A NEW APPROACH TO MIXING TECHNIQUES FOR ENHANCED PERFORMANCE IN AUTOMATED SAMPLE PREPARATION

In the automation of sample dilution or derivatization, the performanc e of the mixing technique employed when adding solvents or reagents to samples is critical. This paper presents a newly developed mixing met hod based on conventional aspiration and dispensing of liquid techniqu es, but which considerably improves the precision of mixing. The paper discusses the results of a comparison of the technique with other met hods and describes the application of the technique to several differe nt types of sample solutions, including a highly concentrated glucose solution. The mixing technique was performed on a Gilson XL Sampling I njector, with a 1/25 dilution of a paraben solution in 2 ml vials to g ive relative standard deviations of 0.2 to 0.3% (N = 10).