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All Journal VALENSI CAKRA KIMIA (Indonesian E-Journal of Applied Chemistry) Jurnal Kimia (Journal of Chemistry) Ecotrophic, Journal of Environmental Science JURNAL KIMIA SAINS DAN APLIKASI The Journal of Pure and Applied Chemistry Research Jurnal Riset Kimia Jurnal Kimia Riset ALCHEMY Jurnal Penelitian Kimia Indonesian Journal of Chemistry Chemistry Indonesian Journal of Chemical Research Jurnal Ilmu Pendidikan Indonesia Aceh International Journal of Science and Technology Seminar Ilmiah Nasional Teknologi, Sains, dan Sosial Humaniora (SINTESA)

Irdhawati Irdhawati

Department Of Chemistry, Faculty Of Mathematic And Natural Sciences, Udayana University, Bali 80361 Indonesia

Author-ID : 485902

Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Environmental Science Health Professions Materials Science & Nanotechnology Mathematics Medicine & Pharmacology Physics Social Sciences

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DAYA SERAP KULIT KACANG TANAH TERAKTIVASI ASAM BASA DALAM MENYERAP ION FOSFAT SECARA BATH DENGAN METODE BATH Irdhawati Irdhawati; Alling Andini; Made Arsa
Jurnal Kimia Riset Vol. 1 No. 1 (2016): Juni
Publisher : Universitas Airlangga

AbstrakKulit kacang tanah digunakan sebagai adsorben untuk menyerap ion fosfat dalam larutan. Sebelum digunakan sebagai adsorben, kulit kacang tanah dicuci, dikeringkan, dihaluskan menggunakan blender dan diayak dengan ukuran partikel ≤ 100 mesh. Serbuk halus diaktifkan dengan asam (H2SO4) dan basa (NaOH) pada berbagai konsentrasi. Selanjutnya, adsorben dengan dan tanpa aktivasi digunakan untuk menentukan kadar fosfat yang terserap secara optimum. Parameter adsorpsi yang digunakan adalah waktu kontak dan kapasitas adsorpsi. Kapasitas adsorpsi diukur dengan mereaksikan ion fosfat dengan adsorben, dan sisa analit dalam larutan ditambahkan dengan amonium molibdat membentuk senyawa kompleks amonium fosfomolibdat berwarna biru dalam larutan asam. Konsentrasi senyawa kompleks ditentukan dengan metode spektrofotometri UV-Visible.Hasil dalam proses aktivasi menunjukkan konsentrasi optimum asam adalah 0,05 M, dan basa sebesar 0,5 M. Waktu kontak optimum diperoleh 45 menit untuk adsorben tanpa aktivasi dan aktivasi basa, sedangkan untuk aktivasi asam 30 menit. Kapasitas adsorpsi optimum berturut-turut adalah 8,5 mg/g; 8,8 mg/g, dan 10,4 mg/g menggunakan adsorben tanpa aktivasi, teraktivasi asam dan teraktivasi basa. Adsorben teraktivasi basa memiliki kapasitas adsorpsi tertinggi dibandingkan adsorben tanpa aktivasi dan teraktivasi asam. Kata kunci: kulit kacang tanah, ion fosfat, adsorpsi, amonium fosfomolibdat AbstractPeanut shell was used as adsorbent to adsorb phosphate ion in solution. Before using as adsorbent, the peanut shell was washed, dried, mashed and sifted with particle size <100 mesh. The fine powder was activated by acid (H2SO4) and base (NaOH) with various concentrations. Furthermore, the adsorbent with and without activation was used to determine the optimum phosphate concentration that can be adsorbed. The parameters adsorption such as contact time and adsorption capacity, were examined. The adsorption capacity was measured by reacting the phosphate ion with adsorbent, and the rest of analyte in the solution reacted with ammonium molybdate formed ammonium phospho molybdate complex compound whose blue color in acidic solution. The concentration of complex compound can be determined by UV-Visible spectrophotometry method. The results in activation process showed the optimum concentration of acid is 0.05 M, and base is 0.5 M. The optimum contact time obtained 45 minutes for adsorbent without and base activated, while 30 minutes for acid activated. The optimum adsorption capacity is 8.5 mg/g, 8.8 mg/g, and 10.4 mg/g using adsorbent without, acid, and base activated, respectively. Adsorbent in base activated has the highest adsorption capacity compared with no and acid activated. Keywords: peanut shell, phosphate ion, adsorption, ammonium phospho molybdate

TEKNIK VOLTAMETRI PELUCUTAN ANODIK GELOMBANG PERSEGI UNTUK PENENTUAN KADAR LOGAM Cu DALAM KANGKUNG AIR Irdhawati Irdhawati; Liana Sari; Ida Ayu Raka Astiti Asih
Jurnal Kimia Riset Vol. 1 No. 2 (2016): Desember
Publisher : Universitas Airlangga

ABSTRAK Analisis logam berat Cu(II) dilakukan dengan metode voltametri pelucutan anodik gelombang persegi. Penelitian ini bertujuan untuk mengetahui validitas metode voltametri pelucutan anodik yang digunakan dalam pengukuran kadar logam Cu(II) dalam sampel kangkung air di muara sungai Badung. Elektroda glassy carbon digunakan sebagai elektroda kerja, Ag/AgCl sebagai elektroda pembanding, dan kawat platina sebagai elektroda pembantu. Parameter yang dioptimasi meliputi waktu deposisi dan laju pindai dalam larutan standar Cu(II) 500 ppb. Validasi metode ditentukan dengan menentukan rentang konsentrasi linier, limit deteksi, keberulangan pengukuran, dan persen perolehan kembali. Teknik voltametri pelucutan anodik kemudian digunakan untuk mengukur kadar logam Cu(II) pada sampel kangkung air.Hasil optimasi pengukuran kadar logam Cu(II) yaitu waktu deposisi optimum 60 detik dan laju pindai optimum 10 mV/detik. Pengukuran validitas larutan standar logam Cu(II), rentang konsentrasi linier larutan 50 ~500 ppb dan memiliki nilai koefisien korelasi 0,9983. Limit deteksi 35 ppb, keberulangan pengukuran memiliki rasio Horwitz kurang dari 2, dan persen perolehan kembali 99,35% ± 0,4526. Hasil pengukuran sampel tanaman kangkung memiliki kandungan logam Cu(II) sebesar 4,0 ppm. Berdasarkan Keputusan Direktur Jenderal Pengawasan Obat dan Makanan batas maksimum cemaran logam dalam makanan untuk logam Cu(II) adalah 5,0 ppm. Oleh karena itu dapat diketahui bahwa kandungan logam Cu(II) tidak melebihi kadar maksimum yang diperkenankan. Kata Kunci : logam berat, voltametri pelucutan anodik gelombang persegi, kangkung airABSTRACTHeavy metal analysis of Cu(II) was measured by square wave anodic stripping voltammetry method. The aim of this research is to know the validity of square wave anodic stripping voltammetry method for determination of Cu(II) in water spinach from the estuary of Badung river. Glassy carbon, Ag/AgCl, and Pt wire electrodes were used as working electrode, reference electrode and counter electrode, respectively. Optimized parameter involved the deposition time and scan rate in standard solution Cu(II) 500 ppb. Furthermore, the validation method was examined by determination of linear concentration range, limit of detection, repetition of measurement, and percent of recovery. Moreover, the result of validation was used for observing of heavy metal Cu(II) content in water spinach. The result of optimum deposition time is 60 s. Meanwhile, the scan rate optimum is 10 mV/s. Measurement for standard solution 50 ~ 500 ppb on linear concentration range, with correlation coefficient 0,9983. Limit of detection is 35 ppb, repetition of measurement for metal has Horwitz ratio less than 2, and percent recovery of Cu(II) measurement is 99,35% ± 0,4526. The measurement of Cu(II) content in the water spinach sample contain Cu(II) 4,0 ppm. Based on Decree of Directorate General for Drug and Food Control, the treshold line for Cu(II) contamination for food is 5,0 ppm. Therefore, the water spinach sample contain Cu(II) is less than accepted value. Keyword : Heavy metal, square wave anodic stripping voltammetry, water spinach

Teknik Voltammetri Pelucutan Anodik Menggunakan Elektroda Glassi Karbon dalam Penentuan Kadar Logam Fe dalam Terong Ungu Irdhawati Irdhawati; Vivi Eka Indrayani; Emmy Sahara
Jurnal Kimia Riset Vol. 4 No. 2 (2019): Desember
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/jkr.v4i2.15897

Terong ungu adalah salah satu jenis tanaman yang banyak dibudidayakan. Tingginya permintaan terong menyebabkan petani menggunakan pupuk dan pestisida dari bahan kimia untuk meningkatkan produksi. Penggunaan bahan kimia yang berlebihan dapat mencemari lingkungan. Dalam penelitian ini kadar logam Fe dalam terong ungu ditentukan dengan teknik voltammetry pelucutan anodic. Elektroda kerja yang digunakan adalah glassi karbon, Ag/AgCl sebagai elektroda pembanding, dan kawat platina sebagai elektroda lawan. Parameter pengukuran yang dioptimasi meliputi waktu deposisi, potensial deposisi, dan laju pindai. Selanjutnya dilakukan validasi rentang konsentrasi linier, limit deteksi, limit kuantisasi, keberulangan, dan perolehan kembali. Hasil yang diperoleh yaitu waktu deposisi optimum selama 40 detik, potensial deposisi optimum pada -0,27 V, serta laju pindai 2,5 mV/s. Linieritas larutan standar Fe berada pada rentang 5 sampai 100 mg/L, dengan koefisien korelasi 0,9964. Limit deteksi dan limit kuantisasi berturut-turut 18,36 mg/L dan 37,79 mg/L. Keberulangan pengukuran menghasilkan nilai rasio Horwitz yang lebih kecil dari dua. Perolehan kembali standar logam Fe yang ditambahkan ke dalam larutan sampel diperoleh 100,00 ± 0,07%. Kadar Fe dalam terong ungu pada kondisi pengukuran optimum diperoleh 80,40 ± 1,85 mg/kg. Nilai tersebut lebih kecil dari Standar Nasional Indonesia (SNI) untuk kadar logam dalam bahan pangan yaitu 5000 mg/kg.

Modification of Carbon Paste Electrode with Crown Ether (Dibenzo-18-Crown-6) for Ascorbic Acid Analysis Using Differential Pulse Voltammetry Method Irdhawati Irdhawati; Manuntun Manurung; Anisha Maulinasari
ALCHEMY Jurnal Penelitian Kimia Vol 11, No 2 (2015): September
Publisher : UNIVERSITAS SEBELAS MARET (UNS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/alchemy.11.2.728.175-191

In this research, the modified carbon paste electrode with crown ether (dibenzo-18-crown-6) has been prepared, for determination of ascorbic acid. Some of parameters observed were optimization of crown ether composition in carbon paste, pH of solution, linear concentration range, limit of detection, reproducibility, and recovery. The optimum performance of the prepared electrode was applied for determination of commercialsampleswhich contain of ascorbic acid. The result of this research showsthat the optimum composition of crown ether in carbon paste is 0.6 % at pH 4. Linear range of concentration obtained is from 2 - 200 μM. The detection limit and percentage of recovery are 1.243 μM and 101.31 %, respectively. The modified electrode has HorRat value less than 2, it indicates a good reproducibility. Analysis of 4 commercial samples which contain of ascorbic acid were in agreement with the content listed in the label with the suitability of 94 - 100 %.

Comparison of Wet and Dry Digestions in the Analysis of Fe in Spinach by Atomic Absorption Spectrophotometry Irdhawati Irdhawati; I Gusti Ayu Putu Yunita Riyastini; Manuntun Manurung
The Journal of Pure and Applied Chemistry Research Vol 11, No 1 (2022): Edition January-April 2022
Publisher : Chemistry Department, The University of Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.jpacr.2022.011.01.607

The method of digestion as a part of sample preparation is very important to determine the accuracy of the analysis result. In this study, the methods of wet and dry digestions were applied to determine of Fe content in several kinds of spinach obtained from the traditional market in Denpasar Bali. This research aimed to compare the result of Fe analysis by AAS method using both of digestion methods. This research was divided into several steps starting from sampling, determination of the samples species, sample preparation, digestion by wet digestion using aqua regia and dry digestion in the furnace, and Fe analysis by AAS. The result showed that the concentrations of Fe in root spinach, red spinach, cut spinach, and tricolor spinach through wet digestion method varied between 68.08–105.45 mg/kg, while the concentrations of Fe by dry digestion obtained between 27.52–42.03 mg/kg, which was over the accepted value. Based on the one-way ANOVA statistical test with a significance level of 5%, there was a significant differences of Fe concentration in spinaches by wet and dry digestions.

Carbon Paste Electrode Modified by Dibenzo-18-crown-6 for the Determination of Paracetamol Using Differential Pulse Voltammetry Technique Irdhawati Irdhawati; Ni Ketut Shinta Mas Methaninditya; Anak Agung Bawa Putra
Indonesian Journal of Chemistry Vol 23, No 1 (2023)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.74393

The fabrication, optimization and validation of measurement using a modified carbon paste electrode (CPE) with dibenzo-18-crown-6 were carried out for the determination of paracetamol in commercial products. The pH, dibenzo-18-crown-6 concentration in carbon paste, and scan rate parameters were optimized. Validation of the measurement was observed from linear concentration range, LoD, LoQ, precision, and percentage of the recovery. The result showed that the optimum pH was at 2, the optimum concentration of dibenzo-18-crown-6 in carbon paste was 0.6%, optimum scan rates were 35 mV/s for CPE, and increased to 50 mV/s using modified CPE. The linear concentration range for CPE was obtained at 10-300 µM with LoD and LoQ of 28.88 and 96.28 µM, respectively. Meanwhile, CPE modified with dibenzo-18-crown-6 gave wider linear concentration range at 1–700 µM with LoD and LoQ of 52.36 and 174.53 µM, respectively. The CPE and modified CPE had good precision, with Horwitz ratio values of less than two. The percentage of recovery for two samples with three replicates measurements was obtained (89.81 ± 1.38)% and (108.02 ± 0.42)% for samples A and B, respectively. Dibenzo-18-crown-6 modified CPE was used for the determination of paracetamol in both samples yielding 97–98% compared with the paracetamol composition on its labels.

Activated Bentonite Modified-Carbon Paste Electrode for Determination The Level of Copper Ion (Cu2+) in Tomato Irdhawati Irdhawati; Ekki Inur Ingtyas Mawarni; Ayu Jyostosya Yotirani Arya Wijana; Feby Silvia Sitio; Ni Putu Gita Widi Saraswati; Emmy Sahara
Aceh International Journal of Science and Technology Vol 9, No 3 (2020): December 2020
Publisher : Graduate Program of Syiah Kuala University

Voltammetry is an electroanalytical method measure current as a function of applied potential. The working electrode in the voltammetry method dramatically affects the result of the electrochemical analysis. Modification of the working electrode can improve measurement performance. In this research, the carbon paste electrode (CPE) was modified with Bentonite (CPEB) to determine copper's level using differential pulse voltammetry technique. CPE and CPEB were used as working electrodes, handmade Ag/AgCl as a reference electrode, and Pt wire as the counter electrode. The measurement parameters were optimized, including the composition of bentonite in carbon paste and scan rates. Furthermore, the measurement conditions were validated, involved linear concentration range, detection limit (LoD), the limit of quantization (LoQ), repeatability, and recovery. The results showed that bentonite's optimum composition was 40% of the total weight of graphite and activated bentonite. The scan rate optimum for Cu2+ measurement was obtained at 20 mV/s with CPE and became faster to be 25 mV/s with CPEB. The linearity of the standard solution measurement of Cu2+ using CPE was in the range of 5 to 100 μg/L and changed to 5 to 500 μg/L using CPEB. LoD and LoQ values of standard solution Cu2+ measurement with CPEB were slower than CPE. The Horwitz ratio calculation was smaller than two for both CPE and CPEB. The recovery of Cu2+ standard measure in sample solution as the matrix was obtained 93,49 ± 6,39%. According to the Decree of the Ministry of Health Number, the level of Cu2+ in the tomato sample was found 6.019 ± 0.69 mg/kg, which is over than threshold value of Cu2+ (5 mg/kg) 03725/B/SK/VII/89.

KINETIKA TRANSFER ION DOPAMIN PADA ANTARMUKA AIR-NITROBENZENA SECARA VOLTAMETRI Nyoman Sudarma; Mrs Irdhawati; James Sibarani
Seminar Ilmiah Nasional Teknologi, Sains, dan Sosial Humaniora (SINTESA) Vol 1 (2018): PROSIDING SINTESA
Publisher : LPPM Universitas Dhyana Pura

Show Abstract | Download Original | Original Source | Check in Google Scholar

ABSTRAKPenelitian transfer ion dopamin secara elektrokimia pada antarmuka air-nitrobenzena dengan metode voltametri telah dilakukan. Pengukuran transfer ion ini menggunakan sistem 3 elektroda yaitu 2 elektroda Ag/AgCl sebagai elektroda kerja dan elektroda pembanding, dan elekroda platina sebagai elektroda pembantu.Penelitian diawali dengan pembuatan elektroda pembanding Ag/AgCl yang kemudian dilakukan karakterisasi terhadap elektroda tersebut. Kinetika transfer ion dopamin diketahui dengan melakukan perhitungan nilai potensial standar dan energi bebas Gibbs transfer ion dopamin melalui pengukuran larutan standar dopamin dan tetra metil amonium klorida (TMACl) dengan metode voltametri siklik. Hasil karakterisasi elektroda pembanding Ag/AgCl menunjukkan kelayakan elekroda dengan nilai slope sebesar 60,71 dan r = 0,9984. Potensial standar transfer ion dopamine adalah 0,173 V dan proses berlangsung secara spontan dengan perubahan energi bebas Gibbs (ΔG) sebesar -16,64 kJ/mol.Kata kunci: transfer ion dopamin, antarmuka air-nitrobenzena, voltametriABSTRACTResearch dopamine electrochemical ion transfer at the water-nitrobenzena interface by voltammetry method has been conducted. This measurement uses three electrode system that was two electrode Ag/AgCl electrode as the working electrode and reference electrode, and platinum electrodes as counter electrode. The research comparison begins with the manufacture of electrodes Ag/AgCl were then performed to characterize the electrode. Kinetics of transfer ion dopamine is known to perform calculations potential sandard value and Gibbs energy through measurements the dopamine standard and ammonium chloride and metal tetra (TMACl) solution by cyclic voltammetry method. The results of the reference electrode characterization of Ag/ AgCl electrodes demonstrate the feasibility of the slope value of 60.71 and r = 0.9984. Dopamine standard ion transfer potential is 0.173 V and the process takes place spontaneously with the change in Gibbs free energy (ΔG) of -16.64 kJ/ mol.Keywords: dopamine transfer ion, water-nitrobenzene interface, voltammetry.

ZEOLITE-MODIFIED CARBON PASTE ELECTRODE FOR DETERMINATION OF COPPER USING ANODIC STRIPPING VOLTAMMETRY METHOD Irdhawati Irdhawati; Hery Suyanto; Putu Yani Andani
ALCHEMY Jurnal Penelitian Kimia Vol 13, No 1 (2017): Maret
Publisher : UNIVERSITAS SEBELAS MARET (UNS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/alchemy.13.1.1808.1-16

In this research, the unmodified and modified carbon paste electrode with zeolite has been prepared, for determination of Cu(II) using anodic stripping voltammetry method. The parameters observed involved deposition time, scan rates, zeolite composition in carbon paste, and validation of working electrode. The optimum performance of carbon paste electrode modified with zeolite was applied for determination of Cu(II) in wastewater of the gong fabrication. The results of this research showed the optimum of deposition time and scan rates obtained at 410 s and 7.5 mV/s for unmodified carbon paste electrode, respectively. The optimum composition of zeolite-modifier is 20% from total graphite, with deposition time 380 s and scan rates 10 mV/s. The detection limit of the measurement of Cu(II) standard solution using unmodified carbon paste electrode is 46.13 ppb, is lower than unmodified carbon paste electrode, 99.93 ppb. Zeolite-modified carbon paste electrode has good precision and accuration. The concentration of Cu(II) in waste water of gong fabrication , using carbon paste electrode modified with zeolite is 93.54 ± 0.87 ppb.

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
ALCHEMY Jurnal Penelitian Kimia Vol 17, No 1 (2021): March
Publisher : UNIVERSITAS SEBELAS MARET (UNS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/alchemy.17.1.41568.54-62

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.

Co-Authors Alling Andini Anak Agung Bawa Putra Anisha Maulinasari Arisma Damayanti Ayu Jyostosya Yotirani Arya Wijana Carver J M Ekki Inur Ingtyas Mawarni Emmy Sahara Feby Silvia Feby Silvia Sitio Gede Widihati, Ida Ayu Henu Sumekar Hery Suyanto Hery Suyanto I Gusti Ayu Putu Yunita Riyastini I W BUDIARSA SUYASA I Wayan Hermawan I. A. R. Astiti Asih Ida Ayu Gede Widihati Iryanti Eka Suprihatin James Sibarani Liana Sari Made Arsa Manuntun Manurung Manuntun Manurung Nadya Sarilla Agatha Ni G. A. M. Dwi Adhi Suastuti Ni Kadak Nevi Titasia Ni Ketut Esati Ni Ketut Shinta Mas Methaninditya Ni Ketut Yuni Sri Lestari Ni Made Puspawati Ni Putu Antari Dewi Ni Putu Gita Widi Saraswati Nur Alisyah Gani Nyoman Sudarma Putu Yani Andani Rosanti Suryani Tince Mbatu Suarya P Titasia, Ni Kadak Nevi Triyunita Sinthadevi, Ni Nyoman Vivi Eka Indrayani Wirajana, Nengah WIWIK SUSANAH RITA Yudha Taufantri

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