KI starch test

Weigh to 0.1 mg 2.5 to 3 g of the purified aniline, transfer to a 1 1 volumetric flask contg 900 ml distd w and 50 ml coned HCl. Fill the flask to the mark and shake it until the soln is uniform. Transfer a 100 ml aliquot to a 400 ml beaker, add 10 ml coned HCI and cool the soln to 15°. Titrate slowly with the 0.2N KBrO,-KBr soln. Near the end of titration, test, after the addition of each drop of die soln, by spotting KI-starcH test paper. The end point is indicated by the It blue coloration which can be duplicated after a 2-tnin period. When the end point is reached, an addnl drop of the KBrOj KBr soln will color the mixt yel, thereby corroborating the end point indicated hy the test paper. Calculate the normality of KBrOs KBr by the following formula ... 

Heat test (Abel test). The oldest and the most popular qualitative test is the heat test introduced in Great Britain by Abel in 1865 [86]. It is called the Abel test on the Continent of Europe and the KI starch test in the U.S.A. It consists in warming a sample of nitroglycerine or nitrocellulose (or dynamite or smokeless powder) in a test tube in which a potassium iodide-starch paper moistened with aqueous glycerol solution is suspended (Fig. 1). Warming is carried out until the... 

KI-Starch Test. See Abel s Test A2-L Kreulen, Aluminum Block of A145 L... 

KI-Teat Test or Kl-Starch Test. Same as Abel Test... 

Stability. When subjected to 82.2°C heat test as described in 4.3.4, NG shall not change the color of the std KI-Starch paper in less than 10 mins... 

Abel s Test or Kl—Starch Test was designed by Sir F. A.Abel to determine the stability of propellants and explosives. It involved heating a small sample of an expl in a test tube closed with a stopper provided with a hook on which is suspended a strip of KI—Starch paper, moistened at the upper half with 50% glycerin in water. The tube is heated in a constant temp bath and the time necessary to produce a slight brownish (or other) coloration at the border between the moistened and dry areas of the indicator paper is observed. The longer the time required the greater the stability of substance under test. The test is usually conducted either at 65.5° or 82.2°, but other temps may also be used. More detailed descriptions of the test are given under propellants and under some expls, such as TNT... 

Abel s Test(KI Heat Test or Kl-Starch Test) (Epreuve d Abel, in Fr.) A brief description is given on pA2 of this volume. The test is also described in TM 9—1910(1955)>57—60... 

Procedure. Ten tests are done in series 0.1ml of horse Hb solution is pipetted into each beaker 0.020 ml serum is added to nine of the beakers. The content of the remaining one is used as a blank. Three ml 0.1 M KI is added to each beaker. A mixture of 100 ml acetate buffer, 10 ml ethyl hydroperoxide solution and 10ml iodine solution (8) is then prepared. (This mixture is only fit for use for 20 minutes.) At 60-second intervals 10 ml of this mixture is added to the beakers. Nine minutes and 15 seconds after the addition, 2 drops of starch solution are added, and titration with 0.01 N Na2SaOa is started after 9 minutes and 30 seconds. The titration should last, as closely as possible, 30 seconds. The temperature is measured in the reaction mixture. 

Anon, "Military Explosives , PATR 9-1910/TO 11A-1-34(1955) Sensitivity to Impact (pp 43-7) Sensitivity to Friction (47-9) Sensitivity to Frictional Impact, which includes Rifle Bullet Impact Test (49) Sensitivity to Heat and Spark, which includes Explosion Temperature Test (49-52) Sensitivity to Initiation by Sand Test (52-3 Fig 10 on p 54) Stability Determinations, which include 75°C International Test, 100°C Heat Test, Vacuum Stability Test, and Potassium Iodide-Starch (KI)... 

A) Anon, IEC, NewEdn, 14, 305(1936)(Peroxide formation in ethers and a test for peroxides in ether) [Procedure a) Add 10ml ether (sample to test) to 150ml of 2N sulfuric acid soln, followed by 3 drops of 1% soln of Amm molybdate (a catalyst to favor the liberation of dine) and 15ml of 10% KI soln. Shake well aiiJ allow to stand for 15 mins b) Titrate the liberated iodine with 0.05N Na thiosulfate and shake well after each addn until near discoloration of soln c) Add a few cc of starch soln and continue titration until disappearance of blue color]... 

The acids attack KI and the liberated iodine colors the starch paper c)Koehler Mar-querol(Ref 2) do not recommend the use of Abel s test for NC propellants contg Ca carbonate - Bergmann-Junk test(qv) gives more reliable results... 

Starch in helical conformation is indicated by the blue color developed with iodine. In a typical test, a tissue or extract is submerged in a KIS solution. DP heterogeneity is a factor the higher the DP, the higher is the I2 absorption and the more intense is the violet-blue color. The starch-iodine reaction is sensitive enough for starch to be a titrimetric indicator of I2, mindful of the nonstoichiometry and nonspecificity of the reaction. 

After the original solution has passed into the column and the effluent has been satisfactorily freed of the 7-min phosphate (i.e., glucose-1-phosphate should have bound to the column), wash the column with deionized H20 until the effluent no longer gives a positive test for starch (i.e., a blue color forms on mixing a drop of effluent with a drop of 0.01 M I2 in 0.01 M KI). About 500 ml of water will be required to remove all of the starch from the column. 

Notes a)Although this test is one of the oldest in existence, it is still used very extensively b)In this test, nitrogen dioxide, which starts to evolve at the moment of decompn of a propellant or an expl, forms, on contact with wetted portion of the test paper, a mixture of nitrous and nitric acid. The acids attack KI and the liberated iodine colors the starch paper c)Koehler Mar-querol(Ref 2) do not recommend the use of Abel s test for NC propellants contg Ca carbonate — Bergmann—Junk test(qv) gives more reliable results... 

Reaction Sequence A 100 mL of a 1C % aqueous solution of KI are placed in each Erlenmeyer flask. 100 ml, of chlorine water are added to one flask, 100 mL of bromine water to the other in both cases the solution immediately turns brown. The contents of the two flasks are now transferred to the five large test tubes, to which the following substances are added test tube 1, freshly pre pared starch solution test tube 2, a few grams of solid KI test tube 3, diethyl ether test tube 4, toluene test tube 5, -hcxanc (or -hcptanc). The contents of the first test tube turn to a deep blue-black, while the brown color in the second becomes much deeper. In the other test tubes two layers are formed in each case the lower aqueous layer is much lighter in color, while the upper organic layer.s arc colored yellow(test tube 3), wine-red (test tube 4) and violet (test tube 5) respectively. 

In the test method (ASTM D-2078), a sample is dissolved in chloroform and reacted with Wijs solution for 30 min in the dark at 25°C. At the end of the reaction, the solution is mixed with potassium iodide (KI) and titrated with sodium thiosulfate and starch indicator and compared to a blank determination. 

In both tests, the iodine is set free, for combined iodine has no action on starch. In the chlorine test, the superior affinity of chlorine seizes on the metal with which the iodine is united— thus KI + Cl = KCl + I. 

---