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CeVO4 as visible light driven photocatalyst was synthesized using Senna occidentalis (L.) Link leaves extract (SOE) by sol-gel method which can increase the degradation of malachite green (MG) under visible irradiation. The products were characterized using Fourier Transform Infrared Spectrophotometer (FTIR), X-ray Diffraction (XRD), and Field Emission Scanning Electron Microscope Energy Dispersive Spectroscopy (FESEM-EDS). UV–Vis Diffuse Reflectance Spectrophotometer (UV–Vis DRS) absorption spectrum indicated that the band gap of the CeVO4 is about 2,76 eV, and XRD patterns of the samples were indexed to tetragonal zircon type CeVO4 structure. Photocatalytic activity of the synthesized CeVO4 nanoparticles was evaluated for degrading the MG under visible light irradiation, showing as an active catalyst on photodegradation of the MG up to 77% under experimental condition of this study.

Ketidakpastian merupakan salah satu bagian penting dari nilai acuan suatu bahan acuan bersertifikat. Pada penelitian ini, komponen – komponen ketidakpastian pada penentuan nilai acuan kobalt (Co) dan Mangan (Mn) dalam bahan acuan matriks Air Minum Kemasan (AMK) telah berhasil diidentifikasi dan ditentukan dengan mengacu pada ISO/Guide 35:2017. Komponen yang berkontribusi pada nilai acuan Co dan Mn yaitu komponen ketidakpastian yang bersumber dari homogenitas sampel, ketidakpastian asal stabilitas jangka panjang penyimpanan dan ketidakpastian yang bersumber dari karakterisasi. Proses karakterisasi nilai acuan dilakukan dengan perbandingan dua metode yaitu ICP-MS dan ICP-OES menggunakan internal standar Ytrium dan kalibrasi eksternal. Nilai acuan logam Co dan Mn beserta ketidakpastiannya yaitu 14,8 ± 2,7 µg Kg-1 dan 41,6 ± 7,5 µg Kg-1 pada tingkat kepercayaan 95% dengan faktor cakupan 2. Adapun sumber kontributor terbesar ketidakpastian nilai acuan ditemukan berasal dari komponen stabilitas jangka panjang yaitu sebesar 1,17 µg Kg-1 (8%) dan 3,59 µg Kg-1 (9%) masing-masing untuk Co dan Mn.

Main text The need for quality assessment of anthropogenic impact on environmental pollution is increasing due to discharge from various industries, the use of chemicals in agriculture and the consumption of fossil fuels. Diminishing resources such as natural waters used for the cultivation of agricultural products, plant and animal habitats are under severe pollution pressure and are at constant risk. Several parameters, such as Pb, Cd, Ni, Hg were listed by Water Framework Directive in Directive (2008/105/EC) in the priority substances. Cadmium and Hg were identified as priority hazardous substances whereas As is an important contaminant for its potential toxicological and carcinogenic effects. An inter-comparison study is organised in EURAMET TC-MC in order to demonstrate the capability participants for measuring five elements in river water. The participants carried out measurements for analytes: Pb, Cd, Ni and As as mandatory elements, and Se as an optional one. Participants were asked to perform the measurements with respect to the protocol provided. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Certified reference materials (CRMs) provide measurements of quality and metrological traceability related to the International System of Units (SI). In this study, a candidate reference material (RM) for determination of nutrients (Ca, Cu and Zn) in milk powder has been developed and will become the first Indonesian milk CRM. Several analytical parameters for the preparation and measurement of the candidate RM have been optimized based on a microwave acid digestion and ICP-MS method. A 25 kGy60Co dosage of gamma radiation has been applied for the sterilization of the sample prior to storage at room temperature. The CRM BCR-BD151 Skimmed Milk Powder from European Reference Material (ERM) and CRM7512a Trace Elements in Milk Powder from National Metrology Institute of Japan (NMIJ) were used to validate the measurement method and to control the measurement quality. The results showed that, according to ISO/IEC Guide 35:2006, the prepared milk was found to be sufficiently homogenous as a matrix of nutrient reference materials with % inhomogeneity less than 2% for Ca, Cu, and Zn.

The quality control of the final product of biogas is essential for providing a maximum level of consumer’s satisfaction. The most important criteria for any biogas product are its regulatory compliance and safety. Based on a desk study of document and laboratory experiment, this paper overviews the development of infrastructure of quality to control the quality of biogas, aiming at summarising the experience, problems and demonstrating development status of quality infrastructure in Indonesia in the hope of providing references for the present condition. The discussion is made to cover issues related to biogas that are emphasized on three pillars of the infrastructure of quality in Indonesia, i.e., standardization, metrology, and conformity assessment. From the overview, the critical conclusion where understanding and continuing the development quality infrastructure of assuring the safety and quality of biogas remain essential.

As a consequence of the globalization of trade and industries, the presence of an accurate and traceable measurement has become very important for quality assurance of a product or service in the market, including pH measurement. pH measurement is a basic analysis used in a wide variety of applications, such as agriculture, wastewater treatment, industrial processes, research and development, and environmental monitoring. The reliable and comparable results of pH measurement are advantaged as one of the parameters for quality control that will affect the decision making. The Electrochemistry Laboratory under Deputy of National Measurement Standard – National Standardization Agency of Indonesia (SNSU–BSN) has a main duty to ensure the reliability, comparability, and traceability of pH measurements in Indonesia, as a commitment in building chemical metrology infrastructure. In this article, all the activities related to the establishment of traceability chain for pH measurement in Indonesia are comprehensively discussed. As of currently, the Electrochemistry Laboratory has successfully developed the secondary method for pH measurement using differential potentiometric cell, production of certified reference material (CRM) for buffer solution (oxalate, phthalate, phosphate, and borate buffer), dissemination by proficiency testing (PT) schemes for pH measurement, participation in the key comparison (KC) of APMP.QM-K91 for phthalate buffer, and claim submission for the Calibration Measurement Capabilities (CMCs) of phthalate buffer (pH 3.97-4.03) with expanded uncertainty 0.004.

Lignocellulosic bioethanol from corncob could be a promising alternative fuel because of abundant resources, and it will not interfere with the food supply. Pretreatment is the first step in a lignocellulosic bioethanol process. One of the effective pretreatments is alkaline pretreatment because it gives the cellulose-rich material for enzymatic hydrolysis. However, it produces black liquor as wastewater that provides environmental impacts. The black liquor from Empty Fruit Bunch (EFB) pretreatment was collected and used for pretreatment of corncob to reduce wastewater from bioethanol production. The pretreatment process was conducted in a 5-liter reactor. The pretreated corncob was hydrolysis with cellulase enzyme and converted to ethanol by Saccharomyces cerevisiae. The delignification of corncob using EFB-black liquor was 45.82%. The black liquor pretreatment was increasing ethanol production 3.25 times than untreated substrat after saccharification and fermentation process by Saccharomyces cerevisiae (36.39 g/l).

Modified cassava flour is made from fermented cassava and applied to substitute wheat flour. Mocaf wastewater was produce from the cassava soaking and fermentation process. This wastewater contains organic pollutant that must be treated before thrown into the environment. The objective of this study is to reduce COD, TSS, and TDS in Mocaf wastewater using electrocoagulation. The study was conducted on a laboratory scale using a batch reactor electrocoagulation with an aluminum electrode. The voltage of electro coagulator was varied (12, 18, and 24 Volt) with process time was 0, 30, 60, 90, 120, 150, and 180 minutes. The results showed that removal of COD, TDS, and TSS in mocaf wastewater increases with an increasing electrolysis time. COD, TSS, and TDS removal could achieve 73%, 90%, and 36% respectively. Kinetic adsorption data fitted with a pseudo-second-order for COD removal. At the end of electrolysis time, the pH of wastewater towards neutral.

Proficiency testing (PT) performance evaluation based on a consensus value for the assigned value is commonly used because it is considered cheap and thus easily approachable, and also gives a good confidence to the PT participants, since their results contribute to the establishment of the assigned value. However, the consensus value has a weakness in that it could be significantly different from the true value due to largely inexperienced laboratories participating in the PT scheme. Starting from 2013, the Research Center for Chemistry, Indonesian Institute of Sciences, tried to conduct a PT scheme using reference values for cadmium, copper, and iron in drinking water samples in order to increase the reliability of measurement results from Indonesian testing laboratories. The PT sample is a candidate reference material with reference values which were calculated from the measurement results using two comparable methods of inductively coupled plasma optical emission spectrometry and graphite furnace atomic absorption spectrometry. Data evaluation of the PT results was based on ISO 13528 and calculated with the z-score statistic method using PROLAB software. Sixty-two laboratories from the whole Indonesian region participated, and about 94 % and 71 % showed good performance for copper and iron, respectively, since the values were above the quantification limit, and the mean of the result was close to the reference values. However, there was a big difference between the mean and the reference value for cadmium due to the lack of knowledge and experience of most laboratories in Indonesia to measure the trace concentrations of elements such as cadmium. The results of the participants all together were so poor, that the use of consensus value would have been of less quality than the reference value. Therefore, the only way to evaluate cadmium in this PT scheme was by using the reference value.

In proficiency tests the selection of an appropriate assigned value is one of the most critical points. Determination of the assigned value for proficiency test can be done in 2 ways: based on reference value and consensus value. The use of such a consensus value as an assigned value is a commonplace in proficiency testing, because there is seldom at present a cost effective alternative. However, the consensus value has a weakness in that it could be significantly different from the true value due largely inexperienced laboratories. Therefore in this work, the reference values were used as the assigned values for all analytes of interest. The reference values in spiked drinking water samples were produced by the Metrology in Chemistry Laboratory of Research Center for Chemistry - Indonesian Institute of Sciences (RCChem-LIPI) with traceable to SI units through standard solutions from the National Institute Standard and Technology, USA. The reference values of cobalt and manganese were obtained by measurement using two from three comparable methods of Graphite Furnace-Atomic Absorption Spectrometry (GF-AAS), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) while that for cadmium was obtained by a primary method of ICP-Isotope Dilution Mass Spectrometry (ICP-IDMS).The obtained reference values were used to evaluate the laboratory performance result in a proficiency testing scheme of cadmium, cobalt and manganese in drinking water which was provided in 2014. All fifty nine laboratories reported cadmium and cobalt at low concentration levels which were about more than 82% showed satisfactory performance results. Similarly, the results of manganese were also comparable at high level concentrations.

Calibration of measurement systems using well-prepared calibration materials is an important means of making traceability in chemical measurements. Traceability is established through the use of measurement standards (such as certified reference materials) that are appropriate for each parameter. Pure substance certified reference materials such as elemental standard solutions are the most commonly used for calibration, called external calibrations using one, two or multiple standards. In this study, one-point calibration method has been applied for characterizing of Fe, Ni and Pb standard solutions. The results show that the concentration of the Fe, Ni and Pb standard solutions with their relative uncertainties were found to be 997.81 ± 6.34 mg/kg, 997.61 ± 8.10 mg/kg, 1004.29 ± 8.62 mg/kg, respectively.

Imaging of latent fingerprint pattern (aka fingermark) is one of the most important and accurate detection methods in forensic investigation because of the characteristic of individual fingerprint. This detection technique relies on the mechanical adherence of fingerprint powder to the moisture and oily component of the skin left on the surface. The particle size of fingerprint powder is one of the critical parameter to obtain excellent fingerprint image. This study develops a simple, cheap and straightforward method to fabricate Nano size black dusting fingerprint powder based on Nano silica and applies the powder to visualize latent fingerprint. The nanostructured silica was prepared from tetraethoxysilane (TEOS) and then modified with Nano carbon, methylene blue and sodium acetate to color the powder. Finally, as a proof-of-principle, the ability of this black Nano silica dusting powder to image latent fingerprint is successfully demonstrated and the results show that this fingerprint powder provides clearer fingerprint pattern compared to the commercial one highlighting the potential application of the nanostructured silica in forensic science.

Two significant parameters to evaluate the measurement results are known as precision and accuracy. Both are associated with indeterminate and determinate error, respectively, that normally happen in such spectrometric measurement method as Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). These errors must be eliminated or suppressed to get high precision and accuracy of the method. Decreasing the errors thus increasing the precision and accuracy of the method. In this study, bracketing method using two-point standard calibration was proposed in order to suppress the indeterminate error caused by instrumental drift thus increasing the result precision, and applied for measuring cadmium in drinking water samples. Certified reference material of ERM CA011b-Hard drinking water UK-metals was used to know the determinate error or measurement bias. When bias is obtained, some corrections are needed to get the accurate measurement result. The result was compared to that by external calibration method.