FLAVORING EXTRACTS. 



157 



Slightly acidulate the ammoniacal solution reserved for vanillin with 10 

 per cent hydrochloric acid. Cool, and shake out in a separatory funnel with 

 four portions of ether, as described for the first ether extraction. Evaporate 

 the ether at room temperature in a weighed dish, dry over sulphuric acid, and 

 weigh. 



If acetanilid has not been previously detected, this residue should be pure 

 vanillin with a melting point within a few degrees of 80 C. 



If acetanilid has been detected, dissolve the residue in 15 cc of 10 per cent 

 ammonium hydroxid and shake twice with an equal volume of ether. Evapo- 

 rate the ether solution at room temperature, dry in a desiccator, and weigh. 

 Deduct this weight from the previous weight, thus obtaining the weight of pure 

 vanillin. The total weight of the acetanilid is obtained by adding the weight of 

 this last extract to that of the residue previously obtained and identified as 

 acetanilid. 



In doubtful cases the ammoniacal solution should be acidified, shaken out 

 with ether, and the melting point of the vanillin, obtained by evaporation at 

 room temperature, determined. 



(b) COLOEIMETBIC METHOD FOB THE DETERMINATION OF VANILLINS 

 (1) PREPARATION OF REAGENTS. 



(a) Vanillin. Prepare a standard solution by dissolving 50 mg in 25 cc of 

 alcohol and diluting to 100 cc with water. 



(ft) Moist lead hydrate. Dissolve 200 grams of lead acetate in 850 cc of water, 

 filter, and add an excess of potassium or sodium hydroxid. Let the precipitate 

 settle and wash thoroughly by decantation with repeated portions of water 

 until perfectly neutral. Keep in 500 cc of water in the reagent bottle, and shake 

 to form an emulsion-like mixture before adding to decolorize. 



(2) DETERMINATION. 



Measure 2 cc of the vanilla extract into a test tube and add about 5 cc of the 

 lead hydrate ; mix thoroughly, pour upon a small wet filter, collect filtrate and 

 (washings in a 50 cc graduated Nessler tube; add an excess of bromin water 

 (3 or 4 drops) and sufficient freshly prepared 10 per cent ferrous sulphate 

 I solution to produce the maximum bluish-green color that will result if vanillin 

 | is present, and fill to the mark with water. 



Compare with solutions containing a known amount of vanillin treated as 

 | directed above. 



(c) DETECTION OF COUMARIN LEACH'S TEST.** 



Dissolve a few of the crystals or the small crystalline residue in a few drops 

 hot water, filter if necessary, and add to the clear solution a few drops of 



ith-normal iodin in potassium todid. In the presence of coumarin a brown 

 ?ipitate will form, which on stirring or shaking will soon gather in dark- 

 flecks, leaving a clear brown solution. The reaction is especially marked 



the iodin reagent is applied with a glass rod to the few drops of solution to 

 tested on a white plate or tile. 



Leach, Food Inspection and Analysis, p. 735. 

 * Ibid., p. 737. 



