Hach DR2400 - Page 199

Chlorine, Total
Chlorine, Total
ChlorineTot_PT_Other_DPD_Eng_Ody.fm Page 5 of 6
Method Performance
Precision
Standard: 1.07 mg/L Cl
2
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Sensitivity
See Section 3.4.5 Sensitivity on page 44 for more information.
Summary of Method
Chlorine can be present in water as free available chlorine and as combined
available chlorine. Both forms can exist in the same water and can be determined
together as the total available chlorine. Free chlorine is available as
hypochlorous acid or hypochlorite ion. Combined chlorine exists as
monochloramine, dichloramine, nitrogen trichloride, and other chloro
derivatives.
The combined chlorine oxidizes iodide in the reagent to iodine. The iodine reacts
with DPD (N,N-diethyl-p-phenylenediamine) indicator along with free chlorine
present in the sample to form a red color which is proportional to the total
chlorine concentration. To determine the concentration of combined chlorine,
run a free chlorine test. Subtract the results from the results of the total chlorine
test to obtain combined chlorine. Test results are measured at 530 nm.
Required Reagents
Quantity Required
Description Per Test Unit Cat. No.
Rapid Liquid Total Chlorine Reagent Set.....................................................................................................25570-00
Includes:
DPD Indicator Powder................................................................................................ 24 g22972-55
Total Chlorine Indicator Solution ....................................................1 mL ................ 473 mL...............22634-11
Total Chlorine Buffer Solution .........................................................1 mL ................ 473 mL...............22635-11
Required Apparatus
Adapter, multi-pathlength cell ...............................................................1 ....................... each....................59466-00
Cylinder, mixing, glass, 100-mL .............................................................1 ....................... each......................1896-42
Dispenser, fixed volume, 1.0-mL RePipet Jr. ........................................2 ....................... each....................21113-01
Pour-Thru Cell Kit....................................................................................1 ....................... each....................59404-00
Required Standards
Chlorine Standard Solution, Voluette
®
Ampule,
50–75 mg/L, 10-mL...................................................................................................... 16/pkg...............14268-10
Chlorine Standard Solution, Voluette
®
Ampule,
50–75 mg/L, 2-mL........................................................................................................ 20/pkg...............14268-20
Water, deionized ................................................................................................................. 4 L ..........................272-56
Program 95% Confidence Limits of Distribution
82 1.06–1.08 mg/ L Cl
2
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 0.02 mg/L Cl
2