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21.
Faecal sterols have been proposed as direct chemical markers for the determination of faecal contamination in inland and coastal waters. In this study, we assess the impact of (a) the concentration of dissolved organic carbon (DOC), (b) the nature of DOC, (c) the salinity and (d) the concentration of sterols and stanols on their solid phase extraction. When natural organic matter (NOM) is modelled by humic acid, increasing DOC concentration from 2.7 to 15.4 mg/L has no significant impact on the recovery of sterols and stanols. The modelling of NOM by a mixture of humic acid and succinoglycan induces a significant (24%) decrease in the recovery of sterols and stanols. For all concentrations of target compounds, no significant increase in recovery is associated with increasing the salinity. Moreover, an increase in the recovery of target compounds is induced by an increase in their concentration. The nine target compounds and the recovery standard (RS) exhibit the same behaviour during the extraction step. Thus, we propose that (a) the concentration of target compounds can be corrected by the RS to calculate more realistic concentrations without modifying their profile and (b) the sterol fingerprint can be investigated in the colloidal fraction of aqueous samples without altering the information it could provide about the source. The application of this analytical method to waste water treatment plant influent and effluents yields results in agreement with previous studies concerning the use of those compounds to differentiate between sources of faecal contamination. We conclude that this analytical method is fully applicable to the determination of sterol fingerprints in the dissolved phase (<0.7 μm) of natural aqueous samples. 相似文献
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In this paper, an efficient and sensitive analytical method for the simultaneous determination of three trace sterols including ergosterol, stigmasterol and β-sitosterol in complicated biological samples was developed by gas chromatography-mass spectrometry (GC-MS) coupled with extraction using novel β-sitosterol magnetic molecularly imprinted polymer (mag-MIP) beads. Physical tests suggested that β-sitosterol mag-MIP beads prepared by a rapid microwave synthesis method possessed the porous morphology, narrow size distribution, stable chemical and thermal property. Due to the greatly enlarging surface area and the strong recognition to the target molecules, β-sitosterol mag-MIP beads have a higher enrichment factor for β-sitosterol (~20-fold) and the higher selectivity for β-sitosterol and its analogs than that of β-sitosterol magnetic nonimprinted polymer (mag-NIP) beads. Under the optimum analytical conditions, all the target compounds achieved good chromatographic separation and sensitive detection without matrix interference. It was interesting that three target sterols were actually found in mushroom samples, and stigmasterol and β-sitosterol were actually found in serum and watermelon samples. The recoveries of spiked sample tests were in range of 71.6-88.2% with RSDs of 2.4-10.0% (n=3). This method is reliable and applicable for the simultaneous determination of trace sterols in real biological samples based on the β-sitosterol mag-MIP bead extraction. 相似文献
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Yun‐Wen Liao Chiy‐Rong Chen Jue‐Liang Hsu Hsueh‐Ling Cheng Wen‐Ling Shih Yueh‐Hsiung Kuo Tzou‐Chi Huang Chi‐I Chang 《中国化学会会志》2011,58(7):893-898
A new sterol, 5α,6α‐epoxy‐3β‐hydroxy‐(22E,24R)‐ergosta‐8,22‐dien‐7‐one ( 1 ), together with eight known sterols, 5α,6α‐epoxy‐(22E,24R)‐ergosta‐8,22‐diene‐3β,7α‐diol ( 2 ), 5α,6α‐epoxy‐(22E,24R)‐ergosta‐8,22‐diene‐3β,7β‐diol ( 3 ), 5α,6α‐epoxy‐(22E,24R)‐ergosta‐8(14),22‐diene‐3β,7α‐diol ( 4 ), 3β‐hydroxy‐(22E,24R)‐ergosta‐5,8,22‐trien‐7‐one ( 5 ), ergosterol peroxide ( 6 ), clerosterol ( 7 ), decortinol ( 8 ), and decortinone ( 9 ), were isolated from the stems of Momordica charantia. Their structures were elucidated by mean of extensive spectroscopic methods, including 1H, 13C, 2D‐NMR and HR‐EI‐MS, as well as comparison with the literature data. Compounds 1 , 4 , 5 , 8 , and 91 were not cytotoxic against the SK‐Hep 1 cell line. 相似文献
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Mansoureh Mousavi Steve S.-F. Yu Der-Lii M. Tzou 《Solid state nuclear magnetic resonance》2009,36(1):24-31
13C cross-polarization/magic-angle spinning (CP/MAS) solid-state NMR spectroscopy has been employed to analyze four vitamin D compounds, namely vitamin D3 (D3), vitamin D2 (D2), and the precursors ergosterol (Erg) and 7-dehydrocholesterol (7DHC). The 13C NMR spectrum of D3 displays a doublet pattern for each of the carbon atoms, while that of Erg contains both singlet and doublet patterns. In the cases of 7DHC and D2, the 13C spectra display various multiplet patterns, viz. singlets, doublets, triplets, and quartets. To overcome the signal overlap between the 13C resonances of protonated and unprotonated carbons, we have subjected these vitamin D compounds to 1D 1H-filtered 13C CP/MAS and {1H}/13C heteronuclear correlation (Hetcor) NMR experiments. As a result, assisted by solution NMR data, all of the 13C resonances have been successfully assigned to the respective carbon atoms of these vitamin D compounds. The 13C multiplets are interpreted due to the presence of s-cis and s-trans configurations in the α- and β-molecular conformers, consistent with computer molecular modeling determined by molecular dynamics and energy minimization calculations. To further characterize the ring conformations in D3, we have successfully extracted chemical shift tensor elements for the 13C doublets. It is demonstrated that 13C solid-state NMR spectroscopy provides a robust and high sensitive means of characterizing molecular conformations in vitamin D compounds. 相似文献
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超声萃取-高效液相色谱-串联质谱法测定大气颗粒物中甾醇类化合物 总被引:1,自引:0,他引:1
采用超声萃取与液相色谱-串联质谱联用,建立了快速测定大气颗粒物中甾醇类化合物的方法.甾醇类化合物用甲醇超声萃取,浓缩后使用液相色谱-串联质谱分析.采用Waters公司Atlantis C18色谱柱(100mm× 2.1 mm,3μm),以乙腈和水混合流动相梯度洗脱,实现了胆甾醇、豆甾醇、菜油甾醇及β-谷甾醇的分离.并在APCI-MS/MS MRM模式下定量检测.在选取的实验条件下,方法回收率在80.3%~97.7%之间,检出限0.015 ng/m3,相对标准偏差小于15%,日内及日间测定精密度小于20%.本方法具有较好的准确性及精密度,实际样品的测试结果表明,方法可以满足大气颗粒物中甾醇类化合物的定量分析要求. 相似文献
26.
Karuna Shanker Subhash Chandra Singh Sangita Pant Pooja Srivastava Akhilesh Kumar Yadav Richa Pandey Ram Kishor Verma Madan Mohan Gupta 《Chromatographia》2008,67(3-4):269-274
A quantitative method using silica gel 60F254 high performance thin layer chromatography plates, automated bandwise sample application, and automated visible mode densitometric
method has been developed for the determination of 24β-ethylcholesta-5,22E,25-triene-3β-ol (ECTO) in the aerial part of Clerodendrum phlomidis. ECTO was used as a chemical marker for the standardization of C. phlomidis plant extracts. The separation was performed on silica gel 60F254 TLC plates using chloroform-methanol (98.5: 1.5, v/v) as mobile phase. The quantitation of ECTO was carried out using the densitometric reflection/absorption mode at 650 nm after
post chromatographic derivatization with anisaldehyde reagent. A precise and accurate quantification can be performed in the
linear working concentration range of 150–400 ng band−1 with good correlation (r
2 = 0.996). The method was validated for peak purities, precision, robustness, limit of detection (LOD) and quantitation (LOQ),
etc. as per ICH guidelines. 相似文献
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Hans-Gerd Janssen Wibo Boers Herrald Steenbergen Roos Horsten Eckhard Flter 《Journal of chromatography. A》2003,(1-2):385-2003
Edible fats and oils are complex mixtures containing a wide range of (classes of) compounds. The most important group of compounds are the triglycerides (triacylglycerides, TAGs). Because of the large number of possible fatty acid combinations, an enormous number of TAGs is possible. In the present feasibility study, the applicability of different modes of comprehensive two-dimensional LC×GC for detailed oil and fat analysis is evaluated. Comprehensive LC×GC was found to be an extremely powerful analytical method for the analysis of complex TAG samples. Using the new comprehensive set-ups, TAGs can be separated according to two independent parameters: carbon number vs. number of double bonds, or fatty acid composition vs. number of double bonds. The information content of comprehensive separations by far exceeds that of the current generation of analytical methods. The quantitative results of the separations show a good agreement with data obtained from standard analytical methods. The comprehensive methods studied can also be used for fingerprinting of oil samples, as well as for the analysis of target compounds or compound groups. Highly detailed separations of olive oil samples were obtained. Zooming in on one region of the chromatogram allowed reliable analysis of wax esters without interferences of sterol esters. 相似文献
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