Contaminants adventitious

We noted in Section VII-2B that, given the set of surface tension values for various crystal planes, the Wulff theorem allowed the construction of fhe equilibrium or minimum firee energy shape. This concept may be applied in reverse small crystals will gradually take on their equilibrium shape upon annealing near their melting point and likewise, small air pockets in a crystal will form equilibrium-shaped voids. The latter phenomenon offers the possible advantage that adventitious contamination of the solid-air interface is less likely. 

Arsenic is another element with different bioavailabiUty in its different redox states. Arsenic is not known to be an essential nutrient for eukaryotes, but arsenate (As(V)) and arsenite (As(III)) are toxic, with the latter being rather more so, at least to mammals. Nevertheless, some microorganisms grow at the expense of reducing arsenate to arsenite (81), while others are able to reduce these species to more reduced forms. In this case it is known that the element can be immobilized as an insoluble polymetallic sulfide by sulfate reducing bacteria, presumably adventitiously due to the production of hydrogen sulfide (82). Indeed many contaminant metal and metalloid ions can be immobilized as metal sulfides by sulfate reducing bacteria. 

Modem real time instmmental methods permit analyses of unstable transient species and the free-radical intermediates as well. These methods have gready expanded the scope and power of VPO studies, but important basic questions remain unresolved. Another complication is the role of surface. Peroxide decompositions and radical termination reactions can occur on a surface so that, depending on circumstances, surfaces can have either an inhibiting or accelerating effect. Each surface has varying amounts of adventitious contaminants and also accumulates deposits during reaction. Thus no two surfaces are exactly alike and each changes with time. 

Adventitious surfactants also have a marked effect on the mechanism of coalescence. In studying the coalescence of curved water surfaces, Lindblad (L8) used aged distilled water that was stored for about 30 h in a polyethylene bottle opened to the air through a narrow polyethylene tube inserted in the water. He found that if fresh distilled water (water exposed not longer than 1 h to the air) was used, the delay time in coalescence was approximately half as long. Consequently, he concluded that this difference is due to some form of contamination which settled into the water or onto the water surface. 

Appendices This section is most likely to contain additional data associated with biological-based products. It should contain information as regards the facilities and equipment used for the manufacture of biotech products. Assessment of the risk of contamination from adventitious agents such as transmissible spongiform encephalopathy agents (TSEs), bacteria, mycoplasma, fungi or viruses should also be provided. Additional information on novel excipients that have not been used before should also be included in this section. 

Nevertheless, the comparisons presented between the behavior of ultra-thin and thick film catalysts (cf. Tables XI, XIII, XIV) where adventitious surface contamination is insignificant, makes it clear that metal particle size can be a real determinant to the course of these reactions, and... 

Several key issues have to be addressed in the downstream processing of biopharmaceuticals regardless of the expression system. The removal of host cell proteins and nucleic acids, as well as other product- or process-related or adventitious contaminants, is laid down in the regulations and will not differ between the individual expression hosts. The identity, activity and stability of the end product has to be demonstrated regardless of the production system. The need for pharmaceutical quality assurance, validation of processes, analytical methods and cleaning procedures are essentially the same. 

Also at issue, is the EU s threshold for adventitious or accidental contamination. The EU Parliament recently lowered the Commission s proposed 1% threshold to. 5%, which the US claims will add significant costs, be difficult to comply with and effectively restrict trade (Larson, 2002b). The EU proposal would also require labeling for highly processed products that do not have a detectable presence of biotechnology (Larson, 2002b). 

Adventitious (contaminant) carbon Is — 284.6 eV. cCarbon line attributable to the carbonate species. 

Contaminants 2 Any adventitiously introduced materials (e.g., chemical, biochemical, or microbial species) not intended to be part of the manufacturing process of the drug substance or drug product.2... 

Characterization and Testing of Cell Banks Test for adventitious agents, endogenous agents, and molecular contaminants (toxins, antibiotics) to confirm identity, purity, and suitability for manufacturing use... 

Spectral intensities were measured as integrated peak area of each element and relative error for ratios of elemental intensity is about 10 % for aU elements except carbon. The adventitious surface carbon (contamination) was estimated at approximately 10% of the total carbon measured. The concentration of carbon is, therefore, supposed to be in relative error by ca. 20 %. 

According to the high resolution spectra (Fig. 3), the apparent percentage of the ester species (286.5 eV) appears smaller than that of the carbonyl species (288.6eV) on both DOS-and ATBC-oiled sheets, indicating the contribution of the contamination by adventitious hydrocarbon species. The measured percentage of the carbonyl carbon of as-received sheets is 10.9 % for DOS and 18.0 % for ATBC, those of which roughly correspond to the calculated ratios of DOS (9.2 %) and ATBC (21.0 %), respectively. But the effect of contamination makes it difficult to have further insight into the deviation from the calculated values. 

Widening interest in the quaHty of the environment has led to increased demand for information on a wide range of trace-metal contents of foodstuffs. Trace metals in foodstuffs are normally determined by spectroscopic techniques after complete destruction of the organic matrix. Destruction is achieved either by wet oxidation or by dry ashing additional treatment is normally required in order to obtain the metals of interest in a form suitable for analysis. Both methods of destruction are time consuming and tedious this is particularly true of the wet-oxidation procedure, which has the additional disadvantage of being potentially hazardous the methods require considerable analytical skill and experience. Both methods are prone to produce erroneous results either by the loss of an element of interest or by adventitious contamination from the component parts... 

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