Zhu-Jun Zhang | PubMed Health

PubMed2006

[Quality standard for Xindi soft capsule].

OBJECTIVE: To establish the quality control standard of Xindi soft capsule. METHOD: Quercetin, kaempferol and isorhamnetin were isolated by TLC with chloroform-ethyl formate-formic acid (5:4:1). The chromatographic separation was performed on a Diamonsil C18 column (4.6 mm x 250 mm, 5 microm). Acetonitrile-water-phosphoric (30:70:0.1) as mobile phase. The flow rate was 1 mL x min(-1) and column temperature was set at 40 degrees C. The UV detection wavelength was set at 254 nm. RESULT: Quercetin, Kaempferol and Isorhamnetin could be identified by TLC. Quercetin showed a good linear relationship at a range of 0.412-1.648 microg, r = 0.999 9, the average recovery was 96.8%, and RSD was 0.9% (n = 6). Kaempferol showed a good linear relationship at a range of 0.021-0.083 microg, r = 0.999 8, the average recovery was 96.9%, and RSD was 2.0% (n = 6). Isorhamnetin showed a good linear relationship at a range of 0.183-0.732 microg, r = 0.999 9, the average recovery was 97.1%, and RSD was 1.6% (n = 6). CONCLUSION: The method is accurate with the good reproducibility and can be used for the quality control of Xindi soft capsule.

Capsules↗

PubMed2003

Speciation of chromium by in-capillary reaction and capillary electrophoresis with chemiluminescence detection.

A sensitive method for the simultaneous determination of chromium(III) (Cr3+) and chromium(VI) (CrO4(2-)) using in-capillary reaction, capillary electrophoresis (CE) separation and chemiluminescence (CL) detection was developed. The chemiluminescence reaction was based on luminol oxidation by hydrogen peroxide in basic aqueous solution catalyzed by Cr3+ ion followed by capillary electrophoresis separation. Based on in-capillary reduction, chromium(VI) can be reduced by acidic sodium hydrogensulfite to form chromium(III) while the sample is running through the capillary. Before the electrophoresis procedure, the sample (Cr3+ and CrO4(2-)), buffer and acidic sodium hydrogensulfite solution segments were injected in that order into the capillary, followed by application of an appropriate running voltage between both ends. As both chromium species have opposite charges, Cr3+ ions migrate to the cathode, while CrO4(2-) ions, moving in the opposite direction toward the anode, react with acidic sodium hydrogensulfite which results in the formation of Cr3+ ions. Because of the migration time difference of both Cr3+ ions, Cr(III) and Cr(VI) could be separated. The running buffer was composed of 0.02 mol l(-1) acetate buffer (pH 4.7) with 1 x 10(-3) mol l(-1) EDTA. Parameters affecting CE-CL separation and detection, such as reductant (sodium hydrogensulfite) concentration, mixing mode of the analytes with CL reagent, CL reaction reagent pH and concentration, were optimized. The limits of detection (LODs) of Cr(III) and Cr(VI) were 6 x 10(-13) and 8 x 10(-12) mol l(-1) (S/N=3), respectively. The mass LODs for Cr(III) and Cr(VI) were 1.2 x 10(-20) mol (12 zmol) and 3.8 x 10(-19) mol (380 zmol), respectively.

Buffers↗