Study On The Determination Of Organic Compounds By Coordinate Ion Absorbing Square Wave Polarography

In the solution of NH3-NH4Cl supporting electrolyte, the non-electro-active organics VB1 and Vc have not appeared reductive peak on the cathode.The amount of the organic compounds can't be measured by the routine voltammetry. It is discovered that when Cd2+ and Zn2+ were induced into solution, a new peak is appeared in the forward scan cures, and those reductive peak have the proportional relation with the concentration of the organic compounds. The amount of non-electro-active organics compounds is indirectly measured quantitatively by the coordinate ion absorbing square wave polarography. Three mechanisms for the adsorption systems of Zn2+ Cd2+ and the Vc VB1 were put forward:firstly,the system of Zn2+,Cd2+ and VB1,because there are -CH2CH2-OH,-NH2,-S-,=N+< groups in the VB1, it adsorb towarding to the cathode and coordinate with inorganic ion. This configuration can activate the VB1 make it obtain electrons more easy, so a new coordination absorbing peak is appeared.Then the reduced VB1 is oxidized in the anode. It forms catalytic circular system. The site of the new peak shift to left about 1000mv against Zn2+ peak.The secondly, the system of the Cd2+ -Vc, because the existence of the adsorbed layer consisting from coordinate ion of Vc and Cd2+, which retard the reduction of Cd2+. The concentration of Vc varies with peak current in the form of inverse ratio. Thirdly, the system of the Zn2+ Vc, as Vc can't be activated by Zn2+complex ion, the peak potential and current are not shifted according concentration of Vc. At the same time it can't redard metal ion reduction. This developed method enlarge the region of the determination of non electro-active organic. It has definite theoretical meaning and applied value on the quantitative analysis of pharmaceutics and chemical reagents.When adding fixed concentration of Cd2+ and Zn2+ in the buffer solution, the peak potential and peak current are not changeable, and a new absorbing peak appears at-0.360v, the height of new peak varies directly with the concentration of VB1, the linear range is 4×10-6 to 4×10-3mol/L for Cd2+ and 2×10-6 to 4×10-3mol/L for Zn2+, the linear correlation coefficient is 0.9997 and 0.9998 respectively, the shape of the peak is very fine,and the repeatability is very well.When Cd2+ was added into buffer solution, the SWV peak current of Cd2+ at-0.856 V linearly decreased with addition of ascorbic acid in the range of 6×10-6～1×10-3mol/L. Along with the increasing of the concentration of Vc, the peak current reduced accordingly, so the concentration of Vc can be measured by the peak current. Because of the oxidation of Cu2+ and strong reduction of Vc, the time of this reaction was not easy to control, so the reappearance of this peak current was badly. It can not determine Vc. If Zn2+ as coordinate ion was added into the buffer solution of NH3- NH4Cl, it was discovered that the reductive peak height of Zn2+ didn't changed with the concentration of Vc. So it can't be use as coordinate ion to determine Vc. Cd2+ can be chose as coordinate ion to determine the concentration of Vc by using standard curve method.For the other dissolubility component of a health care capsule sample, such as citric acid, DL—malate acd and calcium pantothenate, there is no interference peak appear at the range of—200～—1500mV. Making use of the standard addition method, take Zn2+ as coordination ion, get the accurate effect of the concentration of VB1. By using the standard curve method, take Cd2+ as coordination ion, the concentration of Vc was measured combining the proceeding recovery rate experiment. The recovery rate is 99.0%. The satisfied results could be obtained.In the process of preparation of nano-metre particle such as BaTiO3,the non-ion surfactant alkyl polyglycolether(A-20) can control the shape and size of nano-metre particle. And the quality of BaTiO3 can be ameliorated. Because A-20 has not electrochemical activity, it cannot be measured by voltammetry. When A-20 is added into Cd2+ solution, because A-20 has the tendency to be absorbed on the surface of platted Hg glass carbon cathode, it will reduce the peak current of Cd2+ quantitatively, and Cd2+ can be used as the coordination ion to determine the concentration of A-20.The recovery ratio is 94.5%.Besides the VB1 Vc and A-20,the concentration of non-electro-active cationic surface active agent dodecyldimethylbenzyl ammonium chloride (DDBAC) can be determined by the Cd2+, according the effect of the peak current of Cd2+ when adding DDBAC to the Cd2+ basic electrolyte. The experiment results indicated this was a adsorption dynamics process. It has complex relationship among the adsorption time, the concentration of the surfactant and the peak current. The adsorption mode of CdCl+ and quaternary cation R+ was designed and the parameters were fitted in the type of non-linear with the Origin 7.0. The model interpreted the relationship of the DDBAC concentration, adsorption time and the peak current, also can be used to calculate the peak current of complex process. The adsorption of the CdCl+ is faster than the R+, the R+ adsorption is a slowly processing. The absorbing peak current mathematical mode of Cd2+ and DDBAC system isThe peak current can be calculated for complicated absorption process from the equation.The fit value and estimated value are satisfited. The relative standard deviation of the method is 2.2% when determinating benzyl ammonia chloride at-0.660mv, and the recovery fraction of addition standard is 96.8%, so the effect is satisfacted.