Oman ZUAS
Indonesian Institute of Sciences, Research Center for Chemistry (P2 Kimia), Department Member
- Analytical Chemist (Chemical Metrologist)edit
Research Interests:
Measurement of carbon dioxide (CO2), oxygen (O2), and nitrogen (N2) concentration in modified atmosphere packaging (MAP) food is critical to be carried out by the food industry. A slight variation in concentrations of CO2, O2, and N2 in... more
Measurement of carbon dioxide (CO2), oxygen (O2), and nitrogen (N2) concentration in modified atmosphere packaging (MAP) food is critical to be carried out by the food industry. A slight variation in concentrations of CO2, O2, and N2 in food packaging may have a significant impact on product quality and safety for human health. Accurate and reliable measurement of CO2, O2, and N2 concentrations in food packaging is crucial, and it can only be achieved by calibrating the gas analyzer. This study aimed to develop gas mixtures for the calibration of CO2, O2, and N2 gas analyzers at a typical concentration range of modified atmosphere packaging. The calibration gas mixtures were prepared gravimetrically by following ISO 6142. The concentration ranges of CO2, O2, and N2 for calibration gas mixtures were set at 9-19% mol/mol, 1-5% mol/mol, and 74-88%mol/mol, respectively. Each parent gas was identified for its impurities using gas chromatography with a pulsed discharge helium ionization d...
A study on the effect of temperature on the reduced highly ordered TiO2 nanotube arrays (reduced-HOTNAs) and their CO gas-sensing performance is reported. The reduced-HOTNAs were prepared by anodizing method followed by annealing in the... more
A study on the effect of temperature on the reduced highly ordered TiO2 nanotube arrays (reduced-HOTNAs) and their CO gas-sensing performance is reported. The reduced-HOTNAs were prepared by anodizing method followed by annealing in the presence of urea at various temperatures (i.e. 450, 500, 550, 600 and 700?C) under N2 atmosphere. The reduced-HOTNAs were characterized by FTIR, FE-SEM, XRD, UV-Vis DRS, Raman spectroscopy and photoelectrochemical techniques. The sensing performance of the reduced-HOTNAs was assessed against CO gas in air mixture. The results show that the reduced-HOTNAs annealed at 450 ?C (reduced- HOTNAs-450) is a material with the most significant improvement in sensitivity to detect CO compared with other reduced-HOTNAs. The reduced-HOTNAs-450 exhibits best sensing performance at a relatively low CO concentration in the range of 2-25 ppm at 300?C. Findings of this study indicate that improvement of the reduced-HOTNAs-450 sensitivity might be attributed to the pre...
Biomass gasification has been widely known method to produce syn-gases, which can be considered as great alternative substitution for fossil fuels. However, accurate verification of the syn-gas composition requires a reliable and... more
Biomass gasification has been widely known method to produce syn-gases, which can be considered as great alternative substitution for fossil fuels. However, accurate verification of the syn-gas composition requires a reliable and validated method for simultaneous measurement of H 2 , CO 2 , CH 4 , and CO. In order to fulfill the aforementioned requirements, which is the objective of this study; a GC-TCD method for simultaneous measurement of H 2 , CO 2 , CH 4 , and CO component in syn-gas has been validated in accordance to ISO/IEC 17025 and its application for real samples. For the method validation purpose, all of the performance parameters were evaluated and discussed in detail in this study. Intraday precision and interday precision were found to be acceptable having the %RSD below 0.67xCV Horwitz and below 1.0xCV Horwitz, respectively. The bias value falls within +2σ for entire components, indicating that the method accuracy can be accepted. Coefficient correlation for all comp...
Research Interests:
Pure TiO2 and CeO2-doped TiO2 (3 % CeO2-97 %TiO2) composite nanocrystals were synthesized via co-precipitation method and characterized using TGA, XRD, FTIR, DR-UV-vis and TEM. The XRD data revealed that the phase structure of the... more
Pure TiO2 and CeO2-doped TiO2 (3 % CeO2-97 %TiO2) composite nanocrystals were synthesized via co-precipitation method and characterized using TGA, XRD, FTIR, DR-UV-vis and TEM. The XRD data revealed that the phase structure of the synthesized samples was mainly in pure anatase having crystallite size in the range of 7 nm – 11 nm. Spherical shapes with moderate aggregation of the crystal particles were observed under the TEM observation. The presence of the CeO2 at TiO2 site has not only affected morphologically but also induced the electronic property of the TiO2 by lowering the band gap energy from 3.29 eV (Eg-Ti) to 3.15 eV (Eg-CeTi). Performance evaluation of the synthesized samples showed that both samples have a strong adsorption capacity toward Congo red (CR) dye in aqueous solution at room temperature experiment, where the capacity of the CeTi was higher than the Ti sample. Based on DRUV data, the synthesized samples obtained in this study may also become promising catalysts ...
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Carbon monoxide (CO) in nitrogen was one of the first types of gas mixtures used in an international key comparison. This comparison dates back to 1998 (CCQM-K1a) [1]. Another key comparison on carbon monoxide is the CCQM-K51 at the lower... more
Carbon monoxide (CO) in nitrogen was one of the first types of gas mixtures used in an international key comparison. This comparison dates back to 1998 (CCQM-K1a) [1]. Another key comparison on carbon monoxide is the CCQM-K51 at the lower amount fraction of 5 μmol/mol. Since then, many National Metrology Institutes (NMIs) have developed Calibration and Measurement Capabilities (CMCs) for these mixtures. Recently, NMIs in the APMP region have actively participated in international comparisons to provide domestic services. At the 2017 APMP meeting, several NMIs requested a CO comparison to establish CO/N2 certification for supporting industrial needs, which was to be coordinated by KRISS. Consequently, this supplementary comparison provides an opportunity for APMP regional NMIs to meet their industrial needs. It is a replica of APMP.QM-S9.[2] 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 ...
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This paper reports on the effect of flow rate of helium (He) carrier gas on the key parameters of gas chromatography equipped with thermal conductivity detector (GC-TCD) for the measurement of carbon dioxide (CO2 ), propane (C3H8) and... more
This paper reports on the effect of flow rate of helium (He) carrier gas on the key parameters of gas chromatography equipped with thermal conductivity detector (GC-TCD) for the measurement of carbon dioxide (CO2 ), propane (C3H8) and carbon monoxide (CO) in gravimetric standard gas mixture (Grav-SGM). The carrier gas has a function to transport vaporized molecules through the column during the GC separation process. The study provides opportunity to experimentally investigate the effect of gas flow rate on the several key parameters of the GC-TCD including retention time, peak area, peak height, response factor, resolution and selectivity. The results show that all key parameters were found to be carrier gas flow rate dependent. The increase of the gas flow rate could significantly decrease the retention time, peak area and response factor of the gas components. While both resolution and selectivity factor were observed to have a substantial decrease with increasing the flow rate o...
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Research Interests:
Research Interests:
Halogenated alkanes may have potentially human health effect as a result of their persistence, bioaccumulation and toxicity after their release from environment into the food chain and water products. It is leading to increase attention... more
Halogenated alkanes may have potentially human health effect as a result of their persistence, bioaccumulation and toxicity after their release from environment into the food chain and water products. It is leading to increase attention for legislation aimed at prevention and great pressure to reduce the production and emission rate of halogenated alkanes. Besides many research efforts to understand the fate and (eco)toxicological effects of the halogenated alkanes. Several investigators have used animal in vivo in conventional toxicity studies of halogenated alkanes. Nevertheless, experimental by using animal testing is always time and resource demanding. Thus, it is not deemed suitable for screening of large number of potential toxicants. The main objective of this work was to investigate the comparability of yeast resazurin assay versus MTT assay for determining in vitro acute toxicity (EC50) of halogenated alkanes. The MTT assay was conducted using Chinese Hamster Ovary (CHO cel...
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In this work, monitoring the effect of packaging type and storage temperature on the short term stability of calibration standard solution KCl 1 M were conducted. The KCl 1M were packaged in two types of packaging i.e., high-density... more
In this work, monitoring the effect of packaging type and storage temperature on the short term stability of calibration standard solution KCl 1 M were conducted. The KCl 1M were packaged in two types of packaging i.e., high-density polyethylene (HDPE) and glass bottle. The effects of packaging type and storage temperature were monitored for four weeks at 25 °C and 40 °C. The conductivity values of KCl 1 M in the HDPE and glass bottle were 111.61 mS/cm and 111.62 mS/cm, respectively. The results indicated that the KCl 1M solution at 25 °C in both HDPE and glass bottle were found to be good in short term stability and there was no significant different between the two packaging types. At temperature of 40 °C, however, short term stability of the KCl 1 M in a glass bottle was better than the HDPE bottle.
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High accurate result of carbon dioxide (CO2) measurement is of great importance since the result (data) is used as the foundation for decision making related to regulated monitoring program and law enforcement. In this study, therefore,... more
High accurate result of carbon dioxide (CO2) measurement is of great importance since the result (data) is used as the foundation for decision making related to regulated monitoring program and law enforcement. In this study, therefore, method for measurement of high level of carbon dioxide (CO2) in nitrogen (N2) matrix using gas chromatography thermal conductivity detector (GC-TCD) was validated to achieve the optimum performance of the method. For this purposes, identity confirmation, selectivity, limit of detection (LoD), limit of quantitation (LoQ), repeatability, reproducibility, accuracy, and linearity of the method were evaluated. The result shows that the GC-TCD method has good precision in term of repeatability and reproducibility having values of 0.07 and 0.37%, respectively. No bias of the method can be found and an excellent linearity of the method was obtained in the range of 2 - 13.97% mol/mol. Thus, based on the result evaluation under given criteria of this study, it...
Research Interests:
Measurement of carbon dioxide (CO2), oxygen (O2), and nitrogen (N2) concentration in modified atmosphere packaging (MAP) food is critical to be carried out by the food industry. A slight variation in concentrations of CO2, O2, and N2 in... more
Measurement of carbon dioxide (CO2), oxygen (O2), and nitrogen (N2) concentration in modified atmosphere packaging (MAP) food is critical to be carried out by the food industry. A slight variation in concentrations of CO2, O2, and N2 in food packaging may have a significant impact on product quality and safety for human health. Accurate and reliable measurement of CO2, O2, and N2 concentrations in food packaging is
crucial, and it can only be achieved by calibrating the gas analyzer. This study aimed to develop gas mixtures for the calibration of CO2, O2, and N2 gas analyzers at a typical concentration range of modified atmosphere packaging. The calibration gas mixtures were prepared gravimetrically by following ISO 6142. The concentration ranges of CO2, O2, and N2 for calibration gas mixtures were set at 9-19% mol/mol, 1-5% mol/mol, and 74-88%mol/mol, respectively. Each parent gas was identified for its impurities using gas chromatography with a pulsed
discharge helium ionization detector (GC-PDHID). The compositions of CO2, O2, and N2 in the mixtures were verified by evaluating the internal consistency within the prepared gas mixtures using gas chromatography with a thermal conductivity detector (GC-TCD). The short term stability of the prepared gas mixtures was evaluated
using an equal division method. The result showed that good internal consistency was achieved between the gravimetrical and GC’s verification values, having linear regression coefficient (R2 ) ≥ 0.999. The t-test result has shown that CO2 has better short term stability than O2 and N2. In conclusion, the developed calibration gas mixtures at a typical concentration range of modified atmosphere packaging have shown satisfying results for CO2 component. However, further evaluation is still required to minimize the instability of O2 and N2 components.
crucial, and it can only be achieved by calibrating the gas analyzer. This study aimed to develop gas mixtures for the calibration of CO2, O2, and N2 gas analyzers at a typical concentration range of modified atmosphere packaging. The calibration gas mixtures were prepared gravimetrically by following ISO 6142. The concentration ranges of CO2, O2, and N2 for calibration gas mixtures were set at 9-19% mol/mol, 1-5% mol/mol, and 74-88%mol/mol, respectively. Each parent gas was identified for its impurities using gas chromatography with a pulsed
discharge helium ionization detector (GC-PDHID). The compositions of CO2, O2, and N2 in the mixtures were verified by evaluating the internal consistency within the prepared gas mixtures using gas chromatography with a thermal conductivity detector (GC-TCD). The short term stability of the prepared gas mixtures was evaluated
using an equal division method. The result showed that good internal consistency was achieved between the gravimetrical and GC’s verification values, having linear regression coefficient (R2 ) ≥ 0.999. The t-test result has shown that CO2 has better short term stability than O2 and N2. In conclusion, the developed calibration gas mixtures at a typical concentration range of modified atmosphere packaging have shown satisfying results for CO2 component. However, further evaluation is still required to minimize the instability of O2 and N2 components.
Research Interests:
Research Interests:
Research Interests:
This paper reported the method development and validation of a gas chromatography with thermal conductivity detector (GC-TCD) method for the measurement of the gaseous products of hydrodeoxygenation (HDO). The method validation parameters... more
This paper reported the method development and validation of a gas chromatography with thermal conductivity detector (GC-TCD) method for the measurement of the gaseous products of hydrodeoxygenation (HDO). The method validation parameters include selectivity, precision (repeatability and reproducibility), accuracy, linearity, limit of detection (LoD), limit of quantitation (LoQ), and robustness. The results showed that the developed method was able to separate the target components (H2, CO2, CH4 and CO) from their mixtures without any special sample treatment. The validated method was selective, precise, accurate, and robust. Application of the developed and validated GC-TCD method to the measurement of by-product components of HDO of bio-oil revealed a good performance with relative standard deviation (RSD) less than 1.0% for all target components, implying that the process of method development and validation provides a trustworthy way of obtaining reliable analytical data.
The potential application of the GC-TCD using column coupling method was investigated by means of comparison with the single column method for the identification of gas mixture containing 5 inorganic and 6 hydrocarbon gases. The results... more
The potential application of the GC-TCD using column coupling method was investigated by means of comparison with the single column method for the identification of gas mixture containing 5 inorganic and 6 hydrocarbon gases. The results indicate the useful of column coupling method, relative to the single column method. In addition, the flow rate of carrier gas and column temperature on the retention time of the target components have a notice-able effect. Application of the column coupling method for qualitative identification of the targeted components in natural gas samples indicate that the method can be used for routine work.