the use of 1,2-naphthoquinone-2-semicarbazone-4-sulphonic acid and 1,2-naphtho-quinone-2-thiosemicarbazone-4-sulphoic acid as indicators in the titrimetric estimation of phosphate , molybdate , tungstate and sulphate with lead has been examined .
C0036621
semicarbazone
C0039946
thiosemicarbazone