Buffers blood plasma

For plasminogen-deficient fibrinogen from blood plasma, the anticoagulated blood was centrifuged and the plasma was frozen and washed with saline solution. Treated with charcoal and freeze-thawed. Dialysed versus Tris/NaCl buffer. [Maxwell and Nikel Biochem Prep 12 16 1968.]... 

The important buffer system of blood plasma is the bicarbonate/carbonic acid couple ... 

Some applications of buffers. Many products, including aspirin and blood plasma, are buffered. Buffer tablets are also available in the laboratory (far right to make up a solution to a specified pH. 

The most important type of mixed solution is a buffer, a solution in which the pH resists change when small amounts of strong acids or bases are added. Buffers are used to calibrate pH meters, to culture bacteria, and to control the pH of solutions in which chemical reactions are taking place. They are also administered intravenously to hospital patients. Human blood plasma is buffered to pH = 7.4 the ocean is buffered to about pH = 8.4 by a complex buffering process that depends on the presence of hydrogen carbonates and silicates. A buffer consists of an aqueous solution of a weak acid and its conjugate base supplied as a salt, or a weak base and its conjugate acid supplied as a salt. Examples are a solution of acetic acid and sodium acetate and a solution of ammonia and ammonium chloride. 

Basic procedure (ACW kit) Mix 1500 pL of ACW reagent 1 (diluter) with 1000 pL of ACW reagent 2 (buffer) and 25 pL of photosensitizer reagent (lumi-nol based). Start measurement after brief vortexing. Assayed solution (or control) is added before addition of photosensitizer reagent. Volume of ACW reagent 1 is reduced by the volume of assayed plasma sample. Standard substance ascorbic acid. Duration of measurement 2-3 min. Measured parameter effective lag phase = lag-phase sample - lag-phase blank. Assayed amount of human blood plasma 2 pL. 

Serum albumin is the most abundant protein in blood plasma. Its primary function is to control the colloidal osmotic pressure in blood, but is also important for its buffering capacity and for its ability to transport fatty acids and bilirubin, as well as xenobiotic molecules. The physiological implications of its esterase-like activity are unknown (see Sect. 3.7.5). 

The second dissociation step in phosphate (H2P04/HP04 ) also contributes to the buffering capacity of the blood plasma. Although the pKa value of this system is nearly optimal, its contribution remains small due to the low total concentration of phosphate in the blood (around 1 mM). 

The tension or osmotic pressure of a solution also, ionic strength, usually measured as weight percentage. Often the tonicity of a solution is presented as relative to some physiological solution (e.g., blood plasma). See Hypertonic Hypotonic Isotonic Isotonic Buffers... 

Blood plasma is buffered in part by the bicarbonate system, consisting of carbonic acid (H2C03) as proton donor and bicarbonate (HCO ) as proton acceptor ... 

Tin metabolic acidosis (p. 652) there is an increase in glutamine processing by the kidneys. Not all the excess NH4 thus produced is released into the bloodstream or converted to urea some is excreted directly into the urine. In the kidney, the NH% forms salts with metabolic acids, facilitating their removal in the urine. Bicarbonate produced by the decarboxylation of a-lcetoglutarate in the citric acid cycle can also serve as a buffer in blood plasma. Taken together, these effects of glutamine metabolism in the kidney tend to counteract acidosis. ... 

Phosphate, present to an extent of 0.01 M, is one of the main buffers in blood plasma, whose pH is 7.45. Would phosphate be as useful if the plasma pH were 8.5 ... 

Transferrin of blood plasma is encoded by a separate gene but has a similar structure. Transferrin of chickens appears to be identical to conalbumin of egg whites. The iron-binding proteins of body fluids are sometimes given the group name siderophilins. Transferrins may function not only in transport of iron throughout the body but also as iron buffers that provide a relatively constant iron concentration within tissues. 

A means to avoid such tedious optimization can be envisaged by employing stoichiometric monomers to develop strong interactions with the template as mentioned above. The other way is to incorporate hydrophilic comonomers (2-hydroxyethyl methacrylate (HEMA), acrylamide) or cross-linkers (pentaerythri-toltriacrylate, methylene bisacrylamide) in the polymer. This results in an increase of the hydrophilicity of the polymer. Indeed, the use of HEMA for a MIP directed towards the anesthetic bupivacaine resulted in high imprinting factors due to reduced non-specific hydrophobic adsorption in aqueous buffer. This was not the case when HEMA was omitted from the polymerization mixture [27]. These conditions were exploited for the direct and selective extraction of bupivacaine from blood plasma samples. 

Vinnikova [22, 23] described the spectrophotometric determination of mefenamic acid at 490 nm after conversion to its colored complex with Fast Red B salt at pH 6.60 (phosphate buffer). The method was applied for the determination of free and bound mefenamic acid, and found to be useful for studying the blood plasma protein binding, absorption, distribution, metabolism, and excretion of mefenamic acid. 

Indapamide can be analyzed in blood, plasma and urine by HPLC and fluorescence methods. A specific and sensitive assay method for the analysis of indapamide in urine, blood and plasma was developed (31). The method uses a 250 x 4.6 mm i.d. Zorbax ODS (5 pm particle size) column and a mobile phase of 0.1 M sodium acetate buffer (pl =3.6)/acetonitrile at a ratio of 65/35 (v/v). This method uses an internal standard of sulfanilanilide. Calibration curves obtained by plotting the ratio of the peak height of indapamide to that of sulfanilanilide versus the concentration of indapamide were linear over the concentration ranges of 25-200 ng/mL for plasma and 50-400 ng/mL for blood and urine using UV detection at 241 nm. Another publication reports a high performance liquid chromatographic assay method for monitoring indapamide and Its major metabolite in urine (32). 

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