Threshold concentration monitoring based on pattern recognition analysis of differential near-infrared spectra

RSC Advances ◽  
2014 ◽  
Vol 4 (67) ◽  
pp. 35405-35414 ◽  
Author(s):  
Sanjeewa R. Karunathilaka ◽  
Gary W. Small
Keyword(s):  
Pattern Recognition ◽  
Ir Spectroscopy ◽  
Near Infrared ◽  
Continuous Process ◽  
Threshold Concentration ◽  
Near Ir ◽  
Near Infrared Spectra ◽  
Monitoring Applications ◽  
Monitoring Procedure ◽  
Pattern Recognition Analysis

A threshold concentration monitoring procedure based on near-infrared (near-IR) spectroscopy is described for use in continuous process monitoring applications.

Efforts to Quantify Changes in Near-Infrared Spectra Caused by the Influence of Water, pH, Ionic Strength, and Differences in Physical State

1995 ◽  
Vol 49 (2) ◽  
pp. 181-187 ◽  
Author(s):  
James B. Reeves
Keyword(s):  
Amino Acids ◽  
Ionic Strength ◽  
Infrared Spectra ◽  
Physical State ◽  
Near Infrared ◽  
Near Ir ◽  
Near Infrared Spectra ◽  
Influence Of Water ◽  
Water Ph ◽  
Crystalline Sugars

The application of near-infrared spectroscopy to high-moisture samples has shown that the accuracy does not match that found for dried materials. The objective of this work was to attempt to quantify the effects of water, pH, ionic strength, and differences in physical state on near-infrared spectra with the use of model compounds. Spectra were compared by regression analysis of second derivatives after spectral subtraction of water. Spectra from 4900 to 4100 cm−1 at a resolution of 4 cm−1 were examined. Regression results showed spectra to be more similar among amorphous sugars and among dissolved sugars than among crystalline sugars. Also, spectra of amorphous sugars were statistically more similar to spectra of dissolved sugars than to spectra of crystalline sugars. While the spectra of one dissolved or amorphous sugar were statistically similar, this was not true for amino acids. Spectra of amorphous amino acids were similar to those of crystalline forms and neither were similar to those of dissolved forms. Spectrally, polymeric carbohydrates appeared very similar to one another when dry and behaved like amino acids when wet. Finally, efforts to directly relate these findings to near-IR spectroscopy calibration problems will require further research.

Effects of Data Sampling Rate on Pattern Recognition Analysis of FT-IR Interferograms

1992 ◽  
Vol 46 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Gary W. Small ◽  
Scott E. Carpenter
Keyword(s):  
Pattern Recognition ◽  
Sampling Rate ◽  
Data Sampling ◽  
Monitoring Applications ◽  
Data Sampling Rate ◽  
Ft Ir ◽  
Pattern Recognition Analysis ◽  
Improved Performance ◽  
Mixture Samples ◽  
The Impact

Fourier transform infrared (FT-IR) data of pure and mixture samples of benzene and nitrobenzene are used to investigate and improve methods for interferogram-based qualitative analyses. For use in dedicated monitoring applications, the methodology employed is based on the application of pattern recognition analysis to short, digitally filtered interferogram segments. In the work described here, the impact of the interferogram data sampling rate on the analysis is studied. The results of this study indicate that optimal pattern recognition prediction performance is achieved by use of linear discriminants developed from faster sampled interferogram data. These findings suggest that improved performance can be obtained in FT-IR monitoring applications through the use of spectrometer designs based on a decreased interferogram scan length, coupled with faster sampling electronics.

Evaluation of potential factors affecting the measurement of cerebrovascular reactivity by near-infrared spectroscopy

1998 ◽  
Vol 95 (4) ◽  
pp. 497-504 ◽  
Author(s):  
Rocco TOTARO ◽  
Giovanna BARATTELLI ◽  
Valentina QUARESIMA ◽  
Antonio CAROLEI ◽  
Marco FERRARI
Keyword(s):  
Ir Spectroscopy ◽  
Flow Velocity ◽  
Transcranial Doppler ◽  
Near Infrared ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Cerebrovascular Reactivity ◽  
Co2 Reactivity ◽  
Near Ir ◽  
Reactivity Indexes

1.Near-infrared (IR) spectroscopy is based on the relative transparency of skin, skull and brain to the light in the near-IR region (700–1100 ;nm) and on the oxygen-dependent tissue absorption changes of haemoglobin. 2.We evaluated the most relevant factors (reproducibility, venous return, age and sex) that might affect reliability of near-IR spectroscopy to test CO2 cerebrovascular reactivity. 3.Thirty-four healthy volunteers were enrolled in the study. The protocol consisted of a 3-min baseline, a 3-min hypercapnia (5% CO2 in air) and a 2-min recovery. Transcranial Doppler sonography measurements were simultaneously performed. The CO2 reactivity test was repeated on 27 subjects after 1 ;h to assess reproducibility. CO2 reactivity was also evaluated at different body positions (supine, 35° Trendelenburg and 35° reverse Trendelenburg), and over a gradual increase of the inspired CO2. 4.Changes in near-IR spectroscopy and transcranial Doppler sonography parameters were significantly correlated with variations of end-tidal CO2 (P< 0.005). A significant correlation between the reactivity indexes of near-IR spectroscopy parameters and flow velocity was also found (P< 0.01). A high reproducibility was also found for deoxyhaemoglobin (rI = 0.76), oxyhaemoglobin (rI = 0.68) and flow velocity (rI = 0.60) reactivity indexes. No significant differences between the reactivity indexes of different body positions were found (P> 0.05). The reactivity index of oxyhaemoglobin and deoxyhaemoglobin decreased (P< 0.05) and increased (P< 0.01) with age respectively. 5.We found that near-IR spectroscopy is a reliable and reproducible method for the evaluation of cerebrovascular reactivity and might be considered, after appropriate validation, for the assessment of patients with cerebrovascular disease.

Novel Sampling Device for Obtaining Process Near-Infrared Spectra of High-Pressure Gases

1998 ◽  
Vol 52 (5) ◽  
pp. 746-749 ◽  
Author(s):  
Chris W. Brown ◽  
Amit Mangal ◽  
Stanley M. Barnett
Keyword(s):  
High Pressure ◽  
Near Infrared ◽  
Cylinder Axis ◽  
Sampling Device ◽  
Near Ir ◽  
Near Infrared Spectra ◽  
Infrared Measurements ◽  
On Line ◽  
Background Gas ◽  
Sample Measurement

A novel sampling device for making real-time, on-line, near-infrared measurements of high-pressure gases has been constructed and tested. The design makes it possible to measure background spectra between each sample measurement. The position of a floating piston inside a cylindrical cell is controlled by the pressure differences between the sample gas and the background gas. The optical path is transverse to the cylinder axis so that the sample gas is in the beam when its pressure is highest and the background gas is in the beam when its pressure is highest. At 350 psia, a pressure difference of ∼20 psia will drive the piston to the end having the lower pressure and allow the spectrum of the higher pressure gas to be measured. Near-IR spectra of CO2 as a function of pressure and of 15 different natural gas samples were measured and analyzed.

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