MACHEREY-NAGEL TNb 220 Tube test NANOCOLOR Robot Total Nitrogen Instructions

: June 3, 2024
: MACHEREY-NAGEL

Table of Contents

Overview
Method
- Interferences
- Reagents and accessories
Quality control
- Procedure
Customer Support
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MACHEREY-NAGEL TNb 220 Tube test NANOCOLOR Robot Total Nitrogen Instructions

Overview

The test is suitable for the photometric determination of total nitrogen.
The test is suitable for surface water, ground and drinking water and wastewater.

Measuring range: 5–220 mg/L N (method 0881)
Number of tests: 20
Wavelength for photometric determination: 345 / 350 / 365 nm
Shelf life: 12 months
Reaction time: 10 minutes
Storage temperature: 15–25 °C
Storage conditions: upright

Method

Oxidative decomposition with subsequent interference compensation and photometric determination with 2,6-dimethylphenol in a sulfuric acid/phosphoric acid mixture. Decomposition: Analogous to DIN EN ISO 11905-1 H36. Determination: Analogous to ISO 7890-1; DIN 38405-D9.

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 tested. Data in mg/L:

Cl- , COD: 10000

This method is not suitable for analyzing seawater.
Turbidities cause higher measurement values.

Reagents and accessories

Contents of reagents set:

2 x 20 test tubes R0
1 reagent R2
1 decomposition reagent
1 NANOFIX compensation reagent
1 measuring spoon orange
Required devices:
MACHEREY-NAGEL photometer
MACHEREY-NAGEL heating block
Digital piston pipette 200–1000 µL (REF 91671) with pipette tips (REF 91667)

Standards

NANOCONTROL Multi standard Sewage inflow (REF 925012)

Sampling and preparation

See DIN EN ISO 5667-3-A 21.
Adjust to pH 5–9 prior to analysis

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: 22
Standard deviation of the method: ± 2.79 mg/L N
Coefficient of variation of the process: ± 2.54 %
Confidence interval: ± 6.44 mg/L N

Specified data for procedure:

Sensitivity (absorbance of 0.010 A corresponds to): 1.55 mg/L N
Accuracy of a measurement value: ± 4.79 mg/L N

LOT-specific certificates are available at www.mn-net.com.

Procedure

Open test tube A
Pipette 0.5 mL of sample into test tube
Add 1 level measuring spoon of decomposition reagent
Seal test tube and shake vigorously
Heat for 30 min at 120°C
Take the tube from the heating block
Swirl
Cool to room temperature
Open test tube
Add 1 NANOFIX compensation reagent
Seal test tube and shake vigorously
Open test tube TNb 220
Pipette 0.5 mL decomposition solution into the tube
Add 0.5 mL R2
Seal test tube and turn upside down 3×
Wait 10 min
Clean outside of test tube
Measure

Notes

When using other photometers, make sure measurements are possible in test tubes (16 mm OD) and calibrate the method.
Correction value e. g. for colored or turbid samples possible (see photometer manual).
The pH value of the sample to be decomposed must be between pH 5 and 9; if necessary, adjust with sodium hydroxide solution or sulfuric acid. Nitrogen concentrations above the double measuring range can simulate results within the single measuring range and thus cause a wrong evaluation. Dilute the sample until the measured value is within the measuring range previously indicated by the test. For waters of unknown concentrations we recommend that
you perform the test with very different dilutions (e.g. 1+9, 1+99) until the last dilution confirms the previous value. For samples which consume large amounts of oxidizing substances (e.g. for COD values above 10,000 mg/L O2), decomposition can be incomplete.
In such cases repeat the decomposition with the previously diluted original sample.
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.
10/2020