SANITARY STUDIES OF BAKING POWDERS 



4. The determination of aluminum in the presence of iron and 



organic matter 



MATTHEW STEEL 



(Laboratory of Biological Chemistry of the Long Island College Hospital) 



(Received for publication, January 25, 1916) 



Contents 



Page 



I. Introduction 173 



IL Experimental work 1 74 



1. Reagents and apparatus employed 174 



2. Standardization of the KMnO* sol 175 



3. Estimation of iron in the Standard FeCla sol 175 



4. Estimation of iron in the Standard FeCU sol. in the presence of 



sodium alum 176 



5. Estimation of iron in the Standard FeCU sol. by the unmodified 



A.O.A.C. method 176 



6. Estimation of aluminum by the modified A.O.A.C. method (Steel) 176 



7. Estimation of iron and aluminum by the Government Research 



Committee method 177 



8. Estimation of aluminum by the Schmidt-Hoagland method 178 



9. Estimation of aluminum in the presence of organic matter by each 



of the three methods noted in sub-sections 6, 7, and 8 180 



III. Discussion of the relative merits of the three methods (accuracy and 



precision attainable in aqueous sol. and in the presence of large 

 amounts of organic matter) 181 



IV. Conclusions 182 



I. Introduction. A f ew years ago the author ( i ) , at the Sug- 

 gestion of Dr. Gies, undertook a study of the absorption of alu- 

 minum from aluminized foods. In the course of this research it 

 became necessary to make a careful comparative study of the best 

 methods for the estimation of aluminum. The details of this study 

 of the methods were not published in connection with the data on 

 absorption of aluminum, but the following Statements were made: 

 "After several trials of all the Standard methods had been com- 



173 



