Hach DR2400 - Page 240

Chromium, Total
© Hach Company, 2003. All rights reserved. Printed in the U.S.A. 3/04 1ed
Page 4 of 4 ChromiumTot_UniCell_Other_DCH_Eng_Ody.fm
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3. To adjust the calibration curve using the reading obtained with the
0.70-mg/L standard solution, touch
Options on the current program menu.
Touch
Standard Adjust.
4. 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.
Perform the hexavalent chromium procedure as described above. See Section
3.2.4 Adjusting the Standard Curve on page 40 for more information.
Method Performance
Precision
Standard: 0.50 mg/L Cr
6+
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
Chromium(VI) ions react with 1,5-diphenylcarbazide to yield
1,5-di-phenylcarbazone and Chromium(III), which forms a red complex.
Measurements are taken at 543 nm.
Required Reagents
Description Unit Cat. No.
Chromium - Cr (VI), UniCell™ HCT 156........................................................................ 23/pkg.............. HCT 156
Optional Reagents
Chromium Standard, 50-mg/L ........................................................................................ 100 mL.............. 810-42 H
Required Apparatus
Adapter, 16-mm Cell .......................................................................................................... each....................59457-00
Optional Apparatus
Digital Reactor Block.......................................................................................................... each....................DRB 100
Flask, volumetric, 100-mL ................................................................................................. each....................14574-42
Graduated cylinder, mixing, 100-mL............................................................................... each....................20886-42
Pipettor, (Jencons) 1–5 mL................................................................................................. each....................27951-00
Replacement tips for 27951-00 .......................................................................................... 100/pkg.............27952-00
Pipettor, (Jencons) 100–1000 µL........................................................................................ each....................27949-00
Replacement tips for 27949-00 .......................................................................................... 400/pkg.............27950-00
pH Paper.............................................................................................................................. 100/pkg.............26013-00
Test tube rack, cooling........................................................................................................ each....................18641-00
Program 95% Confidence Limits of Distribution
803 0.38–0.62 mg/L Cr
6+
Program Portion of Curve ∆Abs ∆Concentration
803 Entire range 0.010 0.01 mg/L Cr
6+