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Biochemistry of Buffering Capacity and Ingestion of Buffers In Exercise and Athletic Performance
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
Bryan Saunders, Guilherme G. Artioli, Eimear Dolan, Rebecca L. Jones, Joseph Matthews, Craig Sale
This is the Henderson-Hasselbalch equation, and it is important since it relates pH, pKa, and the percentage of dissociation of an acid (or a base). From this equation, for example, we can see that an acid is 50% in its undissociated form and 50% in its dissociated form when the pH of the medium is equal to its pKa. Thus, the pKa of an acid can also be interpreted as the pH of the solution at which this acid will be 50% dissociated and 50% undissociated.
Anion Gap and Stewart's Strong Ion Difference
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The ‘traditional’ concept of acid–base balance using the Henderson–Hasselbalch equation assumes that behaves as an independent variable for which the concentration determines the metabolic component of pH balance. However, varies with CO2, and this can lead to confusion when measuring the metabolic component of acid–base balance.
Drug Absorption and Bioavailability
Published in Kate McCombe, Lara Wijayasiri, Paul Hatton, David Bogod, The Primary FRCA Structured Oral Examination Study Guide 2, 2017
Kate McCombe, Lara Wijayasiri, Paul Hatton, David Bogod
What is the Henderson–Hasselbalch equation and how is it useful in predicting drug absorption? The Henderson–Hasselbalch equation describes the derivation of pH as a measure of acidity. pH is calculated using the pKa and the equation can be expressed in two ways:
Acid content and buffer-capacity: a charge-balance perspective
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2022
Troels Ring, Stephen Edward Rees, Sebastian Frische
The charge-balance representation of flux can also be compared with the definition of titratable acidity based on Brønsted-Lowry theory [3]. To do so we apply the definition of titratable acidity: ref represents a reference state in terms of temperature, ionic strength and reference pH, here assumed to be pH = 7.4 while S refers to current pH. HBi is any present acid, nt is the total amount, and Ni the average charge of the buffer at actual pH or reference pH. Generalizing from Henderson-Hasselbalch equation [3], N can be obtained as shown in supplementary materials. 1 applies, e.g. ‘1’ for H3O+ and ‘0’ for H3PO4.
Preformulation studies of l -glutathione: physicochemical properties, degradation kinetics, and in vitro cytotoxicity investigations
Published in Drug Development and Industrial Pharmacy, 2020
Mengyang Liu, Manisha Sharma, Guo-Liang Lu, Naibo Yin, Murad Al Gailani, Sree Sreebhavan, Jingyuan Wen
According to the Henderson–Hasselbalch equation (Equation (6)) [38] and the pKa calculated before, the dissociation of GSH was calculated at different pH aqueous conditions and presented in Figure 9(b). It shows that GSH+ is the main form (almost 90%) in a solution of pH values ranging around 1. GSH± is the main form at pH ranging from 2 to 3, whereas GSH− is the main form at higher pH values, reaching almost 100% when the pH value is above 7. These results show that pH values between 2 and 4 are the most stable pH environment for GSH± which corresponds to the pI calculated value above, indicating that GSH is most stable in this pH range as opposed to basic or strong acidic conditions. To confirm these theoretical calculations, experimental data is required, which is presented in the following sections.
A review of methods for solubility determination in biopharmaceutical drug characterization
Published in Drug Development and Industrial Pharmacy, 2019
Ardita Veseli, Simon Žakelj, Albin Kristl
As the experiment continues, the equilibrium solubility is subsequently determined in the presence of precipitated neutral solid, by monitoring pH changes induced by precipitation and actively seeking equilibrium pH where equal amount of the sample is precipitating and dissolving per unit time. The quantity of the tested solid that is needed for establishing solubility must ensure a concentration above its intrinsic solubility when fully neutral to allow precipitation once the pH is adjusted accordingly. If substance precipitation is not detected, a larger quantity is required. A minimum of 2–5 mg was reported for the experimental volume of 10 ml, but for substances that exhibit a higher solubility, larger amounts are of course necessary [58]. Only 20 – 80 min are required for kinetic and equilibrium solubility determination per sample, making it faster than the pSol method [60]. Alas, the method is also restricted only to ionizable compounds. Seeing as the CheqSol method essentially considers the Henderson-Hasselbalch equation always valid since pH/solubility profiles cannot be directly measured, in some cases it could potentially lead to a source of systematic error [51]. Nevertheless, the error would not affect the experimentally established kinetic or intrinsic values but only the pH/solubility profiles.