Measurement of pH in blood

Measurement of Aldosterone in Blood and Urine Simple and refiable immunoassay methods for measuring aldosterone in blood and urine are readily available. These methods differ primarily in the specificity of the antialdosterone antibodies. Most direct radioimmunoassay methods for plasma aldosterone use antisera generated against an aldosterone-3-monooxime-bovine serum albumin (BSA) conjugate, and use an T-labeled ligand and ANS at pH 3.6 to displace aldosterone from plasma-binding proteins. ... 

Glass pH electrodes are simple to use and maintain. They respond selectively to hydronium ion concentration and provide accurate measurements of pH values between about 0 and 10. They can be small enough to be implanted into blood vessels or even inserted into individual living cells. In precision work, these electrodes are calibrated before each use, because their characteristics change somewhat with time and exposure to solutions. The electrode is dipped into a buffer solution of known pH, and the meter is electronically adjusted until it reads the correct value. 

Rajagopalan et al. [72] described an electron-capture gas chromatographic assay method for the determination of primaquine in blood. The method involves deriva-tization with heptafluorobutyric anhydride to form the diheptafluorobutyramide derivative after a single extraction at alkaline pH. The derivatives are quantitated by electron-capture gas chromatography. Blood levels of primaquine as low as 8 ng/mL can be measured with good precision. 

C. May, L. Wan, J. Williams, M. R. Wellard, G. Pell, C. Langenverg, G. Jackson and R. Bellomo, A technique for the simultaneous measurement of renal ATP, blood flow and pH in a large animal model of septic shock. Crit. Care Resusc., 2007,9,30-33. 

Instruments are offered in the market for clinical determination of electrolytes in blood, plasma or serum. One of them, for example, carries out simultaneous determinations of Na, K, Ca, Mg, hematocrit and pH. The cations are of the free type (see Section m.A) and are measured with specific ion-selective electrodes. In complex matrices such as blood or its derived fractions the concentration of free Ca and Mg is affected by the pH of the solution, for example, a slight change of pH will produce or neutralize anionic sites in the proteins, binding or releasing these cations furthermore, the response of the Mg-selective electrode is also affected by the concentration of free Ca(II). The correction... 

Measurement of pH is one of the most important and frequently used procedures in biochemistry. The pH affects the structure and activity of biological macromolecules for example, the catalytic activity of enzymes is strongly dependent on pH (see Fig. 2-21). Measurements of the pH of blood and urine are commonly used in medical diagnoses. The pH of the blood plasma of people... 

The sorption efficiency of MC was determined as the ratio of the quantity of the adsorbed substance to its initial amount (w / w), expressed in % for a certain ratio (w / w) of adsorbent to substance. Optimal ratios of adsorbent to substance equal 15-20 for barbiturates, 20 - 25 for cyanocobalamin and bilirubin, and 40 - 50 for hemoglobin. The initial concentration of absorbed substances was 100 - 200 pg/ml. The substances were incubated for lmin with MC either in physiological solution or in donor plasma and donor blood at room temperature (pH 7.4). The concentration of substances in the solutions was measured by differential visual and UV-spectroscopy. Concentrations of substances in blood and plasma and adsorption of total plasma proteins was determined by thin-layer chromatography with a fluorescent label. 

Potentiometry is widely used clmicaUy for the measurement of pH, PCO2 and electrolytes (Nah K, CL, Ca h LP) in whole blood, serum, plasma and urine, and as the basis for some biosensors for metabolites of clinical interest. 

In the Henderson-Hasselbalch equation, pK and a are used as constants for a temperature of 37 °C. The temperature-controlled sample chamber of an instrument is specified to be 37 °C 0.1 C, and it is at that temperature that all measurements of pH and partial pressure of gases are made. The body temperature of a febrile patient may be elevated to 40 °C to 41 °C, or a patient may be made hypothermic for cardiopulmonary bypass surgery and have a temperature as low as 23 °C. Most blood gas instruments, on keyboard entry of a patient s actual temperature, can calculate and present... 

Maas AH. IFCC reference methods for measurement of pH, gases and electrolytes in blood Reference materials. Eur J Clin Chem Clin Biochem 1991 29 253-61. 

Amylase isoenzymes are detected after separation over an isoelectric pH gradient. They then diffuse into an overlying, insoluble starch polymer containing a covalently bound dye. Release of the dye indicates where the isoenzymes are on the gel. Salivary and pancreatic amylases are secreted into blood as well as saliva and small intestine and each accounts for about half the amylase content of blood plasma. More recently, monoclonal antibodies specific for human salivary amylase have facilitated the measurement of amylases in serum during salivary gland malfunction, and facilitated the differentiation of salivary from pancreatic amylases (Fig. 12.13). 

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