CARBON PASTE ELECTRODE MODIFIED MOLECULARLY IMPRINTED POLY(3-AMINOPHENOL) FOR VOLTAMMETRIC DETERMINATION OF RHODAMIN B

• Main Author: Kurniawan
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34071
• Institution: Institut Teknologi Bandung

Rhodamine B (RhB) is a synthetic dye that is extensively used colorant in textiles, paper and ceramics. On the other hand, RhB is also often used as colorant in foods such as crackers, syrup, candy, cakes, and even in cosmetic product such as lipstick. Accumulation of RhB in the body can cause damage to liver, kidney, and spleen. Therefore, Ministry of Health passed a regulation No.239 /Men.Kes/Per/V/85 that prohibits the use of RhB as an additive in foods. An accurate analytical methods are therefore required. RhB determination can be performed using several analytical methods such as spectrophotometry, high pressure liquid chromatography, fluorophotometry and solid phase extraction. These methods have several disadvantages in term of complexity of sample preparations and the use of expensive organic reagents. Voltammetry method provides advantages in term of simplicity of analytical procedure, analysis times, and the sensitivity and selectivity. In this study we developed a voltammetric method for RhB determination with carbon paste electrode modified with molecularly imprinted polymers (MIP). Modifications is conducted through electropolymerization of 3-aminophenol from a solution containing 2,0 mM 3- aminophenol and 1,0 mM RhB in phosphate buffer pH 7 using cyclic voltammetry technique (5 cycles) in the potential range of -0,2 V - 1,8 V with scan rate of 100 mV/s. Surface morphology and composition of the carbon paste electrode was studied using SEM-EDS. Measurements of RhB was conducted using square wave voltammetry (SWV) in the potential range of -0,2 V - 1,8 V. The optimum pH of RhB determination was pH 7. Measurement repeatibility of 0,10 mM and 0,0010 mM RhB solution has %RSD of 3,26% and 4,54%, respectively (n=20). Measurements reproducibility obtained with ten electrode from 0,10 mM RhB solution has %RSD of 6,56%. The linearity range of iv calibration curve was found in the concentration range of 0,020 µM – 0,10 µM with limit detection of 3,90 nM. The oxidation of RhB at the modified electrode is controlled by adsorption process. Stability of the modified electrode MIP has decreased until 50% after usage of more than 35 days. The presence of interference compounds such as sodium benzoate, monosodium glutamate, tartrazine E102, sunset yellow E110, carmoisine E122, acid red 138, direct red 243 and reactive red 120 up to concentration of 0,50 mM did not change the oxidation peak current Rhodamine B significantly. Real sample analysis showed that grass jelly sugar syrup and red crackers contain RhB.