Andrey Bogomolov

In‐line analysis of a fluid bed pellet coating process using a combination of near infrared and Raman spectroscopy

Near infrared (NIR) and Raman spectroscopic analyzers applied through an immersion Lighthouse Probe (LHP) were used for simultaneous in‐line monitoring of a fluid bed pellet coating process. Multivariate curve resolution analysis of data, collected from four pilot‐scale batches, has shown that the two techniques deliver complementary information about the process and their combination may be synergistic. This data analysis enabled a much better understanding of some of the process observations and also gave some interesting insights into the best way to use the techniques themselves.

Determination of fat and total protein content in milk using conventional digital imaging

The applicability of conventional digital imaging to quantitative determination of fat and total protein in cows milk, based on the phenomenon of light scatter, has been proved. A new algorithm for extracting features from digital images of milk samples has been developed. The algorithm takes into account spatial distribution of light, diffusely transmitted through a sample. The proposed method has been tested on two sample sets prepared from industrial raw milk standards, with variable fat and protein content. Partial Least-Squares (PLS) regression on the features calculated from images of monochromatically illuminated milk samples resulted in models with high prediction performance when analysed the sets separately (best models with cross-validated R(2)=0.974 for protein and R(2)=0.973 for fat content). However when analysed the sets jointly with the obtained results were significantly worse (best models with cross-validated R(2)=0.890 for fat content and R(2)=0.720 for protein content). The results have been compared with previously published Vis/SW-NIR spectroscopic study of similar samples.

Fat Globule Size Effect on Visible and Shortwave near Infrared Spectra of Milk

Step-wise homogenisation has been applied to raw milk samples of different composition to investigate the effect of fat globule size distribution on diffuse transmission spectra in the region 400–1100 nm. Homogenisation results in significant spectral changes with two distinct phases. Initial even growth of spectral intensity across the whole spectral range, observed at lower degrees of homogenisation, was followed by a drastic fall in absorbance at the long-wave end of spectrum as the fat globules reached some critical size. Fat and protein content in the sample significantly affected the observed dependences of spectra on the applied homogenisation time. These observations have been explained as a superposition of two effects: growing fat globule density and changes in scatter nature as the particle sizes approach the light wavelengths in a corresponding spectral range. The representative layer theory has been used to illustrate the nature of the spectral effects.

In-line monitoring of Saccharomyces cerevisiae fermentation with a fluorescence probe: new approaches to data collection and analysis

Fluorescence analysis, in particular two‐dimensional excitation‐emission matrix (EEM) spectroscopy, is a sensitive in‐line process monitoring tool in the biotechnological production. Before it can be widely adopted by the industry, fast effective algorithms for the analysis of massive and complex fluorescence data should be developed. Weak emission signals are prone to various interferences complicating the modeling, such as excitation light Rayleigh scatter. The scatter is usually considered as an unwanted background to be avoided or removed.

Quantitative analysis of total hydrocarbons and water in oil-contaminated soils with attenuated total reflection infrared spectroscopy

The feasibility of direct (ie, without sample preparation) quantitative analysis of total hydrocarbons and water in oil‐contaminated soils using mid‐infrared spectroscopy and an attenuated total reflection (ATR) probe has been investigated. Spectral characteristics of unpolluted and oil‐contaminated soils composed of sand, clay, dolomite, and humus have been studied over the full mid‐infrared range (4000‐400 cm−1). Spectra of 25 typical soil samples containing varying levels of oil and water have been analyzed using a chalcogenide infrared fiber–based probe with a ZrO2 crystal as an ATR element. The spectral data were used to build calibration models for the analysis of hydrocarbon contamination as well as moisture content of soil samples. The low quality of ATR spectra of drier samples and variable spectral intensity inherent in the ATR measurement of solids has been overcome by suitable data processing. Further improvement of the model performance has been achieved using a variable selection based on the modified genetic algorithm. Our proposed method allows the determination of oil and moisture content in soils with accuracies of 1.1% and 0.6%, respectively, which is sufficient for a number of practical applications. The reported results may be used to develop portable devices for measuring petroleum and water content of soils.

Synergy Effect of Combining Fluorescence and Mid Infrared Fiber Spectroscopy for Kidney Tumor Diagnostics

Matching pairs of tumor and non-tumor kidney tissue samples of four patients were investigated ex vivo using a combination of two methods, attenuated total reflection mid infrared spectroscopy and fluorescence spectroscopy, through respectively prepared and adjusted fiber probes. In order to increase the data information content, the measurements on tissue samples in both methods were performed in the same 31 preselected positions. Multivariate data analysis revealed a synergic effect of combining the two methods for the diagnostics of kidney tumor compared to individual techniques.