Determination of ascorbic acid in nanolitre samples by means of capillary batch injection analysis

Capillary batch injection analysis (CBIA) is applied to the determination of ascorbic acid in nanolitre samples at neutral pH. It is demonstrated that pulsed amperometric detection is superior to constant-potential amperometric detection with respect to signal stability. The calibration plot is linear within the studied concentration range between 0.5 mM and 5 mM and the reproducibility is characterized by a relative standard deviation of 0.80% for 10 successive injections of 188 nL of 3.5 mM ascorbic acid. The attainable sample throughput is up to 500 per hour.