Sensitive determination of gentiopicroside in medicine and bio-fluids using luminol-myoglobin chemiluminescence combined with flow injection technique.

A novel chemiluminescence method for the determination of gentiopicroside is presented, which was based on the inhibitory effect of gentiopicroside on the chemiluminescence reaction between luminol and myoglobin in a flow-injection system. The decrement of chemiluminescence intensity was linear with the logarithm of gentiopicroside concentration over the range from 10.0 pg mL(-1) to 500.0 ng mL(-1) (r(2) = 0.9992), with a detection limit of 3.0 pg mL(-1) (3σ). At a flow rate of 2.0 mL min(-1), a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 3.0% (n = 5). The proposed procedure was applied successfully in the determination of gentiopicroside in pharmaceutical preparations, human urine and serum without any pretreatment procedure. The possible mechanism of the reaction was also discussed.