LASER-BASED MICROCHEMICAL ANALYSIS

Microchemical analysis is the determination of the chemical composition of small volume samples, typically smaller than 1 mm3. The spatial coherence of the laser has been exploited by workers in many fields to probe these small volume samples. This review considers three classes of microchemical analyses: detectors for microscale separations, spectroscopic studies of minute volume samples, and laser-based microscopy. In the first case, high-sensitivity laser-based detectors are coupled with high-efficiency separation techniques to produce powerful analytical tools for submicroliter volume samples. In the second case, highly selective measurements are made on small volume samples through use of either immunological reagents or spectroscopically rich techniques. In the third case, high spatial resolution images of solid samples are created by recording a spectroscopic signal as a sample is moved with respect to a tightly focused laser beam. In each case, measurements with uniquely high sensitivity, selectivity, and spatial resolution are made possible by use of a laser beam.