Performing the absorbance
measurements
For each of the four test solutions, the absorbance will be measured and automatically
compared to its reference value.
Action
Step
Switch on the UV lamp, see
Setting lamp on and off, on page 46
.
1
Select a main menu on the monitor display that shows wavelength 254 nm.
2
Fill one of the supplied syringes with 1.5 to 2 mL of the 0 AU/cm solution.
Make sure that there is no air in the syringe!
3
Fit the syringe in the Union Luer connector and inject the solution. Do NOT
remove the syringe.
4
Wait until the monitored absorbance value is stable.
5
Perform an Autozero operation. See
.
6
Remove the syringe.
7
Inject the other four test solutions in increasing concentration order. Use a
new syringe for each solution.
Note:
Air trapped in the UV cell causes inaccurate measurements. To avoid introduc-
ing air into the cell, gently fill the Luer union up to the edge using test solution
from the syringe that is next. Then insert the syringe into the Luer union.
8
After each injection, wait for a stable absorbance value and enter the mea-
sured values in the Excel column UV -900 Absorbance (AU) in the UV-900
Cell Calibration Excel file.
9
When all absorbance values have been entered, the real cell length is shown
next to the Real cell length Excel cell.
Note:
The regressions coefficient should be larger than 0.999. If not, one or several
measured values are faulty.
10
Monitor UV-900 Operating Instructions 28962214 AD
53
5 Operation
5.5 UV cell calibration
