• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.378-381
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• 2012

The monitoring of the uniconazole residual pesticide for agricultural products was conducted by multiclass pesticide multiresidue methods. Samples were collected from June to November, 2011. Uniconazole pesticide was detected in 49 samples from a total of 3,939 samples. The amount of uniconazole pesticide ranged from 0.09 to 17.89 mg/kg in 49 samples. This method was described for the simultaneous determination of uniconazole by gas chromatography with a nitrogen phosphorus detector (GC-NPD) and mass spectrometry (MS). The limit of detection and quantification were 0.006 and 0.018 mg/kg GC-NPD, respectively. For an evaluation of the GC-NPD method, uniconazole spiked into gyeojachae at a level of 0.5, 5 mg/kg was determined. The recoveries of uniconazole by the GC-NPD method ranged from 83.4 to 101.4%. The results indicate that the method of simultaneous analysis is applicable to uniconazole analysis.

• Analytical Science and Technology
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• v.28 no.2
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• pp.86-97
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• 2015

Recently, the consumption of dietary supplements has increased because of people’s greater interest in health. Unfortunately, the sales of dietary supplements containing unauthorized substances such as drugs have also increased. We developed a rapid, accurate method for the simultaneous determination of antihistamines using liquid chromatography tandem mass spectrometry with a multiple reaction monitoring mode. The limit of detection (LOD) and limit of quantification (LOQ) of the instrument used in this method were in the ranges 0.0003-0.3 and 0.0009-0.6 µg mL⁻¹, respectively. The linearity of the method was > 0.99. The precision levels of the method were 0.1-9.8% (intra-day) and 0.3-9.6% (inter-day), and the levels of accuracy of the method were 82.7-115.0% (intra-day) and 84.3-113.0% (inter-day). The mean of recovery of the method was in the range of 83.9-117.9% and the RSD of the stability was less than 5.9%.

• Analytical Science and Technology
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• v.11 no.5
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• pp.374-385
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• 1998

Phytoestrogens are biologically active compounds derived from plants foods. It had been suggested that phytoestrogens, by inhibiting aromatase in peripheral and/or cancer cells and lowering estrogen levels, may play a protective role as antipromotional compounds during growth of estrogen-dependent cancers. Therefore, simultaneous analysis of estrogens and phytoestrogens is necessary to elucidate the possible involvement of phytoestrogens in estrogen metabolism. In this view, we developed a simple and reproducible procedure to quantitatively determine estrogen and phytoestrogen metabolites. The proposed method consisted of solid phase extraction using preconditioned Serdolit AD-2 resin, enzyme hydrolysis with ${\beta}$-glucuronidase/arylsulfatase from Helix pomatia, liquid-liquid extraction and TMS-ether derivatization. And the final determination was carried out by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring mode (SIM). The precision and accuracy of this method was evaluated through within-a-day and day-to-day test. Recovery range and detection limit were 71.96~105.66%, 2~4 ng/mL, respectively. Using this method, 17 estrogen and 5 phytoestrogen compositions in urine of normal subjects were analyzed. It was found that amounts and relative distribution of urinary phytoestrigens and estrogens showed different pattern in male and female subjects.

• Analytical Science and Technology
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• v.22 no.5
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• pp.407-414
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• 2009

A simultaneous determination method for cholesterol, lanosterol and desmosterol was developed using gas chromatography/mass spectrometry. Urine was enzymatically hydrolyzed with ${\beta}$-glucuronidase/arylsulfatase. Samples were prepared using extractions with a mixture of ethyl acetate-hexane (2:3, v/v), followed by derivatization with a mixture of MSTFA/TMSI/TMCS (100:2:5 v/v/v). All analyses were performed using GC/MS in selective ion monitoring mode. Good linearities ($r^2=0.998{\sim}0.999$) in calibration curve and a satisfactory recovery (80.0%~113%) were achieved. Accuracy and precision values within ${\pm}15%$ in the concentration range of 5 to 200 ng/mL were also observed for all compounds. The developed method was applied to pravastatin-treated (70 and 250 mg/kg/day for 7 days, oral) hyperlipidemia rats. Those sterols were significantly lower in drug-treated rats compared to the controls, which justifies the drug efficacy. Therefore, these results indicate that the developed method was successfully applied to examine statin drug efficacy with urine sample.

• Journal of Food Hygiene and Safety
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• v.8 no.1
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• pp.9-15
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• 1993

In an attempt to quantitate and qualitate residual antibiotics and antibacterial agents in meat simultaneously, we studied a gas chromatography-mass spectrometry(GC/M8) analysis. For a simultaneous analysis of penicillin G, chloramphenicol and thiamphenicol in meat, a simple and rapid clean-up procedure including extraction with 0.01 M EDTA-2Na Mcilvaine buffer (pH 4.0), defatting with n-hexane, and elution with 0.01M-methanolic oxalic acid from Bond Elute $C_{18}$ cartridge, and quantitation by selected ion monitoring (SIM) mode after derivatization was performed. The recoveries (%) of penicillin G, chloramphenicol and thiamphenicol (CV, %) at 1 ppm fortification level were 63.5 (7.6), 76.3 (8.1) and 84.7 (2.0), and the detection limits of those were 0.6, 0.085 and $0.084\;\mu\textrm{g}$ beef, respectively. This method using 81M mode allows excellent detection and quantitation of residual antibiotics and antibacterial agents in meat. Moreover, confirmation by a full scan electron impact mass spectrum is possible if residual level in the sample in above 1 ppm.

• The Korean Journal of Pesticide Science
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• v.14 no.1
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• pp.37-48
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• 2010

The diacylhydrazine insecticides, methoxyfenozide, chromafenozide and tebufenozide are new-generation insecticides. These insecticides induce premature molting and cause the death of insects by mimicking their hormone. Also, these insecticides have already been widely used for vegetables planting in worldwide. Highperformance liquid chromatography (HPLC) is the most widely used procedure for determination of each compound residues in crops. However, simultaneous analysis method of these diacylhydrazine insecticides was not reported. The purpose of this study is to develop a simultaneous determination procedure of methoxyfenozide, chromafenozide and tebufenozide residue in crops using HPLC-UVD/MS method. These insecticide residues were extracted with acetone from representative samples of five raw products which comprised hulled rice, soybean, apple, pepper, and Chinese cabbage. The extract was diluted with saline water, and dichloromethane partition was followed to recover these insecticides from the aqueous phase. Florisil column chromatography was additionally employed for final cleanup of the extracts. The analytes were quantitated by HPLCUVD/MS, using a $C_{18}$ column. The crops were fortified with each insecticide at two levels per crop. Mean recoveries ranged from 89.0 to 104.8% in five representative agricultural commodities. The coefficients of variation were less than 3.9%. Quantitative limits of methoxyfenozide, chromafenozide and tebufenozide were 0.04 mg/kg in crop samples. A HPLC-UVD/MS with selected-ion monitoring was also provided to confirm the suspected residues. The proposed simultaneous analysis method was reproducible and sensitive enough to determine the residues of methoxyfenozide, chromafenozide and tebufenozide in agricultural commodities.

• Analytical Science and Technology
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• v.19 no.1
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• pp.107-114
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• 2006

Early diagnosis and medical intervention are critical for the treatment of patients with metabolic disorders. A rapid analytical method was developed for simultaneous quantification of organic acids and amino acids in urine without labor-intensive pre-extraction procedure showing high sensitivity and specificity. A new method consisted of simple two-step trimethylsilyl (TMS)-trifluoroacetyl (TFA) derivatization using GC/MS-selective ion monitoring (SIM). Filter paper urine specimens were dried under nitrogen after being fortified with internal standard (tropate) in a mixture of distilled water and methanol. Methyl orange was added to the residue as indicator reagent. Silyl derivative of carboxylic functional group was followed by trifluoroacetyl derivative for amino functional group. N-methyl-N-(trimethylsilyl-trifluoroacetamide) and N-methyl-bistrifluoroacetamide were consecutively added and heated for 15-20 min at $65^{\circ}C-70^{\circ}C$, for TMS-TFA derivative, respectively. This reactant was analyzed by GC/MS-SIM. Linear dynamic range showed 0.001-50 mg with the detection limit of (S/N=3) 10-200 ng, and the quantification limit of 80-900 ng in urine. Correlation coefficient of regression line was 0.994-0.998. When the method was applied to the patients 'urine, it clearly differentiated the normal from the patient with metabolic disorder. The study showed that the developed method could be the method of choices in rapid and sensitive screening for organic aciduria and amino acidopathy.

• The Korean Journal of Pesticide Science
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• v.20 no.3
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• pp.247-263
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• 2016

Safe animal feed is important for the health of animals, the environment and for the safety of foods of animal origin. Therefore, the aims of this study were: 1) to validate simultaneous analytical method and 2) to investigate the amount of pesticide residues in animal feed from Republic of Korea as a part of official control. A total of 126 samples were collected in 2015 and analyzed for 105 pesticides. According to pesticides monitoring result, no residue was found in 84.1% of the samples, whereas 15.9% of samples contained pesticide residues below the maximum residue limits (MRLs). Pirimiphos-methyl and cyproconazole were the two most frequently found pesticides. The results show that all commercial feed monitored in 2015 were safe under the Korean MRL and occurrence of pesticide residues in animal feed could not be considered serious threats to human and animal health. However, continuous monitoring with tighter regulation for pesticide residues in animal feed is recommended.

• KIISE Transactions on Computing Practices
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• v.22 no.4
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• pp.195-200
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• 2016

With development of wearable devices, there is an increased interest in bio-signal monitoring techniques that can measure the user's health condition. However, embedding several bio-signal sensors in one wearable device has some inherent problems in terms of limited resources such as its size. Furthermore, such problem also arise when new bio-signal sensors are added. In this paper, we introduced the Bio-Cradle, which is a Plug-in module that can transfer the biological signals in real time from the accelerometer, ECG, or PPG sensor to other wearable devices at the request from the user of wearable devices. When the Bio-Cradle plugged in to the other device, it can transfer several synchronized bio-signals regardless of the type of device.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1306-1311
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• 2011

Recombinant Rhodopseudomonas palustris, harboring the carotenoid-metabolizing gene crtI (CrtIBS), and whose color changes from greenish yellow to red in response to inorganic As(III), was cultured in transparent microplate wells illuminated with a light emitting diode (LED) array. The cells were seen to grow better under near-infrared light, when compared with cells illuminated with blue or green LEDs. The absorbance ratio of 525 to 425 nm after cultivation for 24 h, which reflects red carotenoid accumulation, increased with an increase in As(III) concentrations. The detection limit of cultures illuminated with near-infrared LED was 5 ${\mu}g$/l, which was equivalent to that of cultures in test tubes illuminated with an incandescent lamp. A near-infrared LED array, in combination with a microplate, enabled the simultaneous handling of multiple cultures, including CrtIBS and a control strain, for normalization by the illumination of those with equal photon flux densities. Thus, the introduction of a near-infrared LED array to the assay is advantageous for the monitoring of arsenic in natural water samples that may contain a number of unknown factors and, therefore, need normalization of the reporter event.