钯—抗坏血酸基体改进剂平台石墨炉原子吸收光谱法测定贻贝标样中的砷

本实验建立了钯－抗坏血酸基体改进剂平台石墨炉原子吸收光谱法测定贻贝中砷的方法。研究了基体改进剂氯化钯、抗坏血酸用量对测定的影响，比较了氯化钯－抗坏血酸、氯化钯、硝酸镍三种基体改进剂及平台石墨管、普通石墨管在测定贻贝中砷的灵敏度。方法的相对标准偏差为３．２％，回收率在９７．８％－１０７．４％之间，检出限为１２．０ｎｇ／ｍＬ。     

钯－抗坏血酸基体改进剂平台石墨炉原子吸收光谱法测定贻贝标样中的砷

本实验建立了钯－抗坏血酸基体改进剂平台石墨炉原子吸收光谱法测定贻贝中砷的方法。研究了基体改进剂氯化钯、抗坏血酸用量对测定的影响，比较了氯化钯－抗坏血酸、氯化钯、硝酸镍三种基体改进剂及平台石墨管、普通石墨管在测定贻贝中砷的灵敏度。方法的相对标准偏差为３．２％，回收率在９７．８％—１０７．４％之间，检出限为１２．０ｎｇ／ｍＬ。     

分光光度法测定纯稀土金属中微量硅

本文研究了纯稀土金属中微量硅的钼蓝测定方法,在ｐＨ＝１．２时,加入酒石酸破坏磷钼酸以消除磷的干扰,以抗坏血酸为还原剂,在λ＝８１０ｎｍ处,测定吸光度,测定浓度范围为０．０００５％￣０．０１５％。     

次甲基绿—溴酸钾体系催化光度法测痕量钒（V）的研究

本文基于在抗坏血酸存在下，痕量钒（Ｖ）对溴酸钾氧化次甲基绿褪色的新指示反应，建立了一个催化动力学光度法测痕量钒（Ｖ）的新方法。线性范围为０－０．１２μｇ／２５ｍＬ和０．１２－０．２０μｇ／２５ｍＬ，方法检出限为３．４×１０＾－１０ｇ／ｍＬ。用于人发、水样中痕量钒（Ｖ）的测定，结果满意。     

次甲基绿－溴酸钾体系催化光度法测痕量钒（Ⅴ）的研究

本文基于在抗坏血酸存在下，痕量钒（Ⅴ）对溴酸钾氧化次甲基绿褪色的新指示反应，建立了一个催化动力学光度法测痕量钒（Ⅴ）的新方法。线性范围为０—０．１２μｇ／２５ｍＬ和０．１２—０．２０μｇ／２５ｍＬ，方法检出限为３．４×１０~（－１０）ｇ／ｍＬ。用于人发、水样中痕量钒（Ⅴ）的测定，结果满意。     

石墨炉原子吸收法测定化妆品中的铅和砷

本文研究了石墨炉原子吸收法测定化妆品中铅、砷的方法。用湿式消解法消化样品，易掌握。方法简便，灵敏度高。用本方法测定铅的检出限为０．０１０ｎｇ，砷的检出限为０．０１３ｎｇ，相对标准偏差为０．８％－５．２％，方法的回收率为９６．１％－１０５．８％。     

泡沫塑料吸附—石墨炉原子吸收光谱法测定地质物料中痕量铊

本文研制定了一种泡沫塑料吸附－石墨炉原子吸收光谱法测定地质物料中痕量铊的分析，在所先定的实验条件下，方法检出限为０．０５μｇ／ｇ、样准曲线范围为１０－３００ｎｇ／ｍＬ，Ｔｌ含量水平为０．７１μｇ／ｇ时的测定精度为６．０％，方法回收率９９．０％－１００．０％。经标样及大量样品分析验证，分析方法准确可靠。     

二氢奎尼丁的荧光分析法研究

本文探讨了用荧光光度法检测二氢奎尼丁的方法及实验条件，在０．０５ｍｏｌ／Ｌ Ｈ２ＳＯ４、１％ＨＡＣ介质中最大激发波长２５０ｎｍ、３６０ｎｍ，最大发射波长４４４ｎｍ，量子产率为０．５５（在０．０５ｍｏｌ／Ｌ Ｈ２ＳＯ４介质中）、０．５４（在１％ＨＡＣ介质中）。线性范围０．０５ｎｇ／ｍｌ￣５．０μｇ／ｍｌ。检出限量为０．０１ｎｇ／ｍｌ。本方法简便、快速、灵敏度高，适用于临床医学监测服药病人血浆及尿液中     

波长色散X射线荧光光谱法测定黄金饰品含金量

本文提出应用波长色散Ｘ射线荧光光谱仪测定黄金饰品含金量的方法，本法对原有样品盒进行了改造，增设特制窗口和采取样品固定等措施，以系列参考标样建立校准曲线，用经验系数法校正基体效应。比例模拟法校正含量。９个参考标样和１６个金标牌的测定结果表明，在含金量为３７．５０％－９９．９９％的范围内，方法的准确度好：含金量在９９．９９％－９８．９８％范围时，误差为０．０３％－０．１２％，在９８．９８％－３７．５０％范围时，误差为０．０１％－０．５２％，选用含金量不同的５个参考标样为代表，以０．７和１．４的模拟比例，经不同时间多次测定进行统计，相对标准偏差为０．０５％－０．５０％，说明方法的精密度好，本法操作方便，时样品无破坏     

火焰原子吸收光谱法连续测定茶叶中的锌、铜和锰

本文研究了茶叶中锌、铜、锰微量金属元素的火焰原子吸收分光光度法的测定。方法简便、快速,灵敏度和精密度高,特征浓度锌为０．００９μｇ／ｍＬ／１％,铜为０．０３１μｇ／ｍＬ／１％,锰为０．０１７μｇ／ｍＬ／１％;相对标准偏差为０．９％～５．０％,回收率９２．０％～１０６．０％。     

化学发光抑制法测定抗坏血酸

利用抗坏血酸对DTMC H2 O2 化学发光体系的抑制作用 ,研究了对抗坏血酸进行间接测定的可能性。试验发现 ,化学发光猝灭率 (R)与抗坏血酸浓度在 1 0× 10 - 7～ 8 0× 10 - 6 mol·L- 1 范围内呈线性关系 ,检出限达到 8 0× 10 - 8mol·L- 1 (S N =3)。对 1 0× 10 - 6 mol·L- 1 抗坏血酸进行 10次平行测定 ,其化学发光强度猝灭率相对标准偏差为 4 6 %。该猝灭体系不需要额外的掩蔽剂 ,方法简单、选择性好 ,可直接应用于一些食品中微量抗坏血酸的测定。     

Ascorbic acid stability in fruit juices during thermosonication

Thermosonication is an emerging technology useful for inactivating microorganisms and enzymes in fruit juices. However, the effect of the ultrasound processing on the ascorbic acid content is not clear and the results reported in the literature are contradictory. In this work, the impact of sonication and thermosonication on the ascorbic acid content was first evaluated in model systems. Degassed model solutions at four different pH values (3–6) were processed with or without sonication for 60 min at two different conditions of temperature (25 and 55 °C). In all cases, the ascorbic acid was stable under the treatment. After that, two commercial deaerated fruit juices were processed with and without US at 55 °C. The ascorbic acid was also retained in these juices after the ultrasound processing under the most severe conditions studied. In conclusion, previous degassing/deaerating of fruit juices is recommended to prevent ascorbic acid degradation when thermosonication is applied.     

酶催化动力学光度法测定抗坏血酸

基于抗坏血酸对血红蛋白模拟酶催化体系的抑制作用,建立酶催化动力学光度法测定抗坏血酸的新方法。研究了体系的最佳条件及动力学行为,测定的线性范围为2.0×10-7—5.9×10-5mol/L,方法检出限为7.0×10-8mol/L。对6.0×10-6mol/L的抗坏血酸进行11次平行测定相对标准偏差为2.5%。此方法可用于药剂和蔬菜中抗坏血酸含量的测定。     

Effect of high hydrostatic pressure on phenolic compounds,ascorbic acid and antioxidant activity in cashew apple juice

The cashew apple is native to Brazil, but there is insufficient information regarding the nutritional properties of this fruit. The objective of this study was to evaluate the impact of high pressure processing (HPP) at room temperature (25 °C) on phenolic compound and ascorbic acid contents and antioxidant capacity of cashew apple juice. This study showed that HPP at 250 or 400 MPa for 3, 5 and 7 min did not change pH, acidity, total soluble solids, ascorbic acid or hydrolysable polyphenol contents. However, juice pressurized for 3 and 5 min showed higher soluble polyphenol contents. Antioxidant capacity, measured by the ferric-reducing antioxidant power method, was not altered by HPP, but when treated at 250 MPa for 3 min, it resulted in an increased value when 2,2-diphenyl-1-picrylhydrazyl was used. These data demonstrate that HPP can be used in the food industry for the generation of products with higher nutritional quality.     

催化动力学光度法测定痕量抗坏血酸

研究了在pH4 5的HAc NaAc缓冲介质中 ,利用抗坏血酸对钒催化溴酸钾氧化还原型罗丹明B显色反应具有强烈的活化作用 ,建立了催化动力学光度法测定抗坏血酸的新方法。方法的线性范围为 0～ 7 0 μg·mL- 1 ,检出限为 2 5× 10 - 7g·mL- 1 ,用于维生素C片和西红柿中抗坏血酸的测定 ,结果满意。     

动力学荧光法测定抗坏血酸

在稀硫酸介质中,抗坏血酸活化溴酸钾氧化孔雀绿的反应,使其荧光增强,建立了动力学荧光测定抗坏血酸的新方法。在最佳条件下,测定的线性范围为10—120μg/mL,方法的检出限为0.0158μg/mL。对浓度为20μg/mL的抗坏血酸进行11次平行测定相对标准偏差为2.6%。此方法已用于药剂中抗坏血酸的测定,结果满意。     

Effect of ultrasound,heating and enzymatic pre-treatment on bioactive compounds in juice from Berberis amurensis Rupr.

The aim of the study was to assess the influence of ultrasound (frequency 20 kHz, amplitude 70%, power 140 W for 10 min), heating (80 °C, 5 min) and enzymatic pre-treatment of mash (50 °C, Rohapect 10L at a dose of 0.23 g/1000 g, maceration time 60 min) on the yield, the content of phenolic compounds (including anthocyanins), ascorbic acid, and the antioxidative capacity of Berberis amurensis juice. Additionally, the polyphenols profile of this raw material and juices was identified. 25 phenolic compounds were identified in the fruit and 24 in juices. The content of phenolics in the fruit was 636 mg/100 g. Chlorogenic acid, 4-hydroxybenzoate and quercetin-3-O-glicoside were predominant. The content of anthocyanins in the fruit was 217 mg/100 g f.w., where peonidin-3-O-glucoside (98%) was predominant. The content of ascorbic acid amounted to 16.60 mg/100 g. The yield of the barberry juice pressing process ranged from 56% to 60% – there were no differences between the mash treatment methods. The enzymatic and thermal treatment of the mash resulted in the highest content of phenolic compounds in the juice. The sonication resulted in the highest content of anthocyanins, including peonidin-3-O-glucoside, as the main anthocyanin. The thermal treatment of the mash resulted in a lower loss of ascorbic acid than the other methods. The juice from the mash subjected to pectinolysis or heat treatment exhibited the highest antioxidative capacity.     

Fluorimetric Determination of Cerium(IV) with Ascorbic Acid

A simple, sensitive, and selective method for the determination of cerium(IV), based on the oxidative reaction between cerium(IV) and ascorbic acid, has been described. The fluorescence comes from Ce(III) at λ_excitation 298 nm and λ_emission 358 nm, which, in turn, is obtained from the oxidation of ascorbic acid by Ce(IV) in the presence of sulfuric acid. The optimum conditions such as concentrations of ascorbic acid, sulfuric acid media and pH of the buffer solution were investigated. The fluorescent intensity of the system is linear over the range 0.0531 μg/ml to 0.3322 mg/ml Ce(IV) and detection limit and correlation coefficient are 0.0145 μg/ml and R=0.99987,respectively.     

紫外分光光度法测定芦柑中的还原型维生素C

研究紫外分光光度法测定芦柑中还原型维生素C的新方法。利用活性炭将还原型维生素D氧化为在紫外区无吸收的脱氢抗坏血酸,测定氧化前后的OD245之差,得出芦柑中还原型维生素C的含量。该方法简单、快速、准确性及精密度好,与2,6-二氯靛酚滴定法比较,结果基本一致。     

泡塑富集-石墨炉原子吸收光谱法测定地质样品中微量铊

采用HF-HClO4-HNO3溶解样品,泡沫塑料富集-石墨炉原子吸收光谱法测定岩石、土壤、水系沉积物等地质样品中微量铊。以抗坏血酸为基体改进剂,Fe3+加入量选择200mg,灰化温度为600℃,原子化温度为1600℃。方法用于测定国家一级标准物质,结果与标准值基本一致。方法精密度(RSD,n=8)为2.73%—3.93%,回收率为96.7%—101.3%,检出限可达0.060μg/g。