IR spectroscopic procedure

Spell and Eddy [58] have described IR spectroscopic procedures for the determination of up to 500 ppm of various additives in PE pellets following solvent extraction of additives at room temperature. They showed that lonol (2,6-di- -butyl-p-cresol) and Santonox R... 

Spell and Eddy [3] described infrared (IR) spectroscopic procedures for the determination of up to 500 ppm of various additives in polyethylene (PE) pellets following solvent extraction of the additives at room temperature. They showed lonol (2,6-di-ter -butyl-p-cresol) and Santonox R (4,4 -thio-bis(6-ter -butyl- /-cresol)) are extracted quantitatively from PE pellets by carbon disulfide in 2-3 hours and by isooctane in 50-75 hours. The carbon disulfide extract is suitable for scanning in the IR region between 7.8 and 9.3 (xm, while the isooctane extract is suitable for scanning in the UV region between 250 and 350 nm. 

The standard IR spectroscopic procedure (American Oil Chemists Society) involves dissolution in carbon disulflde with chemical modification if trans levels are < 15%. Peak height only is used for calculation and the overall procedure is slow. By taking advantage of modern multivariate chemometric methods, a more rapid and convenient means of analysis has recently been developed utilizing a... 

Intermediate methods include the earliest procedure based on Stein s equation [33] and one based on Samuels equation [34]. Among the direct methods is an IR spectroscopic method based on the measurement of the dichroic ratio (R), of amorphous absorption bands. In the investigations [35], the amorphous bands 898 cm" and 1368 cm", for which the angles of transition moment are a898 = 39 and aneg = 80 , respectively, were used. Other methods are spectroscopy of polarized fluorescent radiation [35,36], measurement of color di-... 

In this chapter a new technique for the IR spectroscopic analysis of individual microscopic components in coals is described. This method combines new procedures for preparing uncontaminated thin section specimens of coal with a sensitive IR microspectrophotometer which has recently become commercially available. Details of this new technique are discussed and some representative spectra are described. 

A spectroscopic procedure was used in the study of lanthanide complexes of dimethyl formamide and hexamethyl formamide in nitromethane [232]. The observed shifts in spectral bands along with IR data showed that the coordination number for Er(III) to be six and for Pr(III) and Nd(III) an equilibrium mixture of 8 and 9. The maximum number of hexamethyl phosphoramide coordinated to Nd(III) is six with overall coordination number of 8. 

IR spectroscopic evidence for covalent urethane bond formation in the reaction between isocyanates and wood has been obtained. Isolation of holocellulose by the sodium chlorite method, isolation of lignin by the H2SO4 procedure, and subjecting both to IR spectroscopy indicated that isocyanates reacted with both cellulose and lignin (194),... 

Near-IR spectroscopic tomography is discussed in a paper by Tosteson et al. [156], They extend basic concepts of statistical hypothesis testing and confidence intervals to images generated by this new procedure as used for breast cancer diagnosis. 

An IR spectroscopic method was developed for the determination of vinyl acetate content in thick (about 100 micrometres) films of EVAs. The A3460/A3610 ratio was used for the quantitative analysis, the function of this ratio plotted against vinyl acetate content of the EVA films being a convex hyperbola. The technique was simple and rapid and did not require a complicated sample preparation procedure. 11 refs. 

In practical measurements, an instrument (e.g., a pulsed laser, a function generator) that gives an external stimulus to the sample is used in combination with an FT-IR spectrometer. The procedures of spectral measurements are essentially the same as those for normal FT-IR spectroscopic measurements. 

The chemistry involved with crosslinking of diene-based systems is largely speculative. Since crosslinked systems, by their nature, are completely insoluble, all analytical procedures which require solutions of the polymers are unusable. IR spectroscopic techniques are of limited value because the spectrum of polystyrene blocks out most frequencies other methods are difficult in the solid state. Most work reported in this area is based on measuring the fraction of insolubles and some indication of how tightly crosslinked the insoluble component has become (by a swelling index test). The presence of occluded polystyrene in the gel fraction of typical rubber-modified plastics further complicates the issue, although Karam and Tien have attempted to allow for this problem through a modification of the Flory-Rehner equation. 

Figure 2.9 illustrates the IR spectroscopic pattern with and without the applied FSD procedure. The data shows well-defined pairs of submaxima of the broad absorption band within the IR spectroscopic region of 1475 to 1440 cm. ... 

Chloro-1,3,2-oxazaphospholanc (chlorophosphoramidite) 43 derived from (IR, 25)-(-)-cphedrine 42 was prepared for the first time as early as 1977 by its reaction with phosphorus trichloride (Scheme 15) [32, 33], Later, similar procedures were reported for its isolation as a single epimer which, on the basis of spectroscopic and derivatisation studies, has been assigned configuration [34-36],... 

A method for microwave-assisted transesterifications has been described by Van-den Eynde and Rutot [73], The authors investigated the microwave-mediated deriva-tization of poly(styrene-co-allyl alcohol) as a key step in the polymer-assisted synthesis of heterocycles. Several /i-ketoesters were employed in this procedure and multigram quantities of products were obtained when neat mixtures of the reagents in open vessels were subjected to microwave irradiation utilizing a domestic micro-wave oven (Scheme 7.65). The successful derivatization of the polymer was confirmed by IR, 1H NMR, and 13C NMR spectroscopic analyses. The soluble supports... 

Procedure Triturate about 1 mg of the pharmaceutical substance with approximately 300 mg of dry, finely powdered KBr or KC1 of spectroscopic grade, as directed. Grind the mixture thoroughly, spread it uniformly in a suitable die and compress under vacuum at a pressure of about 10 t in-2. Mount the resultant disc in a suitable holder in the spectrophotometer and obtain the IR-spectrum. 

---