Hexanesulfonic Acid Research Articles

Paired-Ion High Pressure Liquid Chromatography of Methotrexate and Metabolites in Biological Fluids

Abstract A paired-ion high pressure liquid chromatography procedure (HPLC) is described for the separation of methotrexate and its major metabolites (7-hydroxymethotrexate, 4-amino-4-deoxy-NlO-methylpteroic acid, methotrexate diglutamate, methotrexate triglutamate), and therapy-related compounds (Diamox and 5-methyltetrahydrofolate). The mobile phase consisted of a 70% solution of 5 mM hexanesulfonic acid, pH 3.75, and 30% methanol eluted on a reverse phase column or columns and monitored at 305 nm or 280 nm UV absorption. The lower limit of sensitivity for methotrexate and 7-hydroxymethotrexate in plasma was 2 ng/ml.

Single column high pressure liquid chromatographic determination of drugs in blood

1. Analysis of anticonvulsants (phenobarbital, diphenylhydantoin and carbamazepine), theophylline and an antiarrhythmic agent (disopyramide) in blood using a simple high pressure liquid chromatography apparatus equipped with a reversed -- phase column is described. A simple extraction of plasma or serum with organic solvent is used to isolate the anticonvulsants and theophylline. Disopyramide is extracted with ether and is further purified by a back extraction into acid. 2. Hexanesulfonic acid -- methanol solutions are used for chromatography of the anticonvulsants and disopyramide while the mobile phase for theophylline is a NH4H2PO4 -- methanol mixture. Chromatographic analysis time for the drugs is approximately 15 minutes. The drugs are monitored by a UV detector at 254 nm except for theophylline which is measured at 280 nm. Quantitation is accomplished by comparison of peak heights with those of internal standards. Quantities of serum or plasma routinely used for analysis are: 200 ul for the anticonvulsants, 100 ul for theophylline and 0.5 ml for disopyramide. Detection limits are less than 1 ug/ml for these quantities.

Reversed-Phase, High-Pressure Liquid Chromatography of Peptides and Proteins with Ion-Pairing Reagents

Reversed-phase, high-pressure liquid chromatography has been successfully applied to the analysis of peptides and proteins by the addition of hydrophilic (for example, phosphoric acid) or hydrophobic (for example, hexanesulfonic acid) ion-pairing reagents, or both, to the mobile phase. Examples described included proteins such as insulin, glucagon, and 1-24 ACTH pentaacetate (ACTH is adrenocorticotrophic hormone).

The photochemical sulphoxidation of n-hexane

The photochemical sulphoxidation of n-hexane in the presence of acetic anhydride giving hexanesulphonic acid has been examined. A maximum yield of 26% is obtained when the sulphoxidation is carried out with a molar ratio of n-hexane:acetic anhydride of 19:1. An increase in the reaction temperature of 28° serves to increase the yield, and for n-decane the limit is reached at about 80°. The reaction is sensitized with acetophenone or p-chloroacetophenone, while it is inhibited by 2,3-dimethylbutane or 1-hexene. Mechanisms involving simultaneous steps of chain reaction via persulphonate radical and a molecular mechanism via excited sulphur trioxide are discussed. The photochemical primary process in the radical chain seems to involve two simultaneous processes, i.e., the energy transfer from excited sulphur dioxide to substrate followed by the homolytic CH bond fission on one hand, and the formation of alkyl radicals by the abstraction of hydrogen with excited sulphur dioxide on the other.