• Journal of Electrochemical Science and Technology
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• 제12권4호
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• pp.415-423
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• 2021

For a battery module where single cells are connected in series, the single cells should each have a similar state of charge (SOC) to prevent them from being exposed to an overcharge or over-discharge during charge-discharge cycling. To detect the existence of unbalanced SOC cells in a battery module, we propose a simple measurement method using a single-frequency response of electrochemical impedance spectroscopy (EIS). For a commercially available graphite/nickel-cobalt-aluminum-oxide lithium-ion cell, the cell impedance increases significantly below SOC20%, while the impedance in the medium SOC region (SOC20%-SOC80%) remains low with only minor changes. This impedance behavior is mostly due to the elementary processes of cathode reactions in the cell. Among the impedance values (Z, Z', Z"), the imaginary component of Z" regarding cathode reactions changes heavily as a function of SOC, in particular, when the EIS measurement is performed around 0.1 Hz. Thanks to the significant difference in the time constant of cathode reactions between ≤SOC10% and ≥SOC20%, a single-frequency EIS measurement enlarges the difference in impedance between balanced and unbalanced cells in the module and facilitates an ~80% improvement in the detection signal compared to results with conventional EIS measurements.

• 한국환경보건학회지
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• 제28권5호
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• pp.53-58
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• 2002

A method for the determination of lead(II) ion using a nafion-EDTA(ethylene diamine tetraacetic acid)-glycerol modified glassy carbon electrode was proposed. Lead(II) ion is accumulated at the electrode by complexation and electrostatic attraction with nafion-EDTA-glycerol and detected at -0.560$\pm$0.015V (vs. Ag/AgCl) by differential pulse voltammetry. For the determination of lead(II) ion, a standard calibration curve if obtained from 10$^{-9}$ M lead(II) ion to 10$^{-7}$ M, and the detection limit(3s) is as low as 5.0$\times$10$^{-10}$ M.

• Mass Spectrometry Letters
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• 제7권3호
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• pp.64-68
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• 2016

Scanning electron microscopy combined with thermal ionization mass spectrometry (SEM-TIMS) was used to determine the precise isotope ratios of ultra-trace levels of uranium contained in individual microparticles. An advanced multiple ion counter system consisting of three secondary ion multipliers and two compact discrete dynodes was used for complete simultaneous ion detection. For verification purposes, using TIMS with complete simultaneous measurement, isotopes were analyzed in 5 pg of uranium of a certified reference material. A microprobe in the SEM was used to transfer individual particles from a NUSIMEP-7 sample to TIMS filaments, which were then subjected to SEM-TIMS and complete simultaneous measurement. The excellent agreement in the resulting uranium isotope ratios with the certified NUSIMEP-7 values shows the validity of SEM-TIMS with complete simultaneous measurement for the analysis of uranium isotopes in individual particles. Further experimental study required for investigation of simultaneous measurement using the advanced multiple ion counter system is presented.

• 분석과학
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• 제36권1호
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• pp.1-11
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• 2023

A new, sensitive, and reliable flow injection methodology was investigated for the determination of lead ion (II) in vegetables' samples using a laboratory-prepared reagent 2-[(6-methoxy-2-benzothiazoly)azo]-4-methoxy phenol (6-MBTAMP). Infrared spectroscopy, UV-visible spectrophotometry, Energy dispersive X-ray spectroscopy (EDX), Elemental Analysis (CHN), nuclear magnetic resonance spectroscopy ¹HNMR, and ¹³CNMR techniques were used to characterize the reagent and lead (II) complex. The method is based on lead ion (II) reacting with the reagent (6-MBTAMP) in a neutral solution to produce a green-red complex with a maximum absorbance at 670 nm. The optimum conditions, such as flow rate, lead ion (II) volume, reagent volume, medium pH, reagent concentration, and reaction coil length were thoroughly examined. The limits of detection (LOD) and quantification (LOQ) were determined to be 0.621 mg·L^-1 and 2.069 mg·L^-1 , respectively, while Sandell's sensitivity was determined to be 0.345 ㎍·cm^-2.

• 한국환경보건학회지
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• 제21권3호
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• pp.87-95
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• 1995

A rapid and selective co-extraction systems of copper and zinc-thiocyanate complex into various types of alkylamine for the simultaneous determination of two metal ions by atomic absorption spectrometry and ion chromatograph have been proposed. The quantitative extractions of Cu(II) and Zn(II) at 0.1 M-thiocyanate and 0.1 M-HCI were achieved with Aliquat 336-$CHCl_3$. The detection limits of Cu and Zn were 2 ppb and 0.9 ppb respectively.

• 한국대기환경학회지
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• 제7권2호
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• pp.137-142
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• 1991

A method is developed for the simultaneous determination of dissolved iron, copper, and zinc in rainwater. The method involves 25-fold evaporative concentration, ion chromatographic separation and subsequent spectrophotometric detection after post-column reaction with 4-(2-pyridylazo) resorcinol. Analytical sensitivities, being defined by the slopes of calibration curves, are 0.93, 0.54, and 0.11 Abs/ $\mu$g/ml for iron, copper, zinc, respectively. Detection limits render around a few tenth of one ng/ml. Precisions evaluated by replicate analysis of real sample are better than 10% RSD. Due to the lack of certified standards for rainwater, the accuracy of the method could not be assessed directly. However, the results of this method agree well with those by inductively coupled plasma mass spectrometry. Analytical results for a suite of Seoul rainwaters are presented herein.

• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.373-377
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• 2003

Various groups of industrial and agricultural pollutants (heavy metal ions, cyanides, and pesticides) can be detected by enzymes. Since heavy metal ions inhibit urease, cyanides inhibit peroxidase, organophosphorus and carbamate pesticides inhibit butyrylcholinesterase, these enzymes were co-immobilized into a bovine serum albumin gel on the surface of an ion-sensitive field effect transistor to create a bioprobe that is sensitive to the compounds mentioned above. The sensitivity of the present sensor towards KCN corresponded to $1\;\mu\textrm{M}$ with 1 min of incubation time. The detection limits for Hg(II) ions and the pesticide carbofuran were 0.1 and $0.5\;\mu\textrm{M}$, respectively, when a 10 min sensor incubation time in contaminated samples was chosen. The total time for determining the concentrations of all species mentioned did not exceed 20 min.

• 대한화학회지
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• 제38권6호
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• pp.418-426
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• 1994

미국 환경청이 지정한 129종의 priority polluatants 중 40종의 비휘발성 염기/중성 유기화합물을 대상물질로 선정하였다. 분석방법으로 초음파 추출법(sonication extraction)과 Soxhlet 추출법(Soxhlet extraction)을 이용하여 토양에 있는 유기물을 추출 및 농축하여 기체크로마토그래프/질량분석기-SIM(selected ion monitoring)법으로 검출하였다. 표준물질이 첨가된 토양시료에 두 추출법을 적용하여 회수율을 구하고 정확도, 정밀도 및 검출한계를 측정하여 미량 분석의 가능성을 조사하였다.

• 대한화학회지
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• 제38권3호
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• pp.246-253
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• 1994

미국 환경청이 지정한 129종의 priority pollutants 중 11종의 비휘발성 산성 유기화합물을 대상물질로 선정하여 토양시료 중의 극미량 분석방법을 연구하였다. 분석방법으로 기체크로토그래프/질량분석기- SIM(selected ion monitoring)법을 검출방법으로 정하고, 토양시료의 추출 및 농축방법으로 사용한 초음파 추출법(sonication extraction)과 Soxhlet(Soxhlet extraction)을 비교 연구하였다. 각 화합물의 회수율, 상대표준편차 및 method detection limit를 측정하여 EPA분석법을 대체할 수 있는지의 가능성을 조사하였다.

• 한국대기환경학회지
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• 제11권4호
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• pp.307-313
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• 1995

An automatic method is developed for the determination of SOx in atmosphere. The method involves SOx sampling in diffusion scrubber followed by ion chromatographic analysis. Filtered air is withdrawn at 1.8.ell./min through a diffusion scrubber of which inner tube is made of PTFE(Gore-tex) membrane tubing. 1mM $H_{2}$ $O_{2}$ is used as absorbing solution so that SOx is oxidized to S $O_{4}$$^{2-}$. The scrubbered solution is automatically injected into ion chromatograhpy eith conductivity detection for sulphate determination. Replacement of commonly used polyproplene membrane with PTFE gives several merits such as easy preparation of diffusion scrubber, better collection efficiency. No measurable memory effect is experienced, and this isin contrast to previous work for ammonia. Detection limit of this method defined by three times standard deviation is 0.56ppbv. The precision is 0.4% RSD at SOx concentration of 7.3ppbv Results for Seoulatmosphere ate presented.