• Journal of the Korean Chemical Society
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• v.41 no.7
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• pp.337-342
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• 1997

Acryloylmethylbenzo-15-crown-5 was prepared from the reaction of 4'-hydroxymethylbenzo-15-crown-5 with acryloyl chloride. And, poly(acryloylmethylbenzo-15-crown-5) [poly(AMB15C5)] was synthesized by radical polymerization using AIBN as initiator in benzene. Coated wire lead(II) ion-selective electrodes ($Pb^{2+}$-CWISEs) using either poly(AMB15C5) or B15C5 as neutral carrier were prepared, respectively. $Pb^{2+}$-CWISEs gave linear responses with slopes of 28$\pm$ 1mV per decade within the concentration range of $10^{-5} M{\sim}10^{-1}$ M, respectively. Also, the detection limits were $10^{-6}$ M and response times were either 3 or 5 min. for B15C5 and poly(AMB15C5), respectively. $Pb^{2+}$-CWISE base on B15C5 was rather unstable than poly(AMB15C5)'s due to solubility of the B15C5 in water. The selectivity coefficients of a variety of interfering ions such as $Mg^{2+},\; Ca^{2+},\; Co^{2+},\; Ni^{2+},\; Cu^{2+},\; Zn^{2+}$ and $Cd^{2+}$ were small ($10^{-4}{\sim}10^{-5}$), while those of $Na^+$ and $K^+$ were large (0.1∼0.01). In addition, the electrode responses depended upon the pH of test solution and the composition of the membrane. In the range pH 3∼6 of test solution, potentials of Pb2+-CWISEs were hardly changed. The optimal contents of B15C5 and poly(AMB15C5) were 7.7 wt% and 13.1 wt%, respectively.

• Journal of the Korean Chemical Society
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• v.47 no.1
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• pp.13-18
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• 2003

The effect of ultrasonic decomposition was introduced to develop a pretreatment method for the analysis of potassium ion in human urine by potentiometry. N-(4’-benzo-15-crown-5)-anthracene-9-imine, which has a good selectivity coefficient for potassium against ammonium, was used as an ion-selective material for the determination of potassium in urine with relatively high concentration of $NH_4{^+}$. Protenis in urine be removed by 85.1% when the sample acidified with 1.0 M $HNO_3$ was preteated for 100 s by sonication. Potential response of the membrane electrode in the pretreated urine had a slope of 54.6(${\pm}0.2,\;n=5$) mV/decade over the linear range of log $[K^+]$=-5~-1(r=0.9997). When an oxidant, $H_2O_2$, was addwd to the urine sonicated with $HNO_3$, the deproteinization increased 10% more than that in case if only $HNO_3$ and then the maximum ratio of ca. 95% was obtained. Moreover, the Nernstian slope for $K^+$ added to the urinary sample increased to 56.7(${\pm}0.1,\;n=3$) mV/decade. When the calibration curves were measured, the slopes did not vary even after the electrode was successively used 20 times with ultrasonic cleaning. The results showed that an ultrasonic pretreatment method provides simplicity in use, reduced treatment time and improved potentiometric characteristics of the membrane as the method effectively removes ca. 95% of proteins in urine.

• Analytical Science and Technology
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• v.33 no.6
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• pp.262-273
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• 2020

A fluorine content analysis method for krill oils, which is a representative oil formulation in foods, was developed in compliance with the Korea Food and Drug Ministry's "Guidelines for Validation of Testing Methods Related to Food". Using this method for krill oils, the presence of impurities was evaluated via combustion-ion chromatography (C-IC). A review of published technical data on fluorine in krill oils showed that while the traditional wet potentiometric method was typically used, it was not reliable. Moreover, there was no food testing/analysis laboratory in Korea to perform a fluorine test analysis on such an oil matrix. Therefore, we identified halogen (fluorine) tests, developed to national and international standards, and developed a test method suitable for krill oils by selecting a C-IC method that is sufficiently applicable to the oil matrix. Based on the characteristics of the oil matrix, the optimal test method was established through various experiments by reviewing the concerns related to loss and interference in the preparation and introduction of samples. The fluorine content test was carried out on 11 krill oil products that were purchased online. Most products (with the exception of only one) were found to contain less than the reporting limit obtained by the test method. Furthermore, after additional testing, a high fluorine content of approximately 2,000 ~ 3,000 mg/kg was detected on the krill surface, although the concentration varied depending on the area of the krill. A comparison with samples from two ISO/IEC 17025 testing laboratories confirmed that there was no significant difference in the statistical analysis results obtained by ANOVA among the three laboratories. A testing guide for fluorine content analysis was completed.