Recovery efficiency buffer effects

EFFECTS OF OTHER BUFFER FORMULATIONS ON RECOVERY EFFICIENCY... 

In order to determine whether the prepared anion-exchange porous membrane is superior to a gel-bead-packed bed in terms of protein recovery efficiency, an experimental comparison was performed with the same porous membrane and bead-packed bed volumes [12]. BSA in a buffer was permeated across the porous membrane and was made to flow downwards through the bed at a constant operating pressure of up to 0.1 MPa. The effluent was sampled from the outside of the hollow-fiber membrane, and from the bottom end of the bed. The effects of the protein solution flow rate on the dynamic binding capacity of the protein were compared between the membrane and the bed. The dynamic binding capacity is defined as the amount of protein adsorbed until the effluent concentration reaches 10% of the feed concentration. The SV as... 

For efficient extraction of macrolide and lincosamide residues from edible animal products, bound residues should be rendered soluble, most if not all of the proteins should be removed, and high recoveries for all analytes should be provided. Since tliese antibiotics do not strongly bind to proteins, many effective extraction methods have been reported. Sample extraction/deproteinization is usually accomplished by vortexing liquid samples or homogenizing semisolid samples with acetonitrile (136—139), acidified (136,140-142) orbasified acetonitrile (143), methanol (14, 144, 145), acidified (145-147) or basified methanol (148), chloroform (149-151), or dichloromethane under alkaline conditions (152). However, for extraction of sedecamycin, a neutral macrolide antibiotic, from swine tissues, use of ethyl acetate at acidic conditions has been suggested (153), while for lincomycin analysis in fish tissues, acidic buffer extraction followed by sodium tungstate deproteinization has been proposed (154). 

The efficiency and economics of oil recovery can be adversely affected by interactions between surfactant aggregates and polymer. Such interactions occur because of mixing at the boundary between surfactant and buffer solutions, and because residual surfactant adsorbed on the rock surface may later desorb into polymer solution. Mixing of polymer and surfactant may also occur throughout the surfactant bank because of the "polymer inaccessible pore volume" effect (1 ). Large polymer molecules are excluded from the smaller pores in the reservoir rock, and travel faster than the surfactant. Thus, polymer molecules enter into the surfactant slug. 

Issues related to sampling procedures, efficiency of extraction, cross-reactivity, and analyte recovery may often require the use of internal standards. The analyst should also be aware that interference - often unexpected - from other food components is also common in the complex matrices that characterize foods. For this reason, a protocol devised for a particular food (e.g., cow s milk) cannot be transferred to an apparently similar food (e.g., sheep s or goat s milk) without suitable experimentation and adequate validation. Removal of interfering materials - once their nature is known - may also be necessary in some cases, and may call for specific procedures, such as addition of precipitating agents, ultrafiltration, dialysis, etc. The easiest way to detect interference, if suspected, is to prepare analyte standards in buffer and in the food matrix at concentrations compatible with the assay. Assays performed with both sets of standards should produce identical curves in the absence of interference. The effects of these treatments on the analyte itself will have to be assessed by experiment. 

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