CARBON PASTE ELECTRODE MODIFIED WITH PHENOL IMPRINTED POLYANILINE FOR DETERMINATION OF PHENOL BY POTENTIOMETRY

• Main Author: RAHMADHANI (NIM:90516003), SRI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31059
• Institution: Institut Teknologi Bandung

Phenol is widely used in industry. Several methods of phenol analysis are developed due to the <br /> <br /> harmful of phenol waste that pollutes the waters, including UV-Vis spectrophotometry, HPLC, <br /> <br /> and GC-MS. These methods have high sensitivity but require expensive instruments, so <br /> <br /> electroanalysis methods are developed with simple instrumentation, have a good selectivity and <br /> <br /> sensitivity. One of the electroanalysis methods that has been developed to analyze phenol is a <br /> <br /> potentiometric method. This method requires two electrodes, the working electrode and the <br /> <br /> reference electrode. The working electrode used is a carbon paste electrode modified with <br /> <br /> molecularly imprinted polymer (MIP) and Ag/ AgCl electrode as a reference electrode. Ag/ AgCl <br /> <br /> reference electrode was made by electrolyzing 0.1 M NaCl solution using Ag wire which was <br /> <br /> placed on the anode (positive electrode) and Pt wire on the cathode (negative electrode) then we <br /> <br /> get solid AgCl formed on the surface of the Ag wire. This Ag/ AgCl reference electrode is then <br /> <br /> compared with commercial Ag/ AgCl electrodes through cyclic voltammogram of K3[Fe(CN)4]/ <br /> <br /> K4(Fe(CN)6. The Ag/ AgCl electrode is considered to be sufficiently well to be used when the <br /> <br /> measurements of the Ipc/Ipa of the two electrodes do not differ much, which are 0.876 for Ag/ <br /> <br /> AgCl commercial electrode and 0.868 for this Ag/AgCl electrode. The carbon paste electrode <br /> <br /> was made by heating graphite powder to a temperature of 70°C. Furthermore, the graphite <br /> <br /> powder was mixed with liquid paraffin to form carbon paste. The carbon paste electrode is <br /> <br /> electrochemically modified by a cyclic voltammetry technique with various concentrations and <br /> <br /> number of cyclic to obtain optimal conditions. In addition, the pH of the solution is also done to <br /> <br /> obtain a stable potential. Due to the phenol electrooxidation process involves two electrons, the <br /> <br /> best results are indicated by the Nernst factor which is close to 59/2 mV/decade. <br /> <br /> Electropolymerization is carried out by 15 cyclic at a potential range of -0.2 V – 1.0 V at a scan <br /> <br /> rate of 100 mV/s with the composition of the solution is 0.1 mM phenol: 0.2 mM aniline in a 0.1 <br /> <br /> M phosphate buffer solution pH 9 and a supporting electrolyte 0.1 M KCl. Phenol is extracted <br /> <br /> from the polymer matrix electrochemically using 0.1 M HCl, so it is expected to form templates <br /> <br /> that can recognize the molecule specifically. The results showed that phenol which analyzes by a <br /> <br /> potentiometric method using carbon paste electrode modified with MIP has a linear range of 10-7 <br /> <br /> M – 10-1 M with a detection limit of 2.5 x 10-7 M. Besides, this electrode also able to respond to <br /> <br /> analytes within 60 – 70 seconds. Accuracy is determined based on the relative error value (% Er). <br /> <br /> The % Er obtained ranges from 1% to 3% which indicates that the determination of phenol by <br /> <br /> this method is quite accurate. Precision is stated with a good coefficient of variation, which is <br /> <br /> lower than 2%. The effect of interference compounds can be seen from the small selectivity <br /> <br /> coefficient (K <br /> < 1), so that these electrodes can be said to be more selective towards phenol <br /> <br /> than other compounds contained in the sample. As a comparison, phenol measurements were <br /> <br /> carried out using UV-Vis spectrophotometry method. Based on the percent recovery value and t <br /> <br /> test, where ttable 4.30 > texp 1.12, it was found that the measurement with a potentiometric method <br /> <br /> using MIP modified carbon paste working electrode has no significantly different when <br /> <br /> compared with the UV-Vis spectrophotometry method