213 



DETERMINATION OF THE IODIN NUMBER OF THE NONVOLATILE 

 ETHER EXTRACT OF PAPRIKA. 



i;\ \v. i>i 



As in this laboratory much difficulty was experienced in obtaining concordant re- 

 sults on determinations of the iodin number of the nonvolatile ether extract <>t' pap- 

 rika, 8 samples of ground paprika sent in as suspected of being Bduttentod with olive 

 oil, and I sample composed of the shells of Hungarian paprika .ground in the labora- 

 tory were examined, various methods of extraction being used. 



Method 1. This consisted in digesting 10 grams of paprika over night with 100 cc 

 of ordinary ether in a stoppered flask. The next morning all ether was decanted off 

 through a double filter and the residue thoroughly washed with 200 cc more ether. 

 The ether was then distilled off and the residue dried to constant weight at 100 ('. 

 and calculated as nonvolatile ether extract, the iodin number of the same being 

 deter ruined on portions of i hi- residue by the official method, using the Ha tins solution. 



Mtihml '. Manipulation the same as in method 1 except that petroleum ether I'.. 1*. 

 50-60 was substituted for sulphuric ether 



Method .*. The official method for the determination of nonvolatile ether extract 

 in spice* as L'i\'-n in r.iilletin 107. 



.\ffthml ;. The Doolittle-< >gden method of extraction with cold anhydrous ether." 



All four <>f the above methods proved unsatisfactory. Methods I and 2 were at 

 once discarded because it was found after repeated trials to he absolutely impo-.-ihle 

 by these methods to obtain portions of identical compo-nion from one lot of ether 

 extract, due to the fact that on standing for a few minutes at 100 in the water oven 

 several drops of a colorless oil appeared on the sidesof the container, while on standing 

 at room temperature needlc-haped T\ -tals. which on microscopic examination proved 

 tobecry-t al- of fai, were seen in the deep red re-idue. It was also frequently found 

 that in spite of careful tilt rat ion minute quant it ies of some body difficultly soluble in 

 chloroform were present in the extract, thus further interfering \\iih the accuracy 

 of the result- 



l'.\ i he otlicial method also it was found ditlicult to obtain duplicate results, appar- 

 ently due to the fact that a drying oil is present in the extract which may oxi.li/c 

 to varying degrees depending on slight difference- in manipulation during the long 

 period of extra- the l>oolittIe-< )-jden method some difficulty, although not 



so much as with the three preceding methods, was experienced in obtaining 

 duplicate determinations of the iodin number; and in addition this method has the 

 disadvantage of allowing only one determination of the iodin number to be made 

 on the product of a .-in-le extraction. The following modification of the Dooliitle- 

 Ogden method was finally devised, and so far has given satisfactory results. Diving 

 duplicates on iodin number determinations agreeing to within 0.2 per cent. 



Method No. 5. Ten grams of paprika spread in a thin layer on a flat -bottomed dish 

 are dried for two hours in a vacuum oven at fit) and L'"> mm. The material is then 

 transferred to a double filter and \\ashed with :)<)<) << of cold anhydrous alcohol-free 

 ether. After distilling off the ether the residue is taken up with fresh ether and 

 filtered into a -mall tared beaker, the filter paper being carefully washed with ether 

 to remove all trace of oil. After again evaporating off the ether t lie residue is dried 

 to con-taut wei_rht at 100. After the final weighing the residue is washed with 

 chloroform into a 100 < . flask and made up to volume with this liquid. Determina- 

 ti..n- ot the iodin number are made on 10 cc portions of this solution, thus making 

 {possible -e\erai duplicate determinations on the residue obtained in a sample extrac- 

 tion. 



oj. Amer. Them. Soc. 1908, 30. MM. 



