Diode laser induced near infra-red fluorescence detection for high-performance liquid chromatography analysis of indocyanine green in plasma

Diode laser induced near infra-red fluorescence (DLINIRF) detection has become important in bioanalysis due to the increased sensitivity and selectivity that can be achieved in biological matrices as well as the ruggedness, low cost, stability and portability of diode lasers. Indocyanine green (ICG) is used as a marker in clinical research to measure hepatic blood flow (HBF) and cardiac output. A high-performance liquid chromatography (HPLC) method employing a simple protein precipitation sample preparation step and DLINIRF detection has been developed to quantitate ICG in plasma. Comparison with absorbance detection demonstrated an increased detectability of more than two orders of magnitude for the DLINIRF detection method. The analysis of ICG in plasma by both detection methods was selective and demonstrated accuracy and precision within acceptable limits.