南方红豆杉总生物碱的含量测定

目的考察南方红豆杉总生物碱的含量测定方法。方法采用分光光度法测定南方红豆杉中总生物碱的含量。以乌头碱为对照品,溴甲酚绿为酸性染料,在pH为3.0±0.1的缓冲液条件下,三氯甲烷萃取,于415 nm波长处测定其吸光度。结果乌头碱在0.009 6～0.022 4 mg/mL质量浓度范围内线性关系良好,回归方程Y=48.813X-0.025 2,r=0.999 6,平均加样回收率为100.26%(RSD为2.04%),其总生物碱含量平均值为0.382%。结论分光光度法简便、准确,可用于南方红豆杉总生物碱的含量测定。     

紫外分光光度法测定半枝莲黄芩苷的含量

目的 :建立紫外分光光度法测定半枝莲黄芩苷的含量的方法。方法 :采用50%乙醇回流提取工艺和紫外分光光度法测定半枝莲中黄芩苷的含量,以黄芩苷为对照品,在278nm波长处测量。结果:得黄芩苷回归方程y=56.985x+0.0083(r2=0.9996),表明黄芩苷在0.00272~0.0136mg/m L浓度范围内线性关系良好,平均加样回收率(n=6)以黄芩苷计为99.8%,RSD为0.58%。结论 :此方法操作简单,精密度、稳定性和重复性良好,可以用于半枝莲中黄芩苷的含量测定方法之一。     

紫外分光光度法测定蒙药广枣药材中总黄酮含量

目的:建立蒙药材广枣中总黄酮(TFC)的含量测定方法,为完善该药材的质量标准提供依据。方法:采用紫外分光光度法,以亚硝酸钠为还原剂,硝酸铝为络合剂,氢氧化钠为显色剂,在510 nm处测定TFC的吸光度值。结果:芦丁质量在0.2~1.2 mg范围内与吸光度呈良好线性关系(r=0.999 0),平均回收率为101.15%,RSD为0.84%(n=9)。结论:本研究所建立广枣中TFC含量测定方法,操作简便,准确可靠,可用于该药材的质量评价。     

分光光度法测定水中铁含量

为避免铁结成的水垢影响锅炉的安全运行,要求锅炉给水必须达到一定标准,对铁的测定显得尤为重要,文章讨论了分光光度法对水中铁的测定。     

火焰光度法测定砼外加剂碱含量

在混凝土工程中外加剂的碱含量高低是影响工程耐久性的重要指标。碱含量的测定方法主要是火焰光度法和原子吸收光谱法,由于火焰光度计设备投入少、选择性强、操作简单,应用比较广泛。本文结合工作体会,谈一谈用火焰光度计测混凝土外加剂K2O、Na2O含量的方法,与同行商榷。     

紫外可见分光光度法测定水中微量汞

介绍了利用巯基棉对汞的吸咐能力很强这一特性，用TU－1221紫外可见分光光度计测定环境水样中微量汞的方法，方法简单，快速，灵敏度高，选择性好。     

吸附剂对益母草生物碱含量测定的影响

目的:寻找益母草胶囊中生物碱含量测定不合格的原因。方法:采用分光光度法,对益母草胶囊进行生物碱的含量测定。结果:通过更换吸附剂,得到满意结果。结论:含量测定中使用的吸附剂对测定有影响,对此不容忽视。     

紫外分光光度法测定可乐中咖啡因的含量

本文建立了用紫外分光光度法测定可乐中咖啡因的方法。可乐经前处理后,以三氯甲烷为萃取液进行富集,于277 nm波长下紫外检测,咖啡因在0~30 ug/mL范围内的线性关系良好,线性回归方程为Y=0.456 X-0.0019,相关系数为0.9998,方法检出限为为3ug/mL,被测物的加标回收率为97.5%~101.3%。     

浅谈混凝土配合比中的碱总含量计算

介绍了混凝土配合比设计的试配要求和所用材料，阐述了试验室配合比计算方法，以及混凝土中的碱总含量计算法，以有效控制混凝土的延伸开裂和损毁现象。     

屏边三七总皂苷的含量测定研究

目的:测定屏边三七中总皂苷的含量。方法:通过实验研究确定了屏边三七总皂苷检测时的显色条件及检测波长。采用紫外-可见分光光度法测定屏边三七中总皂苷的含量。结果:屏边三七中总皂苷在5%香草醛-冰醋酸和73%的高氯酸溶液中,于65℃下加热25 min显色最优,最佳检测波长为543 nm;精密度、稳定性、重复性和加样回收试验等RSD均小于2.5%。结论:屏边三七中总皂苷平均含量为3.60%。所建立的检测方法可靠、结果稳定、重现性好,其可用于屏边三七中总皂苷的含量测定。     

对氨基二甲苯胺分光光度法测定水中余氯

建立了对氨基二甲苯胺分光光度法测定水中余氯的新方法。利用氯气在一定条件下能氧化对氨基二甲苯胺使其成为红色的氧化态形式 ,可以定量测定氯 ,实验条件如下 :最大吸收波长为5 2 0 nm ,p H控制在 2 .5～ 4.0之间 ,缓冲溶液用量为 2 ml,显色液体积为 3ml。氯浓度在 0 .1～2 .0 mg/L范围服从比尔定律。检测限 c L D为 0 .0 2 mg/L,水中常见的离子不干扰测定。该法用于自来水等样品中余氯含量的测定 ,加标回收率在 98%～ 1 0 4 %之间 ,结果准确可靠。     

展示KDR胞外区VEGF结合域的T4噬菌体对肺癌细胞增殖侵袭的抑制作用

目的:构建展示KDR的T4噬菌体并在细胞水平上检测其抑制肿瘤细胞增殖侵袭的作用及机制。方法:利用SOE-PCR的方法将KDR膜外区D2和D3与T4噬菌体小衣壳蛋白SOC基因融合并克隆到pET28b表达载体中,经IPTG诱导表达并纯化后,利用体外展示技术将重组KDR-SOC蛋白展示在T4噬菌体表面,得到T4-KDR噬菌体。MTT法检测T4-KDR噬菌体对肺癌A549细胞的增殖抑制作用,并采用Transwell法检测其对VEGF促侵袭作用的影响。RT-PCR法检测T4-KDR对MMP-2和MMP-9 mRNA水平的影响,并通过Western blot方法检测其对VEGF诱导ERK1/2磷酸化及其下游CyclinD1,p27,Bcl-2和Bax表达水平的影响。结果:KDR-SOC在大肠杆菌中稳定表达,展示KDR的T4-KDR噬菌体具有结合VEGF-165的能力,并显著抑制肿瘤细胞增殖和侵袭活性,降低MMP-2和MMP-9基因mRNA水平。Western blot结果表明T4-KDR噬菌体抑制VEGF诱导ERK1/2的磷酸化,降低CyclinD1及Bcl-2表达的同时,提高p27和Bax的表达。结论:展示KDR的T4噬菌体具有抑制肺癌细胞增殖和侵袭作用,其对MEK/ERK信号通路及其下游调控因子的影响是其作用的重要分子机制。     

高效液相色谱法测定不同产地山药中脱氢表雄酮含量

目的:分析不同产地的山药中脱氢表雄酮的含量,为山药质量标准的建立提供参考。方法:采用高效液相色谱分析,Sun-Fire C18色谱柱(4.6mm×250mm,5μm);甲醇-水(85:15)为流动相;流速为0.8mL.min-1;检测波长204nm。结果:10批不同产地山药中脱氢表雄酮含量介于4.51～47.82mg.kg-1。结论:该方法操作简便,结果稳定可靠,可作为山药质量评价参考指标之一。     

Determination of total sulphur in fuel oils by molecular emission cavity analysis

Molecular emission cavity analysis (MECA) is used for the determination of total sulphur in fuel oils. The sulphur is reduced by heating the sample with Devarda's alloy in an HCl medium, with subsequent liberation of H2S and measurement of the chemiluminescent S2 emission intensity in the MECA cavity. The total sulphur recovery from different sulphur-containing compounds and fuel oils is always ca. 100%. The precision and accuracy are good. Applications to certified and commercial fuel oils are discussed.     

固相萃取光度法测定饮用水中痕量铬

基于固相萃取分离技术结合分光光度法,建立了一种测定饮用水中Cr（Ⅵ）的分析方法。在强酸性介质中,Cr（Ⅵ）与二苯碳酰二肼反应生成Cr（Ⅲ）-二苯偶氮碳酰肼有色络合物,该有色络合物被Sep—PakC18固相萃取小柱富集,用乙醇和硫酸混合液洗脱后分光光度法测定,固相萃取柱不被破坏且可重新处理使用。同时研究了固相萃取条件,讨论了共存离子的干扰及消除。将该方法用于测定饮用水中痕量铬,相对标准偏差RSD为3．5％～5．1％（n=5）,标准加入回收率为99％-105％。     

Relationships between ultraviolet absorbance and total organic carbon in two upland catchments

Regression equations relating u.v. absorbance to total organic carbon (TOC) in river water are compared for streams draining two upland catchments in north-east Scotland which have similar climate, topography and land use but contrasting acidic and basic parent materials. A comparison is also made of regression equations for individual tributaries contributing to the main streams in each catchment. Reasons for observed differences are suggested. Changes in u.v. absorbance vs TOC relationships through storm events are discussed, and the problems associated with using TOC/absorbance relationships to monitor changes in TOC with time through storms are briefly considered.     

Determination of soluble aluminium concentration in alkaline humic water using atomic absorption spectrophotometry

The steps of the standard method to determine soluble aluminium concentration are filtering, followed by acidifying, then analysing with the atomic absorption spectrophotometer (AAS). When applied to alkaline humic water, acidification gives rise to the formation of humic acid as a brown particulate matter. Of the total soluble aluminium in the original water, 49-61% forms complexes with the particulate humic acid upon acidification. Although the AAS is capable of detecting the binding aluminium, the particulate nature of humic acid easily induces inaccurate readings as a result of the non-uniform distribution of the particulate matter. A more precise analysis of soluble aluminium concentration of alkaline humic water is shown to be achievable in basicified solutions instead. Basicified solutions keep humic acid in the soluble form; hence maintain the homogeneity of the sample.     

Determination of total chromium in environmental water samples

It is often desirable to quantify both dissolved Cr(VI) and total Cr in samples accurately. Various protocols are now being utilized to quantify the amount of total chromium in natural waters and each of these has possible interferences. This study describes the shortcomings of each method when particulate iron is present in a water sample, and a more rigorous digestion protocol is tested. Data from bench studies as well as a field survey of 21 water utilities are presented. Additionally, field data from several hundred water utility samples are presented to illustrate the potential for incomplete recovery of total chromium using accepted protocols.     

过硫酸铵分光光度法测定水中锰的优化

考察了采用过硫酸铵分光光度法测定锰的过程中，时间对测量结果的影响。试验表明，过硫酸铵显色后煮沸时间超过10min以后，吸光度的变化较大，测量结果不稳定，煮沸时间以0．5～1．0min为宜。显色冷却转移到50mL比色管后的放置时间也会对测定结果产生影响，推荐放置时间为110～160min。