Improvement of an Automated Sample Injection System for Pillar Array Columns to Increase Analytical Reproducibility

• Published in: Molecules (Basel, Switzerland) Vol. 27; no. 15; p. 4715
• Main Authors: Kuroki, Hiroshi, Koyama, Hirotaka, Tsunoda, Makoto
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 23.07.2022; MDPI
• Subjects: Amino acids; Arrays; Automation; Biomarkers; Coumarin; Dilution; Injection; microchip; miniaturization; on-chip liquid chromatography; Quantitative analysis; Reproducibility
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules27154715

In our previous study, we developed an automatic sample injection system for pillar array columns for quantitative analysis. An autosampler was used to maintain a constant sample injection volume. However, the sample was diluted during injection using the autosampler, thus deteriorating the analytical reproducibility. In this study, we have substituted the autosampler with a syringe pump to overcome the abovementioned problem and improve the system. Sample dilution was avoided by filling the entire capillary with the sample at a constant rate. This improved system also increased the analytical reproducibility. In the previous system, the relative standard deviation (RSD) exceeded 17% of the peak height for coumarin dyes. In contrast, the improved system decreased the RSD to the range 1.2–1.8%. The analytical reproducibility was evaluated by using five types of amino acids. The RSD of each peak height was within 3.0%, confirming good reproducibility. These results indicate that the sample injection method developed in this study can be applied to biological sample analyses as a simple quantitative analysis method for pillar array columns.