Nitrite is diazotized withp-nitroaniline in hydrochloric acid medium and coupled with guaiacol in alkaline medium to give an orange red azo dye having #x3BB;maxat 505 nm and #x3F5;max=4.8 #xD7; 1041. mole#x3F5;1cm#x2212;1. Extraction of the dye into isopentanol shifts the absorption maxima to 540 nm and having #x3F5;max=6.2x1041. mole#x2212;1cm#x2212;1. Beer's law is obeyed in the range of 0.12 to 0.8 ppm nitrite for aqueous system and 0.03 to 0.2 ppm for extractive system. The Sandell sensitivity for the aqueous and extractive systems were found to be 0.00095 #x3BC;g cm#x2212;2and 0.00074 #x3BC;g cm#x2212;2respectively. The method is applicable to polluted waters.
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