ABSTRACT
A method for rapid determination of γ-hydroxybutyric acid (GHB) in beverages (water, sodas, beer) and urine was established by direct analysis real-time mass spectrometry (DART-MS). Samples were analyzed directly after dilution with mixture of methanol and water(1:1,V/V). Instrument parameter settings were optimized to obtain the sensitive and accurate determination of GHB. At the sample introduction speed of 0.5 mm/s, high intensity of[M-H]- ions for GHB were observed in the negative ion and selection ion monitoring mode by utilization of high purity helium gas at 350℃. For different samples of water,sodas,beer and urine,the limits of detection (LODs) (S/N=3) were in the range of 1-2 μg/mL, while the limits of quantification (LOQs) (S/N=10) were in the range of 3-5 μg/mL. The linear correlation coefficients of the standard curves with different sample matrixes were between 0.9899 and 0.9980. The recoveries were in the range of 80.8%-115.2% with the relative standard deviations of 1.9%-12.8%. With its rapid analysis and simple pretreatment steps,the method is expected to have a strong advantage in the rapid screening analysis of large quantities of beverage and urine.
ABSTRACT
Objective To establish a method for rapid detection of JWH-018, JWH-250 and AM-2201 in blood by direct analysis in real-time coupled with tandem mass spectrometry. Methods These samples were extracted by acetonitrile-methanol (4:1), using DART 12Dip-it automatic sampling system. They were analyzed by positive ion and MRM mode. Results The detection limits of JWH-018, JWH-250 and AM-2201 were in good linearity in the range of 0.02-5.00μg/mL. The correlation coefficients were above 0.99 and the detection limits were 0.016μg/mL, 0.003μg/ mL and 0.017μg/mL, respectively. The intra-day and inter-day RSD were less than 15%. Conclusion The method has the advantages of high sensitivity and good accuracy. The sample processing is simple and can be analyzed in short time. This method is suitable for the analysis of JWH-018, JWH-250 and AM-2201 in practical cases.
ABSTRACT
The paper presents a flexible and simple direct analysis in real-time ( DART) device without grid electrode for mass spectrometer injection. It contained inert carrier gas, ionizer, heater and temperature-controller etc. Excluding the grid electrode and then reducing the structure units, the device could be easy to build up in low cost and flexible to connect with a variety of mass spectrometers. The experimental conditions like the kind of carrier gas, flow rate and temperature were investigated for the device. By using argon as carrier gas, flow rate as 7. 5 L/min, and temperature of heat tape as 300 ℃, the device was used to analyze benzene alcohol, linoleic acid, dichlorvos emulsion, mosquito coils, citrus peel, and sample ( propranolol hydrochloride) on thin-layer plate combined with mass spectrometer. The results were accurate and the device was stable and reliable.
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Theapplicationofinternalextractiveelectrosprayionizationmassspectrometry(iEESI-MS)was extended to direct molecular analysis of garlic tissues. By obviating time-consuming sample preparations, fragile active garlic substances such as organosulfur compounds ( e. g. , alliin, allicin ) were successfully detected and identified via collision-induced dissociation ( CID) , together with amino acids ( e. g. , arginine) and saccharides ( glucose, polysaccharides) . Mass spectral fingerprints of different kinds of garlic cloves, as well as various post-treatment ones, were further processed via principal component analysis ( PCA) to better visualize the differences. Our experimental results indicated that iEESI-MS allowed rapid recognition of metabolic changes in the garlic tissue subject to various external stimuli. The merits included simplicity of analysis, high speed ( less than 2 min per sample ) , good specificity, and minimal disturbance to the bioactivity of analytes.
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La espectrometría de masas (MS) en condiciones ambientales es un campo nuevo de gran utilidad y de rápido crecimiento que provee espectros de masas de alta sensibilidad directamente a partir de superficies a presión atmosférica. Para ello se utilizan diversas técnicas de ionización, entre ellas: la ionización por desorción con electrospray (DESI: desorption electrospray ionization), el análisis directo en tiempo real (DART: direct analysis in real time), la ionización por desorción asistida por plasma (PADI: plasma assisted desorption ionization) y la ionización extractiva por electrospray (EESI: extractive electrospray ionization). Este trabajo se refiere en particular a los fundamentos y aplicaciones de DESI-MS con espectrometría de masas de imágenes. Entre otras aplicaciones, DESI es utilizado para el análisis directo de medicamentos y formulaciones farmacéuticas, muestras de fluidos biológicos, análisis forense, impresiones digitales, alimentos, cultivos de bacterias, identificación y distribución espacial de compuestos químicos en tejidos de origen animal y vegetal, y análisis de biomarcadores moleculares. Se destaca la posibilidad de combinación con cromatografía en capa delgada y con electroferogramas a fin de identificar mediante espectrometría de masas los compuestos presentes. Esta técnica no requiere preparación de las muestras y no implica el uso de matrices de ionización. Esto simplifica enormemente el procedimiento experimental y evita la redistribución de los analitos durante la deposición de la matriz. Se discute el análisis forense realizado con DESI-MS y DESI-MS/MS, respecto a: la detección de explosivos y agentes simulantes de guerra química en superficies sólidas cerca o a distancia del espectrómetro, análisis de telas o vestimenta en busca de explosivos y drogas, análisis de imágenes para la verificación de documentos, análisis sobre piel humana, análisis de residuos de disparos, análisis de gases tóxicos industriales y de agentes simulantes de guerra, de destilados de petróleo y de polímeros sintéticos. Se analizan las aplicaciones efectuadas en el campo de la lipidómica, proteómica y metabolómica. Por último, se brinda la información existente sobre el análisis cuantitativo realizado mediante DESI-MS.
Ambient mass spectrometry is a useful and rapidly growing new field that provides high sensitivity mass spectra directly from surfaces at atmospheric pressure. Various ionization techniques, including desorption electrospray ionization (DESI), direct analysis in real time (DART), plasma assisted desorption ionization (PADI) and extractive electrospray ionization (EESI) have been used. This paper refers particularly to the fundamentals and applications of DESI-MS based on imaging mass spectrometry. Among other applications, DESI is used for direct analysis of drugs and pharmaceutical formulations, samples of biological fluids, forensics, fingerprints, food, cultures of bacteria, identification and spatial distribution of chemicals in animal and plant tissues, and molecular biomarkers. It highlights the possibility of combination with thin layer chromatography and electropherograms to identify the compounds by mass spectrometry. This technique requires no sample preparation, and does not involve the use of matrix of ionization. It simplifies greatly the experimental procedure and avoids the redistribution of analytes during matrix deposition. The forensic analysis carried out by DESI-MS and DESI-MS/MS is discussed, including the detection of explosives and chemical warfare agents on solid surfaces near or at a distance from the mass spectrometer, analysis of fabric or clothing for explosives and drugs, image analysis for verification of documents, analysis of human skin, gunshot residue analysis, analysis of toxic gases and industrial warfare agent simulants, petroleum distillates and synthetic polymers. Aplications in the field of lipidomics, proteomics, and metabolomics are analyzed. Finally, current information on the quantitative analysis performed by DESI-MS is provided.
Subject(s)
Mass Spectrometry , Pharmaceutical Preparations , Proteomics , Spectrometry, Mass, Electrospray Ionization , Spectrum Analysis , Biochemistry , Evaluation Studies as Topic , Spectrometry, Mass, Electrospray Ionization/methodsABSTRACT
This study was conducted to investigate the choline intake of Korean adults for the purpose of preparing a basal data required for the establishment of choline adequate intake (AI). The subjects of 56 Korean young adults were recruited from college students of 20 to 30 years old in Daejeon city. The aliquots of foods that the subjects ate for one day were collected with use of duplicate food collection method and choline content of one day meal directly was analyzed with the use of enzymatic method. Choline intakes of male subjects were in the range of 353.5 ~ 1222.5 mg and those of female subjects were in the range of 213.1 ~ 722.3 mg. Mean intakes of choline were 658.2 +/- 243.9 mg/day in male subjects and 423.3 +/- 133.6 mg/day in female, therefore choline intake of men was about 200mg higher than that of women. Median value in total subjects was 496 mg, male's median was 608.8 mg, female's median was 419.9 mg. When the subjects were devided into 4 groups by choline intake, as less than 75%, 75 ~ 100%, 100 ~ 125% and over 125% based on choline AI of USA (males: 550 mg, females: 425 mg), there was no significant difference between men (64.3%) and wemen (67.9%) in the distribution of the subjects whose choline intake is under the range of 75 ~ 125% AI of USA. However, 10.7% of men and 21.4% of female had choline intake less than 75% AI of USA while the cases of choline intake higher than 125% AI were 25% in male and 10.7% in female. Thus, it is assumed that female case in choline-deficient state would be two times more than male. When adjusted by body weight, choline intake was 9.5 +/- 3.4 mg/kg in men, 8.1 +/- 3.1 mg/kg in women and 8.8 +/- 3.3 mg/kg in total subjects. And choline intake per 1,000 kcal of men, women and total subjects were 277.1 +/- 78.4 mg, 275.9 +/- 62.1 mg and 276.5 +/- 70.1 mg respectively. From these results, it is suggested that these levels of 276.5 +/- 70.1 mg/ 1,000 kcal or 8.8 +/- 3.3 mg/kg B.W. can be used as a reference value for the establishment of AI of choline for Korean, because overall choline intake of these subjects was not in lower state compared to other nutrients intakes obtained from calculation of the food the subjects had taken.