Autonomous capillary electrophoresis processing and analysis of dried blood spots for high-throughput determination of uric acid

A new set-up for fully autonomous and high-throughput capillary electrophoresis (CE) analyses of dried blood spot (DBS) samples is presented. The DBS samples were prepared by collecting exactly 5 mu L of capillary blood from a finger-prick onto a pre-punched DBS disc in a disposable plastic CE vial and by in-vial blood drying. The vials with the DBS samples were then loaded into a commercial CE instrument for a fully unmanned sample processing and analysis. A fused-silica capillary of the CE instrument was first used for the transfer of 100 mu L of elution solvent to each vial, in-vial DBS elution, and in-vial eluate homogenization. The same capillary was also used for at-line injection, separation, and selective analysis of the resulting eluates. Novel CE sequences were tailor-programmed for consecutive processing and analyses of multiple DBSs, which facilitated a fully autono-mous determination of uric acid with a throughput of 240 DBS samples per day (24 h). The presented analytical protocol (using 100 mu m i. d./30 cm capillary; 30 mM 2-(N-morpholino)-ethanesulfonic acid, 30 mM L-histidine, and 30 mu M cetyltrimethylammonium bromide background electrolyte solution; and UV detection at 292 nm) provided excellent precision at endogenous and spiked uric acid concentrations with RSD values of peak areas below 3.2%. Calibration curves were linear over the 33.3 -1200 mu M range (R2 better than 0.998), limits of detection and quantification in the original capillary blood were 10 and 33.3 mu M, respectively, and were well below the uric acid clinical range (140-420 mu M). The stability of uric acid in DBS samples stored at laboratory temperature for up to 2 months was also excellent demonstrating less than a 4.2% decrease in uric acid concentrations. The actual set-up might thus be highly attractive for clinical subjects and laboratories because it is minimally invasive and requires minimum intervention from laboratory staff.

Automated summary

A new set-up for fully autonomous and high-throughput capillary electrophoresis analysis of dried blood spot samples is presented. The set-up enables unmanned sample processing and analysis with tailor-programmed CE sequences, allowing for a throughput of 240 samples per day. The analytical protocol provides excellent precision and calibration curves with linear ranges and detection limits suitable for clinical purposes. The stability of the samples stored at laboratory temperature for up to 2 months is also demonstrated.