• Bulletin of the Korean Chemical Society
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• v.15 no.9
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• pp.786-791
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• 1994

A simple and rapid sample pretreatment process necessary for determination of metal oxides in water was proposed. Samples were injected into the continuous-flow tube installed inside the microwave oven and the treated samples were cooled before entered to the Ion Chromatography (IC) or Inductively Coupled Plasma (ICP). By coupling this microwave digestion system with IC or ICP, a fully automatic analytical procedures may be easily established. In this study, two different types of digestion methods were considered; the open tubing method (OTM) and the restraint tubing method (RTM). The RTM was proved to be 3 times faster in digestion period and 10 times higher in detection range than the OTM. Validation of proposed sample digestion system was carried out by using an ICP. The results showed that both of continuous-flow methods, the OTM and the RTM were comparable in accuracies with the conventional batch-type vessel digestion method.

• Analytical Science and Technology
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• v.8 no.4
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• pp.807-814
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• 1995

Accurate measurements of ozone precursors are required to understand the process and extent of ozone formation in rural and urban areas. Nonmethane hydrocarbons (NMHCs) have been identified as important ozone precursors. Identification and quantification of NMHCs are difficult because of the large number present and the wide molecular weight range encountered in typical air samples. A major plan of the research team of the Climate and Air Quality Taiwan Station (CATs) was the measurement of atmospheric nonmethane hydrocarbons. An analytical method has been development for the analysis of the individual nonmethane hydrocarbons in ambient air at ppb (v) and subppb(v) levels. The whole ambient air samples were collected in canisters and analyzed by GC-FID with $Al_2O_3$/KCl PLOT column. Our targeted for quantitative analysis 43 compounds that may be substantial contributors to ozone formation. The retention indices and molar response factors of some commercially available $C_2{\sim}C_{10}$ hydrocarbons were determined and used to identify and quantify air samples. A quality assurance program was instituted to ensure that good measurements were made by participating in the International Nonmethane Hydrocarbon Intercomparison Experiments (NOMHICE).

• Analytical Science and Technology
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• v.6 no.3
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• pp.319-328
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• 1993

Energy transfer process between $Tb^{3+}$ and $Ce^{3+}$ has been studied in LaOCl host. The energy absorbed by $Ce^{3+}$ transfers to $Tb^{3+}$ which has levels emitting strong fluorescence. The probability of energy transfer depends strongly on the concentration or the distance of activator ions. While the energy transferred on $Tb^{3+}$ emits from $^5D_3$ level at low concentration of $Ce^{3+}$, the energy goes back to $Ce^{3+}$(Back Transfer) and then emits from low levels of $Ce^{3+}$ and $Tb^{3+}$ at the high concentration. The Back Transfer process has been identified by the experiment with varying the concentration of the activator, $Ce^{3+}$. The relaxation is more effective if $Ce^{3+}$ intermediates than if not.

• Analytical Science and Technology
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• v.7 no.3
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• pp.387-393
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• 1994

Quantitative analytical conditions for chromium using solvent extraction followed by atomic absorption spectrometry was studied. Trioctylamine(TOA) in tertiary amine or Trioctylmethylammoniumchloride(TOMAC) in quaternary ammonium salt, both containing octyl group was used as an anion exchangers. Absorbance were measured for the different kinds of acid added and as changing the concentration of acid by graphite furnace atomic absorption spectrometer. The maximum absorbance was obtained at the concentrations of HCl, 0.1M to 0.3M for TOA and 0.03M to 0.1M for TOMAC. Mole ratios over 1:1 of TOA or TOMAC dissolved in MIBK solution to chromium in sample shows optimum extraction efficiency while HCl was added to the MIBK. As a result of scrutinizing the extraction process, the methods employed in this experiment turned out to be better extraction efficiency for chromium, compared to similar extraction methods.

• Analytical Science and Technology
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• v.31 no.3
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• pp.112-121
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• 2018

The hydrothermal carbonization method has received great attention because of the conversion process from biomass. The reaction produces various products in hydrochar, bio-liquid, and gas. Even though its yield cannot be ignored in amount, it is difficult to find research papers on bio-liquid generated from the hydrothermal carbonization reaction of biomass. In particular, the heterogeneity of feedstock composition may make the characterization of bio-liquid different and difficult. In this study, bio-liquid from the hydrothermal carbonization reaction of food wastes at $230^{\circ}C$ for 4 h was investigated. Among various products, fatty acid methyl esters were analyzed using two different extraction methods: liquid-liquid extraction and column chromatography. Different elutions with various solvents enabled us to categorize the various components. The eluents and fractions obtained from two different extraction methods were analyzed by gas chromatography with a mass spectrometer (GC/MS). The composition of the bio-liquid in each fraction was characterized, and seven fatty acid methyl esters were identified using the library installed in GC/MS device.

• Analytical Science and Technology
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• v.9 no.4
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• pp.406-410
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• 1996

The adsorption behaviors of transition metal ions on the poly(N,N'-bispalmitoyl-1, 12-diaza-3, 4;9,10-dibenzo-5,8-cyclopentadecane) has been determined by adsorption process in aqueous solution. The order of concentration factor(CF) and the amount of adsorption were Cu(II)

• Analytical Science and Technology
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• v.22 no.2
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• pp.152-158
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• 2009

In this study, we made a new discharge source improving previous SPI source to ionize softly organic compounds. The new SPI source consists of two electrodes as a hollow mesh cathode of half cylindrical shape and a hollow anode. We optimized the geometrical parameter of the SPI source by investigating the I-V curves at the various distance between the cathode and the anode. As the results, we found stable conditions of the soft plasma on broad range of the current and the voltage. The new SPI source attached to quadrupole mass spectrometer (QMS), and we obtained the mass spectra of dichloromethane (DCM). The fragment patterns of DCM appeared similarly with the pattern of electron ionization (EI).

• Journal of Photoscience
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• v.11 no.32
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• pp.65-69
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• 2004

The mechanism of interaction of four coumarin derivatives (CDS) with bovine serum albumin (BSA) was studied using spectrofluorometric technique. It was found that the coumarin ring common to all CDS makes major contribution to interaction. Binding affinities could be related to parachor values of CDS. Stem-Volmer plots indicated the presence of static component in the quenching mechanism. Results also showed that both tryptophan residues of protein are accessible to CDS. The high magnitude of rate constant of quenching indicated that the process of energy transfer occurs by intermolecular interaction forces and thus CDS binding site is in close proximity to tryptophan residues of BSA. Binding studies in the presence of the hydrophobic probe, 8-anilino-l-naphthalein-sulfonic acid showed that there is hydrophobic interaction between CDS and the probe and they do not share common sites in BSA. Thermodynamic parameters obtained from data at different temperatures showed that the binding of CDS to BSA involve hydrophobic bonds predominantly. The effects of various metal ions on the binding of CDS with BSA were also investigated.

• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.63-69
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• 2011

This work discusses the fabrication, development and potential response behaviors of $Ag^+$ ion-selective electrodes ($Ag^+$-ISE) based on N,N'-bis(2-hydroxybenzyl)-1,3-diaminopropane (L1) and N,N'-bis(2-hydroxybenzyl)-2,2-dimethyl-1,3-diaminopropane (L2) as carriers. The observations indicated that the resulting electrode based on L1 toward $Ag^+$ showed stable near-Nernst slope approaching 58.7 mV/dec and the optimum potential response characteristics in a linear range at least five orders of magnitude with a detection limit of $1.0{\times}10^{-6}M$. The proposed electrode displayed the preferential selectivity to $Ag^+$ against other tested cations. The excellent potential analytical characteristics could lead to the successful applications of silver assay in significant real samples, indicating that the proposed $Ag^+$-ISE showed a significant advancement of measurement capabilities. But for the electrode based on L2, the poor potential response characteristics were observed in total experiment process.

• Applied Biological Chemistry
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• v.37 no.5
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• pp.349-355
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• 1994

The present study was conducted to develop the automatic analytical method for determining moisture, nicotine, reducing sugar and total nitrogen contents and color(L, a, b) value in domestic tobacco leaves using near infrared(NIR) spectroscopy. The results of multiple linear regression analysis between chemical and NIR data showed that NIR spectro-scopy can determine those quality components of tobacco samples in 30 seconds, non-destructively. The results using developed calibrations are summarized as follows; The standard error of prediction(SEP) for moisture, nicotine. total nitrogen, reducing sugar contents and color(L, a, b) value in domestic tobacco leaves was 0.28%, 0.25%, 0.07%, 0.75%, 1.25, 0.44 and 1.07, respectively. In addition, The possibility of developing the cheaper filter type NIR instrument, for quality evaluation in the procurement from leaf tobacco cultivators and process control was investigated.