The Effects of Changing Membrane Compositions and Internal Electrolytes on the Respon of Potassium Ion Sensor

A study on the changing of membrane compositions and internal solution towards the response potassium ion sensor was carried out. Potassium ion sensor based on photocured cross linking poly(n-butyl acrylate) membranes with varying composition of valinomycin (val), sodium tetrakis [3.5-bis(trifluoro-methyl) phenyl] borat (NaTFPB), types ion of internal solution were investigated. Effects of varying composition of val, NaTFPB, types and concentration of internal solution were observed on potassium ion sensor. The effect of higher val composition was lower LOD, wider linear range, lower sensitivity but increase selectivity. Higher NaTFPB compositions lead to lower LOD, higher sensitivity and selectivity. The effect of changing internal electrolyte lead to lower LOD, wider linear response range and higher selectivity according to internal electrolyte consisting Na+, Ca2+ and K+, and sensitivity increase following internal electrolyte with Ca2+, K+ and Na+

THE EFFECTS OF CHANGING MEMBRANE COMPOSITIONS AND INTERNAL ELECTROLYTES ON THE RESPON OF POTASSIUM ION SENSOR

A study on the changing of membrane compositions and internal solution towards the response potassium ion sensor was carried out. Potassium ion sensor based on photocured cross linking poly(n-butyl acrylate) membranes with varying composition of valinomycin (val), sodium tetrakis [3.5-bis(trifluoro-methyl) phenyl] borat (NaTFPB), types ion of internal solution were investigated. Effects of varying composition of val, NaTFPB, types and concentration of internal solution were observed on potassium ion sensor. The effect of higher val composition was lower LOD, wider linear range, lower sensitivity but increase selectivity. Higher NaTFPB compositions lead to lower LOD, higher sensitivity and selectivity. The effect of changing internal electrolyte lead to lower LOD, wider linear response range and higher selectivity according to internal electrolyte consisting Na+, Ca2+ and K+, and sensitivity increase following internal electrolyte with Ca2+, K+ and Na+. Key words: ion sensor, ion selective membrane, ionofor, lipofilik sal

THE EFFECTS OF CHANGING MEMBRANE COMPOSITIONS AND INTERNAL ELECTROLYTES ON THE RESPON OF POTASSIUM ION SENSOR

A study on the changing of membrane compositions and internal solution towards the response potassium ion sensor was carried out. Potassium ion sensor based on photocured cross linking poly(n-butyl acrylate) membranes with varying composition of valinomycin (val), sodium tetrakis [3.5-bis(trifluoro-methyl) phenyl] borat (NaTFPB), types ion of internal solution were investigated. Effects of varying composition of val, NaTFPB, types and concentration of internal solution were observed on potassium ion sensor. The effect of higher val composition was lower LOD, wider linear range, lower sensitivity but increase selectivity. Higher NaTFPB compositions lead to lower LOD, higher sensitivity and selectivity. The effect of changing internal electrolyte lead to lower LOD, wider linear response range and higher selectivity according to internal electrolyte consisting Na+, Ca2+ and K+, and sensitivity increase following internal electrolyte with Ca2+, K+ and Na+.Key words: ion sensor, ion selective membrane, ionofor, lipofilik sal

A Biosensor for Urea from Succinimide-Modified Acrylic Microspheres Based on Reflectance Transduction

New acrylic microspheres were synthesised by photopolymerisation where the succinimide functional group was incorporated during the microsphere preparation. An optical biosensor for urea based on reflectance transduction with a large linear response range to urea was successfully developed using this material. The biosensor utilized succinimide-modified acrylic microspheres immobilized with a Nile blue chromoionophore (ETH 5294) for optical detection and urease enzyme was immobilized on the surface of the microspheres via the succinimide groups. No leaching of the enzyme or chromoionophore was observed. Hydrolysis of the urea by urease changes the pH and leads to a color change of the immobilized chromoionophore. When the color change was monitored by reflectance spectrophotometry, the linear response range of the biosensor to urea was from 0.01 to 1,000 mM (R2 = 0.97) with a limit of detection of 9.97 μM. The biosensor response showed good reproducibility (relative standard deviation = 1.43%, n = 5) with no interference by major cations such as Na+, K+, NH4+ and Mg2+. The use of reflectance as a transduction method led to a large linear response range that is better than that of many urea biosensors based on other optical transduction methods

An Electrochemical DNA Microbiosensor Based on Succinimide-Modified Acrylic Microspheres

An electrochemical microbiosensor for DNA has been fabricated based on new acrylic microspheres modified with reactive N-acryloxysuccinimide (NAS) functional groups. Hydrophobic poly(n-butylacrylate-N-acryloxysuccinimide) microspheres were synthesized in an emulsion form with a simple one-step photopolymerization technique. Aminated DNA probe was attached to the succinimde functional group of the acrylic microspheres via covalent bonding. The hybridization of the immobilized DNA probe with the complementary DNA was studied by differential pulse voltametry using anthraquninone-2-sulfonic acid monohydrate sodium salt (AQMS) as the electroactive hybridization label. The influences of many factors such as duration of DNA probe immobilization and hybridization, pH, type of ions, buffer concentrations, ionic strength, operational temperature and non-complementary DNA on the biosensor performance were evaluated. Under optimized conditions, the DNA microbiosensor demonstrated a linear response range to target DNA over a wide concentration range of 1.0 × 10−16 and 1.0 ´ 10−8 M with a lower limit of detection (LOD) of 9.46 ´ 10−17 M (R2 = 0.97). This DNA microbiosensor showed good reproducibility with 2.84% RSD (relative standard deviation) (n = 3). Application of the NAS-modified acrylic microspheres in the construction of DNA microbiosensor had improved the overall analytical performance of the resultant DNA microbiosensor when compared with other reported DNA biosensors using other nano-materials for membranes and microspheres as DNA immobilization matrices

Analysis of Students Misconception using Two-Tier Multiple Choice Diagnostic Test on Electrolyte and Nonelectrolyte Topic in SMAN 2 Padang

This research aims to (1) knowing whether there are misconceptions of 10th grade students at SMAN 2 Padang on the topic electrolyte and nonelectrolyte solutions and (2) the percentage of 10th grade students at SMAN 2 Padang who have misconceptions about the topic electrolyte and nonelectrolyte solutions. This research uses a two-tier multiple choice diagnostic test instrument consisting of 14 item questions. The method used in this research is a quantitative descriptive approach. The sampling technique was taken using a simple random sampling technique. Data collection techniques were carried out through tests given to students of class X MIPA 6 which were attended by 40 people. In this research, the population was all  of 10th grade students at SMAN 2 Padang, while the sample was students of class X MIPA 6. The results of data processing in this research indicate that in general students of class X MIPA 6 have misconceptions with an average percentage of misconceptions of 36.94%. Students experience misconceptions on the sub-concept of the properties of the electrolyte solution by 22.5%, the sub-concept of chemical bonds and electrolyte properties of 43.75%, and the sub-concept of the electrical conductivity of the solution has the highest percentage of misconceptions, which is 44.58%

ANALISIS PENYEBAB KESULITAN SUB MATERI POKOK KIMIA SEMESTER 1 KELAS X IPA 3 MENGGUNAKAN METODE LEAN SIX SIGMA DI SMA NEGERI 8 PADANG

Perencanaan, proses, penilaian dan pengawasan di dalam pembelajaran ialah standar pendidikan yang perlu untuk meningkatkan efisiensi dan efektifitas pada pendidikan dasar dan menengah. Berdasarkan hasil observasi pembelajaran kimia pada semester I kelas X IPA 3 di SMA Negeri 8 Padang, diketahui ada 20 sub materi pokok di bawah kriteria ketuntasan minimal (KKM) 75 yang berpengaruh terhadap kualitas hasil pembelajaran, maka diperlukan metode untuk menemukan penyebab kesulitan siswa. Peneliti memilih menggunakan metode lean six sigma (define, measure dan analyze) yang bertujuan untuk menganalisis secara sistematis penyebab-penyebab kesulitan sub materi pokok kimia di bawah kriteria ketuntasan minimal. Penelitian ini adalah penelitian deskriptif dengan instrument penelitian adalah lembar observasi dan pedoman wawancara, sedangkan teknik pengumpulan data yang digunakan adalah observasi, wawancara, dan studi dokumentasi. Berdasarkan hasil penelitian, diketahui adanya 10 penyebab kesulitan pada satu materi, yaitu materi interaksi antar partikel dengan 30 alasan (8,33 %) pada penilaian 1 (siswa selalu melakukan alasan) yang tersebar pada enam faktor penyebab (man, measure, material, machine, methode, enviroment) dan tujuh pada macro process map (proses 2,3,5,6,7,8 dan 9). Berdasarkan alasan-alasan siswa, dari 10 penyebab kesulitan tersebut ada 6 penyebab kesulitan materi interaksi antar partikel yang juga berpengaruh terhadap mata pelajaran yang lain dengan kelas yang sama maupun berbeda, yaitu parkir sekolah, toilet sekolah, kantin sekolah, peraturan seragam sekolah, kegiatan ekstrakurikuler dan jadwal pelajaran. Namun, ada juga 4 penyebab kesulitan materi interaksi antar partikel yang juga berpengaruh terhadap sub materi pokok kimia yang lain, yaitu kriteria ketuntasan minimal mata pelajaran kimia, perangkat pembelajaran kimia, media pembelajaran kimia dan peralatan praktikum kimia. Oleh sebab itu, untuk mencapai hasil belajar sesuai dengan KKM, perlu untuk menghilangkan atau mengurangi penyebab-penyebab kesulitan tersebut dari proses  tata tertib peserta didik hingga proses pembelajaran

Pengembangan Lembar Kerja Peserta Didik (LKPD) Kimia Hijau Berbasis Problem Based Learning Untuk Fase E

Tujuan dari penelitian ini adalah menghasilkan bahan ajar yang mengaplikasikan Problem Based Leaning (PBL) pada LKPD kimia hijau, serta menilai validitas dan praktikalitas LKPD yang dihasilkan. Penelitian ini menggunakan model pengembangan 4-D. Model 4-D terdiri empat tahapan yaitu tahapan define (pendefenisian), design (perancangan), develop (pengembangan), disseminate (penyebaran). Tetapi dalam penelitian ini dilakukan sampai pada tahap pengembangan. Instrumen penelitian yang dipakai meliputi lembar wawancara, angket validitas, dan angket kepraktisan. Penelitian dilakukan di Laboratorium FMIPA UNP dan SMA Pembangunan Laboratorium UNP. Indeks Aiken's V digunakan untuk menganalisis data hasil validasi, sedangkan persentase kepraktisan digunakan untuk menganalisis data kepraktisan. Berlandaskan pada hasil pengolahan data angket validitas, diperoleh kesimpulan bahwa LKPD kimia hijau berbasis pendekatan pembelajaran berbasis masalah dinyatakan valid, yang ditunjukkan dengan nilai V sebesar 0,89 yang berkategori valid, kemudian hasil analisis uji praktikalitas guru nilai NP sebesar 99%, kategori sangat praktis dan peserta didik diperoleh nilai NP sebesar 83% dengan kategori praktis

HUBUNGAN PERSEPSI SISWA TENTANG PENGELOLAAN KELAS OLEH GURU DENGAN HASIL BELAJAR KIMIA KELAS XI SMA

Telah dilakukan penelitian tentang hubungan antara persepsi siswa tentang pengelolaan kelas oleh guru terhadap hasill belajar kimia kelas XI SMA. Jenis penelitian yang dilakukan ialah deskriptif dengan metode kuantitatif yang bersifat korelasional. Sebanyak 62 orang siswa dijadikan sampel dalam penelitian ini, diambil dengan teknik random sampling dari populasi (124 orang siswa). Teknik korelasi pearson product moment digunakan dalam analisis penelitian ini digunakan untuk menganalisa hubungan antara variabel X ( Persepsi siswa tentang pengelolaan kelas oleh guru) dan variabel Y (Hasil Belajar Kimia). Data persepsi siswa mengenai pengelolaan kelas oleh guru didapatkan dari kuesioner yang disusun berdasarkan model Likert, dan nilai ujian siswa pada semester genap dijadikan sebagai data hasil belajar kimia. Semua analisis uji yand dilakukan menggunakan bantuan program SPSS (Statistical Product and Service Solution) versi 16.0 for windows, diantara uji ini adalah uji linearitas, uji normalitas dan uji hipotesis Hasil analisis yang dilakukan menunjukkan terdapatnya hubungan yang signifikan  antara persepsi siswa tentang pengelolaan kelas oleh guru dengan hasil belajar kimia, dimana (t=6,206 > 2,045) artinya t tabel lebih kecil daripada t hitung yang didapatkan sehingga mengartikan bahwa hipotesis alternatif diterima sedangkan hipotesis nihil ditolak. Kesimpulannya aalah terdapatnya hubungan antara kedua variabel yaitu persepsi siswa tentang pengelolaan  kelas oleh guru (variabel X) dan hasil belajar kimia (variabel Y) kelas XI SMA