共查询到19条相似文献,搜索用时 62 毫秒
1.
提出了紫外分光光度法测定海水中季铵盐含量的方法。通过对不同浓缩倍数的海水进行紫外扫描,确定季铵盐的最大吸收波长为263nm。蒸馏水和海水中季铵盐的质量浓度和其吸光度分别在100mg·mL-1和50mg·mL-1以内呈线性关系。方法的检出限(3S/N)为3.205mg.L-1,平均回收率为94.95%,相对标准偏差(n=5)为1.9%。 相似文献
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紫外分光光度法测定丙酮酸 总被引:6,自引:0,他引:6
基于丙酮酸在紫外吸收光谱290~340nm区有较强的吸收,建立了分光光度法测定丙酮酸(盐)的方法。在pH11.0的水溶液中,位于320nm处,丙酮酸有吸收,而其他有机酸和杂质无吸收或吸收不明显。在320nm处,丙酮酸在0.2~2.8g/L范围内符合比耳定律,其R2为0.9997,平均回收率99.8%,RSD0.46%。该法适合于发酵液和分离提取过程中丙酮酸及其盐类的测定。 相似文献
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食品中甜蜜素的紫外分光光度法测定 总被引:14,自引:2,他引:14
采用紫外分光光度法测定食品中的甜蜜素。该法在0.2~1.0g/L甜蜜素范围内符合比尔定律,回收率为95.0%~102.7%,相对标准偏差(RSD)为2.66%~5.40%,食品中共存的苯甲酸、山梨酸、糖精钠在0~10.0g/L范围内,色 0~2.0g/L范围内不影响测定。方法简捷,准确。 相似文献
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紫外分光光度法测定大豆中大豆异黄酮 总被引:13,自引:0,他引:13
以染料木苷为标准品,利用三波长紫外分光光度法对东北大豆的11个品种进行了异黄酮含量的测定。测定结果表明,“垦丰”和“中豆”两个品种的异黄酮含量较高,分别达到0.246%和0.221%;“东农44单株”和“东农355”两个品种的异黄酮含量较低,分别为0.101%和0.110%。 相似文献
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从花生壳中提取总黄酮物质,并用紫外分光光度法对其进行测定。建立了一种以无水乙醇为溶剂,检测波长为359nm的测定花生壳总黄酮含量的新方法。结果表明,总黄酮含量在0.005~0.025mg/mL范围内与吸光度线性关系良好,相关系数r=0.9995,平均加标回收率为98.5%,测定结果的相对标准偏差为2.1%(n=5)。该法适用于花生壳总黄酮的定量测定。 相似文献
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紫外分光光度法测定中草药中铁的含量 总被引:3,自引:0,他引:3
对白芍、党参、白术、茵陈、天冬、枸杞子、当归、菟丝子、金银花、桔梗中微量元素铁的含量进行了测定,为进一步研究其药理作用提供基础。中草药消化后配制成溶液,用邻二氮菲作显色剂,使用UV-1200型紫外分光光度计在510 nm处测定各样品的吸光度(A),求出样品中微量元素铁的含量。结果显示,当归和金银花中铁的含量较丰富,分别为(135.367 8±0.111 1)μg/g和(125.936 4±0.159 9)μg/g;桔梗含铁量最少,为(3.510 9±0.159 9)μg/g,10种中草药中铁含量有显著性差异(P<0.05)。结果为使用中草药治疗系统疾病提供了可靠数据,10种中草药在用量范围内Fe含量适合人体每天正常摄入量。 相似文献
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溴氧化紫外分光光度法测定维生素C和多酚 总被引:1,自引:0,他引:1
研究了同时测定维生素C和多酚的新方法。在体积分数38%和47.5%的乙醇、6×10-5mol/LBr2、2.5×10-3mol/LKI水溶液中,维生素C和多酚类的表观摩尔吸光系数(L.mol-1.cm-1)分别为5.42×104、8.22×105和5.46×104、8.60×105,维生素C和多酚的相对标准偏差(RSD)分别为2.5%、2.3%和2.1%、2.6%,该法用于绿豆芽、酸橙、未熟苹果、青椒中的维生素C和多酚含量测定,回收率为95.78%~100.7%。 相似文献
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A. Hiroki H.T. Tran N. Nagasawa T. Yagi M. Tamada 《Radiation Physics and Chemistry》2009,78(12):1076-1080
Blend hydrogels based on the carboxymethyl cellulose (CMC) and carboxymethyl chitosan (CMCts) were prepared by γ-irradiation of a high concentrated CMC/CMCts aqueous solution. Properties of the hydrogels, such as gel fraction, swelling ratio, gel strength, and metal adsorption for Pb and Au were investigated. The gel fraction increased with increasing dose, while the swelling ratio decreased with increasing it. The obtained blend hydrogels had high adsorption performance which was controlled by adjusting the composition of CMC/CMCts. 相似文献
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紫外光谱法测定饮料中的咖啡因含量 总被引:3,自引:0,他引:3
建立了一种测定饮料中咖啡因含量的紫外光谱分析法.采用三氯甲烷为萃取剂,控制三氯甲烷与饮料的体积比为8:1,经充分振荡后离心分离,取清液在276 nm处测定紫外吸收光谱,能够满意地测定市售饮料中的咖啡因浓度.分析结果的相对标准偏差小于4%;在饮料中加入不同浓度的咖啡因标准溶液,回收率在94.0%~112.0%之间. 相似文献
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提出了同时测定痕量磺胺嘧啶(SD)和磺胺二甲嘧啶(SM2)的溴取代紫外光度分析法, 实验结果表明: 在6×10-5 mol/L Br2, 2.5×10-3 mol/L KI溶液和体积分数40%乙醇溶液中, 测定SD和SM2的线性范围分别为: 0~2.25 mg/L, 和0~1.125 mg/L, 摩尔吸光系数(L·moL-1·cm-1)分别为: 在水中9.66×104和8.16×104, 在乙醇水溶液中1.25×105, 1.99×105. 用此法对猪肉中SD和SM2进行测定, 猪肉中SD和SM2的质量分数分别为7.53、7.35 mg/kg, 回收率在91.4%~104.4%, SD和SM2的相对标准偏差分别为0.5%、1.5%. 相似文献
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Jonas Enebro Dane Momcilovic Matti Siika-aho Sigbritt Karlsson 《Cellulose (London, England)》2009,16(2):271-280
The benefits of applying cellulose selective enzymes as analytical tools for chemical structure characterization of cellulose
derivatives have been frequently addressed over the years. In a recent study the high selectivity of cellulase Cel45A from
Trichoderma reesei (Tr Cel45A) was utilized for relating the chemical structure to the flow properties of carboxymethyl cellulose (CMC). However,
in order to take full advantage of the enzymatic hydrolysis the enzyme selectivity on the cellulose substrate must be further
investigated. Therefore, the selectivity of Tr Cel45A on CMC was studied by chemical sample preparation of the enzyme products
followed by mass spectrometric chemical structure characterization. The results strongly suggest that, in accordance with
recent studies, also this highly selective endoglucanase is able to catalyze hydrolysis of glucosidic bonds adjacent to mono-substituted
anhydroglucose units (AGUs). Furthermore, the results also indicate that substituents on the nearby AGUs will affect the hydrolysis. 相似文献
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A new study of the enzymatic hydrolysis of carboxymethyl cellulose with a bulk acoustic wave sensor 总被引:4,自引:0,他引:4
A new bulk acoustic wave (BAW) cellulase sensing technique, which is based on the enzymatic hydrolysis process of sodium carboxymethylcellulose (CMC) by cellulase, was established. The frequency shift curves of BAW sensor indicated that the viscosity of the tested solutions decreased during the hydrolysis process. The hydrolysis rate of CMC by cellulase was calculated from the frequency shift curves. The hydrolysis rate of CMC under different pH conditions at 30°C showed that cellulase had high hydrolysis ability approximately at pH 5.0. Kinetic parameters (the Michaelis constant Km and the maximum rate Vmax) of the process were estimated by using a linear method of Lineweaver–Burk plot. Km is 1.95±0.25 mg ml−1 and Vmax is −(4.25±0.58)×10−3 g1/2 cm−3/2 cP1/2 min−1. Also the activation energy (Ea) of the enzymatic hydrolysis, with a value of 51.99±1.26 kJ mol−1, was estimated in this work. 相似文献
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Lidija Fras Zemljič Per Stenius Janne Laine Karin Stana-Kleinschek 《Cellulose (London, England)》2008,15(2):315-321
Adsorption of carboxymethyl cellulose (CMC) as a method to introduce charged (ionizable) groups onto cellulose cotton fibre
surfaces was investigated. The method was based on application of a previously published method used for wood fibres. The
amount of adsorbed ionizable groups was determined indirectly by analysis of CMC in solution by the phenol–sulphuric acid
method and directly by conductometric titration of the fibres. Results from the two methods correlated well. The molecular
weight and purity of the CMC had an influence on its adsorption onto cotton; high molecular weight CMC was preferentially
adsorbed. The adsorbed charge correlated linearly with the amount of CMC adsorbed. The total charge of the cotton fibres could
be increased by more than 50% by adsorption of CMC. It is expected that this modification procedure can be used in a wide
spectrum of practical applications.
Lidija Fras Zemljič and Karin Stana-Kleinschek are the members of the European Polysaccharide Network of Excellence (EPNOE). 相似文献
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《Arabian Journal of Chemistry》2020,13(1):694-708
Targeted drug delivery systems using natural polysaccharide/protein biopolymer for tumor cells are an attractive platform for enriching the therapeutic effects and reducing the side effects of the drug. Carboxymethyl cellulose (CMC) and casein (CA) nanogels (NGs) loaded with curcumin (CUR) were prepared by self-assembly method and fabricated with folic acid (FA) and casein using layer-by-layer (LbL) technique for skin cancer drug delivery. The prepared samples were characterized by techniques like zeta potential, FTIR, XRD, TGA and Cryo-SEM. Both the swelling and in vitro drug release was performed in acidic pH (4.5 and 6.8) and physiological pH 7.4. Hemolysis assays demonstrated that the drug carriers are hemocompatible. Confocal microscope studies indicate facilitated uptake of 2-FA/CA/CUR@CMC-CA NGs in MEL-39 melanoma cancer cell line, which in turn result in a higher potential for apoptosis. Compared to pure CUR and CUR@CMC-CA NGs, the 2-FA/CA/CUR@CMC-CA NGs has lower IC50 value and superior cytotoxicity in MEL-39 cells because of folate-receptor mediated endocytosis evaluated by the cellular viability quantification using MTT assay and optical microscope images. Finally from in vitro skin permeation experiments, 2-FA/CA/CUR@CMC-CA NGs showed 3.47 ± 0.03 to 4.15 ± 0.25 μg/ml CUR concentrations at the stratum corneum, epidermal and dermal layers. Overall, our results put forth 2-FA/CA/CUR@CMC-CA NGs as an aspiring candidate to achieve enhanced anticancer effects against melanoma skin cancer. 相似文献
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《Arabian Journal of Chemistry》2022,15(11):104270
These days, Ophthalmic wound treatment is a major problem; due to its nature, bio/materials are the best choices as wound dressing materials. The main objective of the current survey is to develop and investigate effective wound dressing materials for skin care applications. In these ways, we combined the good biological properties of Cobalt-doped hydroxyapatite particles (CoHAp) with the structural properties of Polycaprolactone (PCL)/ carboxymethyl cellulose (CMC) nanofibers. Electrospinning and co-precipitation methods were used to synthesize nanofibers and CoHAp particles, respectively. Nanocomposites were synthesized in the absence and different percentages of CoHAp. The PCL/CMC, PCL/CMC/CoHA 5 %, PCL/CMC/CoHA 10 %, and PCL/CMC/CoHA 15 % formulated nanocomposites have the diameter of 383 ± 50, 391 ± 84, 441 ± 65, and 495 ± 99 nm, respectively. The synthesized nanofibrous wound dressing porosity and water absorption capacity were in the range of 40 to 60 % and 32 to 63 %, respectively. Hemo and cytocompatibility of the nanofibrous wound dressing were analyzed by in vitro evaluation, and the results were satisfactory and the structures were fully biocompatible. The PCL/CMC/CoHA 10 % wound dressing, were selected as the best nanocomposites for wound healing based on our animal studies on the healing outcomes. The results showed that the PCL/CMC nanofibers-Cobalt-doped HAp wound dressing is an effective bioactive nano-biomaterials for the wound healing process. 相似文献