• Analytical Science and Technology
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• v.34 no.6
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• pp.259-266
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• 2021

Cannabis (Marijuana) is one of the most widely used drugs in the world, and its distribution has been controlled in South Korea since 1976. Identification of 11-nor-Δ⁹-carboxy-tetrahydrocannabinol (THCCOOH) in urine can provide important proof of cannabis use, and it is considered scientific evidence in the forensic field. In this study, we describe a simultaneous quantitative method for identifying THCCOOH and THCCOOH-glucuronide in urine, using simple liquid-liquid extraction (LLE), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). THCCOOH-D₃ and THCCOOH-glucuronide-D₃ were used as internal standards. Validation results of the matrix effect, as well as recovery, linearity, precision, accuracy, process efficiency, and stability were all satisfactory. No carryover, endogenous or exogenous interferences were observed. The limit of detection (LOD) of THCCOOH and THCCOOH-glucuronide were 0.3 and 0.2 ng/mL, respectively. The developed method was applied to 28 authentic human urine samples that tested positive in immunoassay screening and gas chromatography/mass spectrometry (GC/MS) tests. The ranges of concentrations of THCCOOH and THCCOOH-glucuronide in the samples were less than LOQ~266.90 ng/mL and 6.43~2133.03 ng/mL, respectively. The concentrations of THCCOOH-glucuronide were higher than those of THCCOOH in all samples. This method can be effectively and successfully applied for the confirmation of cannabinoid use in human urine samples in the forensic field.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.63-68
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• 2013

Ethyl carbamate (EC) is a contaminant generated in the fermentation processes of various fermented foods. In this study, residue levels of EC in 95 alcoholic beverage samples were determined by using Gas Chromatography/Tandem Mass Spectrometry (GC/MS/MS). All the samples were purified by a liquid-liquid extraction (LLE) method using dichloromethane. The LLE method enables an improvement in time and cost to detection and specificity over the conventional extraction methods. The limits of detection and quantification (LOD and LOQ) to analyze EC were 1.3 and 4.0 ng/mL, respectively. The recovery rates of EC were ranged from 90.0 to 97.5% at the levels of 50, 100, and 500 ug/L. Among traditional grain-based alcoholic beverage samples (n = 34), the average residue levels of EC in takju, yakju, and cheongju were 0.63, 7.01, and 14.11 ug/L, respectively. Among fruit-based alcoholic beverage samples (n = 48), those of EC in japanese apricot spirits, bokbunjaju, grape wines, and other fruit wines were 79.18, 1.66, 2.64, and 2.39 ug/L, respectively. Among distilled or diluted alcoholic beverage samples (n = 13), those of EC in soju (distilled or diluted), general distillates, liquors, and brandies were 0, 3.30, 8.20, and 8.52 ug/L, respectively. Therefore, this study reports that the residue levels of EC in the alcoholic beverages, distributed in the current domestic markets, did not reach its maximum allowed levels of 30 and 400 ug/L established for grape and fruit wines in Canada, respectively.

• Analytical Science and Technology
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• v.28 no.5
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• pp.323-330
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• 2015

Alkaptonuria, a rare inherited metabolic disease, is characterized by a lack of homogentisate dioxygenase and accumulation of homogentisic acid (HGA), leading to homogentisic aciduria, arthritis, and ochronosis. In this study, a rapid analytical method, without an expensive and tedious solid phase extraction step, was developed to quantify HGA in plasma using GC-MS. HGA-spiked pooled plasma samples were subjected to liquid-liquid extraction (LLE) with ethyl acetate, followed by trimethylsilyl derivatization (TMS) and GC-MS quantification using selected ion monitoring. The formation of TMS derivative of the 1 carboxylic and 2 hydroxyl functional groups was performed by reacting BSTFA (with 10% TMCS) for 5 min at 80 ℃. For selected ion monitoring, quantification and confirmation ions were determined based on specific ions (m/z 384, m/z 341 and m/z 252) of the TMS derivative of HGA. Calibration curves of pooled normal plasma specimens showed a linear relationship in the range of 1-100 ng/µL. The precision and accuracy were within a relative standard deviation (RSD) of 1 to 15% and a bias of -5 to 25%. Recoveries were obtained in the range of 99-125% and 95-115% for intra-day and inter-day assay, respectively, at 2, 20 and 80 ng/µL. The limit of detection (LOD) and limit of quantification (LOQ) were 0.4 ng/µL and 4 ng/µL, respectively. No homogentisic acid was excreted from normal Korean plasma samples. Collectively, the results from the present study suggest that this method could be useful for routine diagnosis and therapeutic monitoring of alkaptonuria patients with excellent sensitivity and rapidity.

• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.313-319
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• 2017

Strawberries are one of the main commodities in Korea and have been exported over 30 million dollar. And the safety has recently become an important issue in the agro-trade, pesticide residue is most important matter of safe agricultural products. As strawberries can be cultivated using elevated production system, so it is possible to use the drenching. When spraying the pesticides, the use of drenching can be lower amount of residual than using foliar treatment. In this study, time sequential residual amount of pesticides were compared between drenching and foliar application in strawberries. Pesticides were treated with the standard and double dosage and samples were collected at 0, 3, 6, 9, 13, 16 and 21 day and analyzed by LC and LC-MS/MS after liquid-liquid extraction and QuEChERS. Two pesticides were detected less than 1 mg/kg in all samples for drenching treatment. Carbendazim residues in drenching treatment were 5 to 25 times lower than foliar application. And azoxystrobin was not detected in strawberries of drenching treatment.

• Korean Journal of Food Science and Technology
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• v.37 no.5
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• pp.723-729
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• 2005

Volatile compounds of dropwort (Oenanthe javanica DC), crown daisy (Chrysanthemum coronarium L. var. spatiosum), and sesame (Sesamum indicum L.) were isolated by steam distillation under reduced pressure (DRP) and liquid-liquid continuous extraction (LLE). Aroma extracts of the plants were identified by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) and their antioxidant activities were evaluated in two different assays. The aroma extracts isolated from dropwort, crown daisy, and sesame inhibited the oxidation of hexanal by 25%, 95%, and 99%, respectively, for one month at the $500{\mu}g/mL$ level. They inhibited malonaldehyde formation from cod liver oil by 48%, 54%, and 29%, respectively, at the $500{\mu}g/mL$ level. Their antioxidant activities were comparable to those of the natural antioxidant, ${\alpha}-tocopherol$.