Polarographic Studies Of The Antimalarial Drug Chloroquine Phosphate

In this thesis, a polarographic reduction wave and two polarographic catalytic waves of chloroquine phosphate in the presence of oxidants such as K2S2Og and H2O, were first studied. The mechanisms of the reduction wave and the catalytic wave were proposed. Compared to other methods, these proposed methods had high, good precision and accuracy. In addition, two methods for the determination of phthalic acid in toluic acid and for the determination of maleic acid in tartaric acid by polarography were also proposed in this thesis, which were simple, sensitive and practical. The satisfactory results were obtained by using these proposed methods for determination of samples.This paper includes six parts:PartiThe developments of electrochemistry of quinoline and its derivatives, and antimalaria pharmaceutical chloroquine phosphate were reviewed, respectively.Part n Determination of chloroquine phosphate by single梥weep oscillopolarographyA polarographic method for the determination of chloroquine phosphate was proposed based on its reduction wave with peak potential - 1.61V (vs. SCE) in 4.OX \Q~2 mol/L NH3-H2O-NH4Cl(pH 9.5) supporting electrolyte. The 2nd-order derivative peak current of the reduction wave was rectilinear to chloroquine phosphate concentration in the range of 1.0X 10'8 mol/L -l.OX lO^6 mol/L and 1.0X 10'6mol/L ~ l.OX 10-4mol/L( r = 0.9999, n = 12 ). The relative standard deviation (RSD) was 0.92% for 10 independent measurements of l.OX 10"6 mol/L chloroquine phosphate. The proposed method was applied to the determination of chloroquine phosphate in pharmaceutical tablets.Part IE Determination of chloroquine phosphate using its polarographic catalytic waveA rapid and sensitive method for the determination of chloroquine phosphate was developed based on the parallel catalytic wave of chloroquine phosphate with peak potential - 1.62 V (vs. SCE) in 3.2 X 10'2 mol/L NH3-H2O-NH4C1 (pH 9.5)-1.4 X 10~2 mol/L K2S2O8 supporting electrolyte. The 2nd-order derivative peak current of the catalytic wave was rectilinear to chloroquine phosphate concentration in the range of 1.0 X 10-9~1.0X10'5 mol/L. The recovery was between 95.1% ~ 103.5%. The method was sensitive, simple, rapid, and the result obtained by the proposed method for determination of chloroquine phosphate in tablets agreed with its declared amount.Part IV Study and application of the associtation of chloroquine phosphate with H2O2 by polarographyIn 2.0X 1Q-2 mol/L NH3-H2O-NH4C1 (pH 9.5)- 1.0 X 10'2 mol/L H2O2 supporting electrolyte, chloroquine phosphate yielded a parallel catalytic wave of associtation complex with the peak potential - 1.87V (vs. SCE). The 2nd-order derivative peak current was rectilinear to chloroquine phosphate concentration in the range of 2.OX 10'9 mol/L ~ 1.0 X 10"5 mol/L ( r = 0.9986, n = 10 ). The relative standard deviation (RSD) was 3.4% for 10 independent measurements of l.OX 10"6 mol/L chloroquine phosphate. The recovery was between 95.0% ~ 103.5%. The proposed method was applied to the determination of chloroquine phosphate in pharmaceutical tablets. Here H2O2 as ligand formed an associtation complex with chloroquine phosphate and made the peak potential of chloroquine phosphate changed negative. H2O2 and its reduction species as oxidant oxidized the interminal radical of chloroquine phosphate after 1 e", 1H+ reduction and yielded a catalytic wave. The associtation ratio and formation constant of the associtation complex were determinated, and the effect of the associtation on stability of H2O2 was discussed.Part V Polarographic determination of phthalic acid in toluic acidA polarographic method for the determination of phthalic acid in toluic acid was proposed based on its reduction wave with peak potential - 1.32V (vs. SCE) in 6.4 X 10'2 mol/L H3PO4-KH2PO4 (pH 1.82) supporting electrolyte. The 2nd-order derivativepeak current of the reduction wave was rectilinear to phthalic acid concentration in the range of 5.0X10-7 mol/L ~ 4.0X 10-5 mol/L and 4.0X10-5 mol/L ~ 2.0X10-3 m...