• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2003.11a
• /
• pp.109-112
• /
• 2003

A method to determine As(V) ions in aqueous solution by chemiluminescence method has been studied using a stopped flow system. The method is based on the increased chemiluminescence intensity with the addition of As(V) ion to a solution of lucigenin and hydrogen peroxide. The effects of KOH concentration, $H_2O_2$ concentration and flow rate of reagents on the chemiluminescence intensity have been investigated. The calibration curve for As(V) was linear over the range from $1.0{\times}l0^{-6}$M to $1.0{\times}l0^{-4}$M, the coefficient of correlation was 0.997 and the detection limit was $3.3{\times}l0^{-7}$M under the optimal experimental conditions.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.459-461
• /
• 1995

An omegatron mass spectrometer was designed and fabricated. Experiments have been performed to demonstrate the instrument's operation in the ECR plasma device. By using this analyzer, mass spectra have been obtained in hydrogen plasmas, and typical results are presented. In the plasma omegatron, downstreaming plasma generated by ECR are entering the analyzer through a smsll floating aperture. We employ a biasing technique to reduce the ion velocity along the magnetic field and to keep the ions from drifting to the side pintos, and thus achieved improved ion collection and sensitivity. Mass spectra obtained show that main positive ion components are $H_3{^+}$ and $H_2{^+}$ with the density ratio of $H_2{^+}$ to $H_3{^+}$ $\simeq$ 0.2.

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.771-778
• /
• 1995

The authors have developed an analytical method for determining trace amounts of 285 kinds of chemicals in natural waters by GC-ion trap MS. The results of overall recovery tests at $0.1{\mu}g/l$ showed that the mean recovery was 92.1% and the mean relative standard deviation was 10.8%. The mean of the method detection limits was $0.036{\mu}g/l$. From the results of analysis of real samples, it was confirmed that this method is useful to elucidate the concentration levels and the fate of chemicals in the aquatic environment.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.7
• /
• pp.943-947
• /
• 2002

The two reactions between iron ion (Fe3+ ) and o-chlorophenylfluorone (o-CPF) and copper ion (Cu2+ ) and o-CPF are sensitive at pH 6 in the presence of Triton X-100. We have determined the formation constants of the complexes by the spectral correction technique. Because of the poor selectivity of o-CPF to metals, the competition coordination of only the iron ion from the Cu-o-CPF complex was found and applied to the selective detection of iron traces by the Selective Competition Coordination Determination (SCCD) approach.The analysis of several samples shows that the relative standard deviations are less than 5.0% and the recovery of iron ions between 94.5% and 106%.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.1
• /
• pp.23-26
• /
• 2003

Titanium acetylacetonate was used in the construction of a PVC-based membrane electrode. This sensor shows very good selectivity for iodide ion over a wide variety of common inorganic and organic anions. It exhibits Nernstian behavior with a slope of 59.1 mV per decade. The working concentration ranges of the sensor are with a detection limit of $3.0\;{\times}\;10^{-6}\;M$. The response time of the sensor is very fast (<8 s), and can be used for at least twelve weeks in the pH range of 4.0-9.2. The best performance was obtained with a membrane composition of 30% PVC, 65% dibutylphthalate, 3% titanium acetylacetonate and 2% hexadecyltrimethylammonium bromide. The proposed sensor was successfully applied as an indicator electrode for titration of iodide with silver ion.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.3971-3976
• /
• 2012

A simple method was developed for the analysis of seven stilbene-type fluorescent whitening agents (FWAs) in paper materials by ion-pair reversed-phase high-performance liquid chromatography with fluorescence detection. These stilbene-type FWAs included two disulfonate, two tetrasulfonate, and three hexasulfonate compounds. After optimization of chromatographic conditions, the FWAs were satisfactorily separated using a reversed-phase column (RP-18) with the following isocratic mobile phase: methanol-water (60:40) containing 17.5 mM TBABr and 10 mM citrate buffer (pH = 7.0). The calibration plot was linear in the range from 5 to 500 ng/mL for two disulfo-FWAs and from 1 to 500 ng/mL for the other five FWAs. Precision levels of the calibration curve as indicated by RSD of response factors were 1.2 and 8.1%. Limits of quantitation (LOQ) ranged from 1.2 to 11 ng/mL.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.11
• /
• pp.1832-1838
• /
• 2006

The present paper is focused on sorption concentration of silver (I) on some complex-forming ion exchangers in the initial thiocyanate form and subsequent determination of Ag(I) in the phase of anion exchanger AN-25 by diffuse reflectance spectroscopy. The sorption and kinetic characteristics of the sorbents were investigated. The apparent stability constants of thiocyanate silver complexes in the ion exchanger phase were calculated. The sorption-spectroscopic method is proposed for Ag(I) determination in aqueous solutions. The calibration curve is linear in the concentration range of 10-200 mg/L (sample volume is 10.0 mL) and the detection limit is 2 $\mu$g/mL. The presence of $Na^+,\;K^+,\;Mg^{2+}$ (macrocomponents) as well as of Ni (II), Co (II), Cu (II) do not hinder the determination of silver (I).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.239-239
• /
• 2013

For more than four decades, ion-sensitive field-effect transistor (ISFET) sensors that respond to the change of surface potential on a membrane have been intensively investigated in the chemical, environmental, and biological spheres, because of their potential, in particular their compatibility with CMOS manufacturing technology. Here, we demonstrate a new type of ISFET with dual-gate (DG) structure fabricated on ultra-thin body (UTB), which highly boosts sensitivity, as well as enhancing chemical stability. The classic ion-sensitive field-effect transistor (ISFET) has been confronted with chronic problems; the Nernstian response, and detection limit with in the Debye length. The super-coupling effects imposed on the ultra thin film serve to not only maximize sensitivity of the DG ISFET, but also to strongly suppress its leakage currents, leading to a better chemical stability. This geometry will allow the ISFET based biosensor platform to continue enhancement into the next decade.

• Bulletin of the Korean Chemical Society
• /
• v.13 no.5
• /
• pp.482-486
• /
• 1992

Ion-molecule reactions of acetylene and mixed acetylene-ammonia cluster ions are studied using an electron impact time-of-flight mass spectrometer. The present results clearly demonstrate that $(C_2H_2)_n^+$ cluster ion distribution represents a distinct magic number of n=3. The mass spectroscopic evidence for the enhanced structural stabilities of $[C_6H_4{\cdot}(NH_3)_m]^+$ (m=0-8) ions is also found along with the detection of mixed cluster $[(C_2H_2)_n{\cdot}(NH_3)_m]^+$ ions, which gives insight into the feasible structure of solvated ions. This is rationalized on the basis of the structural stability for acetylene clusters and the dissociation dynamics of the complex ion under the presence of solvent molecules.

• Mass Spectrometry Letters
• /
• v.12 no.1
• /
• pp.26-30
• /
• 2021

The impurity concentration is a crucial parameter for semiconductor thin films. Evaluating the impurity distribution in silicon thin film is another challenge. In this study, we have investigated the doping concentration of boron in silicon thin film using time of flight secondary ion mass spectrometry in dynamic mode of operation. Boron doped silicon film was grown on i) p-type silicon wafer and ii) borosilicate glass using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using well-tuned SIMS measurement recipe, we have detected the boron counts 101~104 along with the silicon matrix element. The secondary ion beam sputtering area, sputtering duration and mass analyser analysing duration were used as key variables for the tuning of the recipe. The quantitative analysis of counts to concentration conversion was done following standard relative sensitivity factor. The concentration of boron in silicon was determined 1017~1021 atoms/㎤. The technique will be useful for evaluating distributions of various dopants (arsenic, phosphorous, bismuth etc.) in silicon thin film efficiently.