Iodine Content of Some Marine Algae^ 
Madelon R. Grimm^ 
The literature on iodine and iodide con- 
tent of marine algae has been reviewed by 
Fritsch (1945), Chapman (1950), and Smith 
(1951). To their extensive bibliographies, the 
contributions of Turrentine (1912) and Cam- 
eron ( 1914 , 1915 ) may be added. 
Since many of the early investigators were 
interested primarily in the economic aspects 
of the algae, they generally disregarded the 
suitability of the species studied for labor- 
atory use. For example, their interests were 
concerned with the extraction and utilization 
of iodine for dietary and medicinal purposes. 
The use of this substance in fertilizer re- 
sources was also promoted. 
In recent years the use of iodine in tracer 
studies with its many applications necessi- 
tates an expanded spectrum of available 
species of algae to determine which organ- 
isms lend themselves to further laboratory 
study in this field. As far as can be determined, 
very little work has been done to ascertain 
the manner in which algae are able to ac- 
cumulate iodine and retain it against enor- 
mous concentration gradients. In search of 
suitable experimental organisms for such stud- 
ies and under the assumption that such 
^ Based in part upon data included in a thesis 
submitted to Cornell University in partial fulfillment 
of the requirements for the degree of Master of Science. 
This investigation was performed under the super- 
vision of Dr. Maxwell S. Doty and Dr. Walter C. 
Muenscher and supported in part by grants from 
Cornell University and Graduate Research Funds of 
Northwestern University. Manuscript received Febru- 
ary 20 , 1952. 
2 Research Department, Division of Microbiology, 
Ciba Pharmaceutical Products, Inc., Summit, New 
Jersey. 
organisms should both accumulate iodine and 
lend themselves to modified microbiological 
procedures, numerous species of marine algae 
were examined. 
The samples studied were collected alive 
in the field and air dried in the laboratories 
of the collectors (see footnotes of Table 1). 
Upon receipt, these collections were cleaned 
and redried at room temperature. A weighed 
amount (usually 1 gm.) was incinerated to a 
black ash in a porcelain crucible over a Bunsen 
burner. The ash was pulverized and mixed 
with 5 milliliters of distilled water and the 
soluble portion separated by centrifugation. 
The supernatant was shaken up with 1 milli- 
liter chloroform, 2 milliliters hydrogen per- 
oxide, and 1 milliliter glacial acetic acid. 
After several minutes, the presence of iodine 
was manifested by a pink to purple color in 
the chloroform layer, the intensity of the 
color increasing with iodine concentration. 
When the nonchloroform layer retained a 
brownish tinge, more hydrogen peroxide and 
acetic acid were added until decolorization 
occurred, and the mixture was reshaken. The 
color of the chloroform layer was compared 
to color standards containing known concen- 
trations of iodine in chloroform. This method 
is assumed to be a satisfactory means of 
estimating the iodide content of the algal 
ash when iodide is present in concentrations 
of over 30 parts per million. 
Quantitative estimations for iodine ob- 
tained in this investigation are presented in 
Table 1 and are expressed in milligrams per 
gram of dry weight of alga and in parts per 
million. Unused portions of the collections 
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