Infrared spectroscopy precision advantage

Therefore, for infrared spectroscopic methods, the total petroleum hydrocarbons comprise any chemicals extracted by a solvent that are not removed by silica gel and can be detected by infrared spectroscopy at a specified wavelength. The primary advantage of the infrared-based methods is that they are simple and rapid. Detection limits (e.g., for EPA 418.1) are approximately 1 mg/L in water and 10 mg/kg in soil. However, the infrared method(s) often suffer from poor accuracy and precision, especially for heterogeneous soil samples. Also, the infrared methods give no information on the type of fuel present in the sample, and there is little, often no information about the presence or absence of toxic molecules, and no specific information about potential risk associated with the contamination. 

LL) F. Pristera et al, PATR 2254(1956) (Analysis of Explosives by Infrared Spectroscopy). A compilation of 68 infrared spectrograms covering all common HE s and many possible expl ingredients, additives and related compds. In the analysis of single or multi-component HE s, infrared specttoscopy is, in most cases, very useful either alone or in connection with other methods. Infrared spectroscopy has the advantages of speed, specificity and very often accuracy precision... 

FT-IR diffuse reflectance measurements have been used to quantitatively determine the amount of silane deposited on a substrate. The advantages of FT-IR are speed and sensitivity, the latter relating to the ultimate analytical precision or the smallest amount of the analyte one can determine. Other classical uses of infrared spectroscopy are as a qualitative identification or structure elucidation tool. 

Infrared spectroscopy has not very often been used to check the deuterium purity of alkynes, with the exception of the case of compounds with the C=CD group. For these compounds a quantitative method, analogous to the one used to determine the deuterium content of deuterium oxide by n.m.r., has been described . Known quantities of the non-deuterated hydrocarbon RC=CH are successively added to the corresponding RC=CD compound of unknown deuterium purity, and the transmittance of the v(=CH) or K=CD) band is followed i>s. the added amounts of RC CH. The method is long but it does not require precise knowledge of the coefficient of molar extinction, e, of the v(=CH) band. Its main advantage is the elimination of errors due to molecular associations. It is not applicable to volatile compounds. 

Stansell and Mojica (1968) have described a procedure for the determination of total body water content of human subjects. They used 11- to 12-g doses of DjO, vacuum sublimation of serum samples, and quantitation of the deuterium by infrared spectroscopy at 2510 cm. The chief advantages given for the procedure were (1) a D2O dose of only 10 ml is required for adult subjects, and (2) the ease of the assay is coupled with satisfactory accuracy and precision. The coefficient of variation based... 

This article provides some general remarks on detection requirements for FIA and related techniques and outlines the basic features of the most commonly used detection principles, including optical methods (namely, ultraviolet (UV)-visible spectrophotometry, spectrofluorimetry, chemiluminescence (CL), infrared (IR) spectroscopy, and atomic absorption/emission spectrometry) and electrochemical techniques such as potentiometry, amperometry, voltammetry, and stripping analysis methods. Very few flowing stream applications involve other detection techniques. In this respect, measurement of physical properties such as the refractive index, surface tension, and optical rotation, as well as the a-, //-, or y-emission of radionuclides, should be underlined. Piezoelectric quartz crystal detectors, thermal lens spectroscopy, photoacoustic spectroscopy, surface-enhanced Raman spectroscopy, and conductometric detection have also been coupled to flow systems, with notable advantages in terms of automation, precision, and sampling rate in comparison with the manual counterparts. 

In order to understand the close picture of the organized phases, conformational properties of the molecular chains in the aggregates are fundamentally important [6-8]. No definitive experimental evidence of the conformational relevance to the organized phases has been reported, possibly because of the limited experimental techniques to provide precise information of the conformational state of the molecules in these systems. Vibrational spectroscopy, which implies infrared and Raman spectroscopy, is one of the most powerful techniques for this purpose, because the spectra exhibit a number of bands characteristic of particular conformational states of the molecular chain [9]. One of the practical advantages of this method over the others is its applicability to the molecular systems in any physical states of the substance. 

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