PubMed · 5483328
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F Wells. 1970-11-28. Ban on barbiturates.. https://doi.org/10.1136/bmj.4.5734.552-a
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This study attempts to combine the advantages of microcolumn high-performance liquid chromatography (micro-HPLC) with those of post-column photochemical derivatization in barbiturate analysis. Some barbiturates are photochemically unstable, leading to photoproducts that show maximum absorption at 270 nm and not the typical one at approximately 220 nm. For this purpose, a laboratory-built photoreactor has been developed to work with micro-HPLC instruments. Its performance is satisfactory in the forensic analysis of barbiturates.
Various noncovalent complexes between native and derivatized cyclodextrins (CDs) and barbiturates were studied using capillary electrophoresis (CE) and electrospray ionization mass spectrometry (ESI-MS). This paper involves the study of four aspects of CD-barbiturate noncovalent inclusion complexes. The first study focused on determining the formation of CD-barbiturate inclusion complexes in ESI-MS. This determination was accomplished by the comparison of migration data from CE with ESI-MS inclusion complex peak abundances, which were found to be complementary. The second study found the possibility of predicting native beta-CD mediated CE elution orders for barbiturates using data from ESI-MS. A third study focused on the formation of barbiturate inclusion complexes with derivatized beta-CD and gamma-CD. As part of this study, the effect of the extent of side chain substitution on native CD complexation behavior was investigated. The results indicated that the number of side chains on the CD does not affect the formation of barbiturate complexes with the hydrophobic CD cavity. Finally, a comparison of the hydroxypropyl-beta-CD-barbiturate and hydroxypropyl-gamma-CD-barbiturate complexes in CE and ESI-MS was made to study the relationship between strength of drug-CD binding and enantioresolution. The results from the above studies indicated that the gas phase and the solution state complexes showed comparable behavior indicating that similar interactions played a role in stabilizing these complexes. While it was possible to use the ESI-MS data to determine drug binding to the CDs, it was not possible to predict whether a separation of the enantiomers of a chiral barbiturate would occur. However, the ESI-MS data could be used to eliminate certain CDs from consideration as chiral selectors.
A series of 30 barbituric acid derivatives were subjected to high-performance liquid chromatography (HPLC) on the 'immobilized artificial membrane' (IAM) column with acetonitrile buffer mobile phase. The retention parameter log k(IAM) was related to the logarithms of partition coefficients determined in octanol-water partition system, log P, to a thin-layer chromatographic (TLC) parameter from partition TLC, R(m0), to an adsorption HPLC retention parameter, log k(0), and to a solubility parameter, delta. It was demonstrated that log k(IAM) correlated significantly to the other parameters of barbiturates determined in partition systems but not to delta. However, log k(IAM) appeared to be a distinctive descriptor of hydrophobicity of barbiturates as compared to the standard log P parameters. The parameter log k(IAM) was shown to correlate with bioactivity data of the agents studied.