湖泊水体中土霉味化合物2-甲基异莰醇的合成与测定

利用甲基格氏试剂和天然樟脑反应，合成土霉味化合物２－甲基异莰醇（ＭＩＢ），并用色谱、质谱和红外光谱对其进行鉴定，然后以合成ＭＩＢ作标样，测定ＭＩＢ的气相色谱保留值及其在东湖水体中浓度随季节变化规律。研究结果表明，东湖水体产生土霉味的主要成份为ＭＩＢ，在１９９５～１９９６年期间，１月、４月和９月为武汉东湖水体中ＭＩＢ浓度的高峰期，经测定东湖水中ＭＩＢ的ＧＣ保留值与合成的ＭＩＢ的ＧＣ保留值完全一致。     

用GC－MS法测定尿中可待因及其代谢物的浓度

建立了用ＧＣ－ＭＳ（ＳＩＭ）内标定量法快速测定人尿中可待因及其代谢物浓度的方法。样品经酸水解、乙醚／异丙醇提取，用ＭＳＴＦＡ－ＭＢＴＦＡ衍生化后进样于ＧＣ－ＭＳＤ，方法灵敏、准确，可用于监测吸毒者尿中可待因、吗啡类药物的浓度。本法已经受ＩＯＣ的１９９２年水平考试的考验。     

用GC—MS法测定尿中可待因及其代谢物的浓度

建立了用ＧＣ－ＭＳ（ＳＩＭ）内标定量法快速测定人尿中可待因及其代谢物浓度的方法，样品经酸水解、乙醚／异丙醇提取，用ＭＳＴＦＡ－ＭＢＴＦＡ衍生化后进样于ＧＣ－ＭＳＤ，方法灵敏、准确，可用于监测吸毒者尿中可待因，吗啡类药物的浓度。本法已经受ＩＯＣ的１９９２年水平考试的考验。     

甲基二甲氧基硅烷的合成研究

以ＭｅＳｉＨＣｌ２和ＭｅＯＨ为原料，采用溶剂法合成甲基二氧基硅烷，研究了各种合成条件对醇解反应的影响，运用ＩＲ，ＧＣ－ＭＳ等手段对反应过程和结果进行了综合分析，提出了最佳合成条件。     

STUDIES ON THE SYNTHESIS OF TRACHYLOBAGIBBERELLINANALOGUE(Ⅱ)SYNTHESIS OF DIMETHYLESTER OF 3-HYDROXY-△1_10-12,16-CYCLOGIBBERELLIN 12

ＳＴＵＤＩＥＳ　ＯＮ　ＴＨＥ　ＳＹＮＴＨＥＳＩＳ　ＯＦ　ＴＲＡＣＨＹＬＯＢＡＧＩＢＢＥＲＥＬＬＩＮＡＮＡＬＯＧＵＥ（Ⅱ）ＳＹＮＴＨＥＳＩＳ　ＯＦ　ＤＩＭＥＴＨＹＬＥＳＴＥＲ　ＯＦ　３－ＨＹＤＲＯＸＹ－△１_１０－１２，１６－ＣＹＣＬＯＧＩＢＢＥＲＥＬ?..     

阳离子改性HZSM-5沸石上低碳醇反应历程的TPSR-MS研究

用ＴＰＳＲ－ＭＳ技术研究了Ｃｕ，Ｚｎ和Ｇａ改性Ｈ－ＺＳＭ－５沸石的活性中心性质及Ｃ１～Ｃ４醇的反应历程。结果表明，Ｚｎ－和Ｇａ－ＺＳＭ－５有两种芳构化活性中心，即Ｂ酸和Ｚｎ，Ｇａ活性物种；甲醇在Ｃｕ－ＺＳＭ－５上只生成二甲醚、ＣＯ和ＣＯ２，而在Ｚｎ－ＺＳＭ－５上芳构化反应历程为：（１）醇经由醚脱水生成烯烃，Ｃ２～Ｃ４醇学可单分子脱水生成烯烃；（２）烯烃中间物齐聚，齐聚物通过氢转移和脱氢途径环化、芳     

FERROMAGNETIC INTERACTION BETWEEN GADOLINIUM（Ⅲ） AND COPPER （Ⅱ）IONS IN N，N＇－BIS（2－AMINOPROPYL）OXAMIDO COPPER（Ⅱ） BRIDGED BINUCLEAR Gd（Ⅲ）－Cu（Ⅱ） COMPLEX

ＦＥＲＲＯＭＡＧＮＥＴＩＣＩＮＴＥＲＡＣＴＩＯＮＢＥＴＷＥＥＮＧＡＤＯＬＩＮＩＵＭ（Ⅲ）ＡＮＤＣＯＰＰＥＲ（Ⅱ）ＩＯＮＳＩＮＮ，Ｎ＇－ＢＩＳ（２－ＡＭＩＮＯＰＲＯＰＹＬ）ＯＸＡＭＩＤＯＣＯＰＰＥＲ（Ⅱ）ＢＲＩＤＧＥＤＢＩＮＵＣＬＥＡＲＧｄ（Ⅲ）－Ｃｕ...     

STUDY ON OXIDATIONS OF BENZILIC ETHERS，OXIMES AND 1，2－DIOLS BY AMMONIUM CHLOROCHROMATE

ＳＴＵＤＹＯＮＯＸＩＤＡＴＩＯＮＳＯＦＢＥＮＺＩＬＩＣＥＴＨＥＲＳ，ＯＸＩＭＥＳＡＮＤ１，２－ＤＩＯＬＳＢＹＡＭＭＯＮＩＵＭＣＨＬＯＲＯＣＨＲＯＭＡＴＥ￥ＧｕｉｓｈｅｎｇＺＨＡＮＧ；ＪｕｎＱｕａｎＷＡＮＧ；ＭｉＦｅｎｇＣＨＥＮＧ；ＫｕｎＣＡＩ（Ｄｅｐ...     

PREPARATION AND CHARACTERIZATION OF NIOBIUM－CONTAINING DIMOLYBDO－15－TUNGSTODIPHOS－PHORIC SALT

ＰＲＥＰＡＲＡＴＩＯＮＡＮＤＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＮＩＯＢＩＵＭ－ＣＯＮＴＡＩＮＩＮＧＤＩＭＯＬＹＢＤＯ－１５－ＴＵＮＧＳＴＯＤＩＰＨＯＳＰＨＯＲＩＣＳＡＬＴ￥ＪｉａｎＧＯＮＧ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＪｉｌｉｎＭｅ...     

植物油的质谱分析：1.蓖麻油

运用一种植物油的系统分析方法测定蓖麻油的精细组分，这包括皂化，ＢＦ３－ＭｅＯＨ甲基化，ＧＣ－ＣＩＭＳ法测定脂肪酸碳链长度和不饱和度，ＡＭＰ衍生化，ＧＣ－ＥＩＭＳ测定不饱和脂肪酸的双链位置，分析了蓖麻油的十一种脂肪酸组分，有五个为未知组分，并测定了其中三个组分的双链位置。     

Determination of musty odorants, 2-methylisoborneol and geosmin, in environmental water by headspace solid-phase microextraction and gas chromatography--mass spectrometry.

A simple and sensitive method for the determination of musty odorants, 2-methylisoborneol (MIB) and geosmin (GSM), in environmental water was developed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry. MIB and GSM were separated within 10 min using a DB-1 capillary column and detected in the selective ion monitoring mode. HS-SPME using a polydimethylsiloxane/divinylbenzene fiber provided effective sample enrichment, and was carried out by fiber exposition at 70 degrees C for 30 min. Using this method, the calibration curves of MIB and GSM were linear in the range of 0-500 pg/mL, with a correlation coefficient above 0.9977 (n=24). The detection limits (S/N=3) of MIB and GSM were 0.9 and 0.6 pg/mL, respectively. This method was successfully applied to the analysis of environmental water samples without interference peaks.     

Determination of Geosmin and 2-Methylisoborneol in Water by Headspace Liquid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry

Geosmin (GSM) and 2-methylisoborneol (MIB) were extracted from water samples, adsorbed in organic solvent microdrop by headspace liquid-phase microextraction (HS-LPME), and were analyzed by gas chromatography-mass spectrometry (GC-MS). Influence factors such as the extraction solvent types, headspace and microdrop volumes, stirring rate, equilibrium and extraction time, and ionic strength for HS-LPME efficiency were thoroughly evaluated. Under optimized extraction and detection conditions, the calibration curves of GSM and MIB were linear in the range of 5–1000 ng/L. The detection limits of GSM and MIB were 1.1 and 1.0 ng/L, respectively. Average recoveries of 95.45–113.7% (n = 5) were obtained and method precisions were also satisfactory. Trace levels of the off-flavor compounds at ng/L in tap water and raw water were successfully quantified.     

Determination of geosmin and 2-methylisoborneol in water using solid-phase microextraction and gas chromatography-chemical ionisation/electron impact ionisation-ion-trap mass spectrometry

A method for the determination of geosmin and 2-methylisoborneol (MIB) in water by solid-phase microextraction (SPME) is presented. Various SPME fibre chemistries have been compared for their efficiency in extracting MIB from water. Extraction conditions including the extraction time and temperature have been optimised. A 30 ml water sample is extracted for 20 min at 60 degrees C using a divinylbenzene fibre, and the extract analysed by gas chromatography with ion-trap mass spectrometry detection. d5-Geosmin and d3-MIB are added as internal standards to compensate for any variability in the SPME process which is not carried out to equilibrium. Chemical ionisation, using acetonitrile as the reagent gas, was found to give superior sensitivity to electron impact ionisation (EI) for the detection of MIB. EI was used as the ionisation mode for detection of geosmin. The method shows good linearity over the concentration range 5-40 ng l-1 and gives detection limits of 1 ng l-1 for both geosmin and MIB. Recovery (93-110%) and precision (3-12%) over this concentration range, for both raw and treated drinking waters, are comparable to currently employed methods such as closed-loop stripping analysis (CLSA). The method offers the advantage of being simple to use, with much shorter analysis times in comparison to CLSA.     

Determination of geosmin and 2-methylisoborneol in water and wine samples by ultrasound-assisted dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry

A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid–liquid microextraction (USADLLME) procedure has been developed to preconcentrate geosmin and 2-methylisoborneol (MIB) from water and wine samples prior to quantification by gas chromatography–mass spectrometry (GC–MS). A two-stage multivariate optimization approach was developed by means of a Plackett–Burman design for screening and selecting the significant variables involved in the USADLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: solvent volume, 8 μL; solvent type: tetrachloroethylene; sample volume, 12 mL; centrifugation speed, 2300 rpm; extraction temperature 20 °C; extraction time, 3 min; and centrifugation time, 3 min. Under the optimized experimental conditions the method gave good levels of repeatability with coefficient of variation under 11% (n = 10). Limits of detection were 2 and 9 ng L⁻¹ for geosmin and MIB, respectively. Calculated calibration curves gave high levels of linearity with correlation coefficient values of 0.9988 and 0.9994 for geosmin and MIB, respectively. Finally, the proposed method was applied to the analysis of two water (reservoir and tap) samples and three wine (red, rose and white) samples. The samples were previously analyzed and confirmed free of target analytes. Recovery values ranged between 70 and 113% at two spiking levels (0.25 μg L⁻¹ and 30 ng L⁻¹) showing that the matrix had a negligible effect upon extraction. Only red wine showed a noticeable matrix effect (70–72% recovery). Similar conclusions have been obtained from an uncertainty budget evaluation study.     

Experiments on moving interaction boundaries and their characteristics of focusing and probing of both guest and host target molecules

In this paper, the concept of a moving interaction boundary (MIB) is proposed with regard to guest and host molecules. With 2-naphthalene-sulfonate (2-NS) and β-cyclodextrin (CD) as the model guest and host compounds, respectively, the relevant experiments were carried out on the MIB in capillary electrophoresis (CE). The experiments show that (1) there are a MIB and a complex boundary (CB) if proper guest and host molecules are used; (2) the MIB system has the characteristic of selective focusing and probing of the target 2-NS; (3) the system also has the characteristic of selective probing of the target host molecule β-CD without UV-absorbance, making the direct UV determination of β-CD from other CDs possible; (4) interestingly, the focusing of the guest molecule is a kind of leaky-sample stacking rather than a collection of analytes in sample sweeping; (5) the mechanism of MIB-induced separation of target analyte from unwanted ones is similar to but different from that of an affinity chromatography. In addition, the utility of MIB was briefly tested for a real sample of wastewater spiked with 2-NS.     

Fuel-specific influences on the composition of reaction intermediates in premixed flames of three C5H10O2 ester isomers

Measurements of the composition of reaction intermediates in low-pressure premixed flat flames of three simple esters, the methyl butanoate (MB), methyl isobutanoate (MIB), and ethyl propanoate (EP) isomers of C(5)H(10)O(2), enable further refinement and validation of a detailed chemical reaction mechanism originally developed in modeling studies of similar flames of methyl formate, methyl acetate, ethyl formate, and ethyl acetate. Photoionization mass spectrometry (PIMS), using monochromated synchrotron radiation, reveals significant differences in the compositions of key reaction intermediates between flames of the MB, MIB, and EP isomers studied under identical flame conditions. Detailed kinetic modeling describes how these differences are related to molecular structures of each of these isomers, leading to unique fuel destruction pathways. Despite the simple structures of these small esters, they contain structural functional groups expected to account for fuel-specific effects observed in the combustion of practical biodiesel fuels. The good agreement between experimental measurements and detailed reaction mechanisms applicable to these simple esters demonstrates that major features of each flame can be predicted with reasonable accuracy by building a hierarchical reaction mechanism based on three factors: (1) unimolecular decomposition of the fuel, especially by complex bond fission; (2) H-atom abstraction reactions followed by β-scission of the resulting radicals, leading to nearly all of the intermediate species observed in each flame; (3) the rates of H-atom abstraction reactions for each alkoxy or alkyl group (i.e., methoxy, ethoxy, methyl, ethyl, propyl) are effectively the same as in other ester fuels with the same structural groups.     

Analysis of off-flavors in the aquatic environment by stir bar sorptive extraction–thermal desorption–capillary GC/MS/olfactometry

The off-flavor compounds 2-methylisoborneol (MIB), geosmin, 2,4,6-trichloroanisole, 2,3,6-trichloroanisole, 2,3,4-trichloroanisole, and 2,4,6-tribromoanisole were analyzed in water samples by stir bar sorptive extraction (SBSE) followed by on-line thermal desorption (TD) capillary GC/MS. Quantification was performed using the MS in the single-ion-monitoring mode (SIM) with 2,4,6-trichloroanisole-D(5 )as internal standard. Quantification limits are 0.1-0.2 ng L(-1) for the haloanisoles, 0.5 ng L(-1) for geosmin, and 1 ng L(-1) for MIB. The relative standard deviations at the quantification limit ranged from 7 to 14.6%. SBSE recovery was evaluated by spiking real water samples and varied from 87 to 117%. More than twenty samples per day can be analyzed by SBSE-TD-capillary GC-MS. The same technique in combination with olfactometry was used to elucidate unknown odorous compounds in water samples.     

Synthesis of PMMA and PMMA block copolymers at elevated temperatures by phosphor ylide‐mediated polymerizations

The MMA polymerization initiated by (1‐naphthyl) triphenylphosphonium triphenylmethyl anion(TPM,NTPP) or the NTPP salt of the methylisobutyrate anion (MIB,NTPP) in THF at temperatures varying from 25 to 70°C appears to be a living polymerization as indicatred by a linear M_n vs. MMA conversion plot and by the narrow MW distributions. As indicated by the proton spectrum of MIB, NTPP in THF d₈ the predominant polymerization intermediate appears to be the ylide formed exclusively by addition of the MIB anion to the 4‐carbon of the 1‐naphthyl group. This ylide shows upfield shifts for the 3‐proton of the cyclohexadienyl ring and of the 6‐ and 8‐protons of the remaining aromatic ring. The rates of the NTPP mediated polymerizations are reduced by factors of around 10⁴‐10⁵ compared to that mediated by the corresponding ylides formed by addition of MIB to the phenyl ring of tetraphenylphosphonium ion. The reductions in rate in the presence of NTPP make it possible to carry out MMA polymerizations under conditions not normally accessible.     

Background and line interference corrections in quantitative GD-OES – New approaches to an old problem

The origin of radiative background in GD-OES is discussed, in connection with the problem of multi-matrix measurements in depth profile analysis. Backed by some experimental evidence in the form of line scans, it is argued that line emission from sample material and the plasma gas (Ar) make up the dominating contributions to the radiative background. The contribution from Ar, in this work termed Matrix-independent Background (MIB), is investigated in more detail. It is shown that, at constant voltage and current, the Ar emission intensity is nearly constant and independent of the pressure, but somewhat matrix-dependent. It is suggested that the MIB can be expressed as a linear function of the intensity of an Ar reference line. This idea is tested experimentally by making intensity measurements on a large set of calibration standards of varying composition. The results are fitted to a calibration function which allows optional definitions of the MIB. It is shown that with a MIB defined as a linear function of the Ar intensity, the different contributions to the spectral background can be more accurately determined than with the MIB defined as a constant.