nitrate (0.6 mole) in 500 ml. of water. This solution m a y be sprayed heavily on t h e front a n d back of t h e chromatogram without danger of bpreading t h e spots. Although this solution darkens rapidly, it is effective for more t h a n 6 months. Both the periodate and ferricyanide sprays have been used satisfactorily upon chromatograms developed with the following solvents, which have proved of particular utility in the separation of glycosides and polyalcohols : n-butyl alcohol pyridine, water (10, 3,3); ethyl acetate, acetic acid, water (9,2,2) ; ethyl acetate, n-propyl alcohol, water (2,1,2-upper layer); methyl ethyl ketone saturated with water; tert-amyl alcohol, n-propyl alcohol, water (4,1,1). KO irrigants tested so far have caused failure of these spray reagents. Table I records the results on unirrigated .test strips of sensitivity tests when the sprays of this paper are used, as well as several of the most sensitive sprays described in the literature. As the sprays of this paper are a3 sensitive as any tested, it is evident that sensitivity has not been sacrificed for the sake of convenience. ACKNOWLEDGMENT
The financial support of a grant from the National Science Foundation is gratefully acknowledged.
Table 1.
Limits of Detection for Various Spray Reagents”
Aniline
Periodate FerriSilver (6) with (or cyanide, ( 1 1 ) , l’ermanOxalate) Benzidine Ammonia ganate 0.5
