The Detection of THCA Using 2-Dimensional Gas Chromatography-Tandem Mass Spectrometry in Human Fingernail Clippings: Method Validation and Comparison with Head Hair

Marijuana use as well as abuse is a significant public health and public safety concern in the United States and using hair to identify marijuana users and abusers has been gaining acceptance in a number of venues including workplace, court ordered, and substance abuse treatment monitoring. After the presentation of a fully validated 2-dimensional gas chromatography-tandem mass spectrometry method for the detection of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCA), the chief metabolite of the main psychoactive compound in marijuana, Δ9-tetrahydrocannabinol (THC), we evaluated the usefulness of fingernail clippings as an alternative specimen type to hair by the analysis of a set of 60 matched pairs of head hair and fingernail clippings. The limit of detection was 10 fg/mg, the limit of quantitation was 20 fg/mg, and the assay was linear from 20 fg/mg to 500 fg/mg. The intra- and inter-assay imprecision and bias studies at 4 different concentrations (50, 100, 500, and 1000 fg/mg) were acceptable where all % Target observations were within 16% of their expected concentrations and all %CV calculations were less than 13.5%. THCA was detectable in more fingernail specimens (53.3%) than hair specimens (46.7%) and the mean concentrations in nails were on average 4.9 times higher than in hair (1813 fg/mg and 364 fg/mg, respectively). The THCA concentrations in hair and nail were strongly associated (r = 0.974, P < 0.01, n = 60) and the association was significant. The study demonstrated that fingernail clippings are a suitable alternative specimen type to hair to monitor for marijuana use and abuse.

Synergistic Effect in Mixed Capillary Gas Chromatographic Stationap Phases Containing Heptakis(2,3,6-tri-o-pentyl)-β-cyclodextrin and Dibenzo-18-crown-6

used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were observed.These effects were affected by the column temperature．mixed ratio and linear velocity of carrier gas．

Comparison of 2-Acetyl-1-Pyrroline (2AP) in Rice Leaf at Different Growth Stages Using Gas Chromatography

Aromatic rice lines were examined for 2-Acetyl-1-Pyrroline (2AP) content in leaf tissue at five different growth stages (tillering, panicle initiation, 50% heading, booting, and maturity). A small plot trial with plot size of 1.42 m × 4.88 m (7 row-plots) was arranged in completely randomize design with three replications. Dry-seeded, delayed flood cultural practice was used in this study. The experiment was conducted at three locations. The average 2AP concentrations in leaf tissue at tillering stages were higher than the other four growth stages. 2AP levels were declined when rice plant reached booting. AP levels decreased slightly at heading stage and decreased significantly at maturity. There was no significant different between 2AP in leaf at 50% heading from three locations as well as the 2AP content in rice grain. Correlations between 2AP in leaf and 2AP in grain were significantly in all five growth stages. The highest correlation coefficient was found between 2AP in leaf at booting and grain (r = 0.811**) and lowest was in the leaf at harvest (r = 0.564**). Results indicated that 2AP could be determined in leaf tissue at early growth stage.

Sampling and determination of carbonyls in stack gas

The GC determination of aldehydes and ketones in stack gas was reported. The stack gas was collected with the dust sampler by isokinetic sampling technique, 2,4 dinitrophenylhydrazine in acidic solution was used to absorb aldehydes and ketones in stack gas specifically, to form their hydrazones, which were determined by GC with a capillary column of SE 54. The GC system can separate nine hydrazones of carbonyls interested with constant recovery rates of 94%—97%, giving lowest detectable limits of 0 05—1 0 ng. The standard gas of carbonyls were determined by this method with relative errors of -5% to -10%, percent coefficients of variation within 5%, and spiking recovery rates of 93%—97%. As an application of the method, the carbonyl pollutants were determined in stack gas samples of a chemical plant.

METHOD FOR IN SITU DETERMINATION OF P_(CO_2) IN SEA-AIR EQUILIBRIUM SYSTEM

The method for determining P CO 2 in the atmosphere and water by using gas chromatography was studied. For determination of P CO 2 in the atmosphere, a sampling method was developed in which the chromatograph was connected to a 6 port valve with a sampling pipe opening to the atmosphere, so gas pressure in the sampling pipe was identical to that of the atmosphere. A semi automatic seawater atmosphere equilibrium system was designed to determine the P CO 2 in seawater. The equilibrium chamber contained in situ seawater and the well equilibrated gas was pushed into the sampling pipe by sample water, so pressure and temperature calibration could be avoided. This method has high accuracy for the determination of P CO 2 in the air and seawater, and was used for in situ determination of P CO 2 in the atmosphere and of the seawater sample in the JGOFS cruise in the East China Sea.

人血清中脂肪酸的GC-MS分析

A method for determination of fatty acids(FA) compositions in human serum by gas chromatography time-of flight mass spectrometry(GC-TOF MS) method was established.The FA in serum were directly transformed into the fatty acid methyl esters by 2.5% H2SO4-methanol.Heptadecanoic acid methyl esters were used as internal standard.The detection and separation of all the FA were performed within 33 min.The established method has the characteristic of simple operation,rapid analysis,high accuracy,large amount of information and safety.So it is suitable for the scientific research to the disease correlating FA.

Metabonomics fingerprint of volatile organic compounds in serum and urine of pregnant women with gestational diabetes mellitus

BACKGROUND Gestational diabetes mellitus(GDM)is a metabolic disease with an increasing annual incidence rate.Our previous observational study found that pregnant women with GDM had mild cognitive decline.AIM To analyze the changes in metabonomics in pregnant women with GDM and explore the mechanism of cognitive function decline.METHODS Thirty GDM patients and 30 healthy pregnant women were analyzed.Solid-phase microextraction gas chromatography/mass spectrometry was used to detect organic matter in plasma and urine samples.Statistical analyses were conducted using principal component analysis and partial least squares discriminant analysis.RESULTS Differential volatile metabolites in the serum of pregnant women with GDM included hexanal,2-octen-1-ol,and 2-propanol.Differential volatile metabolites in the urine of these women included benzene,cyclohexanone,1-hexanol,and phenol.Among the differential metabolites,the conversion of 2-propanol to acetone may further produce methylglyoxal.Therefore,2-propanol may be a potential marker for serum methylglyoxal.CONCLUSION 2-propanol may be a potential volatile marker to evaluate cognitive impairment in pregnant women with GDM.

Gas Chromatography–Mass Spectrometry for Quantitative and Qualitative Analysis of Essential Oil from Curcuma wenyujin Rhizomes

Objectives:A rapid and sensitive gas chromatography–mass spectrometry(GC–MS)method for quantitative and qualitative analysis of essential oil from Curcuma wenyujin rhizomes was established.Methods:The essential oil of C.wenyujin rhizomes was extracted by supercritical CO2 extraction(SFE).Six main bioactive compounds(eucalyptol,β-elemene,curzerene,germacrone,curdione,and curcumol)were analyzed in selected ion monitoring mode(SIM).Results:Curzerene is not originally present in C.wenyujin rhizomes,but is a product of the transformation of furanodiene at high temperature.The six target components demonstrated good linearity(R2>0.9979)over a relatively wide concentration range.The interday and intraday variations had relative standard deviation values less than 5%and the average recovery ranged from 96.95%to 100.04%.The limit of quantitation ranged from 0.032 to 0.235μg/mL.The developed method was successfully used to analyze the six compounds in 17 samples collected from different origins.Significant variation was observed for the concentrations of the six compounds.In addition,51 constituents were identified in C.wenyujin rhizome essential oil,consisting of 87.66%of the total essential oil,including curdione,curzerene,dehydrocurdione,germacrone,1,4-bis(2-benzimidazoyl)benzene,neocurdione,curcumenone,andβ-elemene.Conclusions:The proposed method will be useful in the quality control of C.wenyujin rhizome essential oil production.

顶空气相色谱法研究循环吸入麻醉过程中氧化亚氮对安氟醚血浓度的影响

八只杂种狗分别进行两次实验,第一次用安氟醚混合70％N_2O进行麻醉,一周后单独使用安氟醚麻醉。在实验过程中,采用气相色谱技术,间断测定安氟醚的血浓度。结果表明,在循环吸入麻醉中,N_2O会影响安氟醚的吸收。

DISPERSION RELATION AND LANDAU LEVELS OF INVERSION LAYER SUBBAND ON p-HgCdTe

Starting from Kane's model and taking into account the surface electron spin-orbit interaction, we have derived the dispersion relation and Landau levels of inversion layer subband on narrow-gap semiconductors. The capacitance-voltage spectroscopy, magnetoconductivity oscillations and cyclotron resonance spectroscopy for the p-Hg_(1-x)Cd_x Te MIS structure sample at temperature 4.2 K have been measured. From the experimental data, the subband parameters and spin-orbit coupling intensity, which are involved in the expressions of subband dispersion relation and Landau levels, have been determined. As a result, the inversion layer electron subband dispersion relation and Landau level fan chart for HgCdTe as well as the zero field spin splitting effect, the shifting and the crossing effect of Landau levels have been described quantitatively.