The state of the art and prospects for the development of quantitative optical spectroscopy methods for analyzing the composition of small chemically active components of a nonequilibrium plasma are discussed. The possibilities of the methods are considered in their combination with the conditions of applicability both for fundamental research in the field of plasma physics and chemistry, and for monitoring the performance of technological processes in reactors in the interests of power engineering, micro-, and nano-electronics, medicine, the creation of optical coatings, the generation of active radicals and excited particles.