An automated method for the analysis of tertiary amines has been developed using a basic automatic analyzer arrangement. The method is based o n a modification of the familiar dye complex extraction method for amines. T h e method is simple and is not subject to adsorption of the dye on components of the analytical train. A new technique for automated extraction is also described as part of the method.
T h e specificity of the method can be highly controlled by suggested changes in the dye reagent formulation enabling certain amines to be analyzed in the presence of other amines. The method has been designed for the analysis of solid samples.
LARGE NUMBER of commercially useful com-
A pounds are tertiary amines. These compounds traditionally involve difficult and exacting assay procedures. A simple, general automated method for these compounds would be very desirable. It would be of even greater value if a controllable degree of specificity could b e incorporated into the automated method since many of these compounds are produced or formulated as mixtures with other amines. The work described in this paper in large measure achieves these objectives.
The majority of published analytical methods for tertiary amines (1-13) are based on some modification of a dye complex formation with a halogenated acid dye as first observed b y LaMer and Downes ( ) and later supplemented b y Griffiths (15). Prudhomme (11) was the first t o utilize this principle as the basis of his method for the determination of quinine with eosin.
Lehman and Aitken (8) used bromothymol blue to form their amine complex which was extracted into benzene and then reextracted into aqueous alkali. Brodie and Udenfriend ( 2 ) used methyl orange, and Cronheim and Ware (3) were t h e first to use bromocresol purple. EXPERIMENTAL Apparatus-The analytical system consisted of the following modules': ( a ) automatic solid sampler; ( b ) proportioning pump; (c) photoelectric colorimeter (15mm., tubular flow cell); ( d ) linearized recorder.
Preliminary Investigations-Since bromothymol blue is most often used in dye complex methods for tertiary amines, it was investigated for its suit-