (
Table 9 ).
Calibration by entering calibration values
Enter concentration/absorbance
1. Select the Enter Values and press Next.
Table 9 Calibration settings
Mode Descriptions
Enter values
A calibration table is created by entering the concentration values and the absorbance values of
the analyte solution. The absorbance values are plotted versus standard concentrations and the
calibration curve is displayed as a graph (page
66 ).
Read Standards
A calibration table is created by entering the concentration values of the standard solutions and
then measuring the absorbance of the analyte solutions. The absorbance values are plotted
versus standard concentrations and the calibration curve is displayed as a graph (page
68 ).
Enter Formula
If the calibration curve can be determined from the mathematical relationship between
concentration and absorbance by linear regression, etc., the corresponding formula can be
selected (linear, 2nd or 3rd order polynomial) from a list and the appropriate factors can be
entered (page
69 ).