MACHEREY-NAGEL 985038 NANOCOLOR COD HR 1500 Tube Test Instructions

NANOCOLOR®COD HR 1500
REF: 985038
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 38409–H41, 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 and wastewater.

• Measuring range: 20–1500 mg/L O2 (method 0381)
• Number of tests: 20
• Wavelength for photometric determination: 595 / 605 / 620 nm
• Shelf life: 12 months
• Reaction time: 120 minutes
• Storage temperature: 15–25 °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 following contaminants do not interfere with the test up to the indicated concentrations. The cumulative effect of different interfering ions has not been tested.
Data in mg/L: Cl  -: 2000
Important: For samples in which the chloride content is high, shake  the tube to suspend the precipitate prior to adding the sample. Ifthe chloride content is greater than 2,000 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 result in high COD values.
This method is not suitable for analyzing seawater.
The use of precipitated mercury sulphate will allow the turbidity to settle.

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 Multistandard Sewage inflow (REF 925012)
• NANOCONTROL COD 1500 (REF 92529)

Sampling and preparation
See DIN EN ISO 5667-3-A 21.www.mn‑net.com

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: 42
• Standard deviation of the method: ± 6 mg/L O2
• Coefficient of variation of the process: ± 0.70 %
• Confidence interval: ± 13 mg/L O2

Specified data for procedure:

• Sensitivity (absorbance of 0.010 A corresponds to): ± 17 mg/L O2
• Accuracy of a measurement value: ± 19 mg/L O2
  LOT-specific certificates are available at www.mn‑net.com.

Procedure

1. Put the sediment in the reaction cuvette into suspension by swirling
2. Open test tube
3. Pipette 2 mL of sample into test tube
4. Seal test tube and shake vigorously (use safety bottle, cuvette will become hot!).
5. Heat for 2 h at 150°C
6. Take the tube from the heating block
7. Shake again after 10 min. while still warm
8. Cool to room temperature
9. Clean outside of test tube
10.  Measure

Disposal
Information regarding disposal can be found in the safety data sheet. You can download the SDS from www.mn‑net.com/SDS.
Notes
Test a sample of COD-free water (REF 918993) to generate a blank value for the reagent.
When using a standard, the measured value is constant over a period of min. 30 min.
The mixture may heat up significantly.
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. 03/2021

Management System EN ISO 13485:2016 ISO 9001:2015
www.tuv.com ID 9000008338
MACHEREY-NAGEL GmbH & Co. KG
Neumann-Neander-Str. 6–8
52355 Düren · Germany
DE Tel.: +49 24 21 969-0info@mn-net.com
CH Tel.: +41 62 388 55 00sales-ch@mn-net.com
FR Tel.: +33 388 68 22 68 sales-fr@mn-net.com
US Tel.: +1 484 821 0984sales-us@mn-net.com

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