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The protein bovine cupri-zinc superoxide dismutase (SOD) was modified by the reaction of lysine residues with an active ester of methoxy polyethylene glycol 5000 (PEG). The extent of modification was determined by capillary zone electrophoresis, matrix-assisted laser desorption/ionization mass spectrometry, Fourier-transform infrared spectroscopy, and Raman spectroscopy and after removing PEG by alkaline hydrolysis of the linkages to SOD followed by quantification of the released PEG using gel-permeation chromatography. There was generally good agreement among the results obtained by these techniques on a typical sample of the PEG-modified protein. The results, extent of protein modification, determined by the preceding methods were compared to that found from the classical trinitrobenzene sulfonic acid (TNBS) procedure. In addition to providing alternatives to the TNBS procedure, results from the described methodologies strongly suggest that the extent of modification determined from the TNBS procedure is overestimated.

The modification of the protein bovine cupri-zinc superoxide dismutase (SOD) by methoxy polyethylene glycol 5000 (MeO-PEG 5000) has been shown to increase the effective pharmacological lifetime of SOD in vivo while maintaining physiological activity. Polyethylene glycol modification has been extensively employed, for similar purposes, in protein chemistry, peptide chemistry, and polymeric drug development. The modification of SOD is accomplished by the reaction of a number of its lysine residues with an active ester of MeO-PEG 5000. The extent of the modification of the SOD must be ascertained for a number of reasons: optimization of activity, control of in vivo half-life, and manufacturing uniformity, as well as regulatory concerns. The classical method used to determine the extent of protein modification by polyethylene glycols has been a titration with trinitrobenzene sulfonic acid (TNBS). Other techniques which have been employed to determine SOD modification include MALDI mass spectrometry, capillary zone electrophoresis (CZE), and ester hydrolysis with subsequent determination of protein and MeO-PEG 5000 by size-exclusion chromatography (SEC). This report describes an attenuated total reflectance (ATR) infrared technique which estimates the MeO-PEG 5000 content of the modified SOD by measuring absorbance intensity of the C-O-C stretch near 1090 cm-1 in its infrared spectrum. The spectroscopic technique requires no preparation of the modified protein sample, and the spectrum is determined in the saline/phosphate buffer drug formulation.

In the course of operating process equipment in the pharmaceutical industry, it is necessary to assure that all product contact surfaces of process equipment contain a minimum amount of residue. The residue may be another product remaining from a previous operation, an excipient, or a "nonformulation" type of material. This report discusses the determination of hydrocarbons, in the form of lubricating greases, on the product contact surface of various tablet presses by use of FT-IR spectroscopy. The FT-IR spectroscopic method provides for both identification and quantitation of the lubricant and was suggested by an EPA method.

Implants are widely employed in the animal health industry to deliver pharmaceuticals over an extended period of time. Currently available implants employ one of several growth promotants which have been approved for food animals by the Food and Drug Administration (FDA). The remainder of the implant is composed of the necessary excipients for binding, strength, and sustained release.

We have recently shown that it is possible to carry out nondestructive infrared (IR) spectroscopic studies of solid objects which are very large1–4. It is, however, of equal interest to be able to examine objects which are very small. Consequently, we have recorded spectra of a single human hair, using IR Fourier transform photothermal beam deflection spectroscopy (PBDS)1–8.

Nearly three decades have passed since Eischens et al. 1 measured the infrared bands of CO chemisorbed on Cu, Ni, Pt and Pd, and their assignments, unscathed by time and criticism, have prompted a great deal of infrared work on the interactions of CO with a wide variety of adsorbents. CO adsorption, followed by a variety of infrared techniques, has now become a valued conventional tool for surface studies. The C-O stretching bands of chemisorbed CO yield data about band frequency, half-width, contour and intensity, as well as band shifts and intensity changes when some parameter is changed, which provide information about the structure of the chemisorbed species and permit deductions to be made concerning the adsorbate-adsorbent interaction and the nature and properties of the surface. However, we now find and show that under certain conditions such data, measured by the conventional transmission/absorption (T/A) techniques, can be susceptible to errors and artifacts stemming from the measurement...

FTIR photothermal beam deflection (PBD) spectroscopy was used to record PBD spectra of IR-absorbing gases in presence of IR-absorbing and non-absorbing solids. The presence of the solid, IR-absorbing or not, causes asymmetry at the juncture of the IR and probe laser

Boccuzzi et al. 1 pointed out that the infrared (IR) spectra of fine powders, i. e., materials typical of the texture of adsorbents and catalysts, are the sum of (a) nearly bulk modes; (b) - surface modes due both to first-order (surface truncation) and second order (change of the surface bond force constant) effects; and (c) impurities and/or adsorbed species. Studies of the latter have led to the valuable and voluminous literature of “IR of adsorbed species.” The second order effects are also of interest to surface studies, but little information has been available. In an elegant and detailed study of silica, Boccuzzi et al. observed various impurity modes associated with surface hydroxyl groups, and also intrinsic modes associated with the clean silica surface and related to the different strength and geometry of the surface bonds with respect to the bulk. Their observation demonstrated that new surface and subsurface siloxane groups were spectroscopically distinguishable from those characteri...

During our studies of the methanation reaction over Ni/SiO2 catalyst we have employed mass spectroscopy to follow the redistribution of isotopes among the reactant and product species. When deuterium was employed in the studies,1 a wide variety of isotopic species resulted. Among the species produced are H2O, D2O, and HOD. If accurate sensitivity and fragmentation data are available on the species in question, matrix algebra may be used to transform mass fragment data into concentrations. For example see the text by Roboz.2

The infrared (IR) study of surface species and reactions occurring on solids has contributed markedly to our understanding of surface chemistry and heterogeneous catalysis, and a wide variety of solids has been examined. However, an entire class of catalysts consisting of metal dispersed on carbon has never been studied because the carbon catalyst support absorbs IR radiation so strongly in even the thinnest practical layers that conventional IR techniques fail. As IR data would be helpful in understanding how such catalysts function, we have explored the feasibility of examining carbon-supported catalysts with photothermal beam deflection spectroscopy (PDS) and describe the first IR spectra ot surface species on a Ni-on-carbon catalyst.

One of the uses of fused-silica crucibles is to contain the silicon melt from which semiconductor crystals are grown by the Czochralski method. For three reasons, it is essential that the water content of the crucibles below. First, the softening temperature of the silica is a direct function of the water content. A low water content is necessary to maintain strength and geometry at the high temperatures used in semiconductor crystal growth. Second, water must not cause the contamination of semiconductor crystals. Third, the rate of devitrification is increased by water content. The water content of the crucibles is expected to be uniform, not varying from the inner wall to outer wall. Information on the variation of the water content of fused-silica crucibles is unavailable in the literature. However, transmission infrared spectroscopy has been used to determine water content in fused silica by correlation of the weight loss on heating with the decrease in the absorbance of the Si-OH band at 3680 cm−1. The weight loss is a consequence of the condensation reaction: 2 Si-OH → Si-O-Si + H2O (1)

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) was used to qualita­ tively identify organic impurities in sulfur. The impurities were furthur graded by sorb- ing carbon disulfide (CS2)/ and measuring the area under the band from 1600 to 1500 cm-1 relative to the sulfur band at 1300 cm-1, as observed in the DRIFT spectrum. The sorption of CS2 was proportional to the amount of organic impurity, was not removed by vacuum at 70 C, and was reproducible whether sorption was by infusion or by exposure to vapor. The infrared spectrum of a material may be used to identify arid classify it chemically.^ Sulfur has its strongest IR bands below 1200 cm-1, while the frequencies of hydrocarbons are found from 1400 to 1600, and 2800 to 3100 cm-1.2,3 A rapid method of determining the presence of organic impurity in sulfur in a semi-quantitative mariner would be an asset in the grading of sulfur and in avoiding problems in sulfur processing. The wide separation in frequencies between sulfur and hydrocarbons makes IR a suitable method for the detection of organic species in sulfur.