Hach DR2400 Manual page 564

Oxygen, Dissolved
Zero
9.
Place the blank in the
cell holder.
Touch .
Zero
The display will show:
0.0 mg/L O
2
Interferences
Interfering Substance
3+
Cr
2+
Cu
2+
Fe
2+
Mg
2+
Mn
2+
Ni
NO -
2
Sample Collection, Preservation, and Storage
Oxygen, Dissolved
Page 2 of 4
10.
Place the ampule into
the cell holder.
Greater than 10 mg/L
Greater than 10 mg/L
Greater than 10 mg/L
Magnesium is commonly present in seawater and causes a negative interference. If the sample
contains more than 50% seawater, the oxygen concentration obtained by this method will be
25% less than the true oxygen concentration. If the sample contains less than 50% seawater, the
interference will be less than 5%.
Greater than 10 mg/L
Greater than 10 mg/L
Greater than 10 mg/L
The main consideration in sampling with the High Range Dissolved Oxygen
Ampul is to prevent the sample from becoming contaminated with atmospheric
oxygen between breaking open the ampule and reading the absorbance. This is
accomplished by capping the ampule with an ampule cap. If the ampule is
securely capped, the ampule should be safe from contamination for several
hours. The absorbance will decrease by approximately 3% during the first hour
and will not change significantly afterwards.
Sampling and sample handling are important considerations in obtaining
meaningful results. The dissolved oxygen content of the water being tested may
change with depth, turbulence, temperature, sludge deposits, light, microbial
action, mixing, travel time, and other factors. A single dissolved oxygen test
rarely reflects the accurate overall condition of a body of water. Several samples
taken at different times, locations, and depths are recommended for most
reliable results. Samples must be tested immediately upon collection, although
only a small error results if the absorbance reading is taken several hours later.
HRS MIN SEC HRS MIN SEC
11.
Wait approximately
30 seconds for the air
bubbles to disperse from
the light path.
Interference Levels and Treatments
Read
12.
Touch
Read.
Results will appear in
mg/L O .
2
OxygenDis_AccuVac_High_HRD_Eng_Ody.fm