Glass hydrolytic resistance

Determination of Hydrolytic Resistance of Glass Grains at 98°C, ISO R719 1968... 

The hydrolytic resistance test described in this chapter is the powdered glass test and not the water attack test as described above see Appendix <661>, USP 27 [1]. 

Bohrer, D., do Nascimento, P. C, Becker, E., Bortoluzzi, F, depoi, E, and de Carvalho, L. M. (2004), Critical evaluation of the standard hydrolytic resistance test for glasses used for containers for blood and parenteral formulations, PDA J. Pharm. Sci. Technol, 58, 96-105. 

Whenever there is a chemical erosion of glass, water or its dissociation products, H+ or OH ions will be involved. Because of this, a distinction is made between the resistance of glass to water (its hydrolytic resistance) and to alkali or acid. Under attack from water or acids, small numbers of cations, particularly monovalent and divalent, are released. On resistant types of glass, a very thin layer of silica gel forms in this way on the glass surface and usually inhibits further erosion. In contrast, hydrofluoric acid, alkaline solutions and, under certain circumstances, phosphoric acid will slowly remove the inhibitor layer and thus the entire surface. Nonaqueous solutions (organic solutions), however, are practically nonreactive with glass. 

EP describes Type I glass as neutral glass with high hydrolytic resistance owing to the chemical composition of the glass itself. Type I is suitable for all preparations whether or not for parenteral use and for human blood and blood components. ... 

EP Soda-lime silica glass with high hydrolytic resistance resulting from suitable treatment of the surface. These containers are suitable for acidic and neutral aqueous preparations for parenteral use. ... 

EP These are soda-lime glasses with only moderate hydrolytic resistance. They are suitable for non-aqueous preparations for parenteral use, for powders for parenteral use, and for preparations not for parenteral use. ... 

These glass containers for pharmaceutical use have to comply with relevant tests such as tests for hydrolytic resistance for EP, and tests chemical resistance for Usp.[ 2] (gg procedure and methods are slightly... 

The chemical stability of glass containers for pharmaceutical use is expressed by the hydrolytic resistance, i.e., the resistance to release of water-soluble mineral substances, evaluated by titrating the released alkalinity. According to the European Pharmacopoeia (2002), aqueous preparations for parenteral use are to be dispensed into glass containers of high hydrolytic resistance, while nonaqueous preparations and powders for parenteral use can be filled into glass containers of moderate hydrolytic resistance. It is obvious that release of alkaline substances may influence photochemical stability by an increase in pH (see Section 14.2.3). 

In terms of its chemical resistance to attack by aqueous solutions, laboratory glasses are generally classified according to (a) hydrolytic resistance, (b) resistance to acids and (c) resistance to alkali, as shown in Tables 3 and 4. 

The polyether sulfones are amorphous and have high glass transition temperatures of between 190 and 290° C. They have good creep behavior, dielectric properties, and thermal and hydrolytic resistance. They are suitable for use in engineering parts, electrical components, as pan and saucepan coatings, and also for the removal of salt from seawater when used in membrane form as sulfonated products. 

The Ph. Eur. classifies glass by hydrolytic resistance the resistance against attack by hydrolysis [17], Hydrolytic resistance is determined by steam sterilisation of the glass with water, followed by titration of the released OH -ions with acid. Based on the amount of OH -ions the Ph. Eur. classifies glass into three different classes ... 

I. Neutral glass or borosilicate glass with high hydrolytic resistance due to the chemical composition of the glass itself... 

III. Soda-Iime-silica glass with only moderate hydrolytic resistance... 

Glass, transparent or amber required hydrolytic resistance depends on usage... 

The glass of eye drop bottles has hydrolytic resistance 1 or ni (see Sect. 24.2.1). Type I glass is preferable and is most universally applicable. 

This eye drop bottle consists of a glass bottle (hydrolytic resistance type I) and an upper part that consists completely of polypropylene. Due to the stiffness of polypropylene the dropper does not have a round but a flattened shape so that the patient needs less strength to create a drop. The polypropylene cap is sealed with a tamper-evident strip to the upper part (Figs. 24.4 and 24.5). After applying the upper part onto the bottle using a special tool, it cannot be unscrewed without this tool, for example by the patient. For larger batches an electrical closing device has been developed. 

The PEEK resia is gray, crystalline, and has excellent chemical resistance T is ca 185°C, and it melts at 288°C. The unfilled resia has an HPT of 165°C, which can be iacreased to near its melting poiat by incorporating glass filler. The resia is thermally stable, and maintains ductiUty for over one week after being heated to 320°C it can be kept for years at 200°C. Hydrolytic stabiUty is excellent. The resia is flame retardant, has low smoke emission, and can be processed at 340—400°C. Crystallinity is a function of mold temperature and can reach 30—35% at mold temperatures of 160°C. Recycled material can be safely processed. Properties are given ia Table 16. 

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