Automated zone-sampling dilution by coupling sequential injection analysis to high-throughput HPLC for the direct...

A novel automated analytical scheme for the rapid determination of gemfibrozil in drug dissolution samples is reported. The procedure is based on direct coupling of a low pressure continuous flow technique such as sequential injection analysis (SI) to HPLC. SI performs automated dilution of the samples based on zone sampling and fills on-line the loop of the high pressure injection valve. Rapid separation of the analyte from the samples' matrix can be achieved in less than 1.0 min, by using a short RP monolithic column (25x4.6 mm id) at a flow rate of 2 mL/min. The SI and HPLC parts of the setup operate independently: during HPLC separation the next sample is treated by SI. This way a maximum throughput of 60 samples per hour is achieved allowing the complete analysis of a batch of six dissolution samples within 12-18 min based on the replicates. The proposed method was validated in terms of linearity, LOD and LOQ, precision, selectivity and accuracy. Its applicability was tested during quality control of four validation batches of a gemfibrozil-containing formulation. The results were in good agreement with the HPLC method proposed by the US Pharmacopeia.