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All Journal Jurnal Riset Kimia
Umiati Loekman
Department of Chemistry, Faculty of Mathematics and Natural Sciences, Andalas University, Kampus Unand Limau Manis Padang
Chemistry

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VALIDASI METODA PENENTUAN ANTIOKSIDAN TOTAL (DIHITUNG SEBAGAI ASAM SITRAT) DALAM SAMPEL JERUK SECARA SPEKTOFOTOMETRI DENGAN MENGGUNAKAN OKSIDATOR FeCl3 DAN PENGOMPLEKS ORTO-FENANTROLIN -, Yefrida; Ulfaningsih, Mega; Loekman, Umiati
Jurnal Riset Kimia Vol 7, No 2 (2014): March
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jrk.v7i2.187

Abstract

ABSTRACTAntioxidant is a compound that can be used to obstruct species oxygen reactive, speciesnitrogen, and other free radicals so it can be used degenerative illnesses inhibition. Citric acid isa natural antioxidant that can be found in some kind of oranges. There are some methode thatusually used to determination the antioxidant, such as CUPRAC, DPPH, and FRAP. Objectiveof this research is studied about alternative method to determine total antioxidant that is countedas citric acid by using FeCl3 as an oxidator and o-phenantroline as a complexant reagent. Instudied of appropriateness of this method, validation has been done with parameter linearity,LoD, LoQ, SDR, and recovery with samples orange, kaffir lime, and lime. Base on the research,the regression equation is Y = 0,066 + 117.35 X and R2 = 0.990 with value of LoD is1.15x10-3M and LoQ is 3.86x10-3 M. The value of SDR and recovery in samples orange, kaffir lime, andlime are 1.64%, 0.53% 2.14%, and 100.47%, 93.58%, 93.78%, respectively. Base on validationmethod data, can be concluded that this method appropriate to be used to determination of totalantioxidant for samples orange, kaffir lime, and lime.Keywords : Antioxidant, Validation Method, Spectrophotometry
THE OPTIMATION SIMULTANEUOS DETERMINATION OF LEAD(II) AND CADMIUM(II) BY ADSORPTIVE STRIPPING VOLTAMMETRY (ADSV) -, Deswati; Suyani, Hamzar; Loekman, Umiati; Sari, Nilam
Jurnal Riset Kimia Vol 5, No 2 (2012): March
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jrk.v5i2.198

Abstract

A selective and sensitive adsorptive stripping voltammetric (AdSV) method for simultaneous determination of lead(II) and cadmium(II) were proposed. The aim of this study was to get the optimum condition for simultaneuos determination of lead(II) and cadmium(II). The parameters were studied such as: variation of accumulation potential, accumulation time, pH, and variation ofcalcon concentration. In this case, the optimum conditions were reached at accumulation potential –0.7 V, accumulation time 80 s, concentration of 0.12 mM calcon, and pH 7.0. At the optimumconditions the relative standard deviation were 2.90% and 1.46% for Pb(II) and Cd(II) respectively for eight replicates (n = 8) measurements. The method was applied for the direct determination of Pb(II) and Cd(II) in sea water around Bungus, Padang City. Concentration Pb(II) and Cd(II) insample were 9.918 μg/L – 27.320 μg/L for Pb(II) and 7.997 μg/L - 32.521 μg/L for Cd(II), with recovery of 99.48%, and 103.28 for Pb(II), and Cd(II) respectively.
DEGRADASI ZAT WARNA SUDAN I SECARA SONOLISIS DAN FOTOLISIS DENGAN PENAMBAHAN TiO2-ANATASE -, Safni; Loekman, Umiati; Febrianti, Fitra; -, Maizatisna; Sakai, Tadao
Jurnal Riset Kimia Vol 1, No 2 (2008): March
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jrk.v1i2.67

Abstract

 ABSTRACT Degradation of Sudan I dye had been done with sonolysis and photolysis by adding anatase-TiO2.  Sonolysis method were performed using an ultrasound with frequency  of 45 kHz. Photolysis method were performed using an irradiation of UV light with λ = 359 nm.  Degradation of 4 mg/L Sudan I with addition of 0.1000 g anatase-TiO2 at pH = 7.0, temperature 25 ± 1°C, percentage of degradation 64.04% within 180 minutes sonolysis.  Degradation of 4 mg/L Sudan I using photolysis with addition of 0.1000 g anatase-TiO2 at pH = 7.0 and percentage of degradation 100% within 180 minutes photolysis. Degradation of 4 mg/L Sudan I using sonolysis and photolysis  simultaneously with addition of 0.1000 g anatase-TiO2 at pH = 7.0 and percentage of degradation 94.04% within 180 minutes treatment.   Keywords : degradation, sonolysis, photolysis, Sudan I, anatase-TiO2.
Co-Authors A.A. Ketut Agung Cahyawan W Deswati Deswati Fitra Febrianti Hamzar Suyani Maizatisna - Mega Ulfaningsih Safni Safni Tadao Sakai Yefrida -