The effects of endodontic irrigants and calcium hydroxide on lipopolysaccharide (LPS; endotoxin) were analyzed using the highly selective technique of mass spectrometry/gas chromatography with selected ion monitoring. An aqueous solution of LPS was mixed with one of a variety of endodontic irrigants for 30 min. Because it is a commonly used interappointment dressing, calcium hydroxide was also applied to LPS for 1, 2, or 5 days. LPS inactivation was measured by quantitation of free fatty acid release. Water, EDTA, ethanol, 0.12% chlorhexidine, chlorhexidine + sodium hypochlorite, and sodium hypochlorite alone showed little breakdown of LPS. Long-term calcium hydroxide--as well as 30-min exposure to an alkaline mixture of chlorhexidine, ethanol, and sodium hypochlorite--did detoxify LPS molecules by hydrolysis of ester bonds in the fatty acid chains of the lipid A moiety.

This paper reports on the equilibrium and kinetics of the reactive extraction of hydrophobic ibuprofen (IBU) enantiomers from the organic phase to the aqueous phase by hydroxypropyl-β-cyclodextrin (HP-β-CD). The modeling and experimental data of extraction performance factors were investigated to obtain the optimal extraction conditions. The best conditions identified involve the use of an HP-β-CD concentration of 0.03 mol/L and pH value of 2.5 at 10 °C. The theory of extraction accompanied by chemical reactions was used to obtain the intrinsic kinetics of the extraction of IBU enantiomers by HP-β-CD. The effects of process parameters, including the agitation speed, interfacial area, initial concentration of IBU enantiomers, initial concentration of extractant, and pH value of aqueous phase, on the initial extraction rate were separately studied. The reactions are first order in IBU and second order in HP-β-CD with forward rate constants of 7.21 × 10–4 m6/(mol2·s) for S-IBU and 4.58 × 10–4 m6/(mol2·s) for R-IBU, respectively.

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