LaMotte SMART Spectro Spectrophotometer - Manual (Page 109)

þNOTES: Reagents are light sensitive. Unused reagents should be stored in
the shipping container, and in the refrigerator if possible, until needed.
A reagent blank should be run with each set of samples and with each lot of
reagents.
The reacted blank will be stable if stored in the dark.
To eliminate error caused by contamination, wash all glassware with 20%
sulfuric acid.
For greater accuracy, a minimum of three repetitions should be performed
and the results averaged.
Some samples may be digested completely in less than two hours. The
concentration may be measured at 15 minute intervals while the vials are
still hot until the reading remains unchanged. The vials should be cooled to
room temperature before the final measurement is taken.
COD–LR 4/4 SMART SPECTRO TEST PROCEDURES 03.05