• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1698-1702
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• 2013

Glucose is a common medical analyte measuring in human serum or blood samples. The development of a primary method is necessary for the establishment of traceability in measurements. We have developed an isotope dilution liquid chromatography tandem mass spectrometry as a primary method for the measurement of glucose in human serum. Glucose and glucose-$^{13}C_6$ in sample were ionized in ESI negative mode and monitored at mass transfers of m/z 179/89 and 185/92 in MRM, respectively. Glucose was separated on $NH_2P$-50 2D column, and the mobile phase was 20 mM $NH_4OAc$ in 30% acetonitrile/70% water. Verification of this method was performed by the comparison with NIST SRMs. Our results agreed well with the SRM values. We have developed two levels of glucose serum certified reference material using this method and distributed them to the clinical laboratories in Korea as samples for proficiency testings. The expended uncertainty was about 1.2% on 95% confidence level. In proficiency testings, the results obtained from the clinical laboratories showed about 3.6% and 3.9% RSD to the certified values. Primary method can provide the traceability to the field laboratories through proficiency testings or certified reference materials.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.645-650
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• 2017

This technical note demonstrates the feasibility of using laser ablation inductively coupled plasma mass spectrometry for the characterization of U-7Mo/Ale5Si dispersion fuel. Our measurements show 5.0% Relative Standard Deviation (RSD) for the reproducibility of measured $^{98}Mo/^{238}U$ ratios in fuel particles from spot analysis, and 3.4% RSD for $^{98}Mo/^{238}U$ ratios in a NIST-SRM 612 glass standard. Line scanning allows for the distinction of U-7Mo fuel particles from the Al-5Si matrix. Each mass spectrum peak indicates the presence of U-7Mo fuel particles, and the time width of each peak corresponds to the size of that fuel particle. The size of the fuel particles is estimated from the time width of the mass spectrum peak for $^{98}Mo$ by considering the scan rate used during the line scan. This preliminary application clearly demonstrates that laser ablation inductively coupled plasma mass spectrometry can directly identify isotope ratios and sizes of the fuel particles in U-Mo/Al dispersion fuel. Once optimized further, this instrument will be a powerful tool for investigating irradiated dispersion fuels in terms of fission product distributions in fuel matrices, and the changes in fuel particle size or shape after irradiation.

• Food Science of Animal Resources
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• v.28 no.3
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• pp.301-305
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• 2008

This study was carried out to develop an accurate and rapid analysis method to measure the contents of iodide and chloride in infant formula using an ion selectivity electrode. The infant formula SRM 1846 (Standard Reference Material 1846, NIST, USA) was used as a CRM (Certified reference material). Samples were dissolved in water with 3% acetic acid and filtered through filter paper and adjusted to pH 7.0 with 0.1N NaOH. At pH 7.0, the iodide content of the CRM was $1.04{\pm}0.03\;mg/kg$ compared to the specification of $1.11{\pm}0.1\;mg/kg$ of CRM, and the recovery was $93.7{\pm}2.7%$. The chloride content was $5114.3{\pm}240\;mg/kg$ compared to the specification of $4,920{\pm}300mg/kg$ of CRM, and the recovery was $103.9{\pm}4.9%$. Ion selectivity electrodes could be successful1y used to determine the concentration of iodide and chloride ions in infant formula by a simple and rapid pretreatment of sample matrixes.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.327-334
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• 2016

This study was conducted to establish the standard method for the contents of biotin in milk formulas. To optimize the method, we compared several conditions for liquid extraction, purification and instrumental measurement using spiked samples and certified reference material (NIST SRM 1849a) as test materials. LC-MS/MS method for biotin was established using $C_{18}$ column and binary gradient 0.1% formic acid/acetonitrile, 0.1% formic acid/water mobile phase is applied for biotin. Product-ion traces at m/z 245.1 ${\rightarrow}$ 227.1, 166.1 are used for quantitative analysis of biotin. The linearity was over $R^2=0.999$ in range of $5{\sim}60{\mu}g/L$. For purification, chloroform was used as a solvent for eliminating lipids in milk formula. The linearity was over 0.999 in range of 5~60 ng/mL. The detection limit and quantification limit were 0.10, 0.31 ng/mL. The accuracy and precision of LC-MS/MS method using CRM were 103%, 2.5% respectively. Optimized methods were applied in sample analysis to verify the reliability. All the tested milk formulas were acceptable contents of biotin compared with component specification and standards for nutrition labeling. The standard operating procedures were prepared for biotin to provide experimental information and to strengthen the management of nutrient in milk formula.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.8
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• pp.1108-1117
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• 2003

In Guadeloupe small ruminants (SR) are reared for meat production under pasture conditions. Intensive rotational grazing systems (irrigated, fertilised and high stocked) allow reasonable levels of production but generate high post-grazing residues. Experiments were designed to control them. A system in which residuals were mown (RM) was tested in comparison to the control system (Residuals Remained, RR). The same design was carried out for two years with Creole goat (G) and Martinik sheep (S). An accelerated reproductive rate (3 parturitions over 2 years) was carried out. Systems were compared at three parturition seasons per year(dry, intermediate and rainy seasons). Each group was composed of 20 goats ($36.0{\pm}2.5kg$) or 20 ewes ($46.8{\pm}2.4kg$). The female body traits did not vary according to pasture management and seasons. The stocking rate averaged 1,400 kg LW/ha. The mean fertility rate for does varied significantly (p<0.05) within the kidding season, from $80.4{\pm}0.5%$ to $93.7{\pm}2.9%$ while the mean litter size was $2.30{\pm}0.07$ total kids born. No effect of pasture system was observed. Corresponding values for ewes were $83.2{\pm}12.8%$ vs. $75.6{\pm}12.5%$ (p<0.05) and $2.43{\pm}0.24$ vs. $2.03{\pm}0.29$ (p<0.01) total lambs born for SRM and SRR ewes, respectively. A seasonal effect was observed upon ewe performances. The preweaning mortality of kids and lambs averaged 16.3% and 14.4%, respectively. It was 7 and 9 percentage points more (p<0.01) for RR than for RM kids and lambs, respectively. For both species, weaning took place at an average age of $81.4{\pm}3.6days$. In Creole kids, live weight at birth and at weaning were $1.9{\pm}0.2kg$ and $8.9{\pm}0.8kg$, respectively. In the Martinik sheep, the traits averaged $2.9{\pm}0.2kg$ and $18.9{\pm}0.9kg$. For both traits in both species, significant (p<0.05) group${\times}$season interactions were recorded. The consequences of elimination of post-grazing residues varied according to the SR species, the environmental conditions and the animal physiological status. The forage characteristics were not limiting factors since forage availability in the RM systems (2,300 and 2,600 kg DM/ha, respectively) and chemical composition were at satisfactory levels (CP content averaged 12 and 10%). It is recommended to develop new grazing system which would allow the use of post-grazing residues instead of mowing the refusals.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.5
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• pp.453-467
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• 2000

The aim of this research is to collect and characterize fine particles (FPM:$\leq$2.5${\mu}{\textrm}{m}$) and coarse particles (CPM: 2.5~10${\mu}{\textrm}{m}$) using a low volume air sampler provided by the IAEA, at urban (Taejon) and rural area(Wonju) for a period of about two years(April 1996 to May 1998) and to promote a use of nuclear analytical techniques for air pollution studies. For the collection of airborne particulate matter (PM(sub)10), the Gent stacked filter unit sampler and polycarbonate membrane filters were employed. The concentration of trace elements in collected APM samples were determined byu instrumental Neutron Activation Analysis. For validation of the analytical data, internal quality control were implemented by using both the comparison of the analytical results of standard reference materials(NIST SRM 1648) and interlaboratory comparison for proficiency test (NAT-3). The standard uncertainty was less than 15% and Z-score of two samples were within $\pm$1. The monitoring of (PM(sub)10) mass concentration and elemental concentrations were carried out weekly. The average mass concentration of (PM(sub)10) in urban and rural areas were 59.2$\pm$36.5$\mu\textrm{g}$/㎥ and 41.4$\pm$23.7$\mu\textrm{g}$/㎥, respectively. To investigate the emission source, the enrichment factors were calculated for the fine and coarse particle fractions at two sites, respectively and these values were classified for anthropogenic and soil origin elements.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.327-333
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• 2014

A method for analysis of five artificial sweetners (sodium saccharin, aspartame, acesulfame-K, sucralose, cyclamate) in beverage samples was developed using high-performance liquid chromatography/triple quadrupole mass spectrometry (HPLC/MS/MS). The method uses a single-step dilution for sample preperation. Seperation was achieved on a $C_{18}$ column ($2.1{\times}150mm$, $3.5{\mu}m$) with A- 2% methanol (1 mM ammonium acetate), B-95% methanol (1 mM ammonium acetate) as mobile phase with gradient mode. The quantitation of target compounds was performed by external calibration in selected reaction monitorning (SRM) mode. The coefficient of determination of calibration curve for sodium saccharin, aspartame, acesulfame-K, sucralose and cyclamate were 0.9957, 0.9991, 0.9943, 0.9982 and 0.9948, respectively. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 0.001~0.022 mg/L and 0.004~0.073 mg/L, repectively. Recoveries for beverage samples were in the range of 92.76~113.50% with RSD < 10.91%. The method has applied to the determination of the five sweetners in 102 beverage samples. Three artificial sweetners-aspartame, acesulfame-K, sucralose were detected from 42 samples. Sodium saccharin and cyclamate were not detected in all samples.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.411-417
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• 2017

This study was conducted to establish the analysis method for the contents of choline in infant formulas and follow-up formulas by ion chromatograph (IC). To optimize the method, we compared several conditions for extraction, purification and instrumental measurement using spiked samples and certified reference material (CRM; NIST SRM 1849a) as test materials. IC method for choline was established using Ion Pac CG column and 18 mM $H_2SO_4$ mobile phase. The parameters of validation were specificity, linearity, LOD, LOQ, recovery, accuracy, precision and repeatability. The specificity was confirmed by the retention time and the linearity, $R_2$ was over 0.999 in range of 0.5~10 mg/L. The detection limit and quantification limit were 0.14, 0.43 mg/L. The accuracy and precision of this method using CRM were 95%, 2.1% respectively. Optimized methods were applied in sample analysis to verify the reliability. All the tested products were acceptable contents of choline compared with component specification for nutrition labeling. The standard operating procedures were prepared for choline to provide experimental information and to strengthen the management of nutrient in infant formula and follow-up formula.

• Analytical Science and Technology
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• v.25 no.1
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• pp.25-32
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• 2012

Isotope dilution mass spectrometry (ID-MS) based on liquid chromatography tandem mass spectrometry (LC/MS/MS) was developed for the accurate determination of sorbic acid in tea-drink. An isotope analogue of sorbic acid, $^{13}C_2$-sorbic acid, was obtained by custom synthesis. MS was operated in the negative mode with selected reaction monitoring (SRM) mode of $[M-H]^-$ ${\rightarrow}$ $[M-CO_2H]^-$ channel at m/z 111 ${\rightarrow}$ 67 for sorbic acid and at m/z 113 ${\rightarrow}$ 68 for its isotope analogue. Chromatographic separation was accomplished with a C18 column and an isocratic mobile phase of 55% of 50 mM ammonium acetate (pH 4.5) and 45% of methanol. Homogeneous reference materials were prepared for validation of this method, including repeatability and reproducibility tests, by fortifying tea-drink with sorbic acid in our laboratory. Repeatability and reproducibility studies showed that the ID-LC/MS method is a reliable and reproducible method which provides less than 3.8% of relative standard deviation (RSD) for the analysis of sorbic acid.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.233-239
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• 2010

Four genes (yqfR, yfmL, ydbR, deaD) were identified as putative DEAD-box RNA helicase genes in the genomic sequence of Bacillus subtilis by homology search. To understand the function of these genes, each of the genes was deleted and the constructed strains were tested for their growth charateristics at different temperatures. The growth rate of ydbR deletion mutant ($T_d$=53 min) was a little bit reduced at $37^{\circ}C$ as compared to that of wild type strain (CU1065). But the growth rate of other three (yqfR, yfmL, deaD) deletion mutants ($T_d$=30-40 min) is nearly equal to the growth rate of wild type ($T_d$=32 min). On the other hands, the growth rate of deletion mutants were reduced at $22^{\circ}C$ in order of yqfR ($T_d$=151 min), yfmL ($T_d$=214 min), ydbR ($T_d$=343 min), which showed cold-sensitive phenotype. The deletion mutant of deaD ($T_d$=109 min) grew equally as compared to the growth rate ($T_d$=102 min) of the wild type at $22^{\circ}C$ and did not show cold-sensitive growth. Double, triple and quadruple deletion mutants of these genes were constructed, and growth rate of these mutants were measured at various temperature conditions ($22^{\circ}C$, $37^{\circ}C$, $42^{\circ}C$) using LB broth. Multiple deletion mutations showed more severe cold-sensitive growth than single deletion mutations, and double deletion of ydbR and yfmL ($T_d$=984 min) showed most cold-sensitive growth than any other double mutants. Such a cold-sensitive growth of these mutations is quite similar to the result of csdA or srmB deletion in E. coli and suggested that physiological role of ydbR and yfmL is related with ribosome assembly.