• Environmental Analysis Health and Toxicology
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• 제16권4호
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• pp.181-188
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• 2001

A gas chromatographic method was established for the simultaneous determination of urinary nicotine and cotinine. The analytes in basified urine containing a sufficient amount of Na$_2$S0$_4$were extracted into dichloromethane by vigorous shaking. Into the transferred organic phase was added a small amount of acidified methanol (0.5 N HCI in methanol), followed by concentrating the mixture to dryness using a mild stream of nitrogen gas. The concentrate was reconstituted with methanol and the final solution analyzed using the gas chromatograph equipped with the nitrogen-phosphorus detector. The reproducibility tests showed coefficients of variation less than 11％ for both compounds. The percent recovery for both analytes ranged from 88 to 103％. The estimated method detection limits for nicotine and cotinine were 0.60 and 5.1 ng/mL, respectively. Extraction efficiencies for both nicotine and cotinine apparently declined without the addition of Na$_2$S0$_4$into the urine. Moreover, the absence of methanolic HCI in the extract resulted in almost complete evaporation of nicotine and partial loss of cotinine during the concentration process, indicating that the formation of nicotine-HCI and cotinine-HCI species is prerequisite to the suppression of the loss of both compounds.

• 한국식품저장유통학회지
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• 제7권4호
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• pp.409-413
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• 2000

식물추출물로부터 보다 안전하고 효과있는 새로운 tyrosinase 저해제를 개발하기 위한 연구의 일환으로 먼저 기존의 spectrophotometric assay를 개선한 새로운 TLC 검색방법을 사용하여 여러 식물추출물을 검색한 결과 백자인의 메탄올추출물이 강한 tyrosinase 저해활성을 갖고 있음을 알 수 있었다. 따라서 백자인의 메탄올추출물로부터 tyrosinase 저해제를 분리하기 위하여 먼저 탈지 메탄올추출물을 에테르, 에틸아세테이트 및 부탄올로 순차적으로 용매분획한 후 이 중 활성이 강한 에테르 추출물을 얻었다, 다음 에테르 추출물을 5% NaHCO$_3$로 씻은 후 산성화하여 얻은 강산성에테르추출물을 silica gel, Sephadex LH-20 및 분취 TLC를 각각 이용하여 4가지의 tyrosinase 저해물질을 분리하였으며, 이 중 화합물 2 ($IC_{50}$/=26 $\mu\textrm{g}$/ml)와 3 ($IC_{50}$/=30 $\mu\textrm{g}$/ml)은 tyrosinase 저해제로 잘 알려진 ascorbic acid ($IC_{50}$/=28 $\mu\textrm{g}$/ml)와 유사하게 강한 tyrosinase 저해활성을 나타내었으며, 현재 그들의 화학구조를 동정하고 있다. 이러한 결과를 미루어볼 때 백자인으로부터 분리된 tyrosinase 저해제는 식품의 효소적갈변저해제로써 뿐만 아니라 기미, 주근깨 및 검반점을 예방할 수 있는 미백화장품 및 의약품의 신소재로써 활용될 수 있을 것으로 기대된다.

• 약학회지
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• 제51권3호
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• pp.206-213
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• 2007

Recently estimating the uncertainty of an analytical result has become an essential part of quantitative analysis. This study describes the uncertainty of the measurement for the determination of methamphetamine and its major metabolite amphetamine in human hair, The method consists of washing, drying, weighing, incubation and extraction with methanolic HCI solution, clean-up, trifluoroacetyl derivatization, and qualification/quantification of residues by gas chromatography/mass spectrometry (GC/MS). Traceability of measurement was established through traceable standards and calibrated volumetric equipment and measuring instruments. Measurement uncertainty associated with each analyte in real samples was estimated using quality control (QC) data. The main source of combined standard uncertainty comprised two components, which are uncertainties associated with calibration linearity and variations in QC, while those associated with preparation of analytical standards and sample weighing were not so important considering the degree of contribution. Relative combined standard uncertainties associated with the described method ranged for individual analytes from 4.99 to5.03%.