CARBON PASTE ELECTRODE MODIFIED WITH MOLECULARLY IMPRINTED POLY(GLUTAMIC ACID) FOR VOLTAMMETRIC DETERMINATION OF MELAMINE

• Main Author: Purnamasari, Nuri
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34144
• Institution: Institut Teknologi Bandung

Melamine is an organic compound synthesized commercially from urea and is produced in large amount. It is mainly used to synthesize melamine-formaldehyde resin to make laminate, plastic, glue, plate, and other kitchen tools. Melamine has high nitrogen content (66% of mass). Melamine was added into milk products by non-responsible producer to give the impression of high protein contents in milk. Melamine has low oral acute toxicity, but in high concentration it can be chronic and can cause kidney failure or even death, especially for infant and kids. Melamine entering human body could combine with cyanuric acid to form insoluble melamine-cyanuric crystal in kidney that could causes kidney failure. Several analytical techniques have been applied to determine melamine in milk products, such as HPLC, SPE, UV, GC-MS and LC-MS/MS. However, most of these techniques are not widely available in laboratory. Compared to method mentioned above, electrochemical sensor has the advantage in term of its simplicity, time of analysis an, sensitivity, cost, and portability. Chemical sensors based on molecularly imprinted polymer (MIP) have become one of most developed sensor because of its high selectivity to target molecule. In this research, we developed carbon paste electrode (CPE) modified with Molecularly Imprinted Polymers (MIP) using glutamic acid as monomer for voltammetric determination of melamine. CPE surface was modified with MIP using electropolimerization technique. By using this technique, the polymer thickness can be controlled easily. Solution used to make MIP consists of 0,02 M glutamic acid and 0,01 M melamine in phosphate buffer of pH 7. The MIP was made using cyclic voltammetry technique (6 cycle) in potential range of ?0,8 V – 2 V and scan rate of 100 mV/s. Due to non-electroactive property of melamine, measurements were conducted using background solution consisting of 2 mM K4Fe(CN)6 in 0,2 M NaCl solution. During electropolymerization process, melamine is trapped in polymer matrix. Removal of melamine from polymer matrix was done by extraction using acetonitrile-water solution (1:1). Stirring was conducted during extraction processes. Three 5-minutes stirring were needed for complete removal of melamine. Optimum contact time needed for melamine to get into the cavity is 60 seconds. The optimum pH of measurement was 7. The calibration curve was linear in the concentration range of 0.01 mM – 0.40 mM (R2 = 0.996) with detection limit of 14.18 ?M. The %RSD of repeated measurement was of 8.23% (n 10). Influence of interference has been studied but we still unable to remove interferences from real sample so that the determination of melamine can be conducted.