Lithium Orotate Dissociation
It is something of an open question as to whether lithium orotate (LiOr) dissociates in solution (free Li+ and the base orotate), or whether it remains as an metalorganic complex.
This should be approachable by measuring 3 characteristics of LiOr solutions:
1. conductance -- higher conductance implies free ions
2. osmolality -- higher osmolality implies dissociation
3. free Li+ concentration -- Li-selective electrode will detect Li+ if dissociated, but not in LiOr complex.
Free Li+ Concentration
Osmolality
Test Solutions
Make mixtures of LiCl, Li2CO3, and LiOr and several "physiological" solutions. Measure free Li+ with electrode. For Tris and plasma, also measure osmolality.
1. Tris
Tris-LiCl, Tris-LiOH, Tris-LiOH-Orotate (across concentration and pH ranges)
2. Simulated Gastric Fluid (SGF)
Li+ electrode cannot function at low pH (~2.0) of SGF, so need to neutralize mixtures with sodium bicarbonate (NaCH03). Assay free Li+ when added before or after neutralization.
Measure at 37° C, across concentration ranges:
SGF-LiCl -> + NaHC03, SGF-Tris-LiOr -> + NaHC03, SGF -> + NaHC03 + LiCl, SGF -> + NaHC03 + Tris-LiOr
3. Rat plasma
Blood taken from terminal cardiac puncture, heparinized, plasma separated and frozen at -20° C.
Measure at 37° C, across concentration ranges:
plasma-LiCl, plasma-Li2CO3, plasma-LiOr
4. Artificial Urine (AU)
Artificial urine prepared according to DIN EN 1616:1999, from Pickering Laboratories (Mountain View, USA).
Measure at 37° C, across concentration ranges:
AU-LiCl, AU-Li2CO3, AU-LiOr