高效液相色谱荧光法测定辣椒酱中的罗丹明 B

[目的]建立辣椒酱中罗丹明B的高效液相色谱荧光检测法。[方法]将样品中的罗丹明B用一定比例的丙酮和正己烷提取,经过氧化铝固相萃取柱净化浓缩后,用液相色谱荧光检测器检测其含量。[结果]试验得出,罗丹明B在0．005—0．050mg／kg浓度范围内,线性关系良好,相关系数为0．999;方法的定量检测限为0．005mg／kg,平均回收率高。[结论]该试验建立的方法快速、准确、灵敏度高,适用于辣椒酱中罗丹明B的测定。     

Analysis of Oleanolic Acid and Ursolic Acid,Potential Antifertility Agents in Moringa （Moringa oleifera） Seed

Oleanolic acid （OA） and ursolic acid （UA） are isomeric tritcrpenes that are difficult to separate chromatographically. Studies have indicated that both OA and UA have antifertility properties in several livestock species, suppressing attainment of puberty, gonad function and gamete production. Being able to determine the presence and quantity of the OA and UA in moringa and pawpaw seeds will allow for calculation of optimal inclusion levels of these acids in animal diets for antifertility-activity. The purpose of the study was thus to quantify the levels of OA and UA in Moringa and pawpaw seed powder by means of ultra-high performance liquid chromatography with electrospray ionization tandem mass spectrometry （UHPLC-ESI-MS/MS）. Only OA was detected in moringa seeds at a concentration level of 0.508 p.g/g ＋ 0.032 pg/g dry weight. UA and OA could not be detected in pawpaw seeds used in this study. The presence of OA in moringa seeds suggest that the seeds can be included in tilapia diets as a potential antifertility treatment to control precocious breeding in tilapia culture in small scale farming systems in Sub-Saharan Africa. Further studies are warranted to determine the levels of OA and UA composition in moringa seeds from other parts of the Sub-Saharan Africa （other than Zambia）.     

Properties of neutral phosphate buffer extractable organic matter in soils revealed using size exclusion chromatography and fractionation with polyvinylpyrrolidone

Abstract

A neutral phosphate buffer (NPB) extraction method has been used to estimate the amount of available N in soil. However, the properties of soil NPB-extractable organic N have not been fully elucidated. The purpose of the present study was to characterize the properties of organic matter in the NPB extracts of soils. The NPB extracts were obtained from three soil samples, and the organic matter in the extracts was separated into three fractions according to its solubility in acid and adsorption onto polyvinylpyrrolidone (PVP). High-performance size exclusion chromatography (HPSEC) with ultraviolet (UV) and fluorescence detections was applied to the NPB extracts and their fractions. The HPSEC analysis of the NPB extract revealed the presence of a single broad peak, irrespective of the detection methods. The broad peak was identified as humic substances using the on-flow measurements of UV absorption spectra and fluorescence emission spectra. Among the fractions, the PVP-non-adsorbed fulvic acid (FA) fraction accounted for the largest proportion of organic C or N in the NPB extract, followed by the PVP-adsorbed FA and humic acid (HA) fractions. The peak of humic substances was observed for all fractions using HPSEC with the on-flow measurement of UV absorption and fluorescence emission spectra. The molecular weight of the humic substances varied with each fraction. When the Coomassie Blue-reactive substances (CBRS) were quantified using a Bradford protein assay, they were detected in the NPB extract and almost half were distributed in the PVP-non-adsorbed FA fraction. However, humic substances were considered to be the main constituents of CBRS in the soil NPB extract because of their reactivity with Coomassie Blue and the absence of proteinaceous materials. Furthermore, an incubation experiment revealed that the organic matter available to microorganisms was included in the HA and PVP-non-adsorbed FA fractions. Based on the HPSEC analysis of the NPB extracts and their fractions, it was observed that the humic substances in the NPB extract, particularly in the HA and PVP-non-adsorbed FA fractions, were available to microorganisms.     

ASE及GPC技术在测定对羟基苯甲酸酯类防腐剂中的应用

建立了一种适用于食品中对羟基苯甲酸酯类(甲酯、乙酯、丙酯、丁酯)等常见防腐剂测定的简便快速的前处理方法。样品用环己烷/乙酸乙酯混合液(1∶1,V/V)提取,通过加速溶剂萃取仪(ASE)萃取,萃取液经凝胶渗透色谱仪(GPC)净化后,进GC-FID检测。4种对羟基苯甲酸酯在0.5~40.0 mg.kg-1范围内呈良好的线性关系,对于5.0 g的样品检出限分别为0.5 mg.kg-1、0.5 mg.kg-1、0.6 mg.kg-1、0.6 mg.kg-1(S/N≥3),添加平均回收率85%~110%,RSD10%。与国标前处理方法对照,本法具有灵敏度高、选择性好、回收率高、可靠性强、简单快捷等优点。     

固相萃取-气相色谱法测定沉积物中六氯环己烷、双对氯苯基三氯乙烷的残留量

通过对样品前处理方法和气相色谱条件的改进,建立一套稳定的沉积物中六氯环己烷、双对氯苯基三氯乙烷残留的气相色谱检测方法,满足实验室批量测定样品的要求。选择40 mL正己烷和丙酮混合液(V_正己烷∶V_丙酮=1∶1)作为提取液,并加入2 g铜粉去除硫化物,用Florisil SPE 小柱和CarbonGCB SPE 小柱串联净化,采用10 mL正己烷和丙酮混合液(V_正己烷∶V_丙酮=9∶1)进行洗脱,浓缩后用DB1701气相毛细管柱分离,用带电子捕获检测器的气相色谱仪（GC-ECD）检测,外标法定量。本研究选择沙质性状的沉积物作为基准进行加标回收实验,平均回收率在74.5%～92.0%,相对标准偏差在3.09%～6.67%;检出限为α-HCH:1.96×10^-4 mg/kg, β-HCH：1.45×10^-6mg/kg,γ-HCH：1.90×10^-4 mg/kg, δ-HCH：1.98×10^-4mg/kg, p,p′-DDD:2.47×10^-6 mg/kg, o,p′-DDT：1.08×10^-4mg/kg, p,p′-DDE：1.59×10^-4 mg/kg, p,p′-DDT：2.52×10^-4mg/kg。采用泥质性状的沉积物对本方法进行验证,加标回收率和相对标准偏差都符合沉积物样品的药残检测要求。     

用反相高效液相色谱-紫外检测法测定1-脱氧野尻霉素的含量

以0.05 mol/L HC l为溶剂提取蚕粉和桑叶粉中的1-脱氧野尻霉素(DNJ),并用9-芴基氯甲酸甲酯(FMOC)为衍化剂,在pH 8.5的硼酸盐缓冲液中进行衍生化反应,生成具有紫外吸收的DNJ-FMOC络合物,再用反相高效液相色谱-紫外检测法对其分离测定。结果表明,反应产物的色谱图分离效果良好,DNJ-FMOC的峰面积与DNJ浓度呈高度正相关关系,加样回收率平均为100.7%。精密度试验、稳定性试验、重现性试验、回收率试验表明,该方法稳定可靠,可以作为测定家蚕、桑叶及有关药物样品中DNJ含量的有效方法。     

MAE-SAFE-GC×GC/HR-TOFMS法鉴定熟制中华绒螯蟹挥发性风味成分

采用微波辅助萃取耦合溶剂辅助风味蒸发法(MAE-SAFE)提取中华绒螯蟹两大可食部位-体肉(不含足钳肉),性腺(含肝胰腺)的挥发性风味成分,并应用全二维气相色谱-高分辨飞行时间质谱技术(GC×GC/HR-TOFMS)结合保留指数及精确质量数进行香气定性分析.共鉴定出122种挥发性成分,60种物质经精确质量数二次定性,在同原料研究中检出种类最多.其中性腺检出108种化合物,体肉75种,性腺中具有更为丰富的醛类,酮类及含氮类化合物.MAE-SAFE法获得的20种酮类、27种醇类、7种含氮类,4种含硫类化合物,使得其对该类极性热敏性挥发性成分化合物具有其他前处理方法所不具有的富集优势,温和快速的加热萃取方式保证了所获香气成分的真实性.GC×GC/HR-TOFMS的高分辨率和高峰容量使得(E)-2-戊烯-1-醇与(Z)-2-戊烯-1-醇等多种同分异构体实现完全分离,甲酰胺(氨味),麦芽酚(焙烤样香)及其前体物4H-2,3-二氢-3,5-二羟基-6-甲基吡喃-4-酮为首次在中华绒螯蟹中检出,为后续进行关键香气成分的筛选提供了可靠全面的香气成分信息.     

气相及气相色谱质谱法测定食品中非法添加的石蜡

[目的]建立食品中违法添加石蜡的检测方法。[方法]分别采用气相色谱及气相色谱质谱法对食品中非法添加的石蜡进行检测。[结果]分别建立了食品中石蜡的定性与定量检测方法,确定了以正二十六烷,正二十七烷、正二十八烷、正二十九烷加和峰面积对石蜡进行定量检测的方案。[结论]该方法简便、稳定、适用性强,可用于食品中的石蜡的准确测定。     

固相微萃取—气相色谱/质谱测定杨树叶片的挥发性物质

在45℃恒温下,采用固相微萃取方法萃取黑杨叶片的挥发性物质,然后采用气相色谱/质谱法分析挥发性物质的化学成分.结果表明,化学成分主要为邻羟基苯甲醛、顺-3-己烯酯、顺-3-己烯醇、水杨酸-2-乙基己基酯等.