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LY/T 1228-2015

Chinese Standard: 'LY/T 1228-2015'
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BASIC DATA
Standard ID LY/T 1228-2015 (LY/T1228-2015)
Description (Translated English) Nitrogen determination methods of forest soils
Sector / Industry Forestry Industry Standard (Recommended)
Classification of Chinese Standard B10
Classification of International Standard 13.080.10
Word Count Estimation 21,255
Date of Issue 2015-10-19
Date of Implementation 2016-01-01
Older Standard (superseded by this standard) LY/T 1228-1999; LY/T 1229-1999; LY/T 1230-1999; LY/T 1231-1999
Quoted Standard GB/T 601; GB/T 603; GB/T 6682; LY/T 1210-1999
Drafting Organization China Tropical Forestry Research Institute
Administrative Organization State Forestry Administration
Regulation (derived from) National Forestry Anministration Announcement ��2015 No.19��
Summary This standard specifies the determination method of forest soil nitrogen, using Kjeldahl method, continuous flow analyzer and elemental analyzer method for the determination of soil total nitrogen, alkali dissolution method for the determination of forest soil hydrolyzable nitrogen, colorimetry and Determination of Nitrate Nitrogen and Ammonium Nitrogen in Forest Soil by Continuous Flow Analyzer. This standard is applicable to the determination of soil total nitrogen, hydrolyzable nitrogen, nitrate nitrogen and ammonium nitrogen.

LY/T 1228-2015
Nitrogen determination methods of forest soils
ICS 13.080.10
B10
People's Republic of China Forestry Industry Standard
Replacing LY/T 1228-1999, LY/T 1229-1999, LY/T 1230-1999, LY/T 1231-1999
Determination of nitrogen in forest soil
Released on October 18,.2015
2016-01-01 implementation
State Forestry Administration released
Content
Foreword III
Introduction IV
1 range 1
2 Normative references 1
3 Determination of total nitrogen 1
3.1 Kjeldahl method 1
3.2 Continuous Flow Analyzer Method 5
3.3 Elemental Analyzer Method 6
4 Determination of hydrolyzable nitrogen 7
4.1 Method Highlights 7
4.2 Reagents 7
4.3 Instrument 8
4.4 Determination step 8
4.5 Calculation of results 8
4.6 Allowable deviation 8
5 Determination of nitrate nitrogen 9
5.1 Phenol disulfonic acid colorimetric method 9
5.2 Continuous Flow Analyzer Method 11
6 Determination of ammonium nitrogen 13
6.1 Indophenol Blue Colorimetric Method 13
6.2 Continuous Flow Analyzer Method 15
Reference 17
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces LY/T 1228-1999 "Determination of total nitrogen in forest soil", LY/T 1229-1999 "Measurement of hydrolyzable nitrogen in forest soil"
Ding, LY/T 1230-1999 "Determination of nitrate nitrogen in forest soils" and LY/T 1231-1999 "Determination of ammonium nitrogen in forest soils".
This standard is compared with LY/T 1228-1999, LY/T 1229-1999, LY/T 1230-1999 and LY/T 1231-1999.
To change as follows.
--- Added normative references;
--- Determination of total nitrogen increased continuous flow analyzer method and elemental analyzer method;
--- Determination of nitrate nitrogen increased the continuous flow analyzer method;
--- Determination of ammonium nitrogen by the indophenol blue colorimetric method and continuous flow analyzer method;
--- Removed the diffusion method for total nitrogen determination;
---Delete the determination method of ammonium nitrogen in forest soil of LY/T 1231-1999 (magnesium oxide leaching---diffusion method);
--- Modified the Kjeldahl method for total nitrogen determination. semi-automatic nitrogen analyzer and fully automatic nitrogen analyzer instead of semi-micro Kjeldahl distillation unit;
Soil digestion increases the digestion step including nitrate nitrogen and nitrite nitrogen; the distillation and titration steps of ammonium nitrogen are modified.
This standard is proposed and managed by the State Forestry Administration.
This standard was drafted. Forestry Research Institute of Chinese Academy of Forestry.
The main drafters of this standard. Jiao Ruzhen, Dong Yuhong, Sun Qiwu.
introduction
The method for determining total nitrogen in soil is mainly divided into two types. wet burning method and dry burning method. The wet burning method is the sulfuric acid digestion method, and the ammonium nitrogen in the digestion liquid
The measurement methods include a distillation titration method, a diffusion method, and a colorimetric method. Among them, the Kjeldahl method, which is titrated by distillation, is most commonly used.
More improvement, currently used by semi-automatic nitrogen analyzer and automatic nitrogen analyzer. Total nitrogen determination can also be performed using a continuous flow analyzer method
The manual operation is simplified to the automated monitoring of the instrument and the batch samples can be tested continuously. The dry burning method was founded by Dumars in 1831, but
Because the early Dumas method can only detect a few milligrams of samples, its practical application has been greatly limited. In recent years, various automatic
The development of elemental analyzers has made dry burning more and more popular as a routine analysis method for soil elements.
The available nitrogen in the soil varies greatly. The hydrolyzable nitrogen is generally determined by alkali diffusion method in China. This method is easy to operate and the reproducibility of the results is better.
Good, and there is a certain correlation with the nitrogen requirement of forest trees. In recent years, countries have widely used soil ammonium and nitrate nitrogen to replace previous soils.
Hydrolyzable nitrogen index. The determination of ammonium in soil is mainly divided into two methods. direct distillation and leaching. Direct distillation may make the result higher.
At present, it is leached with neutral salt (K2SO4, KCl, NaCl, etc.) solution, generally with 2mol/L KCl solution, ammonium in the extract
The nitrogen can be determined by distillation, colorimetric, ammonia electrode and continuous flow analyzer. Determination of soil nitrate nitrogen, first soluble in water or neutral salt
For liquid extraction, it is required to prepare a clear and colorless extract. The nitrate nitrogen in the extract can be colorimetric, reductive distillation, electrode method, ultraviolet spectrophotometry.
Determined by the method and the continuous flow analyzer method.
Determination of nitrogen in forest soil
1 Scope
This standard specifies the method for determining soil nitrogen in forests. It is determined by Kjeldahl method, continuous flow analyzer method and elemental analyzer method.
Determination of Soil Hydrolyzable Nitrogen in Forest Soil by Total Nitrogen and Alkali Diffusion and Diffusion Method, Determination of Nitrate Nitrogen and Ammonium in Forest Soil by Colorimetric Method and Continuous Flow Analyzer
State nitrogen.
This standard applies to the determination of total nitrogen, hydrolyzable nitrogen, nitrate nitrogen and ammonium nitrogen in forest soil.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
Preparation of GB/T 601 chemical reagent standard titration solution
Preparation of preparations and products used in GB/T 603 test method
GB/T 6682 Analytical laboratory water specifications and test methods
LY/T 1210-1999 Collection and preparation of forest soil samples
3 Determination of total nitrogen
3.1 Kjeldahl method
3.1.1 Method points
The total nitrogen in the soil is decomposed with concentrated sulfuric acid, converted to ammonium nitrogen, alkalized with sodium hydroxide, heated and distilled under the participation of an accelerator.
The ammonia is absorbed by boric acid and titrated with an acid standard solution to determine the total nitrogen content of the soil (not including nitrate nitrogen and nitrite nitrogen). Including nitrate nitrogen and nitrous oxide
Determination of total nitrogen in the soil of nitrogen, before the sample is digested, it is necessary to first oxidize the nitrite nitrogen in the sample to nitrate nitrogen before using the potassium permanganate.
The original iron powder reduces nitrate nitrogen and nitrite nitrogen and converts it into ammonium nitrogen.
3.1.2 Reagents
All reagents were of analytical grade except as noted. Analytical water should meet the specifications of the secondary water in GB/T 6682. Required in the test
Standard titration solutions, preparations and products are prepared in accordance with GB/T 601 and GB/T 603 when no other requirements are indicated.
3.1.2.1 Digestion accelerator
Potassium sulfate (K2SO4) and copper sulfate pentahydrate (CuSO4·5H2O) were mixed at 10.1, finely ground in a mortar, and thoroughly mixed.
3.1.2.2 Sulfuric acid
H2SO4, ρ = 1.84 g/mL.
3.1.2.3 Hydrochloric acid
HCl, ρ = 1.19 g/mL.
Related standard: LY/T 1232-2015    LY/T 1234-2015