[The Design of an ATR Probe for Online Monitoring of Biological Process].

The in situ biological process relays on a high performance attenuated total reflection (ATR) probe while ATR technique is a powerful tool for inline analysis. The basic principle and characteristic of the ATR technique was analyzed in this paper. A low cost and high throughout ATR probe was designed which can be inserted into the biological reactor directly with nondestructive and zero delay monitoring. It shows that the online ATR probe has a wide spectrum range, and the collected spectra has a high signal-to-noise ratio, which can be used in in-line quantitative analysis for biological process.

[Research on Raman spectra quantitative analysis model of ethanol aqueous solution based on net analyte signal].

Raman spectroscopy technique could satisfy industrial field measurement requirements because of the advantages of rapidity and nondestructiveness. Thus, It has been widely used in a variety of quantitative and qualitative analysis fields. The volume ration of alcohol and water in alcoholic beverages, i. e. the ethanol content, is a key factor in the detection of the quality of wine products. The development of the detection system for quick, easy and real-time ethanol content measurement is of great significance for national production. In the present paper, net signal analysis method (NAS) was used in the ethanol content quantitative analysis of Raman spectra from the ethanol aqueous solution. The linear regression model was developed between the net signal of ethanol and its concentration. The results showed that the qualitative analysis method based on net signal analysis was superior to the traditional linear regression method such as the MLR method based on the feature peak intensity and the PLS model. It not only improved the prediction accuracy of the model but also enhanced the robustness of the model. Because the model established by the NAS-MLR method is simple and stable, it is possible to develop the portable measurement instruments in future.

[A path-length correction method on biochemical parameter nondestructive measuring of folium].

Vis/NIR spectroscopy technology is capable of analyzing the content of biochemical parameter in folium rapidly and nondestructively. In the process of spectrum analysis, the variations in path-length between different samples exist, with the random light scattering and leaf thickness perturbations, which influence the precision of quantitative analysis model. In order to resolve this problem, an improved path-length correction method based on Extended Multiplicative Scattering Correction is presented. In this paper, firstly the theory of EMSC algorithm is deduced. EMSC method incorporates both chemical terms and wavelength functions to help realize the efficient separation of path-length and interest concentration. Secondly two experiments were implemented to demonstrate the validity of the method. In Experiment 1, sixteen samples of different thickness but almost the same chlorophyll content were selected, and how the path-length affects the spectrum was compared, after EMSC preprocessing, the variable coefficient of spectrum could approach the repeatability error of spectrometer. In Experiment 2, thirty-two samples of different thickness and chlorophyll content were selected. PLS model established using cross validation was employed to evaluate the efficiency of the presented algorithm. Before the preprocessing, the root mean squared error of prediction is 3.9 SPAD with 5 principal components. After preprocessing, the predicted root mean squared error is 2.2 SPAD with 12 principal components. The results indicate that the improved EMSC preprocessing method could exactly eliminate the spectrum difference caused by the path-length variations between different foliums, enhance the sensitivity of concentration and spectral data, and increase the precision of calibrated model.

[Chlorophyll content nondestructive measurement method based on Vis/NIR spectroscopy].

In the present paper a method based on Vis/NIR spectral analysis technology was applied to the nondestructive measurement of plant chlorophyll content. Firstly, the Vis/NIR spectra in the wavelength range from 500 to 900 nm of the plant leaves were acquired from 35 samples by transmittance and reflectance method, and then three different mathematical treatments were used in original spectra data pretreatment to decrease the noise: moving average smoothing with the segment size 5, first Savitzky-Golay derivative, and wavelet transform (WT) way. Secondly, a total of 35 samples were examined in the test, in which 23 samples were selected randomly for model building and the other 12 for model prediction, then partial least squares (PLS) method was used to develop the quantitative analysis model for chlorophyll content with absorbance spectroscopy, and 7 principal components (PCs) were selected. Finally, this model was used to predict the chlorophyll content of 12 unknown leaf samples in prediction collection. The experiment result indicated that the better prediction performance was achieved with the correlation coefficient between the prediction values and the truth values being 0.93, and the root mean squared error of prediction is about 1.1 SPAD. It could be concluded that it is feasible to measure plant chlorophyll content based on visible/near infrared (Vis/NIR) spectroscopy. And it is also significant in realizing rapid and nondestructive measurement of chlorophyll content in the future.