RP-HPLC法同时测定12种植物油中的3种甾醇含量

采用反相高效液相色谱法(RP-HPLC)建立同时测定植物油中菜油甾醇、豆甾醇和β-谷甾醇含量的方法。采用C8柱(250 mm×4.6 mm×5μm)为色谱柱,流动相A相为乙腈,B相为水,通过梯度洗脱方式,以流量为1 m L/min,紫外检测波长210 nm对植物油中菜油甾醇、豆甾醇和β-谷甾醇进行分离检测。结果表明,菜油甾醇、豆甾醇和β-谷甾醇的质量浓度范围分别为5.12~101.4,5.08~101.6,5.09~101.8μg/m L时,3个甾醇的线性关系良好(线性方程分别为y=3 699x-5 454,y=4 951x+8 889,y=3 994x-3 800;相关系数r2分别为0.998 9,0.999 9,0.999 4),检测限为2.5μg/m L,平均回收率分别为99.79%~100.6%,98.17%~99.80%以及97.76%~102.24%,进样精密度(n=6)分别为2.29%,1.66%,2.12%,重复性RSD分别为2.49%,1.78%,2.72%,稳定性RSD分别为1.95%,2.56%,2.40%。通过对12种植物油中3种甾醇含量进行同时测定,表明相对于气相色谱法(GC),采用HPLC法具有更稳定、更准确、更简便等特点,是同时检测植物油中菜油甾醇、豆甾醇和β-谷甾醇的较好方法。     

多种植物油中黄酮和角鲨烯分布UPLC研究

该文采用超高效液相色谱(UPLC)技术分别建立植物油中黄酮类物质和角鲨烯的定量方法,考察常见13种植物油中黄酮和角鲨烯的分布规律。实验采用70%的甲醇预处理植物油样,制备供试品溶液;经Acquity UPLC的C18柱(2.1 mm×100 mm,1.7μm)分离,以甲醇和0.8%磷酸溶液分别为流动相A相和B相,经梯度洗脱,于360 nm处,分离检测黄酮类组分。采用正交试验优化出植物油中角鲨烯的最佳皂化条件,经Acquity UPLC的C8柱(2.1 mm×100 mm,1.7μm),流动相为乙腈-水(97:3),于波长210 nm分离检测角鲨烯。结果表明:所建方法能有效分离黄酮组分或角鲨烯,在黄酮浓度50~600 ng/m L范围内5种黄酮各自线性关系良好(r≥0.999),检测限和定量限为10.2~15.6 ng/m L和33.6~48.6 ng/m L,平均加样回收率在97.75%~102.21%,重复性(RSD)为2.79%~7.75%;在角鲨烯浓度1~350μg/m L范围内;角鲨烯的线性相关良好(r≥0.999),检测限和定量限分别为27.3 ng/m L和81.9 ng/m L,平均加样回收率为88.18%,重复性RSD为1.96%;13种植物油中能检出角鲨烯,其中橄榄油中最高;只有火麻籽油和沙棘油中检出所列5种黄酮,亚麻籽油检出槲皮素和木犀草素,橄榄油中检出木犀草素和异鼠李素;所建立方法是食用植物油中黄酮类组分或角鲨烯质量控制的好方法,提示植物油的生产工艺可能影响极性黄酮类组分的含量。     

气相色谱-质谱法同时测定人体尿液中16种邻苯二甲酸酯

建立人尿中16种邻苯二甲酸酯的离子阱气相色谱-质谱方法。该方法采用正己烷萃取,经HP-5MS色谱柱(30 m×0.25 mm×0.25μm)分离,使用GC-MS选择离子扫描模式进行分析测试。结果表明:16种邻苯二甲酸酯在0.05～4 mg/L范围内线性良好,r20.99,方法检出限为0.001～0.017 mg/L,定量下限(LOQ)为0.002～0.056 mg/L,加标回收率在80%～120%之间;RSD(n=8)小于10%。并采用该方法测定了90份人尿中的16种邻苯二甲酸酯,检出10种邻苯二甲酸酯,其中DIBP检出率高达50%,DEHP检出率也达到22%。     

食用油中脂肪酸的CGC法分析

采用毛细管气相色谱法(CGC)分离鉴定食用清脉油中17种脂肪酸的组成:DB-23型(60 m×0.25 mm×0.15μm)毛细管气相色谱柱;氢火焰离子化检测器(FID,260℃);分流/不分离进样器(250℃);程序升温:起始温度为50℃,1 min后以20℃/min升到175℃,再以3℃/min升到190℃,保持3 min,最后以5℃/min升到230℃,保持2 min。通过与对照品对比,清脉油中共分离鉴别出17种已知脂肪酸,其中不饱和脂肪酸的含量高达90.18%,饱和脂肪酸的含量仅有9.18%,不饱和脂肪酸主要有油酸、亚油酸、亚麻酸等;饱和脂肪酸主要有棕榈酸、硬脂酸等,其他脂肪酸的含量很少。不饱和脂肪酸与饱和脂肪酸的比例高达9.82:1。所建立的CGC法可适用于混有12种植物油的食用清脉油中脂肪酸检测。     

UPLC同时测定决明子中橙黄决明素、大黄素、大黄酚和大黄素甲醚的含量

建立UPLC同时测定决明子中橙黄决明素、大黄素、大黄酚和大黄素甲醚含量的方法,采用ACQUITY UPLCBEH-C18色谱柱(2.1 mm×50 mm×1.7μm),乙腈和0.1%磷酸水溶液为流动相,采用梯度洗脱,流速为0.6 mL/min,检测波长为284nm。结果表明橙黄决明素、大黄素、大黄酚和大黄素甲醚分别在3.002～30.02μg/mL、2.500～25.00μg/mL、10.430～104.30μg/mL和5.916～59.16μg/mL的浓度范围内均有良好的线性关系(r=0.999 9),回收率均大于95%,RSD均小于2%。该方法快速,准确,重现性好,可用于测定决明子中橙黄决明素、大黄素、大黄酚和大黄素甲醚的含量。     

甘露饮中六种有效成分提取及含量测定

探讨甘露饮中6种有效成分(绿原酸、麦角甾苷、柚皮苷、黄芩苷、甘草酸、熊果酸)最佳提取工艺条件及含量测定方法。优化提取溶剂,通过正交试验法考察料液比、提取时间和提取次数对甘露饮提取工艺的影响。采用Syncronis C18色谱柱(4.6 mm×250 mm,5μm),流动相乙腈(A)-0.1%磷酸水溶液(B)梯度洗脱(0～5 min,5%A;5～40 min,5%～20%A;40～60 min,20%～50%A;60～80 min,50%～90%A;80～90.1 min,90%～5%A;90.1～100 min,5%A),流量1.0 mL/min,柱温35℃,检测波长210 nm,进样量20μL的色谱条件对甘露饮提取物中6种有效成分进行含量测定。最佳提取工艺条件是:60%乙醇为提取溶剂,料液比1∶4,提取时间为1 h,提取次数为1次。绿原酸、麦角甾苷、柚皮苷、黄芩苷、甘草酸、熊果酸分别在4.80～80.00,10.00～100.00,24.00～400.00,30.00～500.00,6.00～100.00,3.60～60.00μg/mL浓度范围内线性关系良好(r~2≥0.999 5)。平均加样回收率在96.12%～101.82%,RSD在1.72%～2.92%。该提取工艺稳定可行,HPLC法能简便、准确地测定甘露饮提取物中6种有效成分的含量。     

HPLC法同时测定冬虫夏草中5种核苷类成分

用高效液相色谱法同时测定冬虫夏草中鸟嘌呤、胸腺嘧啶、腺嘌呤、腺苷、虫草素5种核苷类成分的含量。采用色谱柱为Aichrom Bond-AQ C18柱(250 mm×4.6 mm×5μm),以乙腈-水(7∶93)为流动相,流量为0.8 m L/min,检测波长254 nm,柱温30℃。鸟嘌呤、胸腺嘧啶、腺嘌呤、腺苷、虫草素的质量浓度分别在1.01~5.50μg/m L(r=0.9995)、0.05~1.01μg/m L(r=0.999 8)、0.20~1.98μg/m L(r=0.999 5)、1.01~5.07μg/m L(r=0.999 5)、0.10~1.03μg/m L(r=0.999 6)的范围内与峰面积线性关系良好,平均加样回收率分别为99.1%,97.8%,98.6%,100.4%,99.2%,RSD(n=5)分别为1.15%,2.34%,2.01%,1.75%,1.50%。该方法简便快速、准确度高、重现性好,可用于同时测定冬虫夏草中鸟嘌呤、胸腺嘧啶、腺嘌呤、腺苷、虫草素5种核苷类成分。     

GC-MS/SIM测定橡皮擦中5种N-亚硝胺及其前体物的迁移量

采用气相色谱-质谱(GC-MS/SIM)测定14种不同品牌、型号橡皮擦中5种亚硝胺及其前体物.以人工汗液为模拟迁移物,经固相萃取柱净化后,对其进行定性定量分析。5种N-亚硝胺在0.005-10μg/m L范围内呈良好的线性关系,相关系数均为0.999以上。采用本方法对橡皮擦样品进行测定,其中N-亚硝胺的总检出含量为29.09-34.1μg/Kg,N-亚硝胺前体物的总检出含量为25.26-51.68μg/Kg。     

液相色谱串联质谱法测定烟草中的游离氨基酸

建立液相色谱串联质谱法测定烟草中20种游离氨基酸的方法。烟草样品经0.1%的盐酸溶液超声萃取并离心后,直接进样测定。色谱柱采用XTerra MS C18(50mm×2.1mm×2.5μm),0.1%甲酸溶液和乙腈为流动相。结果表明:20种氨基酸的检出限为0.001～0.011μg/mL,标准曲线的拟合度均大于0.999,回收率在86.4%～105.9%之间。该方法操作简单,灵敏度高,适用于烟草中游离氨基酸的检测。     

柱前衍生气相色谱法分离手性二醇类化合物

本文建立了柱前衍生气相色谱法分离1,3-丁二醇、2,3-丁二醇、2,5-己二醇和3,6-辛二醇4种二醇类化合物的手性分离方法。分别使用N-甲基-N-(三甲基硅烷)三氟乙酰胺和三氟乙酸酐为衍生剂与二醇化合物反应,生成相应的衍生物,用CP-Chirasil-Dex CB色谱柱分离二醇对映体,采用分流进样方式,检测器为氢火焰离子化检测器(FID)。在选定的色谱条件下,四种手性化合物分别在2.50～8×10³μg/mL、1.30～8×10³μg/mL、3.5～1×10⁴μg/mL、5～1×10⁴μg/mL范围内呈线性关系,相关系数分别为0.9994、0.9997、0.9990和0.9971,手性分离度均达到2以上,检测限分别为0.8μg/mL、0.4μg/mL、1.8μg/mL、2.5μg/mL。该方法适用于生物酶催化反应所生成的(2R,3R)-2,3-丁二醇、(R)-1,3-丁二醇、(2S,5S)-2,5-丁二醇和(3S,6S)-3,6-辛二醇的检测以及酶促反应过程的监控。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。