Buffering capacity bicarbonate

The buffer capacity of the pit fluid is equal to the change in alkalinity of the system per unit change of pH. Figure 4-491 shows the buffer intensity (capacity) of a 0.1 M carbonate pit fluid. Calculating the initial buffer capacity of the pit fluid allows for prediction of the pH change upon introduction of live acid and also any addition of buffer, such as sodium bicarbonate, required to neutralize the excess hydrogen ions. 

Buffers resist a change in pH when protons are produced or consumed. Maximum buffering capacity occurs 1 pH unit on either side of pAl,. Physiologic buffers include bicarbonate, orthophosphate, and proteins. 

At equilibrium, the concentration of H+ will remain constant. When a strong acid (represented by H+ or HA) is introduced into solution, the concentration of H+ is increased. The buffer compensates by reacting with the excess H ions, moving the direction of the above reaction to the left. By combining with bicarbonate and carbonate ions to form the nonionic carbonic acid, equilibrium is reestablished at a pH nearly the same as that existing before. The buffer capacity in this case is determined by the total concentration of carbonate and bicarbonate ions. When no more carbonate or bicarbonate ions are available to combine with excess H+ ions, the buffer capacity has been exceeded and pH will change dramatically upon addition of further acid. 

A mixture of sodium hydroxide and sodium carbonate, a metering pump being necessary. This method avoids the use of either silicate or phosphate and is popular for woven goods and in circumstances where silicate would pose problems. Ideally the carbonate should be free from bicarbonate. This system has less buffering capacity and gives slightly lower bath stability than methods (1) and (2). 

Note - Some products such as amino acid solutions and multiple electrolyte solutions containing dextrose will not be brought to near physiologic pH by the addition of sodium bicarbonate neutralizing additive solution. This is due to the relatively high buffer capacity of these fluids. 

The most convincing proposal is that camosine plays one or more roles in control of intracellular hydrogen ion concentration (Abe, 2000 Vaughan-Jones et al, 2006). Camosine is an effective physiological buffer it is presumed that this property explains its predominant association with white, glycolytic, muscles which possess relatively few mitochondria and thereby generate lactic acid. Not only may camosine, also possible in its acetylated form, help to directly suppress the rise in hydrogen ion concentration but its ability to activate the enzyme carbonic anhydrase (Temperini et al, 2005) would increase bicarbonate buffer capacity. These properties may help explain camosine s protective action in ischaemia, a condition associated with severe intracellular acidosis. 

Acid-base and electrolyte balance High therapeutic dose especially when used in rheumatic fever, stimulates respiration and causes respiratory alkalosis. Reduction in bicarbonate and potassium level reduces the buffering capacity of the extracellular and intracellular fluid. Hypokalemia may lead to dehydration and hypernatremia. They also interfere with carbohydrate metabolism resulting in accumulation of pyruvic acid and lactic acid. 

The onset of local anesthesia can be accelerated by the addition of sodium bicarbonate (1-2 mL) to the local anesthetic solution. This maximizes the amount of drug in the more lipid-soluble (unionized) form. Repeated injections of local anesthetics can result in loss of effectiveness (ie, tachyphylaxis) due to extracellular acidosis. Local anesthetics are commonly marketed as hydrochloride salts (pH 4.0-6.0) to maximize aqueous solubility. After injection, the salts are buffered in the tissue to physiologic pH, thereby providing sufficient free base concentration for diffusion through the axonal membrane. However, repeated injections of the local anesthetic can deplete the buffering capacity of the local tissues. The ensuing acidosis increases the extracellular cationic form, which diffuses poorly and results in tachyphylaxis. Tachyphylaxis to local anesthetics is common in areas with a limited buffer capacity (eg, the cerebrospinal fluid). 

The blood pH may return to normal in adults with mild overdoses. However, the blood pH can drop too far in children or more severely poisoned adults, resulting in metabolic acidosis. A lower buffering capacity or plasma protein-binding capacity may underlie the increased susceptibility to acidosis in children. Excretion of bicarbonate also means the bicarbonate in the blood is lower, and hence, there is an increased likelihood of metabolic acidosis. 

In principle, it would be logical to combine plots of the buffer index curves of each of the buffer components of milk and thus obtain a plot which could be compared with that actually found for milk. It is not difficult, of course, to conclude that the principal buffer components are phosphate, citrate, bicarbonate, and proteins, but quantitative assignment of the buffer capacity to these components proves to be rather difficult. This problem arises primarily from the presence of calcium and magnesium in the system. These alkaline earths are present as free ions as soluble, undissociated complexes with phosphates, citrate, and casein and as colloidal phosphates associated with casein. Thus precise definition of the ionic equilibria in milk becomes rather complicated. It is difficult to obtain ratios for the various physical states of some of the components, even in simple systems. Some concentrations must be calculated from the dissociation constants, whose... 

Dulbecco s phosphate buffered saline (PBS) is similar to Hanks BSS but bicarbonate is omitted and the levesl of Na2HP04 and KH2P04 are raised to provide increased buffering capacity. It is not used as a basis for growth medium but is often used for washing cell monolayers. PBS is made up in three parts (Appendix 1 Table 2). PBS solution A (PBS-A) lacks the Ca2+ and Mg2 + ions which are... 

Calculate the buffer capacity of 0.1 M sodium carbonate and 0.1 sodium bicarbonate. 

Bicarbonate ions are freely filtered by the glomerulus. The concentration of bicarbonate in the tubular fluid is equivalent to that of plasma. If bicarbonate were not reabsorbed the buffering capacity of the blood would rapidly be depleted. 

Brpnsted theory, 23 Definition of Kb, 38 Lewis theory, 24 HSAB theory, 12 Base saturation (%), 163 Basic organic compounds, 356 Bicarbonate, 30-33 Biotite, 104, 108 Boltzmann equation, 143 Bonding, 6-12 Covalent, 7 Ionic, 7 Boron, 127 Buffer capacity, 86... 

Buffer Capacity and pH The normal pH of the tear fluid is 7.4. Ocular formulations should ideally be formulated between pH 7.0 and 7.7 to avoid irritation of the eye [31], However, in most cases the pH necessary for maximal solubility or stability of the drug is well outside this range. The tear fluid has only a limited buffering capacity, which is mainly due to the dissolved carbon dioxide and bicarbonate. It is therefore recommended to formulate using buffers with a low buffering capacity to allow the tears to regain their normal pH more rapidly [31],... 

Various types of media have been used to cultivate different cell lines. The choice is mostly empirical, but formulations can be optimized for different cell lines and purposes. Most media, however, have the following essential components balanced salt solutions (BSS), essential amino acids, glucose, vitamins, buffers, and antibiotics. The BSS provides a concoction of inorganic salts required by the cells and usually has an osmolality between 260 and 320mOsm/kg, which is similar in range to that experienced by cells in vivo. Balanced salt solution often contains sodium bicarbonate and phosphates, which apart from nutrient value, also act in a buffering capacity. 

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