微流蒸发光散射检测器的研制及评价

构建了适用于纳升级到微升级流量的毛细管分离体系的微流蒸发光散射检测器(μELSD),实现了其与毛细管液相色谱(eLC)的联用.对雾化器孔径和雾化毛细管内径、蒸发管内径和长度、光散射池尺寸、雾化毛细管位置和辅助载气流量等参数进行了优化.在最优条件下,微流蒸发光散射检测器检出限为直接进样葡萄糖1 ng(S/N＞ 10),线性范围0.01～1.0 μg,重复性好,峰面积RSD(n=6)为0.4％,峰高RSD(n=6)为0.3％.本检测器已成功应用cLC-μELSD平台,使用C18毛细管色谱柱(内径250 μm),0.1％甲酸铵溶液(pH 4.5)-甲醇(60∶40,V/V)为流动相,分离检测了3种常用甜味剂,表明本研究构建的系统可以应用于实际分离检测中,具有分析时间快、溶剂消耗量少、样品需求量小的优点.     

蒸发光散射检测技术在石油化工领域中的应用

对高效液相色谱中的蒸发光散射技术进行了综述,介绍了蒸发光散射检测器的仪器结构、工作原理以及影响检测的因素,重点介绍蒸发光散射检测技术在石油化工领域中的应用。     

蒸发光散射检测技术

 对高效液相色谱中的蒸发光散射检测技术进行了综述。重点介绍了蒸发光散射检测器的仪器构造、工作原理、影响检测的因素、检测理论及其在类酯、表面活性剂和药物成分等物质检测方面的应用。 关键词：蒸发光散射检测器;工作原理;检测理论;类酯;表面活性剂;药物     

高效液相色谱仪蒸发光散射检测器校准用标准物质的选择

对高效液相色谱蒸发光散射检测器(ELSD)校准用标准样品蔗糖–甲醇溶液和对乙酰氨基酚–甲醇溶液进行了研究。实验表明,用蔗糖–甲醇溶液和对乙酰氨基酚–甲醇溶液校准具有ELSD的高效液相色谱仪,其保留时间、峰面积、最低检测浓度3个参数均符合检定校准用标准物质要求。但蔗糖–甲醇溶液色谱峰的对称性差且响应值明显低于对乙酰氨基酚–甲醇溶液,因此用后者作为ELSD检校用标准物质更适合。     

校准蒸发光散射检测器选用标准物质的比较与分析

通过对葡萄糖和三氯蔗糖的物理、化学性质的比较,采用高效液相色谱仪和蒸发光散射检测器进行标准溶液色谱峰面积的检测,并用G rubbs检验法对其数据进行异常值检验。结果表明,三氯蔗糖相对于葡萄糖较为稳定,选用三氯蔗糖作为蒸发光检测器校准用标准物质比较合适。     

蒸发光散射检测技术研究进展

目前,高效液相色谱(HPLC)日益普及,所分析的样品范围也越来越广。检测器作为HPLC仪的重要组成部分,其发展在某种意义上决定着HPLC技术的进步[1]。作为一种HPLC检测技术,蒸发光散射检测(ELSD)不仅可弥补常规紫外检测(UVD)不能检测无紫外吸收或只有紫外末端吸收物质的缺陷,而且与     

亲水色谱-蒸发光散射检测器定量分析白坚木皮醇含量

建立白坚木皮醇(Quebrachitol)含量的亲水作用色谱-蒸发光散射检测器(ZICHILIC-ELSD)测定方法。Merck ZIC-HILIC色谱柱(150×4.6mm,5μm);以乙腈-水(体积比为70∶30)为流动相,等度洗脱,流速为1.0mL/min;蒸发光散射检测器,蒸发温度为65℃,雾化温度为50℃,高纯氮压力9.9 MPa。结果表明,白坚木皮醇浓度与其色谱峰面积积分值呈很好的线性关系,相关系数为0.9997。检测限为0.08mg/mL;相对标准偏差为0.48%;加标回收率为100.3%。该方法快速、简便、准确,适合从复杂体系中快速检测白坚木皮醇的含量。     

高效液相色谱仪蒸发光散射检测器两种校准用标准物质的比较选择

对高效液相色谱蒸发光散射检测器(ELSD)校准用标准物质对乙酰氨基酚–甲醇溶液和咖啡因–甲醇溶液进行了比较选择。与对乙酰氨基酚相比,咖啡因的缺点是色谱峰对称性稍差,优点是没有杂质峰,更重要的是咖啡因已经研制出国家二级标准物质,可以很好地溯源,所以咖啡因更适合作ELSD的校准物质。     

反相离子对色谱/蒸发光散射检测器分离唑来膦酸及其有关物质

采用反相离子对高效液相色谱／蒸发光散射检测法研究了唑来膦酸及其有关物质的色谱分析与分离方法。优化了色谱条件，固定相为Hypersil C8柱，以含10 mmol／L正戊胺的5mmol／L乙酸铵缓冲液（用乙酸调节pH至7．0）-甲醇（体积比为97：3）为流动相，流速为1．0mL/min，蒸发光散射检测器检测。在该色谱条件下，唑来膦酸与其有关化合物（包括合成过程中残余的原料咪唑乙酸及分解产物亚磷酸、磷酸盐）的分离良好，唑来膦酸色谱峰与最近杂质峰的分离度大于1．5。本法简便快速，为唑来膦酸的常规分析提供了有效可靠的方法。     

离子色谱法同时分析奶粉中碘离子和硫氰酸根

使用IonPac AS16强亲水性阴离子交换色谱柱分离,紫外和电导两种检测方式串联检测,建立了奶粉中I-和SCN-的同时分析方法。利用电导的检测结果来判断紫外检测的色谱峰纯度,从而指导色谱条件的优化,使I-、SCN-与其它有紫外响应的色谱峰获得最佳分离,最终通过紫外检测器获得高灵敏度的检测结果。该方法为乳制品质量检测提供了可行方法。     

直观推导式演进特征投影法解析多环芳烃的重叠色谱峰

用高效液相色谱法(HPLC)测定多环芳烃时,因芴、苊和菲,茚(1,2,3-cd)芘和苯并(g,h,i)苝的色谱峰严重重叠而影响测定结果。本研究用高效液相色谱-二极管阵列检测器(DAD)和荧光检测器(FLD)测定多环芳烃,在激发波长λex=230nm,发射波长λem=300～500nm范围内采集重叠峰的HPLC-FLD二维色谱数据,再用直观推导式演进特征投影法(HELP)解析它们的重叠色谱峰,分辨结果令人满意。该方法对重叠组分的分辨下限为0.02mg/L。结果表明,用二维色谱荧光数据解析色谱重叠峰,灵敏度更高,可用于环境样品中多环芳烃的测定。     

Electrochemical,fluorescence, and UV detection for HPLC analysis of various cysteine derivatives

Electrochemical (ECD), fluorescence (FLD), and UV spectrophotometric (UVD) detection were used to monitor various S-alk(en)yl-L -cysteines and their corresponding sulfoxide isomers following pre-column derivatization with o-phthaldialdehyde-tert-butylthiol and separation by reversed-phase HPLC. Recording of hydrodynamic voltammograms, FLD stop-flow scanning, and on-line captured UV spectra were methods used for establishing optimal detector settings which were defined as a compromise between favorable selectivity and high sensitivity. Optimal detector settings were found at: (A) 750 mV vs. Ag/AgCl for ECD; (B) excitation at 230 nm and emission at 420 nm for FLD; and (C) 337 nm for UVD. Various aspects of detector practicability such as selectivity, baseline disturbances due to excessive reagent, scanning possibilities, as well as detection limits were evaluated and compared. Minimal detectable amounts of the compounds were in the range of 130-160 fmol for ECD, and 2.5-3.5 pmol and 13-16 pmol for FLD and UVD. In addition, the possibilities and benefits of detector coupling were examined.     

Anomalies in evaporative light scattering detection

A two-dimensional (2-D) “heart-cutting” HPLC system was used to fractionate oligostyrenes into the respective diastereoisomers. For samples of known composition, the response of an ultraviolet (UV) absorbance detector followed the anticipated pattern. The response of an evaporative light-scattering (ELSD) detector on the other hand indicated quite different concentrations for the two diastereoisomers, relative to what was anticipated and what was indicated by the UV detector. Whereas approximately the same concentration was indicated by UV, ELSD in some cases indicated no detection of the later eluting isomer. The magnitude of the errors depended on both the molecular weight and the tacticity of the diastereomers. These anomalies appear to be an artifact of power transform functions imbedded within the firmware processor of the ELSD, invisible to the user.     

Quantification of major lipid classes in human triacylglycerol-rich lipoproteins by high-performance liquid chromatography with evaporative light-scattering detection

Triacylglycerol-rich lipoproteins (TRL), comprising chylomicrons (CM) and very-low-density lipoproteins (VLDL), have been associated with cardiovascular disease. The lipid class content in the remnant particles of these lipoproteins is a determinant for the accumulation of lipids in macrophages and their transformation into foam cells. We have optimized a method for the simultaneous determination of cholesteryl esters (CE), triacylglycerols (TG), free cholesterol (FC), monoacylglycerols (MG), and phospholipids (PL) by HPLC coupled to a light-scattering detector (ELSD). A diol column and a ternary gradient of hexane, 2-propanol, and methanol were applied to CM and VLDL of human origin (n = 10), with excellent precision in terms of repeatability of peak areas and retention times. All peaks were baseline resolved although the resolution of CE and TG was compromised for the sake of simplicity of the solvent gradient. The ELSD response was fitted to second-order equations, with correlation coefficients (r2) higher than 0.999 for a wide range of concentrations (0.25-10 microg of lipid injected). TG were the major lipid class detected in human TRL, accounting for 62% in CM obtained 2 h after the oil intake. In addition we recorded a depletion of TG and CE in CM obtained 2 h after the oil intake of about 60%. We conclude that the method reported here is suitable for a rapid and precise determination of lipid classes in human TRL and, therefore, may be a useful tool for investigations on the atherogenicity of these lipoproteins.     

Use of evaporative light scattering detection for the quality control of drug substances: Influence of different liquid chromatographic and evaporative light scattering detector parameters on the appearance of spike peaks

High performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD) is a versatile, easy to use and inexpensive alternative when it comes to the analysis of substances lacking a chromophor for UV detection. However, in pharmaceutical analysis injection of highly concentrated test solutions are normally required to control impurities at low levels. Under these conditions spike peaks were observed in the chromatograms of the test solutions making a proper evaluation of the impurity profile impossible. The influence of different eluent and ELSD parameters such as eluent composition, eluent flow-rate, ELSD scavenger gas flow-rate and evaporation temperature on the appearance of spike peaks was investigated. It could be shown that spike peaks can be avoided when selecting elevated eluent flow-rates and ESLD scavenger gas flow-rates. Moreover, eluents containing high amounts of organic modifier seem to foster the appearance of spike peaks.     

高效液相色谱法测定庆大霉素C组分的不同检测方式测定结果的比较

各国药典中关于庆大霉素C组分的测定方法均为高效液相色谱法,但检测方式及分离效果不同。为此采用直观推导式演进特征投影法(HELP),对高效液相色谱-二极管阵列检测采集的庆大霉素C组分色谱数据进行解析,分辨出各物质的色谱曲线,在扣除了未分离的杂质峰对庆大霉素C1组分的干扰后,对柱前邻苯二醛衍生化-二极管阵列检测法及目前中国药典 2005 版收载的高效液相色谱-蒸发光散射检测方法测定庆大霉素C组分的准确性进行了比较,并运用柱切换技术,证明二者测定结果的一致性。     

Different detection systems for the HPLC analysis of oxylipins, by-products of the enzymatic generation of 2E-hexenal

The incubation of 13-hydroperoxy-9Z,11E,15Z-octadecatrienoic acid (13-HPOT) with a hydroperoxide lyase containing extract of mung bean seedlings (Phaseolus radiatus L.) led not only to the formation of 2E-hexenal, but also to the generation of several non-volatile by-products (oxylipins). These oxylipins, generated by the catalysis of other 13-HPOT metabolizing enzymes, were analyzed by high performance liquid chromatography (HPLC) without time-comsuming derivatization procedures, which would be necessary for their volatilization and stabilization during gaschromatography (GC). Different detection systems such as an evaporative light-scattering detector (ELSD), diode-array detector (DAD), and particle beam-mass spectrometry (PB-MS) were applied. The utilization of an ELSD represented an improvement of sensitivity compared to a DAD, especially in the case of substances with low UV-activity.     

An investigation into detector limitations using evaporative light-scattering detectors for pharmaceutical applications

Evaporative light-scattering detection (ELSD) high-performance liquid chromatography (HPLC) is an alternative technology to low-wavelength UV analysis that is often employed when compounds lack sufficient absorptivity. Although ELSD provides an additional detector option for liquid chromatographers, studies in our laboratory indicate analyte properties may adversely affect the ability to detect certain molecules. In this investigation, a series of low-molecular-weight compounds of pharmaceutical interest are evaluated with two commercially available ELSDs. It is observed that melting point is a useful analyte property to consider in optimizing ELSD detectors. The melting point of the analyte should be significantly higher than what the compound will experience in the nebulizer/evaporator chambers to achieve the best analyte response. It is found that some analytes could not be distinguished from the evaporated mobile phase background when ELSD temperatures exceed the melting point of the compound. Though useful for many applications and of particular interest for compounds that are weak chromophores, ELSD falls short of being a "universal detector" technology. In addition to boiling points of mobile phase components, scientists should also consider the melting point and volatility of the analyte(s) when optimizing ELSD response.