Hach DR2400 - Page 236

Chromium, Total
© Hach Company, 2003. All rights reserved. Printed in the U.S.A. 3/04 1ed
Page 4 of 4 ChromiumTot_PP_Other_AHY_Eng_Ody.fm
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3. Touch On. Touch Adjust to accept the displayed concentration (the value
depends on the selected chemical form). If an alternate concentration is used,
touch the number in the box to enter the actual concentration, then touch
OK.
Touch
Adjust.
Method Performance
Precision
Standard: 0.25 mg/L Cr
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
Trivalent chromium in the sample is oxidized to the hexavalent form by
hypobromite ion under alkaline conditions. The sample is acidified. The total
chromium content is determined by the 1,5-Diphenylcarbohydrazide method.
Determine trivalent chromium by subtracting the results of a separate
hexavalent chromium test from the results of the total chromium test.
Test results are measured at 540 nm.
Required Reagents
Quantity Required
Description per test Unit Cat. No.
Total Chromium Reagent Set (100 tests).......................................................................................................22425-00
Includes:
Acid Reagent Powder Pillows..........................................................1 pillow........... 100/pkg...............2126-99
ChromaVer
®
3 Chromium Reagent Powder Pillows....................1 pillow........... 100/pkg.............12066-99
Chromium 1 Reagent Powder Pillows............................................1 pillow........... 100/pkg...............2043-99
Chromium 2 Reagent Powder Pillows............................................1 pillow........... 100/pkg...............2044-99
Required Apparatus
Hot plate, 3½-inch diameter, 120 VAC, 50/60 Hz.......................................................... each....................12067-01
or
Hot plate, 4 inch diameter, 240 VAC, 50/60 Hz ............................................................. each....................12067-02
Sample Cells, 10-20-25 mL, w/cap.........................................................2....................... 6/pkg.................24019-06
Water bath and rack .................................................................................1 ....................... each......................1955-55
Required Standards
Chromium, Trivalent, Standard Sol., 50-mg/L Cr
3+
..................................................... 100 mL...............14151-42
Chromium, Trivalent, Standard Sol., 50-mg/L Cr
3+
, Voluette Ampule
®
, 10-mL ..... 16/pkg...............14257-10
Program 95% Confidence Limits of Distribution
100 0.24–0.26 mg/L Cr
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 0.01 mg/L Cr