This study presents a simple flow-based system for the determination of the preservative agent sulfite in food and beverages. The standard method of conversion of sulfite ions into SO2 gas by acidification is employed to separate the sulfite from sample matrices. The sample is aspirated into a donor stream of sulfuric acid. A membrane gas–liquid separation unit, also called a ‘gas-diffusion (GD)’ unit, incorporating a polytetrafluoroethylene (PTFE) hydrophobic membrane allows the generated gas to diffuse into a stream of deionized water in the acceptor line. The dissolution of the SO2 gas leads to a change in the conductivity of water which is monitored by an in-line capacitively coupled contactless conductivity detector (C4D). The conductivity change is proportional to the concentration of sulfite in the sample. In this work, both clear (wine) and turbid (fruit juice and extracts of dried fruit) were selected to demonstrate the versatility of the developed method. The method can tolerate turbidity up to 60 Nephelometric Turbidity Units (NTUs). The linear range is 5–25 mg L−1 SO32− with precision <2% RSD. The flow system employs a peristaltic pump for propelling all liquid lines. Quantitative results of sulfite were statistically comparable to those obtained from iodimetric titration for the wine samples.

Hepatitis B virus (HBV) still remains a major global public health problem. One-half to one-third of the total HBV infected people died due to late detection of HBV. Serological antigen and viral HBV detections can help in the diagnosis, referral, and treatment of HBV. Available methods for HBV detection mostly used bulky instruments. Miniaturization of devices for HBV detection has been started by narrowing down the size of the devices. Several methods have also been proposed to increase the selectivity and sensitivity of the miniaturized methods, such as sandwich recognition of the biomarkers and the use of nano- to micro-sized materials. This review presents recent HBV detections in the last two decades from laboratory-based instruments towards microfluidic paper-based analytical devices (µPADs) for point-of-care testing (POCT) purposes. Early and routine analysis to detect HBV as early as possible could be achieved by POCT, especially for areas with limited access to a central laboratory and/or medical facilities.

Tujuan penelitian adalah untuk mengetahui kondisi optimum serta penggunaan sensor fenol dalam menentukan kadar fenol dalam air. Metode penelitian dilakukan dengan membuat sensor fenol menggunakan Screen Printed Carbon Electrode (SPCE) yang dilapisi dengan membran  kitosan  yang  telah diembankan ionofor CTAPh  (Cethyltrimethylammonium phenoxide). Kinerja sensor fenol diamati pada berbagai variasi konsentrasi ionofor, ketebalan membran dan pH larutan. Konsentrasi ionofor yang dipelajari adalah 0,5%; 1%;1,5%; 2%; dan 2,5%. Ketebalan membran diatur pada ketebalan 60µ m, 80µ m, 100µ m,110µ m. Larutan fenol dikondisikan pada pH 9, 10, 11, 12. Hasil penelitian menunjukkan kinerja sensor fenol optimum pada konsentrasi 1,5%, ketebalan membran 60µ m, dan pH larutan 11. Sensor fenol yang dihasilkan pada penelitian ini memiliki bilangan Nernst sebesar 54,437mV/dekade, kisaran konsentrasi 10-8-10-5M (0,001-1ppm), kosentrasi terkecil yang digunakan 0,001 ppm dan waktu respon 60 detik. Sensor fenol dapat digunakan untuk menentukan kadar fenol dalam sampel air dengan kadar dibawah batas deteksi metode standar.Kata kunci: elektroda selektif ion, ionofor, Screen Printed Carbon Electrode (SPCE), sensor fenol