For the analysis of biological and environmental samples, separation analyses have an important role in the determination of analytes in complex matrices. High-performance liquid chromatography (HPLC) has currently become domi­ nant as a potential tool for the separation of a wide range of analytes in the diverse fields of analysis. As detection systems for HPLC, the ultraviolet-visi­ ble light absorption and, to a lesser extent, refractive index (RI) detectors have been employed most commonly. Although these detection techniques are very universal and conveniently applicable, in general they lack sensitivity. In the case of trace analyses, fluorescence (FL) and electrochemical (EC) detections are utilized owing to their relatively high sensitivity and selectivity. When ul­ tratrace quantities of an analyte in a complex sample matrix (e.g., biologically active compounds such as hormones in body fluids) are to be determined, highly sensitive chemiluminescence (CL) and laser-induced fluorescence (LIF) detections are often very powerful. CL-based techniques as a means of detec­ tion for HPLC have been developed since the 1980s. Although it is not as uni­ versal as FL detection, CL detection is rapidly growing owing to the very low detection limits, wide linear working ranges, and relatively simple instrumenta­ tions.