Handling & Preservation; Interferences; Calibration - LaMotte DC1500 Mode D'emploi

(chloramines). In buff ered samples, bromine reacts with disthyl-p-phenylene
diamine (DPD) to produce a pink-red color in proportion to the concentration of
bromine present.
 HANDLING & PRESERVATION
Chlorine and bromine in aqueous solutions, particularly weak solutions, are not
stable. Exposure to sunlight or agitation will accelerate the reduction of chlorine
and bromine. For chlorine samples, fi ll sample containers to the top and cap tightly.
Analyze samples as soon as possible after collection. Samples to be analyzed for
bromine cannot be preserved or stored.
 INTERFERENCES
The only interfering substance likely to be encountered is oxidized manganese.
The extent of this interference can be determined by treating a sample with
sodium arsenite to destroy the chlorine or bromine present, so that the amount
of interference can be estimated. Chlorine, bromine, and iodine will give a positive
result and should be considered an interference unless the test is being performed
specifi cally for that parameter.
 CALIBRATION
The colorimeter is precalibrated. In order to comply with NPDWR or NPDES reporting
regulations, the calibration should be checked periodically by using a set of
reference standards including a 0 mg/L blank and 0.3, 1.0, and 3.5 mg/L chlorine.
To prepare these standards, a LaMotte 1000 mg/L standard chlorine equivalent
solution (Code 3858) is available. Consult with your local regulatory agency to
determine standardization frequency.
ANALYSIS - CHLORINE
PROCEDURE – FREE CHLORINE
1. Fill the Water Sample Collecting
Bottle (0688) with sample water.
2. Press and hold
colorimeter turns on.
3. Press
ENTER
Menu.
until
to select Testing
Main Menu
Testing Menu
Editing Menu
12:00:00 001/500
All Tests
015 Bromine L DPD
016 Bromine T DPD
024 Chlorine L DPD
025 Chlorine T DPD
12:00:00
5
001/500