Artemisinin is an antimalarial drug containing an internal endoperoxide linkage in its structure. A simple, selective and sensitive high-performance liquid chromatography (HPLC)-peroxyoxalate chemiluminescence (PO-CL) method for the determination of artemisinin was developed. This method is based on the fact that endoperoxide in artemisinin structure can be converted to hydrogen peroxide (H(2)O(2)) under ultraviolet (UV) irradiation and the generated hydrogen peroxide can be measured using PO-CL detection. The HPLC-PO-CL system was optimized on a mobile phase, post column chemiluminescence reagent, UV source and irradiation time. In addition, the system was combined with simple liquid-liquid extraction using n-hexane that allowed selective and sensitive determination of artemisinin in serum. The limit of detection using 0.5 mL of blood was 0.062 micromol/L (17.5 ng/mL) at a signal-to-noise ratio of 3. Calibration curve obtained for artemisinin in human serum 4-80 micromol/L (1.1-22.6 microg/mL) showed a good linearity (r = 0.999).
A sensitive, selective and reliable method has been developed and validated for the determination of halofantrine and its metabolite desbutylhalofantrine in rat plasma using 9,10-diphenylanthracene as an internal standard. The method is based on peroxyoxalate chemiluminescence detection of hydrogen peroxide produced from fused aromatic rings in the structures of halofantrine and desbutylhalofantrine upon UV irradiation. Using spiked rat plasma, good linear relationships were obtained for both halofantrine and desbutylhalofantrine between peak height ratios (vs internal standard) and their corresponding concentrations over a range of 0.01-0.8 microg/mL with correlation coefficients of at least 0.997. The detection limits at signal-to-noise ratio of 3 using 0.2 mL of rat plasma were 1.5 and 1.4 ng/mL for halofantrine and desbutylhalofantrine, respectively. Relative standard deviations (n = 3) intra- and inter-day were between 0.5 and 5.4% for all the studied concentrations. Using this method with simple sample treatment, halofantrine and desbutylhalofantrine in rat plasma could be precisely determined without interference from endogenous substances. The method was successfully applied to the measurement of the time courses of plasma halofantrine concentration after oral administration of the drug (7 mg/kg) to rats.
Isoamyl nitrite is used as a therapeutic reagent for cardiac angina and as an antidote for cyanide poisoning, but it is abused because of its euphoric properties. Therefore, a method to determine isoamyl nitrite is required in many fields, including pharmaceutical and forensic studies. In this study, a simple, rapid and sensitive method for the determination of isoamyl nitrite was developed using a flow injection analysis system equipped with a chemiluminescence detector and on-line photoreactor. This method is based on on-line ultraviolet irradiation of isoamyl nitrite and subsequent luminol chemiluminescence detection without the addition of an oxidant. A linear standard curve was obtained up to 1.0 μM of isoamyl nitrite with a detection limit (blank + 3SD) of 0.03 μM. The method was successfully applied to determine isoamyl nitrite content in pharmaceutical preparations.
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