How to detect calcium content in sodium alginate, and the detection method of calcium content in sodium alginate

　With the wide application of food and industrial medical treatment, sodium alginate has been gradually accepted by enterprises. Today, Qingdao sodium alginate manufacturers share with you how to detect the calcium content of sodium alginate and the detection methods of calcium content of sodium alginate:
　

　　 　Principle: After the sodium alginate sample is dissolved, sodium hydroxide is added to make the pH of the solution greater than 12, triethanolamine is added as masking agent, calcium red is used as indicator, calcium is complexly titrated with standard EDTA solution, and the content of calcium is calculated with the consumed EDTA standard solution.

　　Reagents: All reagents used are analytically pure, and the water is distilled water.

　　(i) Sodium hydroxide solution 2moI/L: Weigh 8g of sodium hydroxide and add water to dilute it to 100mL.

　　(ii) Triethanolamine 10%: measure 10mL of Triethanolamine, add 90mL of water and mix well.

　　(iii) EDTA standard solution 0.01moI/L: refer to GB601— Preparation and calibration in April 15, 2002.

　　4. Calcium red indicator 2%: Take 2g of calcium red indicator, add 100g of solid sodium chloride, mix and grind it in a mortar, and put it in a brown jar.

　　Determination: accurately weigh 0.5g of sodium alginate sample (calibrated to 0.002g) in a 250mL beaker or conical flask, add 100mL of water to dissolve it (heat it if necessary), add 5mL of 2moI/L sodium hydroxide solution, stir it evenly, then add 1mL of 10% triethanolamine solution and 0.1g of solid calcium red indicator, after dissolution, use a 10mL burette with constant stirring.

　　Result calculation:

　　Calcium content of sodium alginate is calculated according to the following formula.

　　X6=( c×V×0.040 08)÷m9×100

　　Where:

　　X6— — Calcium content in the sample, in percentage (%);

　　c— — Molar concentration of EDTA standard solution in mole per liter (moI/L);

　　V— — Volume of EDTA standard solution used for titration, in milliliter (mL);

　　m9— — Sample mass, in grams (g);

　　0.040 08— — The mass of calcium expressed in milligrams equivalent to 1.00mLEDTA standard solution [c(EDTA)=0.01moI/L].

　　Repeatability:

　　Take two parallel samples from each sodium alginate sample for determination, and take its arithmetic average as the result.

　　The relative deviation of the results of two parallel samples is allowed to be less than 5%, otherwise it will be redone.