YC/T 161-2002 Determination of total nitrogen in tobacco and tobacco products - Continuous flow method
Some standard content:
ICS65.160
Registration number: 105912002
Tobacco Industry Standard of the People's Republic of China
YC/T 161—2002
Tobacco and tobacco products
Determination of total nitrogen
Continuous flow method
Tobacco and tobacco products--Determination of total nitrogenContinuous flow method
Published on September 12, 2002
Published by the State Tobacco Monopoly Administration
Implemented on December 1, 2002
YC/T161--2002
This standard is proposed by the State Tobacco Monopoly Administration. Foreword
This standard is under the jurisdiction of the National Tobacco Standardization Technical Committee. The drafting unit of this standard: National Tobacco Quality Supervision and Inspection Center. The main drafters of this standard: Liu Huimin, Wang Fang, Li Rong, Li Ping. 410
1 Scope
Determination of total nitrogen in tobacco and tobacco products
Continuous flow method
This standard specifies the method for determining total nitrogen in tobacco (excluding nitrate nitrogen). This standard applies to tobacco and tobacco products. 2 Normative references
YC/T161~-2002
The clauses in the following documents become the clauses of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, the parties who reach an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this standard. GB/T5606.1 Cigarette sampling
YC/T5 General principles for batch sampling of tobacco leaves
YC/T31 Preparation of tobacco and tobacco product samples and determination of moisture content Oven method 3 Principle
Organic nitrogen-containing substances are digested and decomposed by strong heat under the action of concentrated sulfuric acid and catalyst, and the nitrogen in them is converted into ammonia. Under alkaline conditions, ammonia is oxidized to ammonium chloride by sodium hypochlorite, and then reacts with sodium salicylate to produce a blue dye, which is measured colorimetrically at 660nm. 4 Reagents
Use analytical grade reagents, and water should be distilled water or water of equivalent purity. 4.1 Brij 35 solution (polyethoxylated lauryl ether) Add 250g Brij 35 to 1L water, heat and stir until dissolved. 4. 2 Sodium hypofluorite solution
Pipette 6 mL of sodium hypofluorite (effective chlorine content ≥ 5%) into a 100 mL volumetric flask, dilute to the mark with water, and add 2 drops of Brij 35 (4. 1).
4.3 Sodium chloride-sulfuric acid solution
Weigh 10.0 g of sodium chloride into a beaker, dissolve it with water, add 7.5 mL of concentrated sulfuric acid, transfer it into a 1000 mL volumetric flask, dilute to the mark with water, and add 1 mL of Brij 35 (4.1). 4.4 Sodium salicylate-sodium nitrosoferricyanide solution Weigh 75.0g of sodium salicylate (NazC,HsO3) and 0.15g of sodium nitrosoferricyanide [NazFe(CN)sNO·2HzO] in a beaker, dissolve them in water, transfer them to a 500mL volumetric flask, make up to the mark with water, and add 0.5mL of Brij35. 4.5 Buffer solution
Weigh 25.0g of potassium sodium tartrate (NaKC,H,O.·4H2O), 17.9g of disodium hydrogen phosphate (NazHPO,·12H,O), and 27.0g of sodium hydroxide (NaOH), dissolve them in water, transfer them to a 500mL volumetric flask, and add 0.5mL of Brij35. 4.6 Injector cleaning solution
Transfer 40mL of concentrated sulfuric acid (H,SO.) to a 1000mL volumetric flask, slowly add water, and make up to the mark. 411
YC/T 161—2002
Mercury oxide (HgO), red
4.8 Potassium sulfate (K,SOg)
4.9 Standard solution
4.9.1 Stock solution: Weigh 0.943g ammonium sulfate in a beaker, accurate to 0.0001g, dissolve with water, transfer to a 100mL volumetric flask, and dilute to the mark with water. The nitrogen content of this solution is 2mg/mL. 4.9.2 Working standard solution: Prepare at least 5 working standard solutions according to the total nitrogen content of the sample to be detected. The preparation method is: pipette different amounts of stock solution respectively, add mercury oxide, potassium sulfate, and sulfuric acid in the same amount as the sample digestion, and digest together with the sample. S
Instruments
Common experimental instruments and
5.1 Continuous flow analyzer (see Figure 1), consisting of the following parts: digester, the recommended digestion tube capacity is 75mJ; -sampler;
proportional pump;
dialyzer;
heating tank;
spiral tube;
colorimeter, equipped with 660nm filter;
recorder or other suitable data processing device. 152mm (6 inches)
B60 nm filter
2.0mm×15mm flow cell
sample/white (0.23 mL/min), sample/yellow (0. 16 mL/min), sample
chlorine/chlorine (0. 32 ml/min), air
blue/yellow (1.40mL/min), salt/sulfonic acid solution detection/black (0. 32 mL/min), air
red/red (0. 80 mL/min), salt/sulfonic acid solution detection/gui (0. 42 ml/min). Buffer solution for display/stimulation (0.32 mL/min), sodium salicylate/nitrosoferric chloride orange/yellow (0.16 mL/min), sodium hypochlorite blue/yellow (1.40 mL/min), sulfuric acid solution
Figure 1 Diagram of total nitrogen determination pipeline
5.2 Balance, sensitivity 0.0001g.
6 Analysis steps
6.1 Extract samples according to GB/T5606.1 or YC/T5. 6.2 Prepare samples according to YC/T31 and determine the moisture content. 6.3 Weigh 0.1g of sample into a digestion tube, accurate to 0.0001g, add 0.1g of mercuric oxide (4.7), 1.0g of potassium sulfate, and 112g of concentrated sulfuric acidwwW.bzxz.Net
YC/T 161—2002
6.4 Place the digestion tube on the digestion device for digestion. The working parameters of the digester are: 150C1h, 370C1h. After digestion, cool slightly, add a small amount of water, cool to room temperature, dilute to the scale with water, and shake well. 6.5 Run the working standard push solution and sample solution on the machine. If the concentration of the sample solution exceeds the concentration range of the working standard push solution, the working standard solution should be re-made.
7 Calculation and expression of results
7.1 Calculation of total nitrogen content
The total nitrogen content on a dry basis is obtained by formula (1): m×(iw) × 100
Total nitrogen (%)=
Where:
-The instrumental observation value of the total nitrogen of the sample solution, in milligrams (mg); m--The mass of the sample, in milligrams (mg); W-. The moisture content of the sample.
7.2 Expression of results
The average value of the two measurements is taken as the measurement result, and the result is accurate to 0.01%. 8 Precision
The absolute value difference between two parallel determination results should not be greater than 0.05%. 413
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