Carbonate-bicarbonate, buffer

These are rate constants for the hydrolysis of cinnamic anhydride in bicarbonate-carbonate buffers. The pK of bicarbonate is 10.22. Find the rate constant for hydrolysis, at each pH, at zero buffer concentration. Analyze the data to determine if the acid or base component of the buffer, or both, are responsible for catalysis, and give the catalytic rate constant(s). 

Variations of 5% in the efficiency of the Cd-column are not uncommon due to inhomogeneity of the column higher variations were, however, found unacceptable for certification. Doubts were expressed on the use of bicarbonate-carbonate buffer in comparison with borate buffer, the latter giving more reliable results. 

Coating Buffer The first step in an ELISA is immobilization of the analyte antianalyte antibody on the microtiter plate. Immobilization occurs passively through van der Waals forces and hydrophobic interactions between the protein and the plastic surface. Proteins have minimum net charge and maximum hydrophobicity near their isoelectric points (IEPs) thus, a coating buffer with a pH close to the IEP of the protein aids in its adsorption to the plate. Unfortunately, information about the IEP of the protein may not be available. In such situations, one should evaluate the suitability of commonly used coating buffers such as lOOmM bicarbonate carbonate buffer (pH 8 10), 50mM PBS (pH -7.4), or 50 mM acetate buffer (pH 5) [17,18],... 

Metoclopramide in plasma has been smoothly acylated with HFB-imidazole for gas chromatography with electron capture detection. The extract of the drug (from I ml of plasma) is heated with 20 /tl of HFB-imidazole for 90 minutes at 75 °C and then cooled. Bicarbonate-carbonate buffer of pH 10 (2 ml) is added, the derivative is extracted into 1 ml of hexane and the extract is evaporated to dryness. The residue is dissolved in 50 1 of hexane immediately prior to analysis [119]. A similar method was used for clebropride, although on a smaller scale, and using only 65 °C for 15 minutes [120]. 

Comments Although the reactions with N-substituted L-prolyl chlorides are usually carried out in organic media. Urn et al. [104] cited an example of acylation under Schotten-Baumann type conditions. The reagent was added to the substrate as a solution in ice cold aqueous bicarbonate/carbonate buffer (5% w/v 7 3 ratio) and the solution was agitated for 10 min. The mixture was allowed to stand in an ice bath for a further 20 min. Lim et al. also showed that when the reaction was carried out in an organic solvent, in the presence of triethylamine, racemization occurred, even at — 75 "C. 

Anion exchange column with a bicarbonate/carbonate buffer Conductivity detection combined with ion suppression Detection limit 50 ng... 

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

Dissolve the amine-containing molecule to be thiolated at a concentration of lOmg/ml in cold (4°C) 1M sodium bicarbonate (reaction buffer). For proteins, dissolve them in deionized water at a pH of 7.0-7.5, at room temperature. Note The presence of some buffer salts, like phosphate or carbonate, is incompatible with silver nitrate. 

Common eluents in suppressor ion chromatography are dilute solutions of mineral acids or phenylenediamine salts for cation separations and sodium bicarbonate/sodium carbonate buffers for anion separations. These eluents are too highly conducting to be used without a suppressor column or conductivity detection. Fritz et al. [54-56] have... 

The Henderson-Hasselbach equation allows the ratio of ionized un-ionized compound to be found if the pH and pKa are known. Consider carbonic acid (H2CO3) bicarbonate (HC03 ) buffer system... 

The composite pA of the bicarbonate system, 6.1, may appear to make it ill-suited for buffering blood at physiologic pH of 7.4. Nevertheless, the system is very effective at buffering against additions of noncarbonic acids. Changes in the bicarbonate/carbonic acid ratio in such cases can be regulated by ... 

The excessive amount of bicarbonate in the blood means that blood has a much greater capacity to neutralize acids. Many acids accumulate in the blood during strenuous activity, for example lactic acid. Excretion of bicarbonate through the kidneys and the removal of carbon dioxide through respiration also regulate the carbonic acid/ bicarbonate blood buffer. 

The organoarsenical particulates are extracted ultrasonically from the filters for 30 minutes in 25 mL of an aqueous carbonate/ bicarbonate/borate buffer (Eluent 1, Table I). After sonication the resulting extracts are ready for analysis and no further sample preparation is necessary. 

Carbonate buffer, pH 9.5, containing 150 mM sodium chloride, 30 mM sodium carbonate, and 50 mM sodium bicarbonate. 

High alkalinity is due to the presence of bicarbonates, carbonates and hydroxides of the alkaline earth and alkali metals, principally calcium, magnesium, sodium and potassium. The effect of high alkalinity is to buffer acidity in a soft drink, resulting in the creation of a bland taste, ft is essential therefore to maintain a consistent alkalinity level. The majority of manufacturers aim for below 50 mg/1 as CaC03. Alkalinity may be reduced by coagulation treatment or by ion exchange. 

The slowness of this reaction leads to a fading end point when a solution containing bicarbonate is titrated with sodium hydroxide using methyl orange as an indicator. The rate of liberation of C02 from carbonate buffers in the neutral range is so slow that this reaction has to be catalyzed in our lungs by carbonic anhydrase. 

Blood travels through the human body in more than 96,000 km of blood vessels and it is full of marker molecules [34], The physiological pH is usually 7.4 with a complex buffer system (bicarbonate-carbonic acid, hemoglobinate-hemoglobin, phosphate buffer) [35],... 

Effect of Holding One s Breath on Blood pH The pH of the extracellular fluid is buffered by the bicarbonate/carbonic acid system. Holding your breath can increase the concentration of C02(g) in the blood. What effect might this have on the pH of the extracellular fluid Explain by showing the relevant equilibrium equation(s) for this buffer system. 

All solvents and chemicals were HPLC grade. Organic solvents, sodium carbonate (anhydrous), and sodium bicarbonate were purchased from Fisher Scientific (Fair Lawn, NJ, USA). Carbonate buffer, pH = 10.0, was prepared using the sodium carbonate (anhydrous), and sodium bicarbonate. A solution of 0.1 % triethylamine in methanol was made for the elution solvent. Diethylcarbamazine citrate was obtained from Sigma, and used to make stock solutions (St. Louis, MO, USA). The internal standard, 1-diethylcarbamyl-4-ethylpiperazine (E-DEC) was synthesized by the Division of Medicinal and Natural Products Chemistry at the University of Iowa, College of Pharmacy. Ultra-pure analytical grade Type I water was produced by a Milli-Q Plus water system (Millipore Corporation, Bedford, MA, USA). For the extraction of DEC and of its internal standard, Alltech Extract - Clean C18 cartridges, 500 mg with a 2.8 mL reservoir, and a SPE vacuum manifold (Alltech, Deerfield, IL, USA) were used. 

A description of acid-base balance involves an accounting of the carbonic (H2C03, HCOh COa", and CO2) and noncar-bonic acids and conjugate bases in terms of input (intake plus metabolic production) and output (excretion plus metabolic conversion) over a given time interval. The acid-base status of the body fluids is typically assessed by measurements of total CO2 plasma pH and PCO2, because the bicarbonate/carbonic acid system is the most important buffering system of the plasma. Occasionally, measurement of total titratable acid or base, or other acid and base analytes (e.g., lactate and ammonia [NH3]) is necessary to determine the etiology of an acid-base disorder. 

---