Analytical Letters, cilt.4, ss.721-732, 2007 (SCI Expanded İndekslerine Giren Dergi)
A classic analytical problem is the simultaneous
determination of two or more compounds in the same sample without previous
chemical separation. In this way derivative spectrophotometry is an anaytical
technique of great utility and offers greater selectivity than normal
spectrophotometry. The resolution of binary mixtures of compounds with
overlapped spectra by derivative spectrophotometry is frequently made on the
basis of zero-crossing measurements. A very simple spectrophotometric method
using measurements at zero-crossing wavelength is described for resolving
binary mixtures of the synthetic colorants sunset yellow (E-110) and
erythrosine (E-127). The assay procedure for E-110 and E-127 in Premarin
tablets involves extraction of the colorants from tablets with distilled water
and measurement of first derivative absorbance values at 482.7 nm for E-127,
then filtration from rough paper and measurement of 1D values at 526.3 nm for
E-110. Linear correlations over the concentration ranges of 2.0–10.0 µg mL−1
for E-110 (r = 0.9997) and for E-127 (r = 0.9999) were obtained. Commercially
available tablets containing E-110 and E-127 were analysed by the proposed
method and the HPLC method. Mean values and standard deviations calculated from
seven determinations were 122.5 µg/tablet (RSD = 1.9) of E-110, 119.3 µg/tablet
(RSD = 2.3) of E-127 for the proposed method and 124.3 µg/tablet (RSD = 0.98)
of E-110, 120.9 µg/tablet (RSD = 1.2) of E-127 for the HPLC method. The
statistical evaluations indicated that there was no significant difference
between the mean values and precisions of the two methods at 95% confidence
level (t = 1.68 and 0.24; F = 3.76 and 3.67). This method was satisfactorily
used for determining synthetic mixtures of these dyes in different ratios. The
avarage percentage recoveries are 105.8% and 102.8% for E-110 and E-127
respectively.