Starch paste. Preparation

N/20-iodine solution, N/20-sodium thiosulphate solution, and starch paste prepared as in (a). 

Harrod, M. 1989. Modelling of flow properties of starch pastes prepared by different procedures. J. Food... 

The assay determination of sulfamic acid is made by titration of an accurately prepared sulfamic acid solution using sodium nitrite solution and an external potassium iodide starch-paste indicator. It is based on the reaction... 

Standard 1/10 N nitrite is used to titrate a solution prepared by dissolving 10—100 mg of sulfamic acid and about 6 mL of (1 + 1) H2SO4 in 300 mL of distilled water at 40—50°C. At the end point, the colorless external potassium iodide starch-paste indicator changes to blue. A 1-mL solution of 1/ION NaN02 is equivalent to 9.709 mg of sulfamic acid. The 1/10 N nitrite titrant solution is standardized using primary standard-grade sulfamic acid. For sulfamate assay determination, the same procedure is used as for sulfamic acid. 

C. F. Schonbein also prepared ammonium hypobromite by a process analogous to that employed for the hypochlorite, and obtained a liquid with similar oxidizing properties. The liquid is assumed to contain a mixture of ammonium hypobromite and bromide. C. F. Schonbein likewise inferred the transient formation of ammonium hypoiodite when iodine water and aqueous ammonia are mixed, whereby the liquid is decolorized. The soln. gave a deep blue coloration with starch paste and potassium iodide, etc., and behaved like analogous soln. of the alkali... 

Starch paste is prepared by mixing 15 grams of arrowroot starch with 40 c.c. of cold water and pouring the paste into 400 c.c. of boiling water, the liquid being then kept in a boiling water-bath for half an hour with frequent stirring and subsequently allowed to cool and made up to 500 c.c. with water. 

On repeated administration of the preparation to healthy rats at a 100 mg/kg dose with a break for 72 hours no toxic signs were observed. After 5 injections the weight of the animals increased by 34.6% and after 10 injections by 69.5%. The amount of leucocytes in peripheral blood increased from 8900 to 13600 per mm3 after 5 injections and remained at this level until the injections were stopped. (The preparation was injected per os as a suspension in 1% starch paste). 

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