Total nitrogen prefabricated reagent

NegotiableUpdate on 03/16

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Overview

Total nitrogen prefabricated reagent

Product Details

1. Product Introduction

Yuan Yice developed a total nitrogen (1-150mg/L) detection reagent based on the nitrate chromium transformation acid detection method. The detection wavelength is in the visible light range of 410nm, and it is less affected by organic and inorganic impurities. It can meet the requirements of batch, rapid, and accurate determination of water quality for various environmental water and industrial wastewater.
2. Technical principles
Under alkaline conditions, after potassium persulfate digestion, all nitrogen-containing components in the water sample are converted to nitrate. After removing excess chlorine and oxidizing substances with sodium metabisulfite, nitrate reacts with chromic acid in a strongly acidic medium to form a yellow complex.
The absorbance at a wavelength of 410nm is linearly related to the total nitrogen concentration within the concentration range of 1-150mg/L (calculated as N). By drawing a standard working curve, the total nitrogen concentration in the sample can be accurately quantified.

3. Range
1-150mg/L (calculated as N).
4. application area
Used for the determination of total nitrogen values in water samples such as surface water, groundwater, domestic sewage, and industrial wastewater.
5. Usage
1） First, put on a pair of clean gloves, take out at least 2 alkaline digestion tubes (HR), and unscrew the lids of all tubes. Add 0.50 mL of ultrapure water to one tube (if there is no ultrapure water, commercially available distilled water can be used as a substitute) (this is a blank tube), and add 0.50 mL of the test sample solution to the other tubes (this is a sample tube).
2） Add a packet of total nitrogen (I) (HR) reagent to the digestion tube that has been filled with blank or water sample, cover it with a lid and tighten it (due to the high pressure inside the digestion tube during digestion, it is easy to cause leakage, so it should be confirmed that the lid is not severely skewed or loose when tightening). Invert the solution and reagent inside the tube several times to ensure uniformity.
3） Set the porous digester to a digestion temperature of 120 ℃ and a digestion time of 30 minutes. After reaching the temperature, place all prepared digestion tubes into the slots of the porous digester, press the start timer button, and wait for the sample digestion timer to finish.
4） After the timer of the porous digester is completed, remove the digestion tube (use insulated gloves during operation) and place it on a wooden or steel test tube rack (do not use plastic test tube racks with poor heat resistance), and wait for the digestion tube to cool to room temperature. If the testing time requirement is tight, the lower part of the digestion tube can be soaked or rinsed with tap water after being cooled for 5 minutes to accelerate the cooling speed of the digestion tube.
5） Open the lid that has cooled to room temperature (pay attention to the air pressure), add one packet of total nitrogen (II) (HR) reagent each, and cover the lid upside down and shake well for 15 seconds. Let it stand for 3 minutes.
6） Open the lid again and add 1 packet of total nitrogen (III) (HR) reagent. Cover the lid upside down and shake well for 15 seconds, then let it stand and wait for 2 minutes.
7） Prepare the same number of acid containing color tubes as the alkaline digestion tubes used. Transfer 2.00mL of liquid from the alkaline digestion tubes to the corresponding acid containing color tubes, cover them with lids, invert them 10 times to make the liquid uniform, and let it stand for 5 minutes. (Note: The color development process of the acid containing color tube will generate a large amount of heat. When shaking it upside down, wear insulated gloves.)
8） Adjust the wavelength of the spectrophotometer to 410nm, zero it with a blank tube, and test the absorbance value of the sample tube. Calculate the total nitrogen concentration of the sample based on the existing standard curve.
6. Standard curve drawing method
① Preparation of Standard Series Solutions: Transfer 1.00, 2.00, 5.00, 10.00, and 15.00 mL of 1000mg/L of commercially available national standards
Transfer the sample total nitrogen standard solution to 5 clean 100 mL volumetric flasks, dilute with ultrapure water to the mark and shake well to obtain 10.0, 20.0, 50.0, 100.0, 150.0 mg/L series total nitrogen standard solutions, respectively;
② Draw a standard curve: Take 6 total nitrogen acid digestion tubes (HR), add 2.00 mL of ultrapure water and a series of total nitrogen standard solutions, and follow the detection steps in Section 5 (Usage) above to obtain the corresponding absorbance values A of the series of total nitrogen standard solutions. Plot the absorbance values A with the concentration C of the total nitrogen standard solution as the vertical axis and the corresponding absorbance values A as the horizontal axis, and linearly fit to obtain the formula for the standard curve.
The total nitrogen concentration in the water sample can be calculated by substituting the measured absorbance value of the actual sample into the formula (if the instrument supports the self built test program, the standard curve can be input into the program, and the total nitrogen value can be directly displayed by calling the program test, without further calculation).
7. Precautions
 If the photometer used has a circular hole sample cell that matches the pre installed tube, the pre installed tube can be directly used as a colorimetric tube; If not available, the digested liquid can be aspirated into a 1cm colorimetric dish for further testing;
 If the user's laboratory has Hash DR series instruments (such as DR3900/DR6000/DR900/DR5000/DR2400, etc.), there is no need to draw a standard curve, and the total nitrogen testing program (program number 394) can be directly called for zero adjustment testing.
 This reagent has strong anti-interference ability against various metal ions, but if the total chlorine or total bromine in the sample exceeds 1000mg/L or 60mg/L, it will interfere with the sample testing. If the chlorine and bromine in the sample to be tested are too high, other detection methods should be selected for detection
 During the testing process, the reagent will release a small amount of sulfur dioxide gas, so it should be used in a well ventilated environment.
 The waste liquid used for testing contains a high concentration of sulfuric acid. Personal protective measures should be taken during the experiment, and hands should be washed with clean water after the test is completed. During the sample digestion process, the temperature of the porous digester is relatively high, and attention should be paid to preventing burns;
 Do not pour the waste liquid from total nitrogen testing into the sewer. It should be collected uniformly and entrusted to qualified units for centralized treatment.