Teknik Differential Pulse Voltammetry Menggunakan Elektroda Pasta Karbon Termodifikasi Fe2O3 untuk Penentuan Kadar Fe(III) dalam Air Laut di Pelabuhan Benoa Bali

Irdhawati Irdhawati, Ni Putu Antari Dewi, Ida Ayu Gede Widihati

Abstract

Pelabuhan Benoa merupakan salah satu pelabuhan di Provinsi Bali tempat berlabuhnya kapal/perahu nelayan, kapal penumpang, dan kapal untuk pariwisata. Aktivitas masyarakat di sekitar pelabuhan dapat menjadi sumber pencemar logam berat. Penelitian ini bertujuan untuk mengetahui hasil optimasi dan validasi elektroda pasta karbon tanpa modifikasi (EPK) dan EPK termodifikasi Fe2O3 (EPK Fe2O3) dengan teknik differential pulse voltammetry (DPV) untuk pengukuran Fe(III) dalam sampel air laut di Pelabuhan Benoa. Parameter yang dioptimasi yaitu laju pindai dan komposisi Fe2O3 dalam pasta karbon. Selanjutnya dilakukan validasi pengukuran, meliputi rentang konsentrasi linier, limit deteksi, limit kuantisasi, keberulangan, dan persen perolehan kembali. Hasil yang diperoleh yaitu laju pindai optimum 15 mV/s menggunakan EPK, menjadi lebih cepat yaitu 20 mV/s menggunakan EPK Fe2O3. Komposisi modifier terbaik dalam pasta karbon sebesar 0,5%. Rentang konsentrasi linier pengukuran menggunakan EPK yaitu 5 ~ 100 mg/L menjadi 5 ~ 2000 mg/L pada EPK Fe2O3. Limit deteksi dan limit kuantisasi menggunakan EPK Fe2O3 masing-masing 0,5490 mg/L dan 0,5497 mg/L, lebih rendah daripada menggunakan EPK yaitu 1,0667 mg/L dan 1,0688 mg/L. Keberulangan pengukuran menghasilkan rasio Horwitz yang lebih kecil dari dua. Nilai persen perolehan kembali pengukuran larutan standar dengan matriks larutan sampel yang diambil pada tiga lokasi yang berbeda, yaitu pada Dermaga Barat 97,51±9,92% ; Dermaga Selatan 101,18±10,60%; dan Dermaga Timur 95,50±1,23%. Hasil pengukuran Fe(III) dalam sampel diperoleh 129,98±13,65 mg/L; 114,85±13,75 mg/L; dan 127,77±4,01 mg/L, masing-masing pada Dermaga Barat, Selatan, dan Timur.

Differential Pulse Voltammetry Technique Using Fe2O3 Modified Carbon Paste Electrode for Determination of Fe(III) Levels in Seawater at Benoa Harbor Bali. Benoa Port is one of the ports in the Province of Bali where fishing boats, passenger ships, and ships for tourism are anchored. Activities around the port can be a source of heavy metal pollutants. This study aims to optimize and validates carbon paste electrodes without modification (EPK) and modified by Fe2O3 (EPK Fe2O3) using differential pulse voltammetry (DPV) techniques for Fe (III) measurements in seawater at Benoa Harbor. The optimized parameters were scan rate and the Fe2O3 composition in carbon paste. Meanwhile, the validation was performed, including the range of linear concentration, detection limit, quantitation limit, repeatability, and percent of the recovery. The research found that the optimum scan rate was 15 mV/s using EPK, become faster to 20 mV/s using EPK Fe2O3. The optimum modifier composition in carbon paste was 0.5%. The linear concentration range of measurement using EPK was 5 ~ 100 mg/L to 5 ~ 2000 mg/L at EPK Fe2O3. The detection limit and the quantitation limit using EPK Fe2O3 were 0.5490 mg/L and 0.5497 mg/L, respectively. Those are lower than the detection limit quantitation by EPK i.e., 1.0667 mg/L and 1.0688 mg/L, respectively. Repeated measurements produce a Horwitz ratio which is less than two. The percent of recovery value of the measurement of the standard solution with the sample solution matrix taken from the three different locations are 97.51±9.92% for the West Pier region; 101.18±10.60% for the South Pier region; and 95.50±1.23% for the East Pier region. The Fe(III) measurements to the different samples from the West Pier, South Pier, and East Pier regions were 129.98±13.65 mg/L; 114.85±13.75 mg/L; and 127.77±4.01 mg/L, respectively.

Keywords

differential pulse voltammetry; elektroda pasta karbon; Fe(III); Pelabuhan Benoa; validasi.

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