Simultaneous Determination of Effective Components of Gegen Qinlian Tablets by HPLC

[Objectives]To establish a HPLC method for the simultaneous determination of 14 characteristic components in Gegen Qinlian tablets and the content of Gegen Qinlian tablets in 11 manufacturers.[Methods]A Inertsil ODS-3(250 mm×4.6 mm,5μm)reversed-phase high performance liquid chromatography column was used with acetonitrile-0.02 mol/L ammonium acetate+0.03%triethylamine solution(adjusted with glacial acetic acid to pH of 4.3)as the mobile phase for gradient elution at a flow rate of 1.0 mL/min.The determination wavelength of 8 components(puerarin,daidzin,liquiritin,baicalin,wogonoside,daidzein,ammonium glycyrrhizinate,baicalein)was 250 nm;the determination wavelength of wogonoside was 280 nm;the determination wavelength of 5 components(epierberine,jatrorrhizine hydrochloride,coptisine,palmatine hydrochloride and berberine hydrochloride)was 346 nm.[Results]There was a good linear relationship between the injection volume of puerarin,daidzin,liquiritin,baicalin,wogonoside,epierberine,jatrorrhizine hydrochloride,coptisine,daidzein,palmatine hydrochloride,ammonium glycyrrhizinate,berberine hydrochloride,baicalein and wogonin and peak area(r>0.9990)in the range of 146.26-5850.24,24.13-965.04,18.45-738.00,79.18-3167.32,9.57-382.80,4.76-190.40,2.57-102.80,13.41-536.40,10.60-424.00,11.33-453.22,12.08-483.20,46.73-1869.25,20.28-811.20,12.11-484.50 ng,respectively;the average recovery rates(n=6)were 2.18%,1.79%,1.81%,1.68%,2.27%,2.13%,1.96%,1.07%,0.93%,0.61%,2.92%,0.77%,2.79%and 0.62%,respectively;the precision,repeatability and stability were good,and the RSD was less than 3%.This method was used to determine 16 batches of Gegen Qinlian tablets produced by 11 enterprises.Wogonoside was not detected in a lot of samples,but 14 components were detected for other enterprises,but the content was different.[Conclusions]The method was accurate and feasible and could be used for the overall quality control of this variety.

Determination of paraquat in water samples using a sensitive fluorescent probe titration method

Paraquat （PQ）, a nonselective herbicide, is non-fluorescent in aqueous solutions. Thus, its determination through direct fluorescent methods is not feasible. The supramolecular inclusion interaction of PQ with cucurbit[7]uril was studied by a fluorescent probe titration method. Significant quenching of the fluorescence intensity of the cucurbit[7]uril-coptisine fluorescent probe was observed with the addition of PQ. A new fluorescent probe titration method with high selectivity and sensitivity at the ng/mL level was developed to determine PQ in aqueous solutions with good precision and accuracy based on the significant quenching of the supramolecular complex fluorescence intensity. The proposed method was successfully used in the determination of PQ in lake water, tap water, well water, and ditch water in an agricultural area, with recoveries of 96.73% to 105.77%. The fluorescence quenching values （AF） showed a good linear relationship with PQ concentrations from 1.0 × 10^-8 to 1.2× 10^-5 mol/L with a detection limit of 3.35 x 10-9 mol/L. In addition, the interaction models of the supramolecular complexes formed between the host and the guest were established using theoretical calculations. The interaction mechanism between the cucurbit[7]uril and PQ was confirmed by 1H NMR spectroscopy.