Determination of gasoline range,diesel range,and mineral oil range organics in soils and water by flame lonization gas chromatography

This article describes a method for the determination of gasoline range, diesel range, and mineral oil range organics in soils and water. It represents the culmination of a series of efforts to go beyond typical GRO and DRO methodology currently available in the literature to include a quantitative determination of mineral oil organics having a boiling range up to C₄₄. It also is the result of an attempt to develop a cost‐effective method that enables the analyst to quantify three different types of hydrocarbon components in one GC run under conditions without a concentration step. Method performance is comparable to that of current protocols for GRO and DRO determinations and validated further by comparisons to certified standards and in‐house standards. Accuracy as percentage recovery for GRO in water is 82 to 84 and 91 to 92% for soils. Accuracy as percentage recovery for MRO in water is 84 to 102 and 75 to 80% for soils. Accuracy as percentage recovery for DRO in water is 78 to 100 and 71 to 90% for soils. Results from the analysis of in‐house standards and certified standards for DRO and MRO gave higher recoveries than was demonstrated in the MDL studies. The MDL for DRO in water is 31 mg/l and 14 mg/kg for soils. The MDL for GRO in water is 8 mg/l and 4 mg/kg for soils. For MRO in water, the MDL is 7 mg/l and for soils 10 mg/kg. Future proposed improvements to this method will involve updated software that will allow automatic blank subtraction, automatic calculation of surrogate recoveries and the automatic incorporation of dry weight factors in the final calculations for soils. In addition, a GRO method with a run time of only 24 min will be used routinely when only GRO analyses have to be performed.     

Accurate and efficient method for quantification of urinary histamine by gas chromatography negative ion chemical ionization mass spectrometry

Because of the recognized inaccuracy and unreliability of currently available methods for the quantification of histamine in biological fluids, a method for quantification of urinary histamine by stable isotope dilution assay with negative ion chemical ionization mass spectrometry has been developed. Following the addition of [²H₄]histamine to 1 ml of urine, histamine is extracted into butanol, back-extracted into HCl, derivatized to the pentafluorobenzyl derivative (CH₂C₆F₅)₃-histamine, extracted into methylene chloride, and then quantified with negative ion chemical ionization mass spectrometry by selected ion monitoring of the ratio of ions $\text{m}\text{z}$$\text{430}\text{434}$. Twenty samples can be assayed in 2 days. Precision of the assay is ±2.7% and the accuracy is 97.6%. Lower limits of sensitivity are approximately 100–500 fg injected on-column. This assay provides a very sensitive, accurate, and efficient method for the quantification of histamine in human urine.     

Correlations between PID and FID Field Analytical Instruments in the Analysis of Soil Contaminated with Diesel Fuel

Research was conducted to determine if there is a correlation between the data gathered by field analytical instruments in analyzing soil contaminated with diesel fuel. One instrument was equipped with a flame ionization detector (FID) and the other a photoionization detector (PID). The results showed that the concentration readings of the PID and FID displayed a linear relationship for soil recently contaminated with diesel fuel. However, for soil containing weathered diesel fuel in the field, a logarithmic relationship between the PID and FID readings was displayed. It was also determined by laboratory experimentation that the PID and FID readings both exhibited log-linear decreases over time for uncovered diesel fuel-contaminated soil. It was concluded that the PID and FID can both individually be used to evaluate soil contaminated by diesel fuel and might be interchangeable depending on the needs of the researcher.     

Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber

Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°–54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry.     

气相色谱与触角电位检测器联用技术及其应用

介绍了气相色谱与触角电位检测器联用技术的工作原理、优点及其在昆虫性信息素或其它信息物质鉴定方面的应用。根据作者应用此技术进行赤松毛虫和桑尺蛾性信息素研究的经验 ,重点介绍了气相色谱与触角电位联用技术在实践操作中应注意的问题     

Development and validation of a new gas flame ionization detector method for the determination of finasteride in tablets

A simple, rapid, and sensitive method based on gas chromatography with flame ionization detection is described for the determination of finasteride in tablets. The method is based on the derivatization of finasteride with N,O-bis(trimethylsilyl)trifluoroacetamide-1% trimethylchlorosilane at 60 degrees C for 30 min. The method was validated for specificity, linearity, precision, accuracy, robustness, and limit of quantification. The degree of linearity of the calibration curves, the percentage recoveries of finasteride, and the limit of detection (LOD) and limit of quantification (LOQ) for the gas chromatographic method were determined. The assay was linear over the concentration range of 10 to 50 microg ml(-1) (R approximately 0.999). LOQ and LOD (signal/noise ratio = 10) were found to be 10 and 2 microg ml(-1), respectively. The method was found to be simple, specific, precise, accurate, and reproducible. All of the validation parameters were within the acceptance range. The developed method was applied successfully to estimate the amount of finasteride in tablets. The results were compared statistically with those obtained by the official method using t and F tests. There was no significant difference between the two methods with respect to mean values and standard deviations at the 95% confidence level.     

Comparative evaluation of microarray analysis software

A wide variety of software tools are available to analyze microarray data. To identify the optimum software for any project, it is essential to define specific and essential criteria on which to evaluate the advantages of the key features. In this review we describe the results of our comparison of several software tools. We then conclude with a discussion of the subset of tools that are most commonly used and describe the features that would constitute the “ideal microarray analysis software suite.”     

Screening of free 17-alkyl-substituted anabolic steroids in human urine by liquid chromatography-electrospray ionization tandem mass spectrometry

A qualitative liquid chromatography-electrospray ionization tandem mass spectrometry method was developed for screening of the abuse of 4-chlorodehydromethyltestosterone, danazol, fluoxymesterone, formebolone, metandienone, oxandrolone, and stanozolol. The introduced method measures simultaneously nine different 17-alkyl-substituted anabolic androgenic steroids or their unconjugated metabolites in human urine, using methyltestosterone as an internal standard. Sample preparation involved one-step liquid extraction. Liquid chromatographic separation was achieved on a reversed-phase column with methanol-water gradient containing 5 mmol/l ammonium acetate and 0.01% (v/v) acetic acid. Compounds were ionized in the positive mode and detected by multiple reaction monitoring. All steroids within the study could be selectively detected in urine with detection limits of 0.1-2.0 ng/ml. The method showed good linearity up to 250 ng/ml with correlation coefficients higher than 0.9947. With simple and fast sample preparation, low limits of detection, and high selectivity and precision, the developed method provides advantages over the present testing methods and has the potential for routine qualitative screening method of unconjugated 17-alkyl-substituted anabolic steroids in human urine.     

Comparison of cyclopropene, 1-methylcyclopropene, and 3,3-dimethylcyclopropene as ethylene antagonists in plants

A comparison has been made of cyclopropene (CP), 1-methylcyclopropene (1-MCP), and 3,3-dimethyl-cyclopropene (3,3-DMCP) in their ability to protect plants against ethylene. In bananas, both CP and 1-MCP are effective around 0.5 nL L^–1, and 3,3-DMCP was effective at 1 L L^–1. Bananas treated with CP and 1-MCP again become sensitive to ethylene at 12 days and those treated with 3,3-DMCP at 7 days. Mature green tomatoes are protected by 5–7 nL L^–1 of 1-MPC for 8 days at 25°C and tomatoes treated with 3,3-DMCP at 5–10 L L^–1 are protected for 5 days. Carnation flowers are protected with CP or 1-MCP after exposure to 0.5 nL L^–1 for 24 hours and by 1 L L^–1 of 3,3-DMCP. The display life of Campanula flowers is increased from 3.3 to 5.4 days by 10 L L^–1 of 3,3-DMCP and to 9 days by 20 nL L^–1 of 1-MCP. Ethylene inhibition of pea seedlings is reduced by treatment with 1-MCP at 10 L L^–1 of ethylene but as ethylene is increased to 3000 L L^–1 growth inhibition increases. 3,3-DMCP treatment causes very little reduction of the ethylene effect even at very low concentrations.     

On the evaluation of edgeless diode detectors for patient-specific QA in high-dose stereotactic radiosurgery

PurposeIn this work, the potential of an innovative “edgeless” silicon diode was evaluated as a response to the still unmet need of a reliable tool for plan dosimetry verification of very high dose, non-coplanar, patient-specific radiosurgery treatments. In order to prove the effectiveness of the proposed technology, we focused on radiosurgical treatments for functional disease like tremor or pain.MethodsThe edgeless diodes response has been validated with respect to clinical practice standard detectors by reproducing the reference dosimetry data adopted for the Treatment Planning System. In order to evaluate the potential for radiosurgery patient-specific treatment plan verification, the anthropomorphic phantom Alderson RANDO has been adopted along with three edgeless sensors, one placed in the centre of the Planning Target Volume, one superiorly and one inferiorly.ResultsThe reference dosimetry data obtained from the edgeless detectors are within 2.6% for output factor, off-axis ratio and well within 2% for tissue phantom ratio when compared to PTW 60,018 diode. The edgeless detectors measure a dose discrepancy of approximately 3.6% from the mean value calculated by the TPS. Larger discrepancies are obtained in very steep gradient dose regions when the sensors are placed outside the PTV.ConclusionsThe angular independent edgeless diode is proposed as an innovative dosimeter for patient quality assurance of brain functional disorders and other radiosurgery treatments. The comparison of the diode measurements with TPS calculations confirms that edgeless diodes are suitable candidates for patient-specific dosimetric verification in very high dose ranges delivered by non-isocentric stereotactic radiosurgery modalities.     

First evidence of ethylene production by Fusarium mangiferae associated with mango malformation

Malformation is arguably the most crucial disease of mango (Mangifera indica L.) at present. It is receiving great attention not only because of its widespread and destructive nature but also because of its etiology and control is not absolutely understood. Recently, Fusarium mangiferae is found to be associated with mango malformation disease. There are indications that stress ethylene production could be involved in the disease. Here we have shown the first direct evidence of production of ethylene in pure culture of F. mangiferae obtained from mango. The study also revealed that all the isolates dissected from mango acquire morphological features of F. mangiferae showing most similarity to the features of species with accepted standard features. The isolates of F. mangiferae from mango were observed to produce ethylene in significant amounts, ranging from 9.28–13.66 n mol/g dry wt/day. The findings presented here suggest that F. mangiferae could contribute to the malformation of mango by producing ethylene and probably stimulating stress ethylene production in malformed tissue of mango. Ethylene might be produced through 2-oxoglutarate-dependent oxygenase-type ethylene-forming-enzyme (EFE) pathway in Fusarium sp, which needs to be investigated.     

Speciation analysis and the assessment of bioavailability of manganese in phytomedicines by extraction with octanol and determination by flame atomic absorption spectrometry

Trace elements in phytomedicines are present in the form of metallic complexes. Since n-octanol, a long-chain alkanol, presents a configuration similar to that of carbohydrates and lipids, the lipophilicity and absorptivity of organic medicines may be assessed from their distribution coefficients between octanol and water. This strategy has been used in order to define the species of manganese in a number of phytomedicines and to study the distribution of manganese in decoctions of phytomedicines in the stomach and the intestine. The concentrations of manganese in the original herbal materials and in octanol- and water-soluble fractions were determined by flame atomic absorption spectrometry following mixed acid digestion. The acidities of gastric and intestinal juices, the phytomedical composition and the compatibility of phytomedicines, i.e. the combination of single phytomedicines, greatly affected the manganese complexing ligands and determined the species and bioavailability of manganese. It is concluded that a knowledge of the level of octanol-soluble manganese in a phytomedicine could form the basis of dosage design in order to avoid manganese overload.     

混合菌群YC-BJ1对有机磷阻燃剂的降解及16S rRNA基因多样性分析

作为阻燃剂,有机磷酸酯广泛应用于工业制品和人类生活用品中,是一种全球性的环境污染物,因其具有特殊的理化性质,自然条件下很难水解。因此,对有机磷酸酯的微生物降解成了当下的研究热点。通过持续逐级富集,从北京某垃圾处理厂渗透液中富集到一个混合菌群(编号为YC-BJ1),并在降解特性、底物谱以及物种组成多样性3个方面对其进行定性鉴定。该菌群能够高效降解磷酸三苯酯(Triphenyl phosphate, TPhP)和磷酸三甲苯酯(Tricresyl phosphate, TCrP),培养4 d能够实现对100 mg/L TPhP和TCrP的基本降解,降解率分别为99.8%和91.9%。降解特性研究发现,该混合菌群具有出色的环境适应能力,能够在较宽的环境条件下(温度15–40℃,pH 5.0–12.0, 0%–4%盐)保持对TPhP的降解能力。底物谱分析发现,混合菌群YC-BJ1能够降解部分含氯有机磷阻燃剂,培养4d,对磷酸三(1,3-二氯异丙基)酯(Tris(1,3-dichloroisopropyl)phosphate,TDCPP)和磷酸三(2-氯乙基)酯(Tris(2-chloroethyl) phosphate, TCEP)的降解率分别为16.5%和22.0%。16S rRNA基因物种多样性分析发现,混合菌群YC-BJ1中物种丰度最高的3个菌属分别是生丝微菌属Hyphomicrobium (38.80%)、金黄杆菌属Chryseobacterium (17.57%)和鞘氨醇盒菌属Sphingopyxis (17.46%)。与目前已报道的有机磷阻燃剂降解菌和菌群相比,混合菌群在降解效率和环境适应能力方面都具有极大的优势,有较广泛的应用空间。高效降解菌群的富集能够为有机磷阻燃剂的降解及其环境污染生物修复提供微生物资源,并为其降解机理的探索提供支持。     

模糊聚类分析在中国伞形科当归亚族分类中的应用

针对伞形科前胡族当归亚族上属间界线划分的分歧,采用模糊聚类分析方法,在形态方面以属为分类单位,定量阐明了属间亲缘关系。化学方面,以裂解－气相色谱信息为分类依据肉获得的２７个种的数据揭示了当归亚族中属间的分类关系,结果表明,当归属和在中国分布的山芹属与广义当归属类群相近,并显示了东北长鞘当归和骨缘当归是一个较特殊的类群。     

Hair analysis of histamine after fluorescence labeling by column-switching reversed-phase liquid chromatography with electrospray ionization mass spectrometry and application to human hair

Sensitive determination of histamine (HA) in hair was carried out by column-switching reversed-phase high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS). HA was labeled with excess amounts of 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) at 60 degrees C for 30 min in a mixture of 0.1 M borax (pH 9.3) and acetonitrile (CH(3)CN). The resulting DBD-HA derivative was roughly separated by a Mightysil RP-18 GP (100 x 2mm i.d., 3 microm) with an acidic mobile phase containing 0.1% trifluoroacetic acid. DBD-HA in the fraction flowing due to a position change in the six-port column-switching valve was then completely separated by a Wakopak Navi C30 (150 x 2mm i.d., 5 microm) with 20 mM AcONH(4)-CH(3)CN (8:2). The mass spectrometer was operated in the selected reaction monitoring (SRM) mode for the product ion (m/z 292) obtained from MS-MS measurement using the protonated molecular ion [M+H](+) (m/z 337) as the precursor ion. Good linearity was achieved from the calibration curve obtained by plotting peak area ratios of the internal standard (HA-d(4)) against the injected amounts of HA (1.66-16.6 pmol, r(2)=0.999). The coefficients of variation, at 1.66- and 16.6-pmol injections, were 5.6 and 3.7%, respectively (n=6). Furthermore, the detection limit was 0.167 pmol. The efficiency of the recommended procedure was identified from the determination in the rat hair root after intraperitoneal administration of HA. The proposed method was applied to HA determination in the hair shaft of Dark Agouti rats and healthy volunteers. The variations in the concentrations in 1mg of hair shaft were 0.80-1.84 pmol (mean+/-SD=1.33+/-0.33, n=12) in rats and 0.94-72.3 pmol (17.2+/-21.5, n=16) in humans. The determination of HA in the plasma of rats and humans was also performed successfully by this method. Because the proposed method provides good precision and trace detection of HA in hair, the analytical technique seems to be applicable for the determination of various biogenic amines in hair.     

Inhibition of root elongation by ethylene in wetland and non-wetland plant species and the impact of longitudinal ventilation

The slow gas diffusion rate in flooded soil not only causes oxygen deficiency, but also favours the accumulation of ethylene in root systems to concentrations that may strongly affect root elongation. Previously published experiments showed that root elongation in rice is much less strongly inhibited by ethylene than in some other species less well adapted to wet conditions. Rice roots have also been reported to produce abnormally little ethylene. We tested if these traits are typical of wetland species and are thus likely to be widespread adaptive traits. Comparisons using 14 species indicated that insensitivity to the inhibiting effects of ethylene on root elongation is unlikely to be a common feature of temperate wetland species. However, resistance to longitudinal gas diffusion within roots of wetland species, which largely depends on diameter and the presence of gas-filled channels, was found to be less than in non-wetland species. We show that this can help maintain low internal ethylene concentrations by venting accumulated gas to the shoot and atmosphere.     

Development of a reverse-phase liquid chromatography electrospray ionization mass spectrometry method for lipidomics, improving detection of phosphatidic acid and phosphatidylserine

In the studies of lipid metabolomics, liquid chromatography electrospray ionization mass spectrometry (LC/MS) is a robust and popular technique. Although effective reverse-phase LC methods enabling the separation of phospholipid molecular species have been developed, there are still problems with the separation of phosphatidic acid (PA) and phosphatidylserine (PS). These acidic phospholipids often elute as extensively broad peaks, causing inferior separation, detection, and quantification-a severe limitation of the method. In this study, we have developed reverse-phase LC conditions that reduce the undesired peak tailings in the elution profiles of both PA and PS, by using a starting mobile phase containing a low concentration of phosphoric acid (5 microM) and a high percentage of water (40%). Our method sensitively analyzes PA, PS, and their lysoforms, as well as the other phospholipids within a biological sample, in a single chromatographic step by an LC/MS method and, thus, is suitable for lipidomics.