APLIKASI METODE REGRESI DAN JARINGAN SYARAF TIRUAN UNTUK KAJIAN HKSA INSEKTISIDA TURUNAN FTALAMIDA

Study of Quantitative Structure Activity Relationship (QSAR) to design new insecticidal compounds from phatalamides containing hydrazone (FMH) derivatives has been done using theoritical electronic, hydrofobic and steric descriptors. The descriptors data were obtained from geometrical optimization process based on PM6 semiempirical method. The Insecticidal activities of Lethal Concentration (LC50) were taken from literature, showing the lethal concentration to the Myzus persicae insect. The analysis of relationship between insecticidal activities and descriptors has been done using Multi Linier Regression (MLR), Principal Component Regression (PCR) and Artificial Neural Network (ANN) methods. The best QSAR equation was obtained from ANN analysis indicated by its higher correlation coefficient compared to those of other methods, i.e. 0.88 with ANN architecture of 5-9-1. QSAR equation obtained from ANN analysis is used as a guidance to design new insecticides and it used to calculate insecticidal activities of FMH derivatives. Three new potent insecticide compounds were obtained based on ANN analysis result with higher activity than have been synthesized, e.g.2-(decalinecarbamoyl)-5-chloro-N�-((5-methylthiophen-2-yl)methylene) benzohydrazide (number 47), 2-(decalinecarbamoyl)-5-chloro-N�-((thiophen-2-yl)- methylene) benzohydrazide (number 37) and 2-(decalinecarbamoyl)-N�-(4- fluorobenzylidene)-5-chlorobenzohydrazide (number 28) with log LC50 values are 1.64

PENGEMBANGAN METODE VOLTAMMETRI LUCUTAN UNTUK ANALISIS ASAM URAT MELALUI PELAPISAN ELEKTRODA DENGAN POLIMER CETAKAN MOLEKUL

Development of the stripping voltammetric method for selective uric acid analysis through the glassy carbon (GC) and hanging mercury drop (HMD) electrode coating with molecular imprinting polymer (MIP) has been carried out. The polymer used as coating was synthesized from methacrylic acid (MAA) as monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker and uric acid as template at various molar ratios. The MIP for uric acid was obtained after extraction of uric acid from the polymer network. The resulted MIP was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and N2 adsorptiondesorption. The surface of electrode was coated with the polymer to give MIP-coated electrode at various time and potential. MIP-coated electrode was used as working electrode in voltammetry to determine uric acid concentration. Results show that the polymer has been successfully synthesized and the uric acid has been partially extracted from the framework. SEM images show that the surface of MIP had pores of �0.1 µm in diameter. The N2 adsorption-desorption data suggest that there is a small increase in the pore size distribution from 37.71 to 38.02 � after extraction of the template. The optimal coating potential of MIP on the surface of GC electrode is at -0.4 V (vs Ag/AgCl) during 60 s. The optimal coating potential and time of MIP on the HMD electrode are at -1 V (vs Ag/AgCl) and 60 s, respectively. Uric acid was accumulated on the MIP-coated electrode during 60 s. The polymethacrylic acid is a non-electrical conducting polymer. Polymer which is synthesized using molar ratio of MAA, EGDMA, uric acid at 1:3:1 shows the optimum performance as an uric acid sensor/template. The MIP-coated GC and HMD electrodes have shown their performance as a sensitive voltammetric sensor for uric acid. The analytical performance of the method using MIP coated GC electrode are as follow: sensitivity 0.5 µA/nM/cm 2 , limit of detection 4.1x10 -9 M, and recovery of 99.6 %. The MIP-coated HMD gives the sensitivity of 69.4 µA/nM/cm 2 , detection limit 6.0x10 -10 M and recovery 95.7%. The developed two methods have detection limits 10 4 -10 5 times lower than spectrophotometric one. The MIP-coated GC and HMD are very selective sensor for uric acid. The presence of ascorbic acid not significantly interfered on the uric acid analysis using MIP-coated GC electrode. Using MIP-coated HMD electrode, ascorbic acid, creatine and creatinine is found not to interfere the uric acid analysis. Analysis of uric acid in the real samples of serum by this voltammetric method tends to give the slightly lower results as compared to those done by spectrophotometric method.