the use of 1,2-naphthoquinone-2-semicarbazone , 1,2-naphthoquinone-2-semicarbzone-4-sulphonic acid and 1,2-naphthoquinone-2-thiosemicarbazone-4-sulphonic acid as acid-base indicators has been studied .
C0036621
semicarbazone
C0039946
thiosemicarbazone