INHIBISI INSEKTISIDA KARBAMAT DAN ORGANOFOSFAT PADA ASETILKHOLINESTERASE LEBAH MADU

It is generally already accepted that organophosphate and carbamate insecticides function due to their ability to disrupt the transmission of impulses at certain synaptic junctions in the nervous system by inhibition of acetylcholinesterase. Type of inhibition reaction of carbamate (Baycarb and MIPC) and organophosphate (Dichlorvos and Monochrotophos) insecticides on honey-bee acetylcholinesterase (AChE) is shown in this investigation. For this study, the enzyme was produced by extraction of honey-bee heads using 0.01 M and pH 7.0 aqueous phosphate buffer solution, while N-methylindoxyl acetate (MIA) in absolute methanol at concentration of 0.005 g/mL was used as a substrate stock solution. Enzyme activity was detected using HPLC spectrofluorometer at 450 nm and 495 nm for excitation and emission wavelength, respectively. Based on detection of initial reaction rate between the enzyme with carbamate or organophosphate, it could be concluded that the reactions were competitive inhibition.Keywords: inhibition, acetylcholinesterase, carbamate, organophosphate

ESTIMATION OF PROTEIN CONCENTRATION IN FOOD BY TOTAL NITROGEN AND AMINO ACID ANALYSES

Since protein is the principal constituent of biological organs, a continuous supply is needed in food for growth and repair. Protein quality in food is determined by its assortment of amino acids, whether it is essentially needed or not. The aim of this study is to develop an accurate and precise simple method of protein estimation for food and feed. The validity of simple protein estimation by multiplying the N-total concentration with a constant factor: of 6.25, should be clarified. Protein could be estimated more specifically by summing up the determined amino acids. In this study, the amino acids of some substantially high protein food were analysed by HPLC-ninhydrin, HPLC-o-phthalaldehyde, and HPLC-dansyl techniques, by gas chromatograph after derivation with TFA-butanol, and by formol titration. Method based on HPLC-ninhydrin techniques shows significant correlation (r=0-9992) with its amino acids content and N-total content. The protein as amino acids - N-total conversion factor obtained was 6.95 for N-total content less than 15.5%, and 8.59 for N-total content higher than 15.5%.Key words: food, protein and analytical method

Gasoline Production from Coconut Oil Using The Ni-MCM-41 and Co/Ni-MCM-41 Catalyst

Gasoline have been produced from coconut oil using MCM-41, NiMCM-41, and Co/NiMCM-41 catalyst. The acidity of catalyst was analysed by Fourier Transformation Infra-Red Spectroscopy (FTIR). The yields of cracking product were analysed by Gas Chromatography-Mass Spectroscopy (GC-MS). The catalyst of Co/NiMCM-41 has the highest acidity than MCM-41 and NiMCM-41. It is caused by the effect of adding d orbital from Co and Ni. This cracking process is batch system, and the catalyst pellets were made at the temperature of 400 ºC. The highest gasoline product was obtained using the Co/NiMCM-41 catalyst with 89.53 % w/w yield. The major liquid product from the cracking process using MCM-41, NiMCM-41, dan Co/NiMCM-41 catalysts were estimated as 1-octena, octane, nonane; 1-octene, 1-nonene, nonane; 1-octene, octane, nonane, respectively.

Preparation of Pt-Zeolite Catalyst for Conversion of n-Octanol = Pembuatan Katalis Pt-Zeolit untuk Konversi n-Oktanol.

Pt-zeolite catalyst has been prepared by immersing a sample of zeolite in PtCI4 solution. After separation, the sample was dried and calcinated at 550°C for 4 hours under nitrogen stream. Furthermore, the sample was oxydized with oxygen gas at 350°C for 2 hours and reduced with hydrogen gas at 400°C for 2 hours. Total amount of impregnated metal, acidity and surface are of the samples were determined by using atomic absorption spectrophotometric, gravimetric and gas sorption methods, respectivelly. The activity test was done in a fixed bed reactor and the result of the reaction were analyzed by using gas chromatograph. The result of the characterization showed that the higher total amount of impregnated metal, the lower the surface area and total volume of pores. The acidity and the catalyst activity increase with the increasing of the total amount of impregnated metal. The flow rate of feed and temperature reaction also influence yield conversion. The optimum yield of n-octanol conversion was obtained at 400°C with the showest flow rate of n-octanoland flow rate of H2 gas was equal to 40 ml/minute. Keywords: Catalyst, Impregnation, Characterization and Conversion

INFLUENCE OF TIME AND CONCENTRATION ON TEXTURAL PROPERTIES OF MESOPOROUS CARBONS OF GELATIN PREPARED BY HARD-TEMPLATING PROCESS

 Mesoporous carbons with different textural properties were prepared with gelatin by hard templating process. The effect silica removal condition (time and acid concentration) on the nanocomposite properties was studied during synthesis process. 1, 6, and 24 h silica removal times and 10%, 20%, 30% and 40% HF concentraton were chosen. Textural properties and microstructure of the nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDAX), and N2 adsorption– desorption. Results showed that removal silica time process led to mesoporous nucleation and growth on the surface of mesoporous carbon. At decreasing of removal silica time and HF concentration the surface area and total pore volume increased from 410 to 760 m2/g and 0.14–0.99 cm3/g with almost same of the average pore diameter considerably at 4.1 nm. Furthermore, it was observed more homogeneous pore distribution with decreasing the silica removal time dan HF consentration. In conclusion, the silica removal time and acid concentration play an important role on textural properties of mesoporous carbon which could have a major effect on adsorption properties of sulfuric compound in the fuel

Analisis pengaruh penambahan ion H+ pada sintesis material mesopori Al-MCM-41 menjadi H-MCM-41

The synthesis of mesoporous Al-MCM-41 material made into H-MCM-41 has been done by mixing 5 grams of Al-MCM-41 synthesis into 100 ml of 0.5 M NH4Cl solution, then filtered and washed and dried in an oven at temperature 80 oC for 24 hours. The acid sites contained in the mesoporous material of H-MCM-41 are the Brønsted acid sites (B) and Lewis acid sites (L). The mesoporous material of H-MCM-41 synthesis shows morphological form of hexagonal pore such as honeycomb. It also makes clear that CTAB as a pore structure steering agent has succeeded in forming a hexagonal phase pore from mesoporous H-MCM-41 synthesized material. The size of the pore diameter of the mesoporous material of H-MCM-41 synthesis was 2.88 Å measured using a measuring ruler based on the scale of the resulting image analysis using TEM.Sintesis material mesopori Al-MCM-41 dibuat menjadi H-MCM-41 telah dilakukan dengan cara mencampur sebanyak 5 gram Al-MCM-41 hasil sintesis ke dalam 100 ml larutan NH4Cl 0,5 M, kemudian disaring dan dicuci serta dikeringkan dalam oven pada suhu 80 oC selama 24 jam. Situs asam yang terkandung pada material mesopori H-MCM-41 adalah situs asam Brønsted (B) dan situs asam Lewis (L). Material mesopori H-MCM-41 hasil sintesis menunjukkan bentuk morfologi berupa pori heksagonal seperti sarang lebah (honeycomb). Hal ini juga memperjelas bahwa CTAB sebagai bahan pengarah struktur pori telah berhasil membentuk pori fasa heksagonal dari material mesopori H-MCM-41 hasil sintesis. Ukuran diameter pori dari material mesopori H-MCM-41 hasil sintesis adalah 2,88 Å diukur menggunakan mistar ukur berdasarkan skala gambar hasil analisis menggunakan TEM

Sintesis dan karakterisasi material mesopori MCM-41 menggunakan TMAOH dan garam anorganik K2SO4

The MCM-41 synthesis has been performed starting from the dissolution stage of cetyltrimethylammonium bromide (CTAB) as a pore mold, then added tetramethylammonium hydroxide (TMAOH) and sodium sulfate salt (K2SO4) to improve the stability of the material. The crystallization process is carried out by adding sodium silicate and sodium aluminate dripwise into the solution. Decrease in pH of the solution was done by adding sulfuric acid (H2SO4 50%). The hydrothermal process is then carried out at 90°C for 36 hours, then washed, dried and calcined at 540°C. MCM-41 synthesis results were characterized using XRD, FTIR and TEM. The results showed that MCM-41 was successfully synthesized with a high degree of crystallography with 48Å lattice parameter size and had a uniform hexagonal pore structure.Sintesis MCM-41 telah dilakukan mulai dari tahap pelarutan cetyltrimethylammonium bromide (CTAB) sebagai cetakan pori, kemudian ditambahkan tetramethylammonium hydroxide (TMAOH) dan garam sodium sulfate (K2SO4) untuk meningkatkan stabilitas material. Proses kristalisasi dilakukan dengan menambahkan natrium silikat dan natrium aluminat tetes demi tetes ke dalam larutan. Penurunan pH larutan dilakukan dengan menambahkan larutan asam sulfat (H2SO4 50%). Selanjutnya dilakukan proses hidrotermal pada suhu 90°C selama 36 jam, kemudian dicuci, dikeringkan dan dikalsinasi pada suhu 540°C. MCM-41 hasil sintesis dikarakterisasi menggunakan XRD, FTIR dan TEM. Hasil penelitian menunjukkan MCM-41 berhasil disintesis dengan tingkat kristanilitas yang tinggi dengan unukuran parameter kisi sebesar 48 Å dan mememiliki struktur pori heksagonal yang seragam

Preparation of Nickel/Active Carboncatalyst and its Utilization for Benzene Hydrogenation

The research on the preparation of nickel catalyst impregnated on active carbon by two methods has been carried out. The impregnation of Ni metal was done using nickel(II) chloride as a precursor. The impregnated of Ni metal on samples in A method was made in varying of percentage i.e., 0.5, 1.0 and 2.0% (w/w) as the weight proportion of Ni to active carbon and NiCl2.6H20. The concentration of Ni that would be impregnated on samples in B method was made close to Ni content of samples in A method determined by atomic adsorption spectrometry. Preparation of nickel/active carbon catalyst with A method was done with dipping the active carbon in the nickel(II) chloride solution followed by filtering and then drying at 110 °C for 4 hours, and then calcination by flowing nitrogen and reduction by hydrogen, each at 400 °C at 4 hours. The treatments made on samples in A method was also done on samples in B method, the only difference was evaporating all of precursor solution after dipping active carbon in that precursor solution was done in B method. The characterization includes: iodium adsorption test, determination of nickel content by means of atomic adsorption spectrometry, and acidity by adsorption of ammonia methods. Test of catalyst activity was done by means of hydrogenation of benzene to cyclohexane at 150, 200 and 250 °C, the pressure of 1 atm and the flow rate of hydrogen 6 mL/minute. The products were analyzed by gas chromatographic method. The results show that A method produced a catalyst with relatively low nickel content. However the acidity and ability to convert benzene to cyclohexane were relatively high and it increased as increasing the content of nickel. The temperature of the reaction was achieved at 250 °C which gave the yield on conversion of 25.3678%. The catalyst obtained by B method in the same condition of hydrogenation gave only smaller results

Preparation of Pt-Zeolite Catalyst for Conversion of n-Octanol

Pt-zeolite catalyst has been prepared by immersing a sample of zeolite in PtCl4 solution. After separation, the sample was dried and calcinated at 550 °C for 4 hours under nitrogen stream. Furthermore, the sample was oxidized with oxygen gas at 350 °C for 2 hours and reduced with hydrogen gas at 400 °C for 2 hours. Total amount of impregnated metal, acidity and surface are of the samples were determined by using atomic absorption spectrophotometric, gravimetric and gas sorption methods, respectively. The activity test was done in a fixed bed reactor and the results of the reaction were analyzed by using gas chromatograph. The result of the characterization showed that the higher total amount of impregnated metal, the lower the surface area and total volume of pores. The acidity and the catalyst activity increase with the increasing of the total amount of impregnated metal. The flow rate of feed and temperature reaction also influence yield conversion. The optimum yield of n-octanol conversion was obtained at 400 °C with the showest flow rate of n-octanol and flow rate of H2 gas was equal to 40 mL/minute

OXIDATION KINETICS AND QUANTIFICATION METHOD OF CHOLESTEROL USING CHOLESTEROL OXIDASE ENZYME CATALYST

In view of health, cholesterol is believed as one of many sources can raise several diseases. Hence, both of research in quantification and developing simple, rapid and accurate analysis method of cholesterol in a sample is very important. Aim of this research was to investigate cholesterol oxidation kinetics and its quantification method based on oxidation of cholesterol and formation complex compound of hexathiocyanato ferat(III), {Fe(SCN)6}-3. The kinetics analysis and quantification, involved cholesterol oxidation in 0.1 M and pH 7.0 phosphate buffer solution to produce cholest-4-en-3-one and hydrogen peroxide, in the presence of cholesterol oxidase enzyme. The formed hydrogen peroxide was used to oxidize iron(II) ion, which was reacted furthermore with thiocyanate ion to raise the red-brown complex compound. Results of the study showed that the complex was stable at 10-120 min since the reaction was started, with maximum wavelength of 530-540 nm. While the kinetics analysis gave first order oxidation reaction with a reaction rate constant, kapp = 5.22 x 10-2 min-1. Based on this kinetics data, cholesterol analysis method could be developed i.e. by oxidizing cholesterol within 1.5 h using cholesterol oxidase as a catalyst, and then reacted with Fe2+, in a solution containing thiocyanate ion. Absorbencies of solutions of the complex compound, measured at wavelength of 535 nm, were linearly proportional to their cholesterol concentrations, in the range of 50-450 ppm.   Keywords: cholesterol, quantification, kinetics, hexathiocyanato ferat(III