• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.409-415
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• 2013

Post-harvest fungicide residue was measured in citrus fruits. Samples were collected from local markets in Seoul and analyzed using liquid chromatography coupled with mass spectrometry (LC-MS). LC-MS results were validated for the assay of pesticides by using linearity, accuracy, precision, and limits of detection and quantification. The linearity in the concentration ranged from 0.005 to 2.0 mg/kg ($R^2$ >0.999). Sample recoveries ranged from 80.2 to 98.3% with relative standard deviations below 4.0% for spiking levels from 0.01 to 1.0 mg/kg. The limits of detection ranged between 0.002 and 0.008 mg/kg, and the limits of quantification ranged between 0.006 and 0.027 mg/kg. The highest residue levels for carbendazim, thiabendazole, imazalil, and azoxystrobin in citrus fruits were 0.541, 0.958, 0.721, and 0.052 mg/kg, respectively. The pesticide residues found in citrus fruits were blow maximum residue limits (MRLs) and are not a serious public health problem.

• Korean Journal of Plant Tissue Culture
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• v.21 no.1
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• pp.41-46
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• 1994

Calli were induced from leaf explants of B.falcatum, and selected cell clumps of the calli (900-1, 000${\mu}{\textrm}{m}$) were cultured on MS medium supplemented with 0.1, 0.5, 1.0 or 2.0 mg/L 2, 4-D for 7 days, respectively: The clumps were subsequently transferred onto MS basal medium and subcultured for four weeks. In order to investigate the effect of 2, 4-D pretreatment, the selected clumps were cultured on MS medium supplemented with 0.1 mg/L 2, 4-D for 24, 48, 72, 96, 120 or 144 hours and then transferred to liquid MS basal medium, wherein they were cultured for 4 weeks. Histological observation showed that root initial cells were developed from cells on the surface of clumps or from cells in the inner region. Clumps on the basal medium produced mot within 5 days of culture. The rate of prutruding time was inversely proportional to the concentration of 2, 4-D. The number of adventitious roots per clump preheated with 0.1 mg/L 2, 4-D was an average of 5.2, which was the highest level. On MS medium as control, the clumps formed 3.3 adventitious roots each. As tile concentration of 2, 4-D increased, the number of adventitious roots were declined accordingly: The number of adventitious roots as the period of pretreatment increased upto 120 h.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.312-315
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• 2014

The present study demonstrated the development and validation of the method for the quantification of phenol in food using gas chromatography coupled with mass spectrometry (GC-MS). After spiking of internal standard (Phenol-$d_5$) to food, those samples were extracted with organic solvent mixture (acetone : dichloromethane = 1 : 1, v/v) using ultra sonic extractor and cleaned by gel permeation chromatography (GPC) technique. The amount of phenol was determined by GC/MS. To validate the developed method, we evaluated parameters were the selectivity, linearity, accuracy, precision, and recovery. To demonstrate the selectivity of the method, blank samples of rice, corn, and fish(mackerel) were prepared and subjected to GC-MS analysis. To verify the linearity of the method, six different standard concentrations of phenol at 0.01, 0.05, 0.1, 0.5, 1 and 2.5 mg/kg were evaluated. The correlation coefficient ($r^2$) of calibration curve was 0.9999. The recovery rate for phenol standard calculated by internal standard method were 82.2~101.5% for samples fortified with 0.25, 0.50, and 1.0 mg/kg, respectively. Also the repeatability and reproducibility for validation of precision were 0.2~5.5%. According to the result of the validation, this established method was suitable for AOAC guideline. The limit of detection (LOD) for phenol analysis were 0.03~0.1 mg/kg, and the limit of quantification (LOQ) were 0.1~0.3 mg/kg. Therefore, we established the optimal analysis method for determination of phenol in food using GPC and GC/MS.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.7
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• pp.848-854
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• 2010

The objectives of this study were to estimate genetic parameters for the carcass price and carcass traits contributing to carcass grading and to investigate the influence of each carcass trait on the carcass price using multiple regression and path analyses. Data for carcass traits and carcass prices were collected from March 2003 to January 2009 on steers of Korean cattle raised at private farms. The analytical mixed animal model, including slaughter house-year-month combination, linear and quadratic slaughter age as fixed effects and random animal and residual effects, was used to estimate genetic parameters. The effects of carcass traits on the carcass price were evaluated by applying multiple regression analyses. Heritability estimates of carcass traits were $0.20{\pm}0.08$ for carcass weight (CWT), $0.33{\pm}0.10$ for back fat thickness (BFT), $0.07{\pm}0.05$ for eye-muscle area (EMA) and $0.25{\pm}0.10$ for marbling score (MS), and those of carcass prices were $0.21{\pm}0.10$ for auction price per 1 kg of carcass weight (AP) and $0.13{\pm}0.07$ for total price (CP). Genetic correlation coefficients of AP with CWT and MS were $-0.35{\pm}0.29$ and $0.99{\pm}0.04$, respectively, and those of CP with CWT and MS were $0.59{\pm}0.22$ and $0.39{\pm}0.29$ respectively. If an appropriate adjustment for temporal economic value is available, the moderate heritability estimates of AP and CP might suggest their potential use as the breeding objectives for improving the gross incomes of beef cattle farms. The large genetic correlation estimates of carcass price variables with CWT and MS implied that simultaneous selection for both CWT and MS would be also useful in enhancing income.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.488-493
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• 2007

A survey for total aflatoxins (aflatoxins $B_1$, $B_2$, $G_1$, and $G_2$) was conducted on 245 cereals and processed cereal products, and 148 nuts and processed nut products in Korea, for a total of 393 commercialized ed samples. The total aflatoxins were quantified by the immunoaffinity column clean-up method with high performance liquid chromatography (HPLC) - fluorescence detection (FLD), and were confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Total aflatoxins(AFs) were detected in 37 samples (9.4% incidence), including 2 millet samples, 1 mixed cereal (sunsik), 1 powdered malt sample, 2 processed cereal products, 6 peanut samples, 22 peanut butter samples, and 1 sample each of almonds, adlay tea, and a processed nut product. The contamination levels were $0.04-2.65{\mu}g/kg$ for aflatoxin $B_1$, and $0.04-5.51{\mu}g/kg$ for total aflatoxins. Finally, LC-MS/MS analysis of the contaminated samples was conducted to confirm the detected aflatoxins, and all 37 samples showing aflatoxins by HPLC-FLD were confirmed by LC-MS/MS.

• Journal of Genetic Medicine
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• v.5 no.1
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• pp.21-25
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• 2008

Purpose : In recent years, many countries have adopted newborn screening programs that use tandem mass spectrometry (MS/MS) to screen and the number of diseases screened has also increased. We began screening for inherited metabolic disorders using MS/MS in April, 2001. Our goal was to determine the overall prevalence of metabolic disorders and to assess the effectiveness of newborn screening by MS/MS in Korea. Methods : From April, 2001 to December, 2007, we screened newborns and high risk groups using MS/MS. Acylcarnitines and amino acids were extracted and butylated and were introduced into the inlet of MS/MS. Confirmatory testing including a repeat newborn screening, and urine organic acid and plasma amino acid analysis were performed on a case-by-case basis. Results : The total number of screened subjects 284,933 which comprised 251,799 neonates and 33,134 high risk subjects. The recall rate was 0.4% (1158 tests) and true positive cases were 117 (0.04%). Confirmed metabolic disorders (newborn/high risk group) were as follows; 78 (25/53) amino acid disorders, 27 (16/11) organic acid disorders, and 12 (5/7) fatty acid oxidation disorders. The estimated prevalence of inherited metabolic diseases in newborns was 1:5,000 and that in the total group was 1:2,000. Conclusion : Newborn screening by MS/MS improved the detection of many inherited metabolic disorders. We therefore propose that all newborns be screened by a MS/MS national program and followed-up using a systemic organization strategy.

• 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.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.432-438
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• 2016

Ethoxyquin (EQ, 1,2-dihydro-6-ethoxy-2,2,4-trimethyl-quinoline) is quinoline-based antioxidant used in the animal feed and food industry to protect the raw materials and final products against oxidation. In recent years the use of synthetic antioxidants in fishmeal ingredients carry-over to farmed fish fillets has received increasing attention in food safety. This study was conducted to develop an analytical method to determine EQ in aquatic products. The analytes were confirmed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). The sample was extracted with 1 N HCl (in case of flatfish extracted with 1 N HCl containing 10% acetonitrile). Then, solid phase extraction (SPE) was used for the cleanup. Standard calibration curves presented linearity with the correlation coefficient ($r^2$) > 0.99, analyzed at 0.005-0.2 mg/kg concentration. The developed method was validated according to the Codex Alimentarius Commission (CAC) guideline. The limits of quantitation for EQ were 0.01 mg/kg. Average recoveries ranged from 81.3% to 107%. The repeatability of measurements, expressed as the coefficient of variation (CV, %), was below 10%. The analytical method was characterized with high accuracy and acceptable sensitivity to meet CODEX guideline requirements and would be applicable to analyze the EQ residue in aquatic products.

• Korean Journal of Plant Resources
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• v.21 no.2
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• pp.111-116
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• 2008

This study was carried out to induce plant regeneration via multiple shoot formation from sucker explants of Rubus fruticosus L. ${\times}$ R. parvifolius L. To induce adventitious shoots, the sucker explants were sterilized in 1.2% sodium hypochlorite (NaOCl) solution, and then were cultured on the full and 1/2 MS solid medium supplemented with BA (0.1, 0.5, 1.0, $2.0mg{\cdot}L^{-1}$). After 4 weeks of culture, the highest frequency (83.3%) of shoot formation from sucker explants was obtained from the full MS medium with $1.0mg{\cdot}L^{-1}$ BA. The highest shoot number (3.7) per explant was obtained from the full MS medium with $0.5mg{\cdot}L^{-1}$ BA. After 12 weeks of culture, the number of shoots (15.4) per explant was increased. The highest frequency (95%) of root formation was obtained from the 1/2 MS medium, when the explant with shoot were cultured on the full, 1/2 and 1/4 MS medium. The survival rate of the plantlets after transfer to plastic pots containing sand, soil, and vermiculite (1.1:1, vol.) was 95%. The results indicate that multiple shoot procedure can be applied for an efficient mass propagation of Rubus fruticosus L. ${\times}$ R. parvifolius L.

• KSBB Journal
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• v.22 no.4
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• pp.234-238
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• 2007

We used electrospary ionization ion trap tandem mass spectrometry (ESI-IT tandem MS) to structural elucidation of three different biantennary-type glycans having zero, one, two galactoses (G0, G1, G2). The highest fragment ion in the MS/MS spectra of three glycans was produced by 0,2-ring cleavage of fucose-linked N-acetylglucosamine (GlcNAc) in reducing end. The fragment ions both from precursor ions and 0,2-ring cleaved ions ($^{0.2}An$; n=5 for G0, n=6 for G1 and G2) were not overlapped each other. As results of $MS^n$ analyses, tandem fragmentation trees of each glycans were generated and 2,4-ring cleavages ($^{2.4}A_6$) were occurred in GlcNAc linked to reducing end GlcNAc. This structural elucidation and fragmentation study of N-linked glycans by tandem mass spectrometry can be applied to structural analysis of more complicated glycans.