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Acta Chromatographica
Authors: Young Sang Kwon, Sung-Gil Choi, Seung-Min Lee, Jong-Hwan Kim, and Jong-Su Seo

The applicability of gas chromatography–triple quadrupole mass spectrometry (GC–MS/MS) for determination of dioxins in soil was investigated. The analytical method was validated based on US Environmental Protection Agency (EPA) Method 1613 and European Union (EU) Regulation No. 709/2014 for selectivity, linearity of sensitivity, and instrumental limits of quantification (iLOQs). Method development commenced with determination of retention times for 17 native polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and selection of characteristic ions from GC–MS/MS spectra. The linearity was measured using 1613 standard solutions (CS1–CS5) containing 0.5 to 200 ng/mL tetrachlorodibenzo-p-dioxin/furan (TCDD/F) congeners, 2.5 to 1000 ng/mL pentachlorodibenzo-p-dioxin/furan (PeCDD/F) to heptachlorodibenzo-p-dioxin/furan (HpCDD/F) congeners, and 20 to 2000 ng/mL octachlorodibenzo-p-dioxin/furan (OCDD/F) congeners. The correlation coefficient (R 2) values ranged between 0.9990 and 0.9999, and the iLOQ values ranged from 0.052 to 0.350 pg/μL for TCDD/F congeners, with a relative standard deviation of 2.7–9.6%. The entire analytical method was verified by analysis of certified reference materials (BCR-529 and BCR-530), and the recoveries were 71.79–103.87% and 81.50–103.12%, respectively. Thus, the GC–MS/MS system provides an alternative to GC–high-resolution MS for the simultaneous determination of TCDD/F congeners in soil.

Open access

Abstract  

The analysis of mineral contents in space foods is needed to obtain an information on a comprehensive elemental composition as well as the investigation on the effects of human nutrition and health based on the dietary intake of mineral elements. Recently, six items of new Korean space foods (KSFs) such as kimchi, bibimbap, bulgogi, a ramen, a mulberry beverage and a fruit punch which was developed by the KAERI, and the contents of more than 15 elements in the samples were examined by using instrumental neutron activation analysis (INAA). Five biological certified reference materials, NIST SRM were used for analytical quality control. The results were compared with those of common Korean foods reported, and these results will be applied toward the identification of irradiated foods.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Dong-Yong Chung, Eung-Ho Kim, Young-Joon Shin, Jae-Hyung Yoo, Cheong-Song Choi, and Jong-Duk Kim

Abstract  

The decomposition rate of oxalate by hydrogen peroxide has been investigated by a KMnO4 titration method. The rate equation for decomposition of hydrogen peroxide in the aqueous phase is 1n([H2O2]/[H2O2]0)=–k1·t, where k1=0.2, for [H+]<2M, k1=0.2+0.34([H+]–2), for [H+]>2M. As the acidity increases over 2M, an acid catalysis effect appeard. The new rate equation proposed for the decomposition of oxalate by hydrogen peroxide is

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$- \frac{d}{{dt}}X_{[OX]} = k_2 [H_2 O_2 ]_0 (1 - X_{[OX]} )(e^{ - k_1 t} - \frac{{[OX]_0 }}{{[H_2 O_2 ]_0 }}X_{[OX]} )$$ \end{document}
The rate constant for decomposition of oxalate, k2, increased with nitric acid concentration and the effect of hydrogen ion concentration was expressed as k2=a[H+]n, where the values fora andn were a=1.54, n=0.3 at [H+]<2M, a=0.31, n=2.5 at [H+]>2M, respectively.

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Journal of Behavioral Addictions
Authors: Yeon-Jin Kim, Jae A. Lim, Ji Yoon Lee, Sohee Oh, Sung Nyun Kim, Dai Jin Kim, Jong Eun Ha, Jun Soo Kwon, and Jung-Seok Choi

Background and aims

Internet gaming disorder (IGD) is characterized by a loss of control and a preoccupation with Internet games leading to repetitive behavior. We aimed to compare the baseline neuropsychological profiles in IGD, alcohol use disorder (AUD), and obsessive–compulsive disorder (OCD) in the spectrum of impulsivity and compulsivity.

Methods

A total of 225 subjects (IGD, N = 86; AUD, N = 39; OCD, N = 23; healthy controls, N = 77) were administered traditional neuropsychological tests including Korean version of the Stroop Color–Word test and computerized neuropsychological tests, including the stop signal test (SST) and the intra–extra dimensional set shift test (IED).

Results

Within the domain of impulsivity, the IGD and OCD groups made significantly more direction errors in SST (p = .003, p = .001) and showed significantly delayed reaction times in the color–word reading condition of the Stroop test (p = .049, p = .001). The OCD group showed the slowest reading time in the color–word condition among the four groups. Within the domain of compulsivity, IGD patients showed the worst performance in IED total trials measuring attentional set shifting ability among the groups.

Conclusions

Both the IGD and OCD groups shared impairment in inhibitory control functions as well as cognitive inflexibility. Neurocognitive dysfunction in IGD is linked to feature of impulsivity and compulsivity of behavioral addiction rather than impulse dyscontrol by itself.

Open access