Determination of Dopamine Using the Alkaline Luminol–Hydrogen Peroxide System for Sequential Injection–Zone Fluidics Analysis

ABSTRACT

Luminol–hydrogen peroxide chemiluminescence was used with photon counting in a tubular reactor with sequential injection analysis and zone fluidics for the determination of dopamine. The analyte was zone stacked and sandwiched between alkaline luminol and hydrogen peroxide solutions separated by air bubbles within head and tail zones inside a holding coil. These zones were reversed and rapidly dispensed into the reactor with zone penetration and trapped inside the cell for measurement by fluid stopped-flow techniques. The linear concentration range for dopamine was from 10⁻⁸ to 10⁻⁶ mol/L with a relative standard deviation of 3.30% and a limit of detection of 2.60 × 10⁻⁹ mol/L. The system provided a relative standard deviation of 2.57% and was used for the determination of dopamine in pharmaceuticals with a recovery of 99.63%.

KEYWORDS:

• Chemiluminescence
• dopamine hydrochloride
• hydrogen peroxide
• luminol
• photon countering
• sequential injection analysis
• zone fluidics