No abstract

1461were dispersed within each other with sufficient reproducibility that standard addition could be performed over a wide, controllable range of standard/analyte concentration ratios. I t is interesting to observe that the new variant of the gradient technique is partially based on the underlying concept of FIA titration ( I ) , where elements of fluid with identical D values are exploited, and partially on the concept of zone penetration (5) as designed for selectivity measurements, where elements of fluid with identical delay times t were used.Thus, another variation of the concept dispersed sample zone has been discovered and exploited. Its use is not limited to flame methods, as reaction based assays, like spectrophotometry, would equally benefit from the novel way of performing standard addition. Instruments equipped with photodiode arrays and appropriate fast data collection and storage facilities should increasingly find use in future applications.By use of dlcyclohexylcarbodAmIde (DCC) and dimethylbarblturic acid (DMBA) as reagents, a colorlmetric method for the deterrninatlon of pyrldyl and pyrlmldlnyl compounds has been established. DCC breaks the pyrldlne or pyrlmldine ring to afford giutaconaldehyde or maionaldehyde and then reacts wlth DMBA to produce chromophores. These heterocycles could be determined by measuring the chromophores. The reiatlve standard devlatlons obtained with different amounts of these compounds were In the range of 0.63 to 5.36% ( n