"Linearity Study for a Developed Spectrophotometric Visible (VIS) Analysis of Sodium Valproate from Tablets"

Sodium valproate is a established antiepileptic drug of first choice, primarily used to treat epilepsy, but also bipolar disorder and prevent migraine headaches. Valproate increases concentrations of gamma-aminobutyric acid in the brain, due to inhibition of enzymes responsible for the catabolism of gamma-aminobutyric acid. Main goal of this research consisted in the optimization and development for a new sensitive spectrophotometric quantitative analysis method of sodium valproate from tablets in the Visible field. Following the quantitative color reaction of sodium valproate with diazonium salt of alpha naphthylamine in alkaline medium, a light yellow azo dye was formed and spectrophotometrically analyzed at the wavelength of 386 nanometers. The amount of pure sodium valproate found on pharmaceutical extended-release tablet was 492.578 milligrams compared to the official declared pure amount of 500 milligrams on prolonged-release tablet. Amount found was assigned to a percentage content of 98.5156 percent pure sodium valproate in a pharmaceutical tablet. Mean average percentage error (deviation) from the officially stated value was about 1.4844 percent, which was included within normal limits, below five percent maximum limit allowed by European and Romanian Pharmacopoeias rules (5 percent). Spectrophotometric method was subjected to the statistical validation procedure and was successfully validated. Linear regression was analyzed. Method presented a very good linearity over the entire concentrations range 0.16 – 2.08 microgram on milliliter. Linear regression coefficient R square was 0.999330 and the correlation coefficient R was represented by 0.999665, were within the normal ranges of values.