NY/T 296-1995 Determination of total calcium, magnesium and sodium in soil
Some standard content:
Agricultural Industry Standard of the People's Republic of China
Determination of Total Calcium, Magnesium and Sodium in Soil
Subject Content and Scope of Application
NY/T296-1995
This standard specifies the principle, reagents, instruments and equipment, sample preparation, analysis steps and result presentation of the determination of total calcium, magnesium and sodium in soil. This standard is applicable to the determination of total calcium, magnesium and sodium in soil. 2 Reference Standards
GB7121 Determination of Water Content in Soil
3 Principle
The soil sample is prepared by hydrofluoric acid-perfluoric acid digestion method, or lithium carbonate-hydrogen peroxide, graphite powder glass fusion method (see Appendix A (Supplement)) to prepare the test solution, and the calcium (wavelength 422.7nm) and magnesium (wavelength 285.2nm) contents are determined by atomic absorption spectrophotometry: the sodium (wavelength 589nm) content is determined by flame photometry. When determining calcium and magnesium, a release agent (strontium chloride or lanthanum chloride) needs to be added to overcome the interference of phosphorus, aluminum, high content of titanium and mercapto.
4 Reagents
All reagents are analytically pure except those specified; water refers to deionized water. 4.1 Nitric acid (GB 626, P2O1.42 g/mL). 4.2 Perfluoric acid (GB 623. PZO=1. 67 g/mL). 4.3 Hydrofluoric acid (GB620 not less than 40%). 4.43mol/l. Hydrochloric acid solution: 1 part of hydrochloric acid (GB622, P2U-1.19g/ml.) is mixed with 3 parts of water. 4.520g/l. Boric acid solution: 20.0g of boric acid (GB628) is dissolved in water and diluted to 11. 4.62mol/ Nitric acid solution: 1 part of nitric acid (GB626) is mixed with 7 parts of water. 4.790g/L strontium chloride solution: weigh 90g strontium chloride, add water to dissolve, then dilute to 1L, shake the spoon (this solution contains about 30000mg/1 of strontium).
4.8 Calcium standard preparation solution: 1000m/L, accurately weigh 2.4970g calcium carbonate (SZ3-046, high purity) dried at 110C for 46h. Dissolve in a small amount of hydrochloric acid (1:1), wait until the carbon dioxide is completely released, dilute to 1L with water, and store in a plastic bottle. 4.9 Magnesium standard preparation solution: 1000m%/1, accurately weigh 1.0000g of Jinping magnesium (spectral pure), dissolve in a small amount of hydrochloric acid (1:1), and dilute to 1L with water in a plastic bottle.
4.10 Sodium standard solution: 1000mg/1 Accurately weigh 2.5421g of sodium chloride (standard reagent) that has been pre-dried at 105℃ for 4~~6h, dissolve it in water, make up to 1L, and store it in a plastic bottle. 5 Instruments and equipment
5.1 Soil sieve: pore size 1mm and 0.149mm. 5.2 Agate mortar: diameter 8~12cm.
5.3 Polytetrafluoroethylene crucible volume not less than 30ml. Approved by the Ministry of Agriculture of the People's Republic of China on November 23, 1995 286
Implementation on May 1, 1996
NY/T296-1995
5.4 Electric sand bath with asbestos and electric heating plate: adjustable temperature 5.5 Analytical balance: sensitivity 0.0001g.
5.6 Atomic absorption spectrophotometer.
5.7 Flame photometer.
6 Samples
Take the air-dried soil sample (about 500-1000g) that has passed through the 1mm sieve (5.1) and spread it thinly on kraft paper, divide it into many small squares, take out an equal amount of soil sample from each square with a small spoon (total amount not less than 20g), and further grind it in an agate mortar (5.2) so that it all passes through the 0.119mm aperture sieve. After mixing, put it into a ground-mouth bottle for later use. 7 Analysis steps
7.1 Sample digestion
Weigh 0.5000g of air-dried soil that has passed through a 0.149mm sieve, accurate to 0.0001g, carefully place it in a polytetrafluoroethylene crucible (5.3), add 15l of nitric acid (4.1) and 2.5mL of perchloric acid (4.2), place it in a dry electric second bath or on an electric hot plate (5.4) covered with asbestos cloth, and boil it in a fume hood until it is slightly boiling. When the nitric acid is completely driven out, part of the perchloric acid decomposes to produce a large amount of white smoke, and the sample becomes a paste, remove it and cool it. Use a pipette to add 5mL of hydrofluoric acid (4.3) and 0.5ml of perchloric acid (4.2), place it in a 200225℃ sand bath (5.4) and heat it until the silicate is decomposed. Continue heating until the remaining hydrofluoric acid and perchloric acid are completely driven out and the white smoke stops, then remove it and cool it. Add 10mL of 3mol/1 hydrochloric acid solution (4.4), continue heating until the residue is dissolved (if the residue is not completely dissolved, evaporate the solution to dryness, add 3-5mL of hydrofluoric acid and 0.5mL of perchloric acid, and continue digestion), remove and cool, add 2mL of 20g/1 boric acid solution (4.5), transfer quantitatively into a 250mL volumetric flask with water, and make up to volume. This is the soil digestion solution. At the same time, prepare the reagent blank solution according to the above method. 7.2 Working curve drawing
Accurately pipette 10mL of 1000mg/1 calcium, magnesium, and sodium standard stock solutions (4.8.4.9.4.10), transfer them into 100mL volumetric flasks, and dilute with water to make up to volume. This is the 100m/1 calcium, magnesium, and sodium standard working solution. According to the linear detection range of calcium, magnesium, and sodium of the instrument used, dilute the 100ms/1 calcium, magnesium, and sodium standard working solutions with water to the following standard series solutions. Take 100mg/1. Calcium standard T solution 0.0, 2.5, 5.0, 7.5, 10ml in 5 100mL volumetric flasks, add 2mol/1. nitric acid solution (4.6) and 90g/L chloride solution (4.7) 10mL each, and dilute with water. This standard series of solutions contains calcium 0.0, 2.5, 5.0.7.5, 10 mz/L.
Take 100mg/1. Magnesium standard T solution 0.000.25, 0.50, 0.75, 1.00mL in 5 100mL volumetric flasks, add 2mol/l. nitric acid solution (4.6) and 90g/L strontium chloride solution (4.7) 10ml each, and dilute with water. This standard series of solutions contains magnesium 0.00, 0.25, 0.50, 0.75, 1.00 mg/L. Take 100 mg/mL sodium standard solution 0, 5, 10, 20.30 mL and put them into 5 100 mL volumetric flasks, add 2 mol/L nitric acid solution (4.6) 10 mL respectively, and make up to volume with water. This standard series of solutions contains sodium 0.5, 10, 20, 30 mg/L. Determine calcium and magnesium by atomic absorption spectrophotometry, and determine sodium by flame photometry. Draw working curves for calcium, magnesium, and sodium according to the measured values. 7.3 Determination of calcium and magnesium www.bzxz.net
Take the main digestion solution of the fixed base and dilute it with water until the concentration of calcium and magnesium ions is equivalent to the concentration range of the calcium and magnesium standard series solutions. This is the test solution. Before setting to volume, add 10 ml of 2 mol/L nitric acid solution (4.6) and 90 g/L strontium chloride solution (4.7) to the calcium and magnesium test solutions, so that the acidity of the soil test solution reaches 0.126%~0.200% and the strontium concentration is 3000 mg/ml, and then measure according to the instrument manual. Use the solution with zero calcium and magnesium concentration in the standard series solution to adjust the instrument zero point, and measure the aurora of the calcium and magnesium test solutions and the blank test solution separately. After subtracting the blank test value, find out the corresponding concentration of calcium and magnesium in the test solution from the working curve. 7.4 Determination of sodium
Take a certain amount of sodium digestion solution and dilute it with water until the sodium ion concentration is equivalent to the concentration range of the sodium standard series solution. This is the soil test solution. Before setting to volume, add 10 ml of 2 mol/L nitric acid solution (4.6) to the sodium test solution. So that the acidity of the soil test solution reaches 0.126%~0.200%, and then measure according to the instrument manual. Use the solution with zero sodium concentration in the standard series solution to adjust the instrument zero point, and measure the flame photometric display value of the sodium test solution and the blank test solution. After subtracting the blank test value, find out the corresponding concentration of sodium in the test solution from the working curve. 7.5 Separately weigh the soil sample and determine the soil moisture content according to GB7121. 7.6 Perform no less than two parallel determinations on each soil sample. 8. Expression of analysis results
8.1 Calculation method and formula
The total calcium (magnesium, sodium) content of soil is expressed in nom/k, and is calculated according to the dry soil weight by the following formula: 10-3
Total calcium (magnesium, sodium)××
Wherein: The calcium (magnesium, sodium) concentration of the soil test solution is obtained from the working curve, /L; V,
-digestion solution fixed volume, mL
Vdigestion solution absorption mL
V, test solution fixed volume, ml
-sample weight, nom+
10Conversion factor 1H from mg/L concentration unit to g/k&Conversion factor for converting air-dried soil to oven-dried soil, H——percentage of moisture content in air-dried soil. Expressed as the arithmetic mean of the results of parallel determinations, with one decimal place retained. 8.2 Repeatability
When the measured value is greater than 30g/kg, the relative difference is not greater than 3%; when it is 1030g/kg, the relative difference is not greater than 5%; when it is less than 10g/kg, the relative difference is not greater than 10%. 288
A1 Scope of application
NY/T 296--1995
Appendix A
Lithium carbonate-boric acid, graphite powder fusion method (supplement)
This method is applicable to the determination of total calcium, magnesium and sodium in soil samples when the conditions of hydrofluoric acid-perchloric acid digestion method are not available. A2 Principle
Organic matter and various minerals in the soil are oxidized and decomposed under the action of high temperature and lithium carbonate-boric acid or lithium metaborate flux, and converted into oxides and salts. The molten block is dissolved with nitric acid solution to convert calcium, magnesium and sodium into ionic state. After appropriate dilution, the concentration of calcium and magnesium ions in the solution is determined by atomic absorption spectrophotometer, and the concentration of sodium ions is determined by flame photometry, and then converted into the content of total calcium, total magnesium, and total sodium in the soil.
A3 Reagents
All reagents except those specified are analytically pure, and water refers to deionized water. A3.1 Graphite powder (spectrally pure)
A3.2 Lithium carbonate-boric acid mixed flux (1:2): Weigh 50g lithium carbonate (QB2280) and 100g boric acid (GB628), place in an agate mortar. Grind into powder and store in a plastic bottle for later use. A3.34% (V/V) nitric acid solution: Pipette 40mL nitric acid (pzo=1.42g/mL) into a 1000mL volumetric flask and make up to volume with water. A3.450mg/L lithium solution: weigh 1.3950g lithium metaborate (Q/HG10-1373) into a 1000mL volumetric flask and make up to volume with water. A3.5 Strontium chloride solution: see 4.7.
A3.6 Calcium standard stock solution: see 4.8.
Magnesium standard stock solution: see 4.9.
Sodium standard stock solution: see 4.10.
A4 Instruments and equipment
Soil sieve: see 5.1.
Agate mortar: see 5.2.
Porcelain crucible: volume greater than 30ml.
Muffle furnace: adjustable from room temperature to 1200℃.
Magnetic heating stirrer.
A4.6 Analytical balance: see 5.5.
Atomic absorption spectrophotometer.
Flame photometer.
A5 Sample
See Chapter 6 for sample preparation.
A6 Analysis steps
A6.1 Sample melting
Put graphite powder (A3.1) in a porcelain crucible (A4.3), transfer it into a 900℃ high-temperature muffle furnace (A4.4) after it is filled, burn for 30 minutes, then take it out and cool it at 289
, and press a hole with a flat-headed glass rod. NY/T296—1995
Weigh 0.5000g (accurate to 0.0001g) of air-dried soil that passes through a 0.149mm aperture. Place it on a quantitative filter paper with a diameter of 9cm, mix it thoroughly with 3.75g of lithium carbonate-boric acid mixed flux (A3.2) or 3.75g of anhydrous lithium metaborate, and knead it into a small ball. Put it into the cavity of the graphite powder lined in the cauterized porcelain snail (A4.3), transfer it into the muffle furnace (A4.4), gradually heat it to 950C, keep it for 20 minutes, turn off the power, then take it out, put the sintered block into a beaker containing 100mL 4% nitric acid solution while it is hot, and stir it on a magnetic heating stirrer (A4.5) until it is completely dissolved. Filter the solution into a 250mL volumetric flask, wash the beaker and filter with 4% nitric acid solution (A3.3) in batches, collect the washing liquid into the volumetric flask, and then add 4% nitric acid solution to make up the volume. This is the soil molten solution. At the same time, prepare the reagent blank solution according to the above method. A6.2 Working curve drawing
Accurately take 10mL of each 1000mg/L calcium, magnesium, and sodium standard stock solution (A3.6, A3.7, A3.8), transfer them into 100mL volumetric flasks respectively, and dilute them with water to make up the volume. This is the 100mg/L calcium, magnesium, and sodium standard working solution. According to the linear detection range of calcium, magnesium and sodium of the instrument used, dilute the 100mg/L calcium, magnesium and sodium standard working solutions with 4% nitric acid solution (A3.3) into a standard series solution of not less than three concentrations.
Take 0.0, 2.5, 5.0, 7.5 and 10mL of the 100mg/L calcium standard working solution into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then add 10mL of 90g/L strontium chloride (A3.5) and make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0.0, 2.55.0, 7.5 and 10mg/L calcium. Take 0.0, 0.25, 0.50, 0.75, 1.00mL of 100mg/L magnesium standard working solution and put them into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then add 10mL of 90g/L strontium chloride (A3.5), and make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0.00, 0.250.50, 0.75, 1.00mg/L magnesium. Take 0.5, 10.20, 30mL of 100mg/L sodium standard working solution and put them into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0, 5, 10, 20, 30 mg/L sodium.
Calcium and magnesium were determined by atomic absorption spectrophotometry, and sodium was determined by flame photometry. Working curves for calcium, magnesium, and sodium were drawn according to the measured values. A6.3 Determination of calcium and magnesium
Take a certain amount of soil melt, add 10 ml of 90 g/L strontium chloride (A3.5), dilute with 4% nitric acid solution (A3.3) and make up to the concentration of calcium and magnesium ions equivalent to the concentration range of the calcium and magnesium standard series solutions. This is the soil test solution. Then perform the measurement according to the instrument manual. Use the solution with zero calcium and magnesium concentration in the standard series solution to adjust the instrument zero point, and measure the absorbance of the calcium and magnesium test solutions and the blank test solution respectively. After subtracting the blank test value, the corresponding concentrations of calcium and magnesium in the test solution are found from the working curve. A6.4 Determination of sodium
See 7.4.
A6.5 Separately weigh a soil sample and determine the soil moisture content according to GB7121. A6.6 Each sample shall be measured in parallel for no less than two times. A7 Expression of analytical results
A7.1 Calculation method and formula
See 8.1. Use molten liquid instead of digestion liquid.
A7.2 Repeatability
See 8.2.
Additional remarks:
NY/T296-1995
This standard is proposed by the Ministry of Agriculture of the People's Republic of China. This standard is under the jurisdiction of the National Agricultural Analysis Standardization Technical Committee. This standard was drafted by the Loess Plateau Agricultural Testing Center of the Shaanxi Academy of Agricultural Sciences. The main drafters of this standard are Li Hongen, Guan Qinong and Zhang Yukui. 29110.
A4 Apparatus
Soil sieve: see 5.1.
Agate mortar: see 5.2.
Porcelain crucible: volume greater than 30 ml.
Muffle furnace: adjustable from room temperature to 1200°C.
Magnetic heating stirrer.
A4.6 Analytical balance: see 5.5.
Atomic absorption spectrophotometer.
Flame photometer.
A5 Samples
Sample preparation see Chapter 6.
A6 Analysis steps
A6.1 Sample melting
Put graphite powder (A3.1) in a porcelain crucible (A4.3), transfer it into a 900℃ high-temperature muffle furnace (A4.4) after filling, burn for 30min, then take it out and cool it at 289
, and press a hole with a flat-headed glass rod. NY/T296—1995
Weigh 0.5000g (accurate to 0.0001g) of air-dried soil that passes through a 0.149mm aperture. Place it on a quantitative filter paper with a diameter of 9cm, mix it thoroughly with 3.75g of lithium carbonate-boric acid mixed flux (A3.2) or 3.75g of anhydrous lithium metaborate, and knead it into a small ball. Put it into the cavity of the graphite powder lined in the cauterized porcelain snail (A4.3), transfer it into the muffle furnace (A4.4), gradually heat it to 950C, keep it for 20 minutes, turn off the power, then take it out, put the sintered block into a beaker containing 100mL 4% nitric acid solution while it is hot, and stir it on a magnetic heating stirrer (A4.5) until it is completely dissolved. Filter the solution into a 250mL volumetric flask, wash the beaker and filter with 4% nitric acid solution (A3.3) in batches, collect the washing liquid into the volumetric flask, and then add 4% nitric acid solution to make up the volume. This is the soil molten solution. At the same time, prepare the reagent blank solution according to the above method. A6.2 Working curve drawing
Accurately take 10mL of each 1000mg/L calcium, magnesium, and sodium standard stock solution (A3.6, A3.7, A3.8), transfer them into 100mL volumetric flasks respectively, and dilute them with water to make up the volume. This is the 100mg/L calcium, magnesium, and sodium standard working solution. According to the linear detection range of calcium, magnesium and sodium of the instrument used, dilute the 100mg/L calcium, magnesium and sodium standard working solutions with 4% nitric acid solution (A3.3) into a standard series solution of not less than three concentrations.
Take 0.0, 2.5, 5.0, 7.5 and 10mL of the 100mg/L calcium standard working solution into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then add 10mL of 90g/L strontium chloride (A3.5) and make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0.0, 2.55.0, 7.5 and 10mg/L calcium. Take 0.0, 0.25, 0.50, 0.75, 1.00mL of 100mg/L magnesium standard working solution and put them into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then add 10mL of 90g/L strontium chloride (A3.5), and make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0.00, 0.250.50, 0.75, 1.00mg/L magnesium. Take 0.5, 10.20, 30mL of 100mg/L sodium standard working solution and put them into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0, 5, 10, 20, 30 mg/L sodium.
Calcium and magnesium were determined by atomic absorption spectrophotometry, and sodium was determined by flame photometry. Working curves for calcium, magnesium, and sodium were drawn according to the measured values. A6.3 Determination of calcium and magnesium
Take a certain amount of soil melt, add 10 ml of 90 g/L strontium chloride (A3.5), dilute with 4% nitric acid solution (A3.3) and make up to the concentration of calcium and magnesium ions equivalent to the concentration range of the calcium and magnesium standard series solutions. This is the soil test solution. Then perform the measurement according to the instrument manual. Use the solution with zero calcium and magnesium concentration in the standard series solution to adjust the instrument zero point, and measure the absorbance of the calcium and magnesium test solutions and the blank test solution respectively. After subtracting the blank test value, the corresponding concentrations of calcium and magnesium in the test solution are found from the working curve. A6.4 Determination of sodium
See 7.4.
A6.5 Separately weigh a soil sample and determine the soil moisture content according to GB7121. A6.6 Each sample shall be measured in parallel for no less than two times. A7 Expression of analytical results
A7.1 Calculation method and formula
See 8.1. Use molten liquid instead of digestion liquid.
A7.2 Repeatability
See 8.2.
Additional remarks:
NY/T296-1995
This standard is proposed by the Ministry of Agriculture of the People's Republic of China. This standard is under the jurisdiction of the National Agricultural Analysis Standardization Technical Committee. This standard was drafted by the Loess Plateau Agricultural Testing Center of the Shaanxi Academy of Agricultural Sciences. The main drafters of this standard are Li Hongen, Guan Qinong and Zhang Yukui. 29110.
A4 Apparatus
Soil sieve: see 5.1.
Agate mortar: see 5.2.
Porcelain crucible: volume greater than 30 ml.
Muffle furnace: adjustable from room temperature to 1200°C.
Magnetic heating stirrer.
A4.6 Analytical balance: see 5.5.
Atomic absorption spectrophotometer.
Flame photometer.
A5 Samples
Sample preparation see Chapter 6.
A6 Analysis steps
A6.1 Sample melting
Put graphite powder (A3.1) in a porcelain crucible (A4.3), transfer it into a 900℃ high-temperature muffle furnace (A4.4) after filling, burn for 30min, then take it out and cool it at 289
, and press a hole with a flat-headed glass rod. NY/T296—1995
Weigh 0.5000g (accurate to 0.0001g) of air-dried soil that passes through a 0.149mm aperture. Place it on a quantitative filter paper with a diameter of 9cm, mix it thoroughly with 3.75g of lithium carbonate-boric acid mixed flux (A3.2) or 3.75g of anhydrous lithium metaborate, and knead it into a small ball. Put it into the cavity of the graphite powder lined in the cauterized porcelain snail (A4.3), transfer it into the muffle furnace (A4.4), gradually heat it to 950C, keep it for 20 minutes, turn off the power, then take it out, put the sintered block into a beaker containing 100mL 4% nitric acid solution while it is hot, and stir it on a magnetic heating stirrer (A4.5) until it is completely dissolved. Filter the solution into a 250mL volumetric flask, wash the beaker and filter with 4% nitric acid solution (A3.3) in batches, collect the washing liquid into the volumetric flask, and then add 4% nitric acid solution to make up the volume. This is the soil molten solution. At the same time, prepare the reagent blank solution according to the above method. A6.2 Working curve drawing
Accurately take 10mL of each 1000mg/L calcium, magnesium, and sodium standard stock solution (A3.6, A3.7, A3.8), transfer them into 100mL volumetric flasks respectively, and dilute them with water to make up the volume. This is the 100mg/L calcium, magnesium, and sodium standard working solution. According to the linear detection range of calcium, magnesium and sodium of the instrument used, dilute the 100mg/L calcium, magnesium and sodium standard working solutions with 4% nitric acid solution (A3.3) into a standard series solution of not less than three concentrations.
Take 0.0, 2.5, 5.0, 7.5 and 10mL of the 100mg/L calcium standard working solution into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then add 10mL of 90g/L strontium chloride (A3.5) and make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0.0, 2.55.0, 7.5 and 10mg/L calcium. Take 0.0, 0.25, 0.50, 0.75, 1.00mL of 100mg/L magnesium standard working solution and put them into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then add 10mL of 90g/L strontium chloride (A3.5), and make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0.00, 0.250.50, 0.75, 1.00mg/L magnesium. Take 0.5, 10.20, 30mL of 100mg/L sodium standard working solution and put them into 5 100mL volumetric flasks, add 10mL of 50mg/L lithium solution (A3.4) respectively, so that the standard series solution contains 5mg/L lithium; then make up to volume with 4% nitric acid solution (A3.3). This standard series solution contains 0, 5, 10, 20, 30 mg/L sodium.
Calcium and magnesium were determined by atomic absorption spectrophotometry, and sodium was determined by flame photometry. Working curves for calcium, magnesium, and sodium were drawn according to the measured values. A6.3 Determination of calcium and magnesium
Take a certain amount of soil melt, add 10 ml of 90 g/L strontium chloride (A3.5), dilute with 4% nitric acid solution (A3.3) and make up to the concentration of calcium and magnesium ions equivalent to the concentration range of the calcium and magnesium standard series solutions. This is the soil test solution. Then perform the measurement according to the instrument manual. Use the solution with zero calcium and magnesium concentration in the standard series solution to adjust the instrument zero point, and measure the absorbance of the calcium and magnesium test solutions and the blank test solution respectively. After subtracting the blank test value, the corresponding concentrations of calcium and magnesium in the test solution are found from the working curve. A6.4 Determination of sodium
See 7.4.
A6.5 Separately weigh a soil sample and determine the soil moisture content according to GB7121. A6.6 Each sample shall be measured in parallel for no less than two times. A7 Expression of analytical results
A7.1 Calculation method and formula
See 8.1. Use molten liquid instead of digestion liquid.
A7.2 Repeatability
See 8.2.
Additional remarks:
NY/T296-1995
This standard is proposed by the Ministry of Agriculture of the People's Republic of China. This standard is under the jurisdiction of the National Agricultural Analysis Standardization Technical Committee. This standard was drafted by the Loess Plateau Agricultural Testing Center of the Shaanxi Academy of Agricultural Sciences. The main drafters of this standard are Li Hongen, Guan Qinong and Zhang Yukui. 2913 Determination of calcium and magnesium
Take a certain amount of soil molten liquid, add 10ml of 90g/L strontium chloride (A3.5), dilute with 4% nitric acid solution (A3.3) and make up to the concentration of calcium and magnesium ions equivalent to the concentration range of the calcium and magnesium standard series solutions. This is the soil test solution. Then perform the measurement according to the instrument manual. Use the solution with zero calcium and magnesium concentration in the standard series solution to adjust the instrument zero point, and measure the absorbance of the calcium and magnesium test solutions and the blank test solution respectively. After subtracting the blank test value, find out the corresponding concentration of calcium and magnesium in the test solution from the working curve. A6.4 Determination of sodium
See 7.4.
A6.5 Separately weigh a soil sample and determine the soil moisture content according to GB7121. A6.6 Perform no less than two parallel measurements for each soil sample. A7 Expression of analysis results
A7.1 Calculation method and formula
See 8.1. Replace the digestion solution with the molten liquid.
A7.2 Repeatability
See 8.2.
Additional remarks:
NY/T296-1995
This standard was proposed by the Ministry of Agriculture of the People's Republic of China. This standard is under the jurisdiction of the National Agricultural Analysis Standardization Technical Committee. This standard was drafted by the Loess Plateau Agricultural Testing Center of the Shaanxi Academy of Agricultural Sciences. The main drafters of this standard are Li Hongen, Guan Qinong and Zhang Yukui. 2913 Determination of calcium and magnesium
Take a certain amount of soil molten liquid, add 10ml of 90g/L strontium chloride (A3.5), dilute with 4% nitric acid solution (A3.3) and make up to the concentration of calcium and magnesium ions equivalent to the concentration range of the calcium and magnesium standard series solutions. This is the soil test solution. Then perform the measurement according to the instrument manual. Use the solution with zero calcium and magnesium concentration in the standard series solution to adjust the instrument zero point, and measure the absorbance of the calcium and magnesium test solutions and the blank test solution respectively. After subtracting the blank test value, find out the corresponding concentration of calcium and magnesium in the test solution from the working curve. A6.4 Determination of sodium
See 7.4.
A6.5 Separately weigh a soil sample and determine the soil moisture content according to GB7121. A6.6 Perform no less than two parallel measurements for each soil sample. A7 Expression of analysis results
A7.1 Calculation method and formula
See 8.1. Replace the digestion solution with the molten liquid.
A7.2 Repeatability
See 8.2.
Additional remarks:
NY/T296-1995
This standard was proposed by the Ministry of Agriculture of the People's Republic of China. This standard is under the jurisdiction of the National Agricultural Analysis Standardization Technical Committee. This standard was drafted by the Loess Plateau Agricultural Testing Center of the Shaanxi Academy of Agricultural Sciences. The main drafters of this standard are Li Hongen, Guan Qinong and Zhang Yukui. 291
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