Starch VOLUME

Starch Iodide coloration. To a small volume of starch solution ... 

Absolute diethyl ether. The chief impurities in commercial ether (sp. gr. 0- 720) are water, ethyl alcohol, and, in samples which have been exposed to the air and light for some time, ethyl peroxide. The presence of peroxides may be detected either by the liberation of iodine (brown colouration or blue colouration with starch solution) when a small sample is shaken with an equal volume of 2 per cent, potassium iodide solution and a few drops of dilute hydrochloric acid, or by carrying out the perchromio acid test of inorganic analysis with potassium dichromate solution acidified with dilute sulphuric acid. The peroxides may be removed by shaking with a concentrated solution of a ferrous salt, say, 6-10 g. of ferrous salt (s 10-20 ml. of the prepared concentrated solution) to 1 litre of ether. The concentrated solution of ferrous salt is prepared either from 60 g. of crystallised ferrous sulphate, 6 ml. of concentrated sulphuric acid and 110 ml. of water or from 100 g. of crystallised ferrous chloride, 42 ml. of concentrated hydiochloric acid and 85 ml. of water. Peroxides may also be removed by shaking with an aqueous solution of sodium sulphite (for the removal with stannous chloride, see Section VI,12). 

The experimental conditions necessary for the preparation of a solution of a diazonium salt, diazotisation of a primary amine, are as follows. The amine is dissolved in a suitable volume of water containing 2 5-3 equivalents of hydrochloric acid (or of sulphuric acid) by the application of heat if necessary, and the solution is cooled in ice when the amine hydrochloride (or sulphate) usually crystallises. The temperature is maintained at 0-5°, an aqueous solution of sodium nitrite is added portion-wise until, after allowing 3-4 minutes for reaction, the solution gives an immediate positive test for excess of nitrous acid with an external indicator—moist potassium iodide - starch paper f ... 

Dissolve 20 g, (19 -6 ml.) of anihne in a mixture of 55 ml. of concentrated hydrochloric acid (1) and 55 ml. of water contained in a 350 ml, conical flask. Place a thermometer in the solution and immerse the flask in a bath of crushed ice (2) cool until the temperature of the stirred solution falls below 5°, Dissolve 16 g. of sodium nitrite in 75 ml. of water and chUl the solution by immersion in the ice bath add the sodium nitrite solution (3) in small volumes (2-3 ml. at a time) to the cold anihne hydrochloride solution, and keep the latter weh stirred with the thermometer. Heat is evolved by the reaction. The temperature should not be allowed to rise above 10° (add a few grams of ice to the reaction mixture if necessary) otherwise appreciable decomposition of the diazonium compound and of nitrous acid wih occur. Add the last 5 per cent, of the sodium nitrite solution more slowly (say, about 1 ml. at a time) and, after stirring for 3-4 minutes, test a drop of the solution diluted with 3-4 drops of water with potassium iodide - starch paper (4) if no immediate blue colour... 

The purity of a sample of Na2S203 was determined by a coulometric redox titration using as a mediator, and as the titrant. A sample weighing 0.1342 g is transferred to a 100-mL volumetric flask and diluted to volume with distilled water. A 10.00-mL portion is transferred to an electrochemical cell along with 25 mL of 1 M KI, 75 mL of a pH 7.0 phosphate buffer, and several drops of a starch indicator solution. Electrolysis at a constant current of 36.45 mA required 221.8 s to reach the starch indicator end point. Determine the purity of the sample. 

Fine grinding and air classification make possible the production of some cake flour from hard wheat and some bread flour or high-protein fractions from soft wheat. AppHcation of the process theoretically frees the miller from dependence on different wheats, either hard or soft, that change each crop year. The problem is how to market the larger volume of low protein or starch fractions at prices adequate to justify the installation and operation of the special equipment (46). 

Starches are quite hydrophilic and the granules swell in water to several times their volume. In the preparation of starches for coating, the granules are heated at 93°C to ensure complete breakdown. The starch is then mixed with the pigment while it is fluid. Normal practice is to coat the paper at an elevated temperature to help control viscosity. 

Binders. Paper-coating biaders are either polymers derived from aatural sources or syathetic polymers. The largest volume, aaturally derived biader is starch (qv) (99). Starch is provided ia derivatized form or unmodified form pead com starch is used predomiaanfly for the latter. Unmodified starch is solubilized by thermal conversion or enzyme conversion. The most common derivatized products are acetylated [9045-28-7] oxidized, and hydroxyethylated starches. 

The fermentation industry is based almost exclusively on renewable materials in the form of molasses, starch, etc. Most products are of very high value and relatively low volume such as antibiotics (qv) (23). 

The growth in volume of the enzyme business from 1980 to 1990 is estimated to be 5—10% per year. The estimated worldwide enzyme sales per industry are shown in Table 7. The detergent and starch conversion industries are by far the most important, and account for 60% of total enzyme sales. Five principal industries account for around 85% of enzyme sales, whereas the remaining sales are spread over many different industries. 

A simple test for ether peroxides is to add lOmL of the ether to a stoppered cylinder containing ImL of freshly prepared 10% solution of potassium iodide containing a drop of starch indicator. No colour should develop during one minute if free from peroxides. Alternatively, a 1% solution of ferrous ammonium sulfate, O.IM in sulfuric acid and O.OIM in potassium thiocyanate should not increase appreciably in red colour when shaken with two volumes of the ether. 

In this reaction, iodine is liberated from a solution of potassium iodide. This reaction can be used to assess the amount of ozone in either air or water. For determination in air or oxygen, a measured volume of gas is drawn through a wash bottle containing potassium iodide solution. Upon lowering the pH with acid, titration is effected with sodium thiosulfate, using a starch solution as an indicator. There is a similar procedure for determining ozone in water. 

Components of a highly short chain branched (scb) waxymaize and a more long chain branched (Icb) amylomaize were separated on the semipreparative Sephacryl S-1000 system. Both samples contained high dp components that eluted in the exclusion volume, but the percentage of these components was quite different 90% for the scb waxymaize starch and approximately 10% for the Icb amylomaize starch (Fig. 16.6). The degree of polymerization averages for these samples was determined utilizing the previously established linear... 

Carbon tetrachloride has been used in certain reactions instead of starch solution. One litre of water at 25 °C will dissolve 0.335 g of iodine, but the same volume of carbon tetrachloride will dissolve about 28.5 g. Iodine is therefore about 85 times as soluble in carbon tetrachloride as it is in water, and the carbon... 

Only freshly prepared starch solution should be used. Two millilitres of a 1 per cent solution per 100 mL of the solution to be titrated is a satisfactory amount the same volume of starch solution should always be added in a titration. In the titration of iodine, starch must not be added until just before the end point is reached. Apart from the fact that the fading of the iodine colour is a good indication of the approach at the end point, if the starch solution is added when the iodine concentration is high, some iodine may remain adsorbed even at the end point. The indicator blank is negligibly small in iodimetric and iodometric titrations of 0.05M solutions with more dilute solutions, it must be determined in a liquid having the same composition as the solution titrated has at the end point. 

Procedure. Pipette 25.0 mL standard (0.05M) iodine solution into a 500 mL conical flask and add 5 mL 2M hydrochloric acid and 150 mL distilled water. Weigh accurately sufficient solid sulphite to react with about 20 mL 0.05M iodine solution and add this to the contents of the flask swirl the liquid until all the solid has dissolved and then titrate the excess iodine with standard (0.1M) sodium thiosulphate using starch indicator. If the sulphite is in solution, then a volume of this equivalent to about 20 mL of 0.05M iodine should be pipetted into the contents of the flask in place of the weighed amount of solid. 

Ethanol, CH3CH2OH, is produced from the biological fermentation of the starches in grains, mainly corn. It currently makes up about 10% by volume of gasoline in the United States, thereby reducing pollution as well as the use of petroleum. The oxygen atom in the ethanol molecule reduces emissions of carbon monoxide and hydrocarbons by helping to ensure complete combustion. One bushel of... 

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