Hideki Hattori

DETERMINATION OF CRESOL ISOMERS AND PHENOL IN HUMAN BODY FLUIDS BY CAPILLARY GAS CHROMATOGRAPHY WITH CRYOGENIC OVEN TRAPPING

ABSTRACT A new method for determination of o-, m- and p-cresols and phenol in human body fluids by capillary gas chromatography (GC) has been developed using cryogenic oven trapping. After heating a whole blood or urine sample containing the four compounds and 2,4-dimethylphenol as internal standard in a 7.5 mL-vial at 100°C for 10 min, 5 mL of headspace vapor was drawn into a gastight syringe. All vapor was introduced through an injection port of a GC instrument in the splitless mode into an α-DEX 120 middle-bore capillary column at 0°C of oven temperature for trapping the compounds; the oven temperature was programmed up to 170°C for their detection by GC with flame ionization detection. The present conditions gave sharp peaks for the compounds, a good separation of each peak and low background impurities for whole blood and urine samples. The regression equations for all compounds showed good linearity in the range of 1–10 µg 0.5 mL−1, with r values of 0.9983–0.9998, for both samples. The detection limits (signal-to-noise ratio=3) for the compounds were 0.3–0.5 µg 0.5 mL−1 for whole blood and urine samples. Intra- and inter-day precisions were not greater than 11.6%, for whole blood and urine samples. The data obtained from actual determination of p- and m-cresols in rat whole blood after oral administration of saponaceous cresol solution are also presented.

Acid-induced change in ozone-reactive site in indole ring of tryptophan

It is well established that ozone as well as oxygen activated by tryptophan 2,3-dioxygenase or indoleamine 2,3-dioxygenase cleave the 2,3-C=C bond of the indole ring of tryptophan to produce N-formylkynurenine. In the present study, however, we found that exposure of tryptophan to aqueous ozone at and below pH 4.5 generated a different compound. The compound was identified as kynurenine by high performance liquid chromatography and mass spectrometry. Exposure of N-formylkynurenine to acidic ozone did not generate a significant amount of kynurenine, indicating that the kynurenine was not produced via N-formylkynurenine. Acidic ozone thus appears to cleave the 1, 2-NAC bond in place of the 2,3-C=C bond of the indole ring, followed by liberation of the 2-C atom. The 1,2-NAC bond and 2,3-C=C bond are likely to undergo changes in their nature of bonding on acidification, enabling ozone to react with the former bond but not with the latter bond.

Rapid isolation of some antiepileptic hydantoins and their analogues with Sep-Pak C18 cartridges and capillary gas chromatography with splitless injection

SummaryA simple and rapid method for isolation of seven antiepileptics (2 hydantoin, 2 oxazolidin, and 3 suximide derivatives) from urine and plasma is presented. Urine and plasma (1 ml) samples containing seven antiepileptics were mixed with distilled water (4 ml), and the sample solution was poured into a pretreated Sep-Pak C18 cartridge; this was washed with water and chloroform/methanol was passed through it to elute the antiepileptics. The eluate was mixed with isoamyl acetate and evaporated under a stream of N2. The drugs were detected by gas chromatography with fused silica capillary columns, splitless injection and flame ionization detection. Separation of the seven antiepileptics from each other and from impurities was satisfactory with the use of an SPB-1 capillary column. The detection limit for the seven antiepileptics with the present method was 0.1−1.0 μg/ml urine or plasma. The recovery of the drugs from urine and plasma was more than 70% and 50%, respectively.ZusammenfassungEs wird eine einfache and schnelle Methode zur Extraktion und zum gaschromatographischen Nachweis von sieben Antiepileptika (2 Hydantoin-, 2 Oxazolidin- und 3 Succinimid-Derivaten) in Harn und Plasma beschrieben. Harn und Plasma (1 ml) werden mit dest. Wasser (4 ml) versetzt und auf eine vorbehandelte Sep-Pak C18 Kartusche gegeben. Nach Waschen mit dest. Wasser werden die Verbindungen mit Chloroform/Methanol eluiert. Das Eluat wird mit Isoamylacetat versetzt und unter N2 eingeengt. Dann erfolgt die gaschromatographische Trennung: Quarzkapillarsäule, splitlose Injektionstechnik und FID. Mit der SPB-1 Kapillarsäule gelang eine gute Trennung der sieben Antiepileptika voneinander und von weiteren Substanzen aus der Matrix. Unter den angegebenen Analysebedingungen betrug die Nachweisgrenze 0.1−1.0 μg/ml Harn oder Plasma. Die Wiederfindungsraten lagen bei den Harnanalysen über 70%, im Plasma über 50%; bei einigen wurden Wiederfindungsraten von mehr als 100% ermittelt.