Sequential Injection System with Modified Glass Capillary for Automation in Immunoassay of Chondroitin Sulfate

Abstract

Sequential injection was introduced to perform a multi-step immunoassay. Modified low cost hematocrit glass capillary was employed as the immobilization surface for a competitive immunoassay of chondroitin sulfate (CS), a potential biomarker for cancer. Glass capillary is low cost and adapts well to the flow system without causing back pressure. The analysis time per sample run with automation of the multi-step immunoassay is improved as compared to the conventional batch-wise micro-plate format. The performance of the sequential injection capillary immunoassay (SI-CI) system for CS was evaluated with spiked human serum samples.

Keywords:

• Capillary immunoassay
• Chondroitin sulfate
• Sequential injection

Acknowledgments

This paper was submitted as part of a Special Issue on Flow Injection Analysis.

This work was granted by the Thailand Research Fund (TRF) for S. Kradtap Hartwell, and by Office of the Higher Education Commission for S. Khonyoung through the CHE Ph.D. Scholarship. Additional support came from the Center for Innovation in Chemistry (PERCH-CIC) for all authors. Support for P. Kongtawelert from the National Research Council of Thailand (NRCT) and the National Science and Technology Development Agency, Northern Region (NNSTDA) is also acknowledged.

Notes

Note: Steps 17–20, the discarded air volume (30 µL) needs to be higher than the aspirated air volume (20 µL) to ensure the prevention of air entering the detection flow cell. Therefore, the volume of the reaction zone left to be sent to the detector (50 µL) was lower than the aspirated TMB solution volume (80 µL).