Determinação voltamétrica de aspartame e ciclamato de sódio em produtos dietéticos empregando um eletrodo de diamante dopado com boro.
Resumen
The development of electroanalytical procedures for
aspartame and sodium cyclamate determination in dietary products using a
boron doped diamond (BDD) electrode and the square wave voltammetry
(SWV) is reported in this work. The first procedure development is reported in
related to the determination of aspartame in dietary products employing BDD
electrode and the SWV technique after optimization of the experimental
conditions. The recovery of aspartame from 8 samples ranged from 95.9 % to
104.4 % of the added amount. The analytical curve was linear in the aspartame
concentration range from 9.9 x 10-6 mol L-1 to 5.2 x 10-5 mol L-1 with a detection
limit of 2.3 x 10-7 mol L-1. The relative standard deviation for 5 successive
determinations of 1.0 x 10-4 mol L-1 aspartame was 0.17 % and the relative
standard deviation for 5 determinations of aspartame in different days was 2.8
%. The concentration of aspartame determined in several dietary products using
the BDD electrode and those concentrations determined using a HPLC method
are in close agreement (calculated t-values did not exceed the critical values at
the 95 % confidence level) and within an acceptable range of error. In the
sequence, the analytical determination of sodium cyclamate was studied by
oxidation of this substance on BDD electrode employed the SWV. The
analytical curve for sodium cyclamate was linear in the concentration range
from 5.0 x 10-5 to 4.1 x 10-4 mol L-1 with a detection limit of 4.8 x 10-6 mol L-1.
The relative standard deviation for five successive measurements was 1.1 % and
the relative standard deviation for determinations of 3.0 x 10-3 mol L-1 sodium
cyclamate in five different days was 2,4 %. The recoveries values from five
samples ranged from 98.6 % to 106,0 % and the results found using the
proposed method agreed at the 95% confidence level with those from a HPLC method. Finally, a procedure for simultaneous determination of aspartame and
sodium cyclamate was developed, once the oxidation peak potentials of the
aspartame and sodium cyclamate are 1.6 V and 1.9 V, respectively. The
analytical curves were linear in the aspartame concentration range from
5.0 x 10-6 to 4.0 x 10-5 mol L-1, with detection limit of 3.5 x 10-7 mol L-1 and
from 5.0 x 10-5 to 4.0 x 10-4 mol L-1, with detection limit of 4.5 x 10 -6 mol L-1
for sodium cyclamate. The simultaneous determination of these sweeteners in
various dietary products was implemented with success.