MACHEREY-NAGEL 985022 NANOCOLOR COD 60 Tube Test Instructions
- June 3, 2024
- MACHEREY-NAGEL
Table of Contents
NANOCOLOR®COD 60
REF: 985022
Test Instructions
Overview
The test is suitable for the photometric determination of the chemical oxygen
demand (COD). The test is in accordance with DIN ISO 15705–H45 and is
equivalent to the methods EPA 410.4, APHA 5220D and DIN 38409–H41-1.
The test is suitable for water, surface water, ground and drinking water and
wastewater.
- Measuring range: 5–60 mg/L O2 (method 0221)
- Number of tests: 20
- Wavelength for photometric determination: 345 / 365 nm
- Shelf life: 12 months
- Reaction time: 120 minutes
- Storage temperature: 2–8 °C
- Storage conditions: protected from sunlight, upright.
Method
The organic compounds of a sample are oxidized by heating the sample in a
mixture of sulphuric acid and potassium dichromate. The chemical oxygen demand
(COD) of a ater sample is the concentration of oxygen that is equivalent to
the amount of potassium dichromate consumed.
The change in the potassium dichromate concentration is determined via the
change in absorbance after digestion.
Interferences
The foreign materials shown here do not interfere with the test up to the
indicated concentrations (in mg/L). The cumulative effect of different
interfering ions has not been ested. Data in mg/L: • Cl – 1500
Important: For samples in which the chloride content is high, shake the tube
to suspend the precipitate prior to adding the sample. If the chloride content
is greater than 500 mg/L, you must dilute the sample or use a chloride
masking agent (REF 918911). Once it has reacted in the heating block, the
solution must not be cloudy; turbidity can esult in suppressed COD values.
The use of precipitated mercury sulphate will allow the turbidity to settle.
This method is not suitable for analyzing seawater.
Turbidity leads to lower measured values.
Reagents and accessories
Contents of reagents set:
-
20 test tubes R0
Required devices: -
MACHEREY-NAGEL photometer
-
MACHEREY-NAGEL heating block
-
Digital piston pipette 1–5 mL (REF 916909) with pipette tips
(REF 916916) -
Safety bottle for shaking COD tubes (REF 91637)
Standards
- NANOCONTROL COD 60 (REF 92522)
- NANOCONTROL Multistandard Sewage outflow 2 (REF 925010) www.mn-net.com
Sampling and preparation
See DIN EN ISO 5667-3-A 21.
Quality control
The measurement of a blank value and a standard is recommended before every
measuring series as quality control measure.
Quality data: The following data were determined during production
according to ISO 8466-1 and DIN 38402-A51:
- Number of LOTs: 50
- Standard deviation of the method: ± 0.97 mg/L O2
- Coefficient of variation of the process: ± 2.95 %
- Confidence interval: ± 2.24 mg/L O2 Specified data for procedure:
- Sensitivity (absorbance of 0.010 A corresponds to): 0.39 mg/L O2
- Accuracy of a measurement value: ± 3.87 mg/L O2 LOT-specific certificates are available at www.mn‑net.com.
Procedure
- Open round cell and hold slightly tilted
- Pipette 2 mL of sample into test tube
- Seal test tube and shake vigorously (use safety bottle, cuvette will become hot!).
- Heat for 2 h at 148 °C or for 30 min at 160 °C
- Take the tube from the heating block
- Shake again after 10 min. while still warm
- Cool to room temperature
- Clean outside of test tube
- Measure
Notes
Test a sample of COD-free water (REF 918993) to generate a blank value for the
reagent.
The solution remains cloudy until heated.
When using a standard, the measured value is constant over a period of min. 30
min.
Correction value e. g. for colored or turbid samples possible (see photometer
manual).
When using other photometers, make sure measurements are possible in test
tubes (16 mm OD) and calibrate the method.
Information regarding safety can be found on the box’ label and in the safety
data sheet. You can download the SDS from
www.mn‑net.com/SDS.
10/2019
MACHEREY-NAGEL GmbH & Co. KG · Neumann-Neander-Str. 6–8 · 52355 Düren · Germany
DE / International:
Tel.: +49 24 21 969-0
Fax: +49 24 21 969-199
E-mail:info@mn-net.com| CH:
Tel.: +41 62 388 55 00
Fax: +41 62 388 55 05
E-mail:sales-ch@mn-net.com|
FR:
Tel.: +33 388 68 22 68
Fax: +33 388 51 76 88
E-mail:sales-fr@mn-net.com
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