126 / INDEXES Hydrolysis

Table 4 lists the specifications set by Du Pont, the largest U.S. producer of DMF (4). Water in DMF is deterrnined either by Kad Fischer titration or by gas chromatography. The chromatographic method is more rehable at lower levels of water (<500 ppm) (4). DMF purity is deterrnined by gc. For specialized laboratory appHcations, conductivity measurements have been used as an indication of purity (27). DMF in water can be measured by refractive index, hydrolysis to DMA followed by titration of the Hberated amine, or, most conveniendy, by infrared analysis. A band at 1087 cm is used for the ir analysis. 

Breuer and Prichard [57] have shown that when human hair is exposed overnight to solutions with pH values less than 2, it undergoes irreversible structural changes, evidenced by a weakening of the fibers of up to 30% in the 20% index. Hydrolysis and structural rearrangements most likely occur from such a harsh acid treatment. 

Regression equations were developed between individual metal ion characteristics and toxicity data (LCj(,s) for two species of mollusks, Pema viridis and Mytilus edulis. The four ion characteristics studied were the covalent index, softness index, hydrolysis constant, and ionic index. 

Alkylated aromatics have excellent low temperature fluidity and low pour points. The viscosity indexes are lower than most mineral oils. These materials are less volatile than comparably viscous mineral oils, and more stable to high temperatures, hydrolysis, and nuclear radiation. Oxidation stabihty depends strongly on the stmcture of the alkyl groups (10). However it is difficult to incorporate inhibitors and the lubrication properties of specific stmctures maybe poor. The alkylated aromatics also are compatible with mineral oils and systems designed for mineral oils (see Benzene Toulene Xylenes and ethylbenzene). ... 

Fig. 14. Time dependence of key indexes during en2ymatic hydrolysis (a) degree of hydrolysis (DH) (b) peptide chain length (PCL) (soluble peptides) (c)...

Polytetrafluoroethylene decomposition products thermal decomposition of the fluorocarbon chain in air leads to the formation of oxidized products containing carbon, fluorine and oxygen. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentration should be minimal. (Trade names Algoflon, Fluon, Teflon, Tetran.)... 

Femia, R. E. and Weinberger, R., Determination of reducing and non-reducing carbohydrates in food products by liquid chromatography with post-column catalytic hydrolysis and derivatization comparison with refractive index detection, /. Chromatogr., 402, 127, 1987. 

PVC resists hydrolysis well but is naturally sensitive to light and UV. It must be protected by addition of anti-UV and other protective agents. In these cases, long warranty periods can be allowed, for example ten years and more. For a white, protected, rigid PVC, after natural weathering for 3 years in Michigan, the retention of impact strength is 68% and the yellowness index increases by 5. 

Fig. 4.7 Plot of the log of the relative rates of hydrolysis of MP and the corresponding Ni(II)P vs. the stability index S . The parameter Sj is defined as 100 lE /r- where z = charge,...

Methylation analysis was run by the method of Hakomori ( ), followed by hydrolysis with trifluoracetic acid, sodium borohydride reduction, and acetylation. 6LC was performed on a Hewlett-Packard 5970, used as an inlet for a mass spectrometer. Molecular weight was determined on a Sephacryl S-500 column (2.6 x 70 cm), using deionized water as solvent, upward flow, 2.75 ml/min, and detection by refractive index monitor. Model R-401 (Waters Associates). 

Goni, L, Gareia-Alonso, A., Saura-Calixto, F. (1997). A starch hydrolysis procedure to estimate glyeemie index. 

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