Judul: Electrochemical Sensor for Detection of Chlorotalonil Residue in Grapes
Abstrak: The use of chlorothalonil in grapes as a pest control agent, could bring potential harm for health and the environment. Therefore it is necessary to test the residue of chlorothalonil pesticides in grapes as part of food safety control. Pesticide residue testing generally uses HPLC, GC-MS/MS dan LC-MS/MS. Although have high sensitivity, these technique require very expensive equipment, long analysis times, high sample volumes of reagents and competent testing personnel. Meanwhile, pesticide residues testing in the field generally required fast procedure, portable, and easy to use. Therefore, this research aims to develope testing methods for chlorothalonil pesticide residues with electrochemical sensors which can be an alternative method for testing chlorothalonil pesticide residues in grapes. In this study, a differential pulse voltammetry (DPV) technique was chosen using a glassy carbon electrode (GCE) with graphene oxide (GO) and poly 3,4- ethylenedioxythiopene (PEDOT:PSS). In this study GO synthesis was carried out using the modified Hummers method. The characterization results using Raman and FTIR spectroscopy showed the successful synthesis of GO from graphite. The results showed that the modified GCE treatment GO/PEDOT:PSS was significantly different from the unmodified GCE (p<0,05). The addition of composites to the modified electrode improved the performance of the sensor in detecting chlorothalonil. Meanwhile, the peak current of chlorothalonil reduction in GCE modified with GO and PEDOT:PSS composites with various ratios gave results that were not significantly different (p>0,05). Furthermore, the GO/PEDOT:PSS composite ratio (1:1) was determined as the best composite composition in this study. Chlorothalonil is only slightly soluble in Britton Robinson Buffer (BRB), so it is necessary to explore the use of electrolyte combinations with organic solvents. In this experiment, the ratio of BRB:ACN (1:1) was the optimum electrolyte ratio and pH 9 as the optimum pH. Analytical performance parameters observed in this study were reproducibility and stability resulted in %RSD < 5% which shows acceptable results. Based on the result of selectivity test from GCE/GO/PEDOT:PSS was selective for chlorothalonil from interferences such as ascorbic acid, calcium, calium, magnesium, natrium, and sucrose with the effect result of interference to chlorothalonil has not significantly different (p>0,05). In addition, there was a linear relationship in the chlorothalonil concentration range of 10-200 µM with a correlation coefficient of 0,9966 and a detection limit was 3 µM and a quantitation limit was 8 µM. Good accuracy was also demonstrated by the %recovery obtained from 97.77 – 103,61% and successful detection of chlorothalonil in grapes by the standard multiple point addition method of 273 µM or equivalent to 29,03 mg/kg. As a result of the confirmation test using GC-MS/MS, the detection result of the residual concentration of chlorothalonil in the grapes was 0.03 mg/kg. The measurement result of the electrochemical method were higher and significantly different from those with GC-MS/MS. The concentration values detected in this experiment were quite high above the allowable MRL (Maximum Residu Limit) and still give the respon false positive result. This is possible due to the interference of the complex matrix effect in the grape samples. Optimizing this electrochemical test, require a more extensive matrix effect test. However, the electrochemical
Keyword: Chlorothalonil, electrochemical sensor, graphene oxide, pesticide

Judul: Electrode Based on Allotropy Carbon and Conductive Polymer for Nitrite Detection in Water Environments, Electrode Based on Allotropy Carbon and Conductive Polymer for Nitrite Detection in Water Environments
Abstrak: Nitrit merupakan salah satu polutan anorganik berbahaya dalam lingkungan perairan karena dapat menyebabkan methemoglobinemia dan kanker. Monitoring kadar nitrit di lingkungan perairan seperti sungai sangat penting dilakukan untuk menghindari akibat buruk nitrit bagi kesehatan masyarakat. Teknik elektrokimia dipilih untuk deteksi nitrit karena prosesnya akurat, mudah, cepat, dan memungkinkan analisis secara in situ. Penelitian ini bertujuan mengembangkan sensor nitrit berbentuk glassy carbon electrode (GCE) dan screen printed carbon electrode (SPCE) berbasis alotropi karbon berupa grafena oksida (GO) dengan polimer konduktif poli (3,4-etilenadioksitiofena):poli (stirenasulfonat) (PEDOT: PSS) dan mengevaluasi kinerja analitiknya untuk deteksi nitrit dalam sampel nyata. Tahapan penelitian meliputi sintesis GO dari prekusor grafit, pembuatan komposit GO/PEDOT:PSS, penyiapan elektrode berbasis GO/PEDOT:PSS yang meliputi deposisi GO/PEDOT:PSS pada permukaan GCE dan fabrikasi SPCE dengan teknik pencetakan, karakterisasi elektrode, dan evaluasi kinerja sensor nitrit berupa elektrode berbasis GO/PEDOT:PSS untuk deteksi nitrit di larutan sintetik dan sampel air yang berasal dari lingkungan. GCE termodifikasi komposit GO/PEDOT:PSS dievaluasi secara elektrokimia dengan teknik differential pulse voltammetry (DPV) dan electrochemical impedance spectroscopy (EIS). Respon arus oksidasi nitrit yang diukur dengan GO /PEDOT:PSS/GCE meningkat delapan kali lebih tinggi dibandingkan GCE tanpa modifikasi. Spektrum EIS juga mengonfirmasi bahwa komposit GO/PEDOT: PSS/GCE memiliki resistans yang rendah (109 Ω), artinya kinetika transfer elektron dari analat ke elektrode semakin cepat. Sensor berbasis GO/PED OT:PSS/GCE dapat bekerja pada rentang konsentrasi nitrit 5−200 µM menghasilkan LOD (3S/N) sebesar 0,5 µM dan LOQ (10S/N) sebesar 5 µM. Selain itu, sensor tersebut juga memiliki stabilitas dan ketertiruan dengan %RSD < 5%. Pengukuran nitrit pada sampel nyata dengan sensor GO/PEDOT:PSS/GCE menunjukkan hasil yang tidak berbeda nyata dibandingkan dengan metode standar (spektrofotometri UV Tampak) pada taraf kepercayaan 95%. Sensor berbasis komposit GO/PEDOT:PSS dikembangkan dalam bentuk SPCE untuk memudahkan pengukuran secara in situ. Evaluasi elektrokimia menunjukkan bahwa GO/PEDOT:PSS/SPCE dapat mendeteksi nitrit pada potensial 0,17 V. Namun, resistansnya lima kali lebih besar dibandingkan SPCE komersial. GO/PEDOT:PSS/SPCE dapat mendeteksi nitrit pada rentang konsentrasi 50−1000 µM dengan LOD dan LOQ berturut-turut sebesar 25 µM dan 50 µM. Parameter lainnya seperti stabilitas dan ketertiruan menunjukkan nilai RSD < 5%. Pengukuran nitrit dengan GO/PEDOT:PSS/SPCE pada sampel buatan menunjukkan akurasi sebesar 95,32%, sedangkan pengukuran dengan spektrofotometri UV-Tampak menunjukkan akurasi sebesar 99,6%.
Keyword: air sungai, grafena oksida, nitrit, PEDOT:PSS, sensor elektrokimia

Judul: Tingat Partisipasi Anggota Koperasi Dalam Kegiatan  KUD Mandiri Inti Mina Fajar Sidik Kecamatan Blanakan, Kabupaten Subang, Jawa  Barat.
Abstrak: Pembangunan nasional merupakan penjabaran dan pelaksanaan amanat yang terdapat dalam Undang-Undang Dasar 1945 beserta penjelasannya. Dalam UUD 1945 dan GBHN disebutkan ada tiga unsur penting dalam tata perekonomian Indonesia yaitu sektor negara, sektor swasta dan koperasi. UUD 1945 pasal33 ayat 1 menyebutkan bahwa perekonomian disusun sebagai usaha bersama berdasarkan atas asas kekeluargaan. Menurut UUD 1945 pasal 33 ayat 1 tersebut, bangun usaha yang sesuai adalah Koperasi.
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