| Popis: |
We have been able to show that capillary electrophoresis (CE) can be used for the rapid determination of sulfate in granular detergents. With this method, an aqueous solution of the detergent (5 g/l) is prepared and a small, filtered (0.2 μm) portion is used for the assay. The total analysis time per sample by CE is less than 15 min using duplicate injections, with 2-min washes between each injection. The analytical method and a comparison of results between CE and gravimetric determinations, will be discussed. Sodium sulfate was quantitated by CE and by a BaCl2 gravimetric method using 26 different granular detergents with levels ranging from 2 to 40% Na2SO4. A least squares fit of the gravimetric data plotted versus the CE data resulted in r2 = 0.991, m = 0.92 ± 0.02 and b = − 0.41 ± 0.24 (SEE = 0.864), where m = slope, b = y-intercept, and SEE = standard error of estimate. Day-to-day CE results varied by less than 1.0% Na2SO4. Within a given day, results from replicate samples varied typically by less than 0.5% Na2SO4. The optimum linear range for this method is between 10 to 100 μg/ml, even though the response is linear up to and beyond 180 μg/ml. Sulfate concentrations above 100 μg/ml result in poor resolution for samples with multiple ions. |
