Assay for lithium using tetra-substituted aryl cyclic formazan dyes
AssigneeEastman Kodak Company
InventorsMary H. Delton, Shari L. Eiff
Life of this patent
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Abstract
Tetra-substituted aryl cyclic formazan dyes are useful in assaying for lithium. The dyes have the structure: ##STR1## in which X represents CN or NO.sub.2 ; Y represents CH.sub.2 CH.sub.2, CH.sub.2 CH.sub.2 CH.sub.2 or CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 ; and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each independently represent butyl, halogen, alkoxy or NO.sub.2.
Claims11
A method for analysis of Li.sup.+, comprising the steps of:
- (a) preparing a curve which relates Li.sup.+ concentration to changes in absorbance, at a specified wavelength of a series of solutions comprising the same concentration of a tetra-substituted aryl cyclic formazan dye, a base and varying known concentrations of Li.sup.+ ;
- (b) determining the absorbance, at the specified wavelength of a solution containing the (i) same dye and base concentrations as in step (a) and (ii) an aliquot of an aqueous solution containing an unknown concentration of Li.sup.+ ;
- and
- (c) reading the Li.sup.+ concentration from the curve prepared in step (a) corresponding to the absorbance determined in step (b), wherein the dye has the structure according to:
- ##STR7## in which X represents CN or NO.sub.2 ;
- Y represents CH.sub.2 CH.sub.2, CH.sub.2 CH.sub.2 CH.sub.2 or CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 ;
- and
- R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each independently represent butyl, halogen, alkoxy or NO.sub.2.
A method of quantitative analysis of Li.sup.+ in the presence of Na.sup.+, comprising the steps of:
- (a) preparing a curve which relates Li.sup.+ concentration to changes in absorbance, at a specified wavelength of a series of solutions comprising the (i) same concentration of a tetra-substituted aryl cyclic formazan dye and a base, (ii) the same amount of sodium up to 150 mM and (iii) varying known concentrations of lithium;
- (b) determining the absorbance, at the specified wavelength of a solution containing the (i) same dye and base concentrations as in step (a) and (ii) an aliquot of an aqueous solution containing an unknown concentration of Li.sup.+ ;
- and
- (c) reading the Li.sup.+ concentration from the curve prepared in step (a) corresponding to the absorbance determined in step (b), wherein the dye has the structure:
- ##STR8## in which X represents CN or NO.sub.2 ;
- Y represents CH.sub.2 CH.sub.2, CH.sub.2 CH.sub.2 CH.sub.2 or CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 ;
- and
- R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each independently represent butyl, halogen, alkoxy or NO.sub.2.
An element for the detection of Li.sup.+ comprising an absorbent carrier material containing a tetra-substituted aryl cyclic formazan dye and said absorbent material buffered at a pH of 7 to 11, wherein the due has the structure:
- ##STR9## in which X represents CN or NO.sub.2 ;
- Y represents CH.sub.2 CH.sub.2, CH.sub.2 CH.sub.2 CH.sub.2 or CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 ;
- and
- R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each independently represent butyl, halogen, alkoxy or NO.sub.2.
Dependencies are inferred from the claim text.