dCbdpH

dCbdpH is a proposed physicochemical parameter used in cannabinoid chemistry to describe how the speciation of cannabidiol (CBD) in solution varies with pH. By definition, dCbdpH represents the differential change in CBD species distribution with respect to pH, evaluated at a specified temperature and ionic strength. In practical terms, it can be written as dCbdpH ≈ d fi / d(pH), where fi denotes the mole fraction of CBD in a given protonation or isomeric form.

CBD can exist in multiple forms depending on pH and the molecule's acid-base properties; the derivative dCbdpH thus quantifies the sensitivity of CBD speciation to changes in pH. Values of dCbdpH are context-dependent and vary with solvent composition, salts, and the presence of other cannabinoids or acids.

Measurement and estimation of dCbdpH typically involve preparing buffered solutions across a pH range and quantifying the relative abundance of CBD forms using high-performance liquid chromatography, UV–visible spectroscopy, or mass spectrometry, combined with speciation modeling or Henderson–Hasselbalch analysis. Titratable methods may be used to determine the pH-dependent distribution curve, from which dCbdpH can be derived as the slope at a given pH.

Applications of dCbdpH include guiding formulation development to optimize CBD solubility, stability, and bioavailability, as well as contributing to in vitro and pharmacokinetic modelling under physiologically relevant pH conditions. The concept remains descriptive and is not yet universally standardized; different studies may define or compute it in slightly different ways, limiting cross-study comparability.

See also: cannabidiol, pH, acid-base equilibrium.