• 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.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.387-395
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

• Korean journal of applied entomology
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• v.60 no.3
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• pp.263-268
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• 2021

The venom of honeybees (Apis mellifera L.) is used to treat many diseases because of its anti-inflammatory and analgesic effects. Bee venom consists of several biologically active molecules and exhibits remarkable anti-cancer effects. However, biological amines, which exhibit diverse functionality such as anti-inflammatory and antibacterial effects, have not been previously reported in bee venom. In this study, we determined the content of putrescine in bee venom by using ultra-performance liquid chromatography. The specificity, accuracy, and precision of the assay were assessed, and the assay validated. The linearity of the putrescine assay was r ≥ 0.99, indicating a moderate level of putrescine in the bee venom. The limit of detection and limit of quantification were both 0.9 ㎍/mL, while the rate of recovery was 96.4%-99.9%. The relative standard deviation (RSD) of the intra-day precision and inter-day precision of the putrescine assay were 0.16% - 0.23% and 0.09% - 0.36%, respectively, with the RSD ≤ 5% indicating excellent precision. Thus, the linearity, limit of detection, limit of quantification, and recovery rate of the putrescine assay were satisfactory. The analysis of the bee venom showed that the putrescine content was 3.1 ± 0.09 mg/g. This study provides fundamental data on putrescine content in bee venom, which will prove useful in further studies of its bioactivity.

• Journal of Life Science
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• v.31 no.2
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• pp.144-148
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• 2021

This study aimed to analyze the content and composition of a biological amine, cadaverine, isolated from the venom of worker honeybees (Apis mellifera L.). This biological amine―which has diverse functionality, such as anti-inflammatory and antibacterial effects―has not been previously reported in bee venom. An assay completed in 13 minutes was developed for the cadaverine present in the bee venom using an ultra-performance liquid chromatograph and a Halo C18 column with acetonitrile and water as the mobile phase. The specificity, accuracy, and precision of the assay were verified, and the assay was validated. The linearity for cadaverine in the bee venom was R2=0.99 or above, indicating a moderate level. The limit of detection and limit of quantification were both 0.3 ㎍/ml, and the rate of recovery was 97.6%-99.1%. The relative standard deviation (RSD) of the intra-day precision and inter-day precision for cadaverine was 0.25%-0.44% and 0.25%-1.25%, respectively, with an RSD that fell within 5% indicating excellent precision. Through this novel assay, it was found that the mean content of cadaverine was 1.10±0.05 mg/g. Our results indicated that the linearity, limit of detection, limit of quantification, and rate of recovery of the cadaverine assay were of a satisfactory level, and the cadaverine content of the bee venom was ably determined. This study provides basic data on cadaverine in bee venom, which will prove useful in further studies on the bioactivity of this component.

• Analytical Science and Technology
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• v.19 no.5
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• pp.441-448
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• 2006

11-nor-9-carboxy-${\Delta}^9$-tetrahydrocannabinol (THCCOOH) is the major metabolite of tetrahydrocannabinol (THC) which is the primary psychoactive component of marijuana. It is also the target analyte for the discrimination marijuana use. A method using solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) was developed for the determination of THCCOOH in human urine. Urine samples (3 mL) were extracted by SPE column with a cation exchange cartridge after basic hydrolysis. The eluents were then evaporated, derivatized, and injected into the GC/MS. The limits of detection (LOD) and quantitation (LOQ) were 0.4 and 1.2 ng/mL, respectively. The response was linear with a correlation coefficient of 0.999 within the concentration range of 1.2 (LLE 1.3)~50.0 ng/mL. The precision and accuracy were stable within 1.20% and the recovery was 83.6~90.7%. The recovery of SPE method was lower than that of liquid-liquid extraction (LLE), but there were no apparent differences in LOD, LOQ, precision and accuracy between the two methods. While SPE method is used as a very effective and rapid procedure for sample pretreatment, and clean extracts, LLE method was not suitable for the extraction procedure of THCCOOH in urine. The applicability of the method was proven by analyzing a urine samples from a marijuana abusers.

• Korean Journal of Environmental Agriculture
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• v.37 no.4
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• pp.283-290
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• 2018

BACKGROUND: Pesticide residue analysis is an essential activity in order to establish the food safety of agricultural products. Analytical approaches to the food safety are required to meet internationally the guideline of Codex (Codex Alimentarius Commission, CAC/GL 40). In this study, we developed a liquid chromatograph-tandem mass spectrometer (LC-MS/MS) method to determine the herbicide clopyralid in food matrixes. METHODS AND RESULTS: Clopyralid was extracted with aqueous acetonitrile containing formic acid and the extracts were mixed in a citrate buffer consisted of magnesium sulfate anhydrous, NaCl, sodium citrate dihydrate and disodium hydrogencitrate sesquihydrate followed by centrifugation. The supernatants were filtered through a nylon membrane filter and used for the analysis of clopyralid. The method was validated by accuracy and precision experiments on the samples fortified at 3 different levels of clopyralid. LC-MS/MS in positive mode was employed to quantitatively determine clopyralid in the food samples. Matrix-matched calibration curves were inearranged from 0.001 to 0.25 mg/kg with r2 > 0.994. The limits of detection and quantification were determined to be 0.001 and 0.01 mg/kg, respectively. There covery values of clopyralid for tified at 0.01 mg/kg in the control samples ranged from approximately 82 to 106% with relative standard deviations below 2 0%. CONCLUSION: The method developed in this study meets successfully the Codex guideline for pesticide residue analysis in food samples. This, the method could be applicable to determine pesticides in foods produced domestically and internationally.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.606-613
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• 2005

The badge-type diffusive sampler for the measurement of formaldehyde in indoor air using three types of colorimetric methods such as chromotrophic acid(CTA), 3-methyl-2-benzothiazolinone hydrazone(MBTH), and 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole(AHMT) method. The washing of the collection filter with several cleaning solution was effected with satisfactory results, regardless of the types of cleaning solutions. The concentrations of absorbance solution in each colorimetric method were experimentally determined by considering the sampling rates. The variation blank values in each colorimetric method was below 15%. As compared with CTA and AHMT methods, the reproducibility of MBTH method was excellent and was below 10% relative standard deviation. The collected formaldehyde mass and time-weighted concentration had a good correlation (correlation coefficient > 0.93). The limit of detection and limit of quantitation, and minimum sampling time were closely correlated to the sampling rates for the measurement of formaldehyde in each method.

• Journal of the Korean Chemical Society
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• v.38 no.11
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• pp.819-826
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• 1994

This study described a simple, rapid and cost effective analytical technique for the ultra-trace analysis of dioxins in environmental samples. Liquid-Liquid extraction methods were used for the initial extraction and enrichment of the analyte. Subsequent clean-up procedures were achieved by using strong cation exchanger, silica and Florisil cartridges. Extracts were analysed by HRGC/HRMS-SIM. The efficiency of these analytical methods was tested by recovery and selectivity for elimination of interferences such as phenols, pesticides and PCBs in each step. The mean recovery of 1,2,3,4-TCDD spiked at 10 ppt in sea water was about 92(${\pm}$1.6)%. This analytical method was applied to Kwangyang sea water and 4.5pg/L of 2,3,7,8-TCDD was determined.

• Analytical Science and Technology
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• v.14 no.1
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• pp.44-49
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• 2001

Solid-phase microextraction (SPME) with $85{\mu}m$ polyacrylate fiber, coupled to gas chromatography-mass spectrometry was used to analyze the plasticizers contained in balloon samples. The balloons were identified to be made of polyisoprene by IR spectroscopy. The plasticizers extracted from the balloon samples soaked in acetone-added water solvent for an hour were quantified by external standard method using nine kinds of plasticizers. The quantification method was validated for standard plasticizers in the range of $0.25-25{\mu}g/g$. The detection limits were $0.11-0.38{\mu}g/g$ for different plasticizers. The RSDs for the reproducibility of this quantitation method were 3.7-14.2%. A few of balloons included risky level of plasticizer concerned as and endocrine disrupter, and it is necessary to regulate these products.

• Analytical Science and Technology
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• v.9 no.2
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• pp.198-202
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• 1996

A rapid and simple method for the determination of histamine by reverse-phase high performance liquid chromatography with fluorescence detection was established. 9-Fluorenylmethyl chloroformate(FMOC) was used as fluorescent derivative reagent. The optimum conditions for the derivatization such as pH, reaction time and the concentration of FMOC were investigated. Linearity of calibration curve was obtained between $0.1{\mu}g/ml$ and $0.5{\mu}g/ml$(r=0.992) and the limit of detection was $0.01{\mu}g/ml$.