Identification of Electrolytes in Aqueous Solutions from Near-IR Spectra

1996 ◽  
Vol 50 (4) ◽  
pp. 444-448 ◽  
Author(s):  
Jie Lin ◽  
Jing Zhou ◽  
Chris W. Brown
Keyword(s):  
Aqueous Solutions ◽  
Ir Spectra ◽  
Principal Component Regression ◽  
Principal Component ◽  
Transition Metal Ions ◽  
Water Molecules ◽  
Spectral Library ◽  
Dipole Interactions ◽  
Near Ir ◽  
Solutions Of Electrolytes

Dissolution of electrolytes causes characteristic changes in the near-IR spectrum of water. These changes result from a decrease in the concentration of water; charge-dipole interactions between ions and water molecules; formation of hydrogen bonds between oxygen or nitrogen atoms in some ions and water molecules; production of H+ and OH− ions from dissociation and hydrolysis; absorptions due to OH, NH, and CH groups in some ions; and intrinsic colors of some transition metal ions. Changes in spectra were used for identification of electrolytes in aqueous solutions. Near-IR spectra of 71 solutions of single electrolytes were measured and used to develop a spectral library. This near-IR spectral library was processed with principal component regression (PCR) and used for the identification of single and multiple electrolytes in aqueous solutions with the use of their spectra. Most of the unknown electrolytes were identified correctly. For the others, very similar electrolytes were selected with one ion identified correctly. The near-IR spectral library of aqueous solutions of electrolytes can be used as a simple and fast approach for the identification of electrolytes.

Near-IR Spectroscopic Determination of NaCl in Aqueous Solution

1992 ◽  
Vol 46 (12) ◽  
pp. 1809-1815 ◽  
Author(s):  
Jie Lin ◽  
Chris W. Brown
Keyword(s):  
Aqueous Solution ◽  
Temperature Effects ◽  
Continuous Monitoring ◽  
Principal Component Regression ◽  
Principal Component ◽  
Standard Errors ◽  
Near Ir ◽  
Linear And Nonlinear ◽  
Ir Spectroscopic

The concentrations of NaCl in aqueous solutions have been determined with the use of near-IR spectra between 1100 and 1900 nm. Models expressing the concentration of NaCl are developed with linear and nonlinear regression with the use of the absorbances at selected wavelengths and with principal component regression (PCR) using entire spectra. Temperature perturbations on water bands interfere with the measurement of NaCl but can be removed by linear or nonlinear regressions using the absorbances at the wavelengths where the temperature effects are zero, or they can be accounted for by PCR. Standard errors of 5 mM and a detection limit of IS mM are obtained for NaCl. This technique can be applied for quantitative analysis of NaCl in the laboratory or can be readily adapted for continuous monitoring in process control.

Synthesen und Kristallstrukturen von [PPh3Me]NO2 und [PPh3 Me]HCO2H2O / Syntheses and Crystal Structures of [PPh3Me]NO2 and [PPh3Me]HCO2H2O

1988 ◽  
Vol 43 (10) ◽  
pp. 1279-1284 ◽  
Author(s):  
Mervat El Essawi ◽  
H Gosmann ◽  
D Fenske ◽  
F Schmock ◽  
K Dehnicke
Keyword(s):  
Crystal Structure ◽  
Aqueous Solutions ◽  
Ir Spectra ◽  
Bond Angle ◽  
Water Molecules ◽  
Moist Air ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
Structure Determinations

Triphenylmethylphosphonium nitrite and formate have been prepared by the reaction of [PPh3Me]I with silver nitrite, and lead formate, respectively, in aqueous solutions. [PPh3Me]NO2 (1) forms pale yellow crystals, and [PPh3Me]HCO2·H2O (2) forms white crystals. Both compounds are soluble in water, ethanol, and dichloromethane. In moist air 2 is hydrated to yield [PPh3Me]HCO2·2H2O (3). The compounds were characterized by their IR spectra, 1 and 2 also by X-ray crystal structure determinations.[PPh3Me]NO2 (1): space group P21/n, Z = 4, 2088 independent observed reflexions, R = 0.062. Lattice dimensions (20 °C): a = 914.7(3), b = 1887.5(9), c = 1080.0(4) pm, β = 110.29(3)°. The compound consists of PPh3Me+ ions and NO2- anions with bond lengths of 114.2(6) pm and a bond angle of 124.1(7)°. [PPh3Me]HCO2·H2O (2): space group P21/n, Z = 4, 2973 independent observed reflexions, R = 0.069. Lattice dimensions (-20 °C): a = 931(2), b = 1558(3), c = 1281(2) pm, β = 105.9(1)°. The compound consists of PPh3Me+ ions and formate anions which form centrosymmetric dimeric units [HCO2·H2O]22- through hydrogen bridges of the water molecules. Bond lengths CO 122.4(4) and 120.9(4) pm. bond angle OCO 129.9(4)°.

scholarly journals Measurements of Urea and Glucose in Aqueous Solutions with Dual-Beam Near-Infrared Fourier Transform Spectroscopy

2002 ◽  
Vol 56 (12) ◽  
pp. 1593-1599 ◽  
Author(s):  
Peter Snoer Jensen ◽  
Jimmy Bak
Keyword(s):  
Aqueous Solutions ◽  
Near Infrared ◽  
Principal Component Regression ◽  
Principal Component ◽  
Prediction Errors ◽  
Single Beam ◽  
Dual Beam ◽  
Calibration Models ◽  
Ft Ir ◽  
Beam Technique

This study investigates the use of a dual-beam, optical null, FT-IR spectrometer to measure trace organic components in aqueous solutions in the combination band region 5000–4000 cm−1. The spectrometer may be used for both single- and dual-beam measurements, thereby facilitating comparison of these two modes of operation. The concentrations of aqueous solutions of urea and glucose in the ranges 0–40 mg/dL and 0–250 mg/dL, respectively, were determined by principal component regression using both modes. The dual-beam technique eliminated instrumental variations present in the single-beam measurements that must be taken into account when quantifying trace components from single-beam spectra. The data obtained with the dual-beam technique resulted in more stable calibration models based on principal component regression. These calibration models need fewer factors and yield lower prediction errors than those based on traditional single-beam data.

Depth-Resolved Near-Infrared Spectroscopy

1996 ◽  
Vol 50 (2) ◽  
pp. 285-291 ◽  
Author(s):  
Nadhamuni G. Nerella ◽  
James K. Drennen
Keyword(s):  
Near Infrared ◽  
Principal Component Regression ◽  
Principal Component ◽  
Depth Resolution ◽  
New Drugs ◽  
Penetration Enhancers ◽  
Calibration Model ◽  
Near Ir ◽  
Hydrogel Matrix

While there is substantial evidence proving the success of transdermal drug delivery, there have been few accomplishments in the area of depth-resolved prediction of drug concentration during diffusion through a matrix. Such a method for noninvasive quantification of a diffusing species could assist in the development of new drugs, dosage forms, and penetration enhancers. Near-infrared depth-resolved measurements were accomplished by strategically controlling the amount of reflected light reaching the detectors using a combination of diaphragms with different-diameter apertures. Near-IR spectra were collected from a set of cellulose and Silastic® membranes to prove the possibility of depth-resolved near-IR measurements. Principal component regression was used to estimate the depth resolution of this method, yielding an average resolution of 31 μm. Further, to demonstrate depth-resolved near-IR spectroscopy in a practical in vitro system, we determined concentrations of salicylic acid (SA) in a hydrogel matrix during diffusion experiments carried out for up to three hours. An artificial-neural-network-based calibration model was developed which predicted SA concentrations accurately ( R2 = 0.993, SEP = 123 μg/mL).

Determination of Cholesterol Using a Novel Magnetohydrodynamic Acoustic-Resonance Near-IR (MARNIR) Spectrometer

1993 ◽  
Vol 47 (7) ◽  
pp. 887-890 ◽  
Author(s):  
Robert G. Buice ◽  
Robert A. Lodder
Keyword(s):  
Prediction Error ◽  
Principal Component Regression ◽  
Principal Component ◽  
Acoustic Resonance ◽  
Selection Methods ◽  
Wavelength Selection ◽  
Spectral Techniques ◽  
Near Ir ◽  
Physical Environments

Near-IR spectrometric determination of minor constituents of biological systems is complicated by the fact that near-IR spectra of these materials vary in different chemical and physical environments. In such cases, wavelength selection methods and full-spectral techniques such as partial least-squares and principal component regression (which weight each wavelength in calibration) produce excess error because they must attempt to model both variations in major constituents and variations in the analyte. A magnetohydrodynamic acoustic-resonance near-IR (MARNIR) spectrometer can determine major constituents of biological materials noninvasively and nondestructively, leaving the near-IR spectrum of the analyte to be used quantitatively with less prediction error.

Effect of the Protons Arising in Aqueous Hydrolysing ATP Solutions, IR Investigations

1974 ◽  
Vol 29 (1-2) ◽  
pp. 29-35 ◽  
Author(s):  
Klaus P. Hofmann ◽  
Georg Zundel
Keyword(s):  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Ir Spectra ◽  
Large Change ◽  
Water Molecules ◽  
Degree Of Hydrolysis ◽  
Hydrogen Phosphate ◽  
Phosphate Ions ◽  
Low Degrees ◽  
Phosphate Groups

Abstract IR spectra of 0.3 ᴍ aqueous solutions of Mg0.5K3-nHMn ATP were plotted. The dependence of the spectra on the hydrolysis was investigated for three different K/H ratios of the nonhydrolysed system. Changes to bands provide information as to the protons added to the phosphate groups and base residues as a function of the initial protonation and degree of hydrolysis. More and more proton addition to the -PO3-- groups is observed as the initial protonation increases and as the degree of hydrolysis rises. The same applies as far as the addition of protons to the base residues is concerned to the systems with a higher initial protonation. At low degrees of hydrolysis the PO43- ions which occur do not bind the two hydrolysis protons completely. 150% protonated PO43- ions first form which cross-like via OH+···O hydrogen bonds, which only become more strongly protonated in the systems with a higher initial protonation at large degrees of hydrolysis. The OH+···O bonds between the 150% protonated hydrogen phosphate ions as well as the NH+···N hydrogen bonds between the base residues cause an IR continuum and are thus easily polarizable. An extremely large change to the hydrate structure within narrow hydrolysis ranges is indicated by changes to the bands of the water molecules. The biological relevance of these findings is briefly discussed in the conclusions.

Self-diffusion of water molecules in aqueous solutions of electrolytes

1969 ◽  
Vol 9 (6) ◽  
pp. 852-854 ◽  
Author(s):  
M. I. Emel'yanov ◽  
E. A. Nikiforov ◽  
N. S. Kucheryavenko
Keyword(s):  
Aqueous Solutions ◽  
Water Molecules ◽  
Self Diffusion ◽  
Solutions Of Electrolytes
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