Judul: Deteksi Iodida dan Iodin secara Simultan Menggunakan Elektrode Pasta Karbon Termodifikasi Nanomagnetit.
Abstrak: Penelitian ini menentukan kinerja elektrode pasta karbon (EPK) termodifikasi nanomagnetit untuk mendeteksi iodida dan iodin secara simultan. Magnetit yang dihasilkan berukuran 38.9 nm. Kinerja elektrode ditentukan dengan teknik voltammetri siklik menggunakan analit KI dan I2 dalam elektrolit pendukung KCl dan KClO4 pada daerah pemayaran 0.0-1.2 V. EPK termodifikasi nanomagnetit mampu meningkatkan respons arus oksidasi iodida dan iodin berturut-turut sebesar 1.07 kali dan 3.98 kali lipat dibandingkan EPK nonmodifikasi. Voltamogram menunjukkan bahwa proses redoks yang terjadi dalam elektolit KCl berbeda dengan elektrolit KClO4. Metode ini sensitif, selektif, sederhana dan tidak dipengaruhi oleh keberadaan klorida maupun bromida. Limit deteksi iodida dan iodin berturut-turut sebesar 28 μM dan 4 μM . Respons arus oksidasi yang baik dihasilkan pada larutan pH 7.
Keyword: elektrode, hidrotermal, iodida, iodine, nanomagnetit, voltammetri

Judul: Kinerja Elektrode Pasta Karbon Termodifikasi Nanomagnetit pada Teknik Voltametri Siklik
Abstrak: The performance of nanomagnetite-modified carbon paste electrodes (CPE) are influenced by the characteristics of nanomagnetite. This study determined the performance of a CPE modified with nanomagnetite synthesized by hydrothermal technique from FeCl3, urea, and sodium citrate at 200 °C for 3 hours. The electrode performance was determined by cyclic voltammetry technique by using iodide as analyte in KCl as supporting electrolyte at potential range of 0.0 to 1.2 V. Voltammetric analysis provided two pairs of oxidation and reduction peaks, both of them quasireversible. Nanomagnetite improved the response of iodide oxidation peak current 1.4 fold compared with the unmodified CPE. The electrode sensitivity was 16.04 mA/mM, the detection limit was 0.0462 mM, and the quantitation limit was 0.154 mM. The electrode selectivity was still good until 10- times addition of interference ion. The linearity of correlation of iodide concentration with oxidation peak current was good as well. However the electrode current response decreased after being stored for a month. Overall, the electrode performances were not as good as CPE modified with nanomagnetite synthesized for 12 hours previously reported
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Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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