| Part I. The dissociation constants of oxine and 2-methyloxine are determined in the presence of hexadecyltrimethylammonium bromide, sodium dodecyl sulfate and Triton X-100, three kinds of surfactant, by a spectrophotometric method. The values of the dissociation constants are more or less different from those in the absence of surfactant, because with the surfactant present, the dissociation constants are affected by hydrophobic and ionic interactions. The dissociation constants of oxine and 2-methyloxine in the presence of three kinds of surfactant are listed on the table.;Part III. An extremely stable, sensitive and selective method of spectrophotometric determination of microquantities of nitrite with p-nitroaniline and 2-methyl-8-quinolinol in hexadecyltrimethylammonium bromide solution is described. Beer's law is strictly obeyed between 0.009-1.900ppm (9-1900ppb) at wavelength of 585nm. The molar absorptivity and Sandell sensitivity are 4.722 x 10('4) 1 mole('-1)cm('-1) and 0.00097 ug/cm('2), respectively.;PH of the sample solution, 27 anions and cations concerning their interference and the method of elimination of the sulfite interference are studied. In addition the effect of evaporation by heat for nitrite in water is described, which can improve the detection limit.;Part IV. Cd(II), Zn(II), Ni(II) and Co(II) are determined spectrophotometrically with 5-(p-nitrophenylazo)-2-methyloxine (PNPAMO) in the presence of hexadecyltrimethylammonium bromide (HTAB). Their detection limits are lower than those with oxine or 2-methyloxine, i.e., the molar absorptivities of metal ion-PNPAMO complexes are almost 10 fold higher than those of metal ions with oxine or 2-methyloxine. The solubilities of metal ion-PNPAMO complexes in the presence of HTAB are much higher than in the absence of HTAB and the stability is also better than in the absence of HTAB. Interference effects are discussed; the metal ions, Cu(II), Fe(III), Co(II), Cd(II), Ni(II), an Zn(II) are very serious interferents.;Part II. The metal ions, Co(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(III), Mn(II) and Al(III) are determined spectrophotometrically with oxine or 2-methyloxine in the presence of hexadecyltrimethylammonium bromide (HTAB), sodium dodecyl sulfate (SDS), and Triton X-100 (TX-100). Their optimal pHs, detection limits, and the type of complex formation are discussed.;Part V. Sodium dodecyl sulfate is sorbed on a column of Dowex A-1 chelating resin, this SDS-containing ion exchange column can be used for the separation of Cd(II) and Zn(II) with aqueous solution as an eluent. Almost complete separation and recovery are attained. SDS can be stripped from the column with methanol. |
