Analytical systems are progressing toward the integration and miniaturization of sample preparation steps and determination in a single device. The advantages of miniaturization are evident: a reduction in size, weight, reagent consumption, and waste production, as well as the integration of several reactors, mixers, extractors, pumps, and samplers in the same device. All steps of sample preparation, injection, mixing, purification, separation, and analysis can be implemented in a single device measuring several square centimeters, and a whole class of new devices with new functional, consumer, and analytical parameters can be developed [1].A chemical microchip is a miniature planar device with a multibranch microchannel network fabricated by photolithography using chemical or ionic etching, thermoplastic stamping, or masked spraying from glass/quartz, plastic, or silicon, sometimes containing metal elements. The microchip area is several square centimeters, and the linear dimensions of the channels usually vary from hundreds of micrometers to hundreds of nanometers [1]. Microchip systems are also referred to as micro total analysis systems ( µ -TASs) [2] and labs-on-chip [3].The rapid development of these systems is primarily due to the new potentialities that can be implemented on the basis of integrated microchips [4][5][6][7]. The main distinctions of microchips from the conventional systems used for mass exchange processes are (1) a laminar liquid flow, which improves flow control and (2) a reduced diffusion time because of the shortened distance and the increased ratio between the interface area and the phase volume.Various processes related to mass transfer have been successfully demonstrated on microchips: mixing and reactions of homogeneous systems in a chip [8-10], liquid-liquid extraction in two-phase systems [11][12][13][14][15], solid-phase extraction [16,17], organic synthesis in a two-phase system [18], molecular transport in a threephase system [19], and diffusion filtration of molecules [20,21].Optical methods are most often used as detection methods in microfluidic analytical systems. The leading method is laser fluorescence microscopy (LFM) [22][23][24][25][26][27], which is used as a detection system because of its unique analytical performances, such as high sensitivity and high spatial resolution, ensuring the compatibility of the detector volume with the volume of samples injected into the microchannel. The spatial limitations imposed on microfluidic systems, including the micron dimensions of the microchannel and the sample injection zone, are responsible for the stringent requirements on the spatial resolution of the detector. In addition, state-of-the-art biochemical and analytical studies require highly sensitive detection systems, and the parameters of LFM systems are suitable for detecting analytes at a level of 10 -12 M. However, these systems have a number of limitations due to the relatively narrow range of excitation wavelengths (especially in the shortwave spectral region), the i...
