Kjeldahl is a professional sample protein measuring instrument widely used in various industries. In the process of measuring with Kjeldahl, many solutions are needed to participate in the reaction, such as sodium hydroxide solution, boric acid solution, ammonium sulfate solution, mixed indicator, etc., then these Kjeldahl analyzers are required. How is the solution prepared?
Before preparing the solution required for Kjeldahl tester, first prepare the required equipment: electric drying oven (room temperature ~ 300 ° C), balance (division value 0.1 mg), A-grade glass measuring device () 1000 ml volumetric flask, 100 ml Volumetric flask, 5000ml reagent bottle, 500ml beaker, 50mL beaker, 10mL graduated pipette, 5mL graduated pipette, etc.). After the preparation is completed, the preparation of the solution can be started, and the preparation process of each type of solution is as follows:
1, sodium hydroxide solution
Weigh 400g of sodium hydroxide, dissolve it in deionized water in a 500mL beaker, cool to room temperature, transfer to a 1000mL volumetric flask, dilute to volume, shake and set aside.
2, ammonium sulfate solution
A. Solution (0.140gN/10ml): Take appropriate amount of ammonium sulfate in a drying oven at 105 ° C, dry to constant weight for at least 4 h, take it out and put it into a desiccator and cool to room temperature. Weigh 6.6065g with a balance, then dilute to 100mL volumetric flask with deionized water, shake and set aside.
B. Solution (0.014gN/10ml): Take 10mL of A solution and dilute to 100ml volumetric flask with deionized water, shake and set aside.
C. Solution (0.0014gN/10ml): Take 10mL of B solution and dilute to 100ml volumetric flask with deionized water, shake and set aside.
3. Boric acid solution
Weigh 20.00g of boric acid, dissolve it in deionized water and dilute to 1000ml volumetric flask, shake it to the reagent bottle for use, add methyl red-bromocresol green mixed indicator in a ratio of 100:1, and mix.
4, mixed indicator
1. Methyl red ethanol solution (1g / L): weigh 0.1g methyl red, dissolved in 95% ethanol, diluted to 100mL with 95% ethanol
2. Bromocresol green ethanol solution (1 g/L): 0.1 g of bromocresol green was weighed, dissolved in 95% ethanol, and diluted to 100 mL with 95% ethanol.
3. Mixing indicator: 1 part of methyl red ethanol solution and 5 parts of bromocresol green ethanol solution are mixed at the time of use.
The above is the preparation method of the solution required by the Kjeldahl nitrogen analyzer. Users who need it can carry out the reference operation. When special instructions are required, the preparation of some solutions has certain risks, such as dilution of concentrated hydrochloric acid, so it must be Operate in accordance with the specifications and take precautions to avoid safety incidents.
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