[Determination of sodium by near infrared spectroscopy].

The research on near infrared spectroscopy of sodium in biological and medicine is significant. Sodion is the main component of electrolytes in human blood and electrolytes help maintain the body's acid-base balance. In the present paper the concentration of sodium was determined with the use of NIR spectra. On the basis of NIR spectroscopic measurement mechanism of sodion, prediction models of the concentration of sodium were developed with linear regression using the absorbance at selected wavelengths. In order to reduce temperature perturbations to water bands with the measurement of sodium, Partial least squares regression (PLS) was adopted using select spectra area. The result shows that the determination coefficients (R2) = 99.82%, the root mean square error of cross validation (RMSECV) = 14.5, and the residual prediction deviation (RPD) = 23.7, for the calibration model. It meets the daily requirements of biochemical detection accuracy. This technique can be applied to quantitative analysis of sodion in the hospital laboratory.

[A method for quantitative analysis system of alkane gaseous mixture with near infrared spectroscopy].

A method for online quantitative analysis system of alkane gaseous mixture with near infrared spectroscopy is described in the present paper. A single plane diffraction grating is used as the principal device in the monochromatic spectrum system. The key parameters of the monochromator were deduced and calculated in detail. A quantitative analysis system was designed and constructed according to the parameters. The narrow-band beam testing experiments and spectral scanning experiments of seven kinds of single-component alkane gases were accomplished on the above hardware system platform. The narrow-beam experiments show that a 10 nm narrow-band beam spectra was successfully obtained by the monochromatic system when the entrance slit width is 2 mm. And a step-scanning resolution of the outgoing beam's center wavelength with 0.1 nm can be realized within the spectra of 1.2-1.8 microm. The spectral scanning experiments indicate that there was some stronger characteristi absorption spectrum existing between the spectra of 1.6-1.8 microm, which is consistent with the HITRAN spectral database. And there is serious cross-aliasing phenomenon existing among the absorption spectra. These experiments demonstrate that this method has a successful application in mixed gas monitoring and on-line analysis with the characteristics of simple structure and low cost. And it also provides further technical reserves and opens a path way to spectral analysis in the follow-up studies.

[On-line and in-situ spectral analysis of multicomponent gas mixture with same molecular group].

Aimed at the problem that Fourier transform infrared (FTIR) spectral analysis can't be used solely to analyze complex gas mxiture, in which there are many gas compositions, some compositions have same molecular group, and the concentrations of some compositions range greatly, in the present paper, a new spectral analysis method is proposed. For this method, the effects of gas temperature and gas pressure on the analysis result are taken into account, and feature variable extraction, recognition and correction of spectral disorder, robust modeling and multi-layer modeling with neural network (NN) are used to build gas mixture analysis models. At the end of this paper, on-line analysis of five alkane gases is taken as example to test the performance of the analysis method. CH4, C2 H6, Ca3 Ha8, iso-C4 H10 and n-C4 H10 are taken as object gases while iso-C5 H12 and n-C5 H12 are looked as disturbing gases. The comparison results that analysis result curves of FTIR overlap that of gas chromatograph indicate that FTIR can be solely used in on-line and in-situ analysis of multicomponent gas mixture with same molecular group if the analysis method presented in this paper is used.