The Application Of Piezoelectric Photoacoustic Technique For Component Identification In Solution

As an effective means of material composition detection, photoacoustic spectroscopy(PAS) technique has been widely applied in scientific research, high technology, industrial production and other fields. The PAS only measures the absorption of light to the material and is weakly influenced by the measuring wavelength and particle size distribution, so it is suitable for the measurement of solid,liquid and gas. PAS has the advantages of wide measurement range, nondestructive measurement, low sample consumption and high detection sensitivity, no need for sample preprocessing. It has the superiority of weakly influenced by the measuring wavelength and particle size distribution. Therefore the research on the composition test for solid, gas, especially for the liquid by this technique has attracted more and more attentions in recent years.In this thesis, the photoacoustic spectrum in the visible range of glucose,fructose, sucrose and honey solutions are measured by using the experiment device of single-light photoacoustic spectrometer, and are compared with the data from spectrophotometry method. The spectral characteristics show that the spectral background intensity and spectral profile have some differences for different kinds of solutions. The four kinds of solutions have strong peak value at 485 and 655 nm, but the strength ratios have some differences in these solutions. The intensity ratios of the multi-honey collected by apis cerana ceraca are very close to that of glucose solution,while the intensity ratios of the single-honey collected by apis mellifera ligustica are similar to that of sucrose solution. Besides, there are characteristic peak at 475, 576 and 630 nm for glucose, fructose and the sucrose has apparent characteristic peak at622 nm and 632 nm respectively, these characteristic peaks can be used for detecting whether the natural honey contain adulterants. By comparing two kinds of spectrum of the same solution, the intensity of photoacoustic spectrum is more responsive to the wavelength, indicating photoacoustic spectrometry has a higher sensitivity in the test of material composition.In addition, the photoacoustic spectrum and absorption spectrum of three kinds of Lycium chinense solutions are measured. The spectral features showed that the spectral of three kinds of solutions appear characteristic peaks of glucose at 485 and655 nm, but the strength ratios have some differences in these solutions. These characteristic peaks can be used for detecting the sugar content of Chinese wolfberry To explore the impact of sugar content in solution with the variation of soaking time and soaking temperature, respectively. And the experimental conditions were optimized.The experimental parameters can futher optimize accuracy of machine.