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1.
本文利用新型荧光试剂1,2-苯并-3,4-二氢咔唑-9-乙酸(BCAA)作为柱前衍生试剂建立了测定游离脂肪醇的方法,实验以1-乙基-3-(3-二甲氨基丙基)环己碳二亚胺(EDAC)作为缩合剂,4-二甲氨基吡啶(DMAP)为催化剂,55℃下衍生反应25min后获得稳定的荧光产物。在Eclipse XDB-C8色谱柱上,通过梯度洗脱对12种游离脂肪醇进行了分离和在线质谱定性。采用大气压化学电离源(APCI)正离子模式,对抗静电剂(十二烷基磷酸酯钾盐)中游离脂肪醇进行定性及相应含量测定。脂肪醇的线性回归系数大于0.9997,检测限在9.40-25.32fmol。  相似文献   

2.
The (2,4-dinitrophenyl)hydrazones of carbonyls are separated by liquid chromatography and detected by ultraviolet spectroscopy (diode array detector) and by atmospheric pressure negative chemical ionization mass spectrometry. Results are presented for 78 carbonyls including 18 1-alkanals (from formaldehyde to octadecanal), 16 other saturated aliphatic carbonyls (5 C(4)-C(7) aldehydes and 11 C(3)-C(9) ketones), 16 unsaturated aliphatic carbonyls (9 C(3)-C(11) aldehydes and 7 C(4)-C(9) ketones), 13 aromatic carbonyls (including hydroxy- and/or methoxy-substituted compounds), 10 C(2)-C(10) aliphatic dicarbonyls, 3 aliphatic carbonyl esters, and 2 other carbonyls. Isomers were observed for α,β-unsaturated ketones and saturated carbonyls that bear other oxygen-containing substituents, e.g. methoxyacetone, 2-furaldehyde, and the 3 carbonyl esters. For all but two of the carbonyls studied, the base peak in the negative APCI mass spectrum was the M - 1 ion (NO(2))(2)C(6)H(3)NN [Formula: see text] CR(1)R(2) (R(1) = H for aldehydes), where M is the molecular mass of the carbonyl (2,4-dinitrophenyl)hydrazone derivative. The dicarbonyls 2,4-pentanedione and succinic dialdehyde reacted with DNPH to yield predominantly other products. Concentrations measured by ultraviolet spectroscopy (peak area) and by mass spectrometry (abundance of M - 1 ion) were in good agreement. Applications described include the measurement of 34 C(1)-C(18) carbonyls at levels of 0.015-14 parts per billion (ppb) in urban air and the identification of carbonyls at ppb concentrations as reaction products in laboratory studies of the atmospheric oxidation of unsaturated organic compounds.  相似文献   

3.
Cardiac glycosides (CG) are of forensic importance because of their toxicity and the fact that very limited methods are available for identification of CG in biological samples. In this study, we have developed an identification and quantification method for digoxin, digitoxin, deslanoside, digoxigenin, and digitoxigenin by high-performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS). CG formed abundant [M + NH4]+ ions and much less abundant [M + H]+ ions as observed with electrospray ionization (ESI) source and ammonium formate buffer. Under mild conditions for collision-induced dissociation (CID), each [M + NH4]+ ion fragmented to produce a dominant daughter ion, which was essential to the sensitive method of selected reaction monitoring (SRM) quantification of CG achieved in this study. SRM was compared with selected ion monitoring (SIM) regarding the effects of sample matrixes on the methodology. SRM produced lower detection limits with biological samples than SIM, while both methods produced equal detection limits with CG standards. On the basis of the HPLC/MS/MS results for CG, we have proposed some generalized points for conducting sensitive SRM measurements, in view of the property of analytes as well as instrumental conditions such as the type of HPLC/MS interface and CID parameters. Analytes of which the molecular ion can produce one abundant daughter ion with high yield under CID conditions may be sensitively measured by SRM. ESI is the most soft ionization source developed so far and can afford formation of the fragile molecular ions that are necessary for sensitive SRM detection. Mild CID conditions such as low collision energy and low pressure of collision gas favor production of an abundant daughter ion that is essential to sensitive SRM detection. This knowledge may provide some guidelines for conducting sensitive SRM measurements of very low concentrations of drugs or toxicants in biological samples.  相似文献   

4.
Diphenhydramine (Benadryl) is a popular over-the-counter antihistaminic medication used for the treatment of allergies. After consumption, excretion, and subsequent discharge from wastewater treatment plants, it is possible that diphenhydramine will be found in environmental sediments due to its hydrophobicity (log P = 3.27). This work describes a methodology for the first unequivocal determination of diphenhydramine bound to environmental sediments. The drug is removed from the sediments by accelerated solvent extraction and then analyzed by liquid chromatography with a time-of-flight mass spectrometer and an ion trap mass spectrometer. This combination of techniques provided unequivocal identification and confirmation of diphenhydramine in two sediment samples. The accurate mass measurements of the protonated molecules were m/z 256.1703 and 256.1696 compared to the calculated mass of m/z 256.1701, resulting in errors of 0.8 and 2.3 ppm. This mass accuracy was sufficient to verify the elemental composition of diphenhydramine in each sample. Furthermore, accurate mass measurements of the primary fragment ion were obtained. This work is the first application of time-of-flight mass spectrometry for the identification of diphenhydramine and shows the accumulation of an over-the-counter medication in aquatic sediments at five different locations.  相似文献   

5.
Solid-phase microextraction (SPME) was used to facilitate the measurement of stable carbon isotope compositions (at natural abundance) of six organic compounds representing four compound classes in aqueous solution. Toluene, methylcyclohexane, hexanol, and acetic, propionic, and valeric acids were extracted from aqueous solutions with appropriate SPME phases and thermally desorbed into the split/splitless inlet of an isotope ratio monitoring gas chromatograph/mass spectrometer (irmGC/MS). Hydrophobic compounds (toluene, methylcyclohexane, hexanol) extracted by a nonpolar SPME phase were slightly (≤0.5‰) enriched in (13)C while organic acids extracted with a polar phase were depleted in (13)C to a somewhat greater degree (≤1.5‰) relative to material remaining in the aqueous phase. Isotopic fractionation was not observed to vary systematically as a function of equilibration time or solute concentration. Further, isotope fractionation did not vary consistently with the partition coefficient (K(fw)). However, both salinity and cosolvent effects, which altered the partition coefficients of the solutes, also yielded a reduction in the magnitude of isotopic fractionation (to ≤0.4‰ for the hydrocarbons, ≤0.5‰ for the organic acids). We conclude that fractionations are most likely associated with the interactions of organic compounds with the organic phase coating SPME fibers and are specifically due to mass-dependent energy shifts upon solution of each analyte into the organic phase. In addition, fractionations are also influenced by energy shifts associated with electrostatic forces acting on the analyte in the water phase during the partitioning process. The magnitude of isotopic fractionations can be minimized under conditions appropriate for the analysis of natural waters, and with careful calibration, SPME and irmGC/MS should be a valuable means for isotopic analyses for a wide range of organic constituents in aqueous samples.  相似文献   

6.
7.
以水合氯化钌和乙醇钠为原料,首先制备了乙醇钌的乙醇溶液。通过对乙醇钌的乙醇溶液进行雾化,以2∶1的氮氧比为载气,在400℃常压条件下沉积了RuO2薄膜。采用XRD和AFM分别表征了薄膜的结构及表面形貌,证实了RuO2薄膜的晶体结构,晶粒尺寸为21.4nm。通过电化学测试,RuO2薄膜的容量可达0.818F/cm2(549F/g),充放电性能良好。经1000次循环测试,剩余容量仍然可达到初始容量的92.1%,同时发现RuO2薄膜具有较低的阻抗,有利于薄膜电容器以大电流快速充放电。  相似文献   

8.
本文利用离子色谱法对福州市2015-2016年大气PM2.5样品中4种无机阴离子(F-、Cl-、NO3-、SO42-)和5种水溶性有机物(WSOC)(甲酸、乙酸、乙二酸、丁二酸、戊二酸)进行同步测定,结果表明,无机阴离子曲线相关系数大于0.999,有机酸相关系数大于0.994,检出限范围(0.7-25.7)ng/m3,精密度范围(0.3-7.9)%,回收率范围(84.0-116)%,方法性能满足测试要求。SO42-、NO3-、Cl-为主要的水溶性无机阴离子,3种离子浓度之和占PM2.5质量浓度的32.6%。5种水溶性有机酸WSOC的浓度均值范围为(0.031-0.308)μg/m3,总和占PM2.5质量浓度的1.6%,其中乙二酸的含量相对最高。总体而言,PM2.5中水溶性无机离子和有机酸浓度的季节变化表现为春、冬季高,夏、秋季低的特点。NO3-、乙二酸在夏季表现出不同的浓度特征可能与物质的性质和夏季高温强辐射天气有关。乙二酸与SO42-、NH4+、NO3-有较强的线性相关性,初步推断其主要来源为光化学反应而形成的二次污染物。  相似文献   

9.
建立了凝胶色谱(GPC)净化、气相色谱-串联质谱(GC-MS/MS)测定海产品中得克隆的方法。得克隆包括syn-DP和anti-DP两种异构体,样品中的得克隆经正己烷/丙酮(1:1,v/v)溶液提取、GPC净化后,GC-MS/MS采用多反应监测模式(MRM)采集数据后进行定性/定量分析。得克隆的加标回收率:syn-DP测定回收率为89.3%~102.5%;anti-DP测定回收率为85.4%~102.1%。syn-DP和anti-DP的检出限分别为0.2μg/kg和0.5μg/kg(S/N=3)。方法的相对标准偏差(RSD)均≤10.0%。采用本方法对采自温州的美国红鱼、中国毛虾,采自台州的鲈鱼,以及采自舟山的大黄鱼进行检测分析,结果上述样品均未检出。  相似文献   

10.
本文建立了用超高效液相色谱-串联质谱法对鳗鱼及制品中禾草丹的检测方法。采用乙腈对样品中的禾草丹进行提取,浓缩后用固相萃取SPE小柱、氧化铝、无水硫酸钠进行净化,最后用超高效液相色谱-质谱联用法进行分离和定性定量分析。方法线性相关系数为0.9966,5-20μg/kg,加标样品的回收率在75%-85%之间,相对标准偏差在8.3%-12.7%,定量检出限可达到0.5μg/kg,该方法具有快速、高效、灵敏度高,符合出口检测限量的要求。  相似文献   

11.
HS-GC和HS-GC/MS法测定烟用商标纸中VOCs的结果对比分析   总被引:1,自引:0,他引:1  
黄惠贞 《福建分析测试》2010,19(2):56-59,62
为验证不同品牌、不同类型仪器所测得的商标纸挥发性有机化合物(VOCs)数据的准确性和可比性,在相同的实验室条件下分别用Agilent顶空-气相色谱仪、PE顶空-气相色谱仪、PE顶空-气质联用仪测定某些牌号商标纸的VOCs,对比分析其检测结果后得出结论:除苯以外的15种挥发性有机化合物在Agilent气相、PE气相、PE气质中检测结果比较一致,有较高的可比性;最低浓度标准苯值在气相上的检出值接近理论值,而气质联用仪的检出值则比理论值偏低,但三组检测值之间的绝对偏差均小于两平行数据之间的绝对允差0.10mg/m2,可以认为基本一致。  相似文献   

12.
建立了凝胶色谱(GPC)净化、气相色谱-串联质谱(GC-MS/MS)同时测定猪肉中16种有机氯类农药残留的方法。样品中的待测农药组分经丙酮、正己烷提取、GPC净化去除油脂等杂质,GC-MS/MS采用多反应监测模式(MRM)采集数据后进行定性/定量分析。待测农药的加标回收率在82%~106%之间,方法的相对标准偏差(RSD)≤10.9%,各农药组分的检出限为0.1~0.9μg/kg。  相似文献   

13.
We have developed an ion-pairing HPLC-MS method that has sufficient separation power, selectivity, and sensitivity to investigate the enzymatic behavior of benzonase/alkaline phosphatase upon digestion of oligonucleotides and DNA. Mass spectrometry revealed that this enzyme pair can nonspecifically digest oligonucleotides and DNA into fragments ranging from 2 to 10 nucleotides, i.e., sizes suitable for routine mass spectrometric measurements. Trimers, tetramers, and pentamers are the most prominent digested products. This makes benzonase/alkaline phosphatase a promising choice for DNA and DNA adduct related studies that require a nonspecific enzyme. A computer software program developed in-house was critical in automating the processing of mass spectral data. The methodology described here provides a systematic approach for evaluating the behavior of DNA-cleaving enzymes by mass spectrometry.  相似文献   

14.
LC/NMR and LC/MS (the latter technique in the MSn mode) were used to characterize the organic constituents of industrial wastewater with emphasis on polar, nonvolatile compounds. In the effluent of a textile company, various compounds such as anthraquinone-type dyes and their byproducts, a fluorescent brightener, a byproduct from polyester production, and auxiliaries such as anionic and nonionic surfactants and their degradation products were identified. It is shown that the combined use of both hyphenated techniques provides complementary structural information. If applied under comparable chromatographic conditions, they are well-suited for the nontarget analysis.  相似文献   

15.
Dissimilar friction stir welding(FSW) between aluminum and magnesium alloy was performed, using various tool rotational speed(TRS) at a ?xed travel speed, with tool offset to aluminum to investigate the formation of intermetallic compounds(IMCs) in the banded structure(BS) zone and their effect on mechanical properties. Large quantities of IMCs, in the form of alternating bands of particles or lamellae, were found in the BS zone, where drastic material intermixing occurred during FSW. The BS microstructural characters in terms of the morphology of the bands and the quantity and distribution of IMC particles varied with TRS. All welds exhibited brittle fracture mode with their fracture paths propagating mainly in/along the IMCs in the BS. It is shown that these BS microstructural characters have signi?cant effect on the mechanical properties of the joints. Suggestions on tailoring the BS microstructure were proposed for improving the strength of the BS zone and the ?nal mechanical properties of the Al/Mg FSW joints.  相似文献   

16.
本文研究了在2024铝合金衬底上,环境气氛中C2H2/H2比率对电弧离子镀沉积类金刚石膜层的结构和腐蚀性能的影响。Raman谱分析表明,随着C2H2/H2比率的降低,其D峰和G峰的强度比ID/IG值增加,这意味着膜层中sp^3/sp^2键比率减少,膜层的力学性能下降;同时,G峰的峰位向高波数方向移动,峰的半高宽变窄;D峰的峰位也在向高波数方向移动变化,但峰的半高宽变化相反,逐渐宽化。膜层可以进一步提高铝合金试样的抗腐蚀能力,从自腐蚀电位看,随着C2H2/H2比率的降低,膜层试样的抗腐蚀性能略逐渐增加。  相似文献   

17.
The quality of extra virgin olive oil is associated with the presence of microcomponents whose healing effects have been proved in some special cases. The enzymatic hydrolysis of oleuropein and ligstroside, and of their demethylated analogues, affords four different pentanedialdehydes, and for one of which, 2-(4-hydroxyphenyl)ethyl (3S,4E)-4-formyl-3-(2-oxoethyl)hex-4-enoate, also known as oleocanthal, an anti-inflammatory effect was quite recently carefully assessed. Extra virgin olive oil is now worldwide considered as a functional food whose daily intake, as for the Mediterranean diet, helps consumers in keeping a constant level of nonsteroidal anti-inflammatory drug (NSAID) in the blood. The presence of these active principles provides, therefore, olive oil with an important added value. In the framework of the actions of the recently funded Agrifood Regional Center, which should coordinate the scientific research and production worlds, an absolute analytical method was developed for the mass spectrometric detection of the two most abundant NSAIDs, Tyr-OLPD and HTyr-OLPD (oleopentanedialdehydes (OLPDs) conjugated to p-hydroxyphenylethanol and 3,4-dihydroxyphenylethanol, respectively), by UHPLC-ESI-MS/MS.  相似文献   

18.
Free radicals are conventionally detected by electron paramagnetic resonance (EPR) spectroscopy after being trapped as spin adducts. Albeit this technique has demonstrated utmost efficacy in studying free radicals, its application to biological settings is intrinsically hampered by the inevitable bioreduction of radical-derived paramagnetic adducts. Herein, we describe a reliable technique to detect and quantify free radical metabolites, wherein reduced alkyl- and phenyl-5,5-dimethyl-1-pyrroline N-oxide (DMPO) adducts are converted into ultrastable N-naphthoate esters. To mimic the ubiquitous in vivo microenvironment, bioreductants, exogenous thiols, and sodium borohydride were studied. Nitroxyl reduction was confirmed using EPR and triphenyltetrazolium chloride. The formation of the N-naphthoyloxy derivatives was established by liquid chromatography/mass spectrometry (LC/MS). The derivatives were chromatographed using a binary eluent. HPLC and internal standards were synthesized using Grignard addition. The labeled DMPO adduct is (1) fluorescent, (2) stable as opposed to nitroxyl radical adducts, (3) biologically relevant, and (4) excellently chromatographed. Applications encompassed chemical, biochemical, and biological model systems generating C-centered radicals. Different levels of phenyl radicals produced in situ from whole blood were successfully determined. The method is readily applicable to the detection of hydroxyl radical. Analogously, DMPO, the spin trap, could be detected with extreme sensitivity suitable for in vivo applications. The developed method proved to be a viable alternative to EPR, where for the first time the reductive loss of paramagnetic signals of DMPO-trapped free radicals is transformed into fluorescence emission. We believe the proposed methodology could represent a valuable tool to probe free radical metabolites in vivo using DMPO, the least toxic spin trap.  相似文献   

19.
20.
The catalytic dechlorination of 2,4-dichlorophenol (2,4-DCP) by Ni/Fe bimetallic nanoparticles in the presence of humic acid (HA) was investigated in order to understand their applicability for in situ remediation of groundwater. 2,4-DCP was catalytically dechlorinated to form the final products – phenol (P) via two intermediates, o-chlorophenol (o-CP) and p-chlorophenol (p-CP). It was demonstrated that the carbon mass balances during the dechlorination were between 84% and 92%, and other carbons were adsorbed on the surface of Ni/Fe bimetallic nanoparticles. The experimental results suggest that HA competed for reaction sites on the Ni/Fe bimetallic nanoparticles with 2,4-DCP, and thus reduced the efficiency and rate of the dechlorination of 2,4-DCP. The catalytic degradation slowed down as the increase of HA in solution, and when HA's concentrations were 0, 10, 20 and 30?mg?L?1, the maximum concentrations of o-CP were 0.025, 0.041, 0.039 and 0.034?mM in 10, 30, 30 and 30?min, respectively. High Ni content, low initial pH value, high Ni/Fe nanoparticles’ dosage and high temperature favoured the catalytic dechlorination of 2,4-DCP. The experimental results show that no other intermediates were generated besides Cl?, o-CP, p-CP and P during the catalytic dechlorination of 2,4-DCP.  相似文献   

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