J. Saurina et al., CONTINUOUS-FLOW TITRATION SYSTEM FOR THE GENERATION OF MULTIVARIATE SPECTROPHOTOMETRIC DATA IN THE STUDY OF ACID-BASE EQUILIBRIA, Analytica chimica acta, 312(2), 1995, pp. 189-198
In the present work a continuous flow system to carry out spectrophoto
metric titrations is developed. The titrant solution is generated on-l
ine from mixing two different stock buffer solutions. The composition
of the titrant agent is sequentially varied along the titration by cha
nging the ratio of flow rates of both buffer channels, and therefore t
he pH can be modified. One spectrum is recorded at each pH value when
the absorbance achieves the steady state. The spectral data have been
treated by means of a recently developed self-modelling multivariate c
urve resolution method (SPFAC procedure). This method has been applied
to the study of the acid-base equilibria of 1,2-naphthoquinone-4-sulf
onate (NQS). Four titrations with concentrations of NQS ranging from 1
.6 X 10(-4) to 7.3 X 10(-4) M have been performed, and, in every case,
24 spectra at different pH have been registered. Three species are de
tected in the range of pH studied (6.9-12.3). Their distribution plot
with pH and their unit spectrum have been obtained.