2.3. IDENTIFICATION - uspbpep.com

1 EUROPEAN PHARMACOPOEIA IDENTIFICATION reactions of ions and functional IDENTIFICATION01/2008 IDENTIFICATION REACTIONSOF IONS AND FUNCTIONAL GROUPSACETATESa) Heat the substance to be examined with an equal quantityofoxalic acid R. Acid vapours with the characteristic odourof acetic acid are liberated, showing an acid reaction ( ).b) Dissolve about 30 mg of the substance to be examined in3mlofwater Ror use 3 ml of the prescribed solution. Addsuccessively ml oflanthanum nitrate solution R, M iodineand ml ofdilute ammonia to boiling. Within a few minutes a blue precipitateis formed or a dark blue colour a test-tube about 180 mm long and 18 mm in externaldiameter, place about 15 mg of the substance to be examined,ortheprescribedquantity, small test-tube about 100 mm long and 10 mm in externaldiameter containingwater Rto act as a condenser.

2 On theoutside of the smaller tube, hang a drop oflanthanumnitrate solution R. Except for substances hydrolysable onlywith difficulty, place the apparatus in a water-bath for 5 min,then take out the smaller tube. Remove the drop and mixit with ml M iodineon a tile. Add at the ml ofdilute ammonia R2. After 1 min to 2 min, a bluecolour develops at the junctionofthetwodrops;thecolourintensifi es and persists for a short hydrolysable only with difficultyheat themixture slowly to boiling over an open flame and ,or the prescribed quantity, in 5 ml ofwater R,adddilutehydrochloric acid Runtilanacidreactionoccurs( ),then 1 ml ofpotassium iodobismuthate solution or orange-red precipitate is formed about 15 mg of the substance to be examined in2mlofwater Ror use 2 ml of the prescribed solution.

3 Addabout ml ofdilute hydrochloric acid Rand about mlofthioacetamide reagent R. No precipitate is formed. Adddropwisedilute sodium hydroxide solution precipitate is formed which dissolves on furtheraddition ofdilute sodium hydroxide solution chloride solution is , PRIMARY AROMATICA cidify the prescribed solution withdilute hydrochloricacid Rand add ml ofsodium nitrite solution ,add1mlof -naphthol solution orange or red colour and usually a precipitate of thesame colour are SALTSTo the prescribed solution add g ofmagnesium oxide a current of air through the mixture and direct thegas that escapes just beneath the surface of a mixture M hydrochloric acidand ml ofmethyl redsolution R.

4 The colour of the indicator changes to addition of 1 ml of a freshly prepared 100 g/l solution ofsodium cobaltinitrite SALTS AND SALTS OF VOLATILE BASESD issolve about 20 mg of the substance to be examined in2mlofwater sodium hydroxide solution ,thesolution gives off vapour that can be identified by its odourand by its alkaline reaction ( ).ANTIMONYD issolve with gentle heating about 10 mg of the substanceto be examined in a solution of g ofsodium potassiumtartrate Rin 10 ml ofwater Rand allow to cool: to 2 mlof this solution, or to 2 ml of the prescribed solution,addsodium sulphide solution Rdropwise; an orange-redprecipitate is formed which dissolves on addition ofdilutesodium hydroxide solution 5 ml of the prescribed solution on a water-bath withan equal volume ofhypophosphorous reagent is , NON-NITROGEN SUBSTITUTEDD issolve about 5 mg of the substance to be examined in 3 mlofmethanol R, add ml of a solution containing 100 g/lofcobalt nitrate Rand 100 g/l ofcalcium chloride add, with shaking, ml ofdilute sodium hydroxidesolution R.

5 A violet-blue colour and precipitate are ) To 1 ml of the prescribed solution add ml offerricchloride solution R1. A dull-yellow precipitate, soluble inether R, ) ,treatedifnecessary as prescribed, in a test-tube. Moisten with mlto ml ofsulphuric acid R. Gently warm the bottom of thetube. A white sublimate is deposited on the inner wall ofthe ) Dissolve g of the substance to be examined in 10 mlofwater Ror use 10 ml of the prescribed solution. ml ofhydrochloric acid R. The precipitate obtained,after crystallisation from warmwater Rand dryingin vacuo,has a melting point ( )of120 Cto124 ) To g of the substance to be examined add 10 ml ofdilute hydrochloric acid Ror use 10 ml of the prescribedsolution.

6 Heat to boiling for 1 min. Cool and filter ifnecessary. To 1 ml of the solution obtained add 20 ml ofwater R. A white or slightly yellow precipitate is formedwhich on addition of ml to ml ofsodium sulphidesolution Rturns )Toabout45mgofthesubstancetobeexaminedad d10 ml ofdilute nitric acid Ror use 10 ml of the prescribedsolution. Boil for 1 min. Allow to cool and filter if 5 ml of the solution obtained add 2 ml of a 100 g/lsolution ofthiourea R. A yellowish-orange colour or anorange precipitate is formed. Add 4 ml of a 25 g/l solutionofsodium fluoride R. The solution is not decolorised within30 ) Dissolve in 2 ml ofwater Ra quantity of the substanceto be examined equivalent to about 3 mg of bromide (Br )or use 2 ml of the prescribed solution.

7 Acidify withdilutenitric acid Rand add ml ofsilver nitrate solution (1) IDENTIFICATION reactions of ions and functional groupsEUROPEAN PHARMACOPOEIA and allow to stand. A curdled, pale yellow precipitateis formed. Centrifuge and wash the precipitate with threequantities, each of 1 ml, ofwater R. Carry out this operationrapidly in subdued light disregarding the fact that the precipitate obtained in 2 ml ofwater Randadd ml ofammonia R. The precipitate dissolves ) Introduce into a small test-tube a quantity of the substanceto be examined equivalent to about 5 mg of bromide (Br ) R,about75mgoflead dioxide R, acid Rand shake the inside of the upper part of the test-tube with a pieceof filter paper and allow to stand for 5 min.

8 Prepare a stripof suitable filter paper of appropriate size. Impregnate it bycapillarity, by dipping the tip in a drop ofdecolorised fuchsinsolution Rand introduce the impregnated part immediatelyinto the tube. Starting from the tip, a violet colour appearswithin 10 s that is clearly distinguishable from the red colourof fuchsin, which may be visible on a small area at the top ) To ml of a neutral solution containing a quantityof the substance to be examined equivalent to mg of calcium (Ca2+) per millilitre or to ml of theprescribed solution add ml of a 2 g/l solution ofglyoxal-hydroxyanil Rinethanol (96 per cent) R, sodium hydroxide solution Rand ml ofsodium carbonate solution Rand add 1 ml to 2 ml ofwater layer is coloured )

9 Dissolve about 20 mg of the substance to be examined orthe prescribed quantity in 5 ml ofacetic acid ferrocyanide solution Add about 50 mg ofammonium chloride ,crystalline precipitate is AND BICARBONATESI ntroduce into a test-tube g of the substance to beexamined and suspend in 2 ml ofwater Ror use 2 ml ofthe prescribed solution. Add 3 ml ofdilute acetic acid the tube immediately using a stopper fitted with aglass tube bent twice at right angles. The solution or thesuspension becomes effervescent and gives off a colourlessand odourless gas. Heat gently and collect the gas in 5 ml ofbarium hydroxide solution R. A white precipitate is formedthat dissolves on addition of an excess ofhydrochloricacid ) Dissolve in 2 ml ofwater Ra quantity of the substance tobe examined equivalent to about 2 mg of chloride (Cl )oruse 2 ml of the prescribed solution.

10 Acidify withdilute nitricacid Rand add ml ofsilver nitrate solution allow to stand. A curdled, white precipitate is and wash the precipitate with three quantities,each of 1 ml, ofwater R. Carry out this operation rapidly insubdued light, disregarding the fact that the supernatantsolution may not become perfectly clear. Suspend theprecipitate in 2 ml ofwater Rand add ml ofammonia precipitate dissolves easily with the possible ) Introduce into a test-tube a quantity of the substance to beexamined equivalent to about 15 mg of chloride (Cl )ortheprescribed quantity. Add g ofpotassium dichromate Rand 1 ml ofsulphuric acid R. Place a filter-paper stripimpregnated with ml ofdiphenylcarbazide solution Rover the opening of the test-tube.