Buffer Standards for the Biological pH of the Amino Acid N-[2-Hydroxyethyl]piperazine-N′-[3-propanesulfonic acid], HEPPS, From (278.15 to 328.15) K

Abstract

For the HEPPS buffer under investigation, there are seven buffer solutions without NaCl and eight buffer solutions that contain Cl− and have an ionic strength (I = 0.16 mol·kg−1), which is similar to that of blood plasma. These buffer solutions have been evaluated in the temperature range of (278.15 to 328.15) K using the extended Debye- Hückel equation and the Bates-Guggenheim convention. The previously determined Ej values have been used to determine the operational pH values of HEPPS buffer solutions at (298.15 and 310.15) K. These are recommended as secondary standard reference solutions for pH measurements in saline media with an isotonic ionic strength of I = 0.16 mol·kg−1.

A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling

“…2 were developed for individual compounds to consider p K a dependences on T k and I s based on published data (e.g. Bates et al , 1973 ; Feng et al , 1989 ; Roy et al , 2006 , 2009 , 2011 ). However, in the case of zwitterionic buffers, e.g.…”

Good’s buffers as novel phase-forming components of ionic-liquid-based aqueous biphasic systems

“…GBs are zwitterionic compounds consisting of N -substituted taurine and glycine derivatives. Most of these buffers display p K a values between 6 and 8, have a good solubility in water, do not readily permeate through cell membranes, do not chelate with metal-ions, are chemically stable and resist to enzymatic degradation, and are easily prepared and purified from low-cost materials [27, 29, 30]. Taking into account the collective benefits of GBs and ILs, we propose here their combined use as phase-forming components of ABS.…”

“…Taking into account the collective benefits of GBs and ILs, we propose here their combined use as phase-forming components of ABS. Among the available GBs, N-tris(hydroxymethyl)methylglycine (Tricine), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), N-cyclohexyl-2-aminoethanesulfonic acid (CHES), and 2-(N-morpholino)ethanesulfonic acid (MES) were selected because they are suitable buffers for pH control in the physiological pH region (although an alkaline species needs to be added for this purpose) [29,30]. Novel ternary phase diagrams for ABS composed of GBs and ILs were determined at 25 °C, and their ability as novel liquid-liquid systems for extraction/purification purposes was evaluated by partitioning studies carried out with standard aqueous solutions of two amino acids that can be produced in fermentative medium (L-tryptophan and L-phenylalanine) [31, 32].…”

Physicochemical Properties of Buffers Used in Simulated Biological Fluids with Potential Application for In Vitro Dissolution Testing: A Mini-review

“…The pH of the distal colon of fed healthy adults is reported to be approximately 8.1 (35). Table 3 provides pKa' data for buffers relative to this target pH range (3,9,16,17,25,34,(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47). The buffers listed first are those included in the formulations for the simulated biological fluids provided in Marques et al (3) and Klein (9).…”