共查询到20条相似文献,搜索用时 0 毫秒
1.
《Analytical letters》2012,45(10):1875-1883
Abstract A method is developed for the 2nd and 3rd order derivative spectrophotometric determination of 0.5–6 and 0.5–7 μ.ml?1 of ascorbic acid, respectively. For its determination in soft drinks a blank solution is prepared from the soft drink to be analyzed in order to avoid the interference from the other additives and colouring matter present. 相似文献
2.
《Analytical letters》2012,45(12):2367-2376
Abstract A method is developed for the simultaneous 2nd order spectrophotometric determination of 1 to 7 μg.mL?1 of each of benzoic and sorbic acids in non vegetal soft drinks, using a blank prepared from the same soft drink to be analyzed in order to avoid the interferece from other additives and colouring matter present. 相似文献
3.
应用超声技术辅助预处理,以纳米银为活性基底,在溶液pH 5.0、纳米银与阿斯巴甜(APM)混合比例1∶1、混合温度30℃、加热时间6 min的条件下,利用表面增强拉曼光谱(SERS)结合化学计量法对纯品及软饮料中APM进行定量检测。结果表明:APM在0.5~100 mg/L范围内线性关系较好,其中水标准溶液的相关系数为0.993 3,检出限(LOD)为0.41 mg/L,苏打水、雪碧、可乐、芬达等标准溶液的相关系数为0.974 7~0.984 8,加标平均回收率为88.4%~121%,相对标准偏差小于7%。运用SERS检测软饮料中APM具有分析速度快、无损、环境污染小等优点,适用于食品中阿斯巴甜的定量分析,为食品添加剂的进一步表征和检测建立了依据,显示了SERS技术在化学物质检测领域具有巨大潜力。 相似文献
4.
同时测定碳酸饮料中苯甲酸钠、山梨酸钾和安赛蜜的高效液相色谱法 总被引:7,自引:1,他引:7
采用反相HPLC法,在C18柱上以甲醇-乙酸铵溶液为流动相,检测波长230nm,快速测定碳酸饮料中苯甲酸钠、山梨酸钾和安赛蜜含量。对该法的定量线性范围(苯甲酸钠、山梨酸钾为50-150mg/L,安赛蜜为30-90mg/L)和重现性进行了考察,其平均回收率和相对标准偏差分别为92%-100%,1.4%-2.6%。 相似文献
5.
6.
Enqin Xia Ting Yang Xuan Zhu Qing Jia Jun Liu Wenlong Huang Jindong Ni Huanwen Tang 《Molecules (Basel, Switzerland)》2022,27(13)
Determining the level of phthalic acid esters (PAEs) in packaged carbonated beverages is a current need to ensure food safety. High-selectivity and -accuracy identification of individual PAEs can be achieved by chromatographic and mass spectrometric (MS) techniques. However, these methods are slow; involve complicated, expensive instruments in professional laboratories; and consume a large amount of organic solvents. As such, a food analysis method is needed to conveniently and rapidly evaluate multiple contaminants on site. In this study, with the assistance of ultrasound, we quickly determined the total PAEs in soft drinks using 1.5 mL of petroleum ether in one step. Then, we determined the characteristic molecular fluorescence spectrum of all PAEs in samples (excitation (Ex)/emission (Em) at 218/351 nm) using selectively concentrated sulfuric acid derivatization. The relative standard deviations of the fluorescent intensities of mixed solutions with five different PAEs were lower than 7.1% at three concentration levels. The limit of detection of the proposed method is 0.10 μmol L−1, which matches that of some of the chromatographic methods, but the proposed method uses less organic solvent and cheaper instruments. These microextraction devices and the fluorescence spectrometer are portable and provide an instant result, which shows promise for the evaluation of the total level of PAEs in beverages on site. The proposed method successfully detected the total level of PAEs in 38 kinds of soft drink samples from local supermarkets, indicating its potential for applications in the packaged beverage industry. 相似文献
7.
8.
气相色谱-串联质谱法结合QuEChERS方法快速检测软包装饮料中8种光引发剂 总被引:4,自引:0,他引:4
建立了QuEChERS-气相色谱-串联质谱法快速检测软包装饮料(橙汁、苹果汁、桃汁、菠萝汁和凉茶)中8种光引发剂残留的分析方法。样品以乙腈快速提取,NaCl和无水MgSO4除水后,经N-丙基乙二胺(PSA)和C18粉末净化,用气相色谱-串联质谱(GC-MS/MS)分析,采用多反应监测(MRM)模式检测。在0.01,0.1和0.5 mg/kg的添加水平下,5种软包装饮料的平均回收率为60.4%~99.1%;相对标准偏差(RSD)为1.2%~15.9%;检出限(LOD)为0.2~0.8μg/L。结果表明:本方法简便、快速、安全、价格低廉,重现性良好,可用于软包装饮料中多种光引发剂残留的快速确证检测。 相似文献
9.
10.
Dr. Hazel I. A. Phillips Dr. Aleksey V. Chernikov Dr. Nicholas C. Fletcher Prof. Dr. Alison E. Ashcroft Dr. James R. Ault Dr. Maria H. Filby Dr. Andrew J. Wilson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(43):13733-13742
The composition of a dynamic mixture of similar 2,2′‐bipyridine complexes of iron(II) bearing either an amide (5‐benzylamido‐2,2′‐bipyridine and 5‐(2‐methoxyethane)amido‐2,2′‐bipyridine) or an ester (2,2′‐bipyridine‐5‐carboxylic acid benzylester and 2,2′‐bipyridine‐5‐carboxylic acid 2‐methoxyethane ester) side chain have been evaluated by electrospray mass spectroscopy in acetonitrile. The time taken for the complexes to come to equilibrium appears to be dependent on the counteranion, with chloride causing a rapid redistribution of two preformed heteroleptic complexes (of the order of 1 hour), whereas the time it takes in the presence of tetrafluoroborate salts is in excess of 24 h. Similarly the final distribution of products is dependent on the anion present, with the presence of chloride, and to a lesser extent bromide, preferring three amide‐functionalized ligands, and a slight preference for an appended benzyl over a methoxyethyl group. Furthermore, for the first time, this study shows that the distribution of a dynamic library of metal complexes monitored by ESI‐MS can adapt following the introduction of a different anion, in this case tetrabutylammonium chloride to give the most favoured heteroleptic complex despite the increasing ionic strength of the solution. 相似文献
11.
12.
Paraskevas D. Tzanavaras Constantinos K. Zacharis Theano D. Karakosta Anastasia Zotou Demetrius G. Themelis 《Analytical letters》2013,46(11):1718-1731
In the present study we propose a new automated analytical scheme for the determination of quinine in soft drinks and beverages by coupling zone-fluidics (ZF) to liquid chromatography (LC). Certain pretreatment tasks involving precise liquid handling, such as sample dilution and addition of the internal standard (ISTD) were automated by ZF. After on-line filling of the loop of the LC injection valve, separation was carried out in less than 2.5 min by using a reversed phase monolithic column (100 × 4.6 mm i.d.) at a flow rate of 2 mL min?1. The ZF and LC parts of the setup operated independently: during LC separation the next sample was treated by ZF allowing a high throughput of 24 h?1. The proposed assay was thoroughly validated in terms of linearity (up to 150 mg L?1), LOD (0.25 mg L?1), LOQ (0.8 mg L?1), precision, accuracy, and ruggedness. The ZF-LC method was successfully applied for the determination of quinine in beverages and soft-drinks. 相似文献
13.
14.
Alberto O. Santini 《Microchemical Journal》2008,90(2):124-128
The construction and the analytical evaluation of a potentiometric sensor, namely, Pt∣Hg∣Hg2(Sac)2∣Graphite, where Sac stands for saccharinate ion, are described. This electrode has a wide linear dynamic range between 5.0 × 10− 7 and 1.0 × 10− 2 mol L− 1 with a near-Nernstian slope of − 58.1 ± 1.1 mV decade− 1 and a detection limit of 3.9 × 10− 7 mol L− 1. The potentiometric response is independent of the pH of the solution in the pH range 3.0-9.0. The electrode is easily constructed at a relatively low-cost with fast response time (within 10-30 s) and can be used for a period of 10 months without significant change in its performance characteristics. The proposed sensor displayed good selectivities over a variety of other anions (carboxylates and inorganic anions). The potentiometric sensor was successfully applied to the determination of saccharin in real food samples, that is, in instant tea powders, diet soft drinks and strawberry dietetic jam. 相似文献
15.
Yu Jin Jang Yoon Hee Jang Li Na Quan Ho‐Cheol Kim Seungmoon Pyo Dong Ha Kim 《Macromolecular rapid communications》2013,34(18):1487-1492
Hybrid Pt(platinum)/carbon nanopatterns with an extremely low loading level of Pt catalysts derived from block copolymer templates as an alternative type of counter electrodes (CEs) in dye‐sensitized solar cells (DSSCs) are proposed. DSSCs employing hybrid Pt/carbon with tailored configuration as CEs exhibit higher short‐circuit current and conversion efficiencies as well as stability with a lapse of time compared with conventional cells on the basis of sputtered Pt thin films, evidencing that the new class of hybrid nanostructures possess high potential for cost‐effective electrodes in energy conversion devices.
16.
B. Saville 《Angewandte Chemie (International ed. in English)》1967,6(11):928-939
Many chemical bonds of differing types and strengths have recently been regarded by Pearson[1] as representing partnerships between (Lewis) acids and (Lewis) bases. Most acceptor molecules or ions (acids) can be placed in one or other of two categories, graphically termed “Hard” and “Soft”. There are also two broad categories of donor molecules or ions (bases) which can also be termed Hard and Soft. On the whole, strong chemical bonds are partnerships between either a Hard base and a Hard acid or a Soft base and Soft acid, whereas weaker bond types most usually result in cases of either Hard base-Soft acid or Soft base-Hard acid interactions. The present paper shows how this concept of acidity and basicity can be applied in the interpretation of multi-center chemical reactions involving interconnected acid-base relationships. In particular, fourcenter substitutions and additions involving cooperative attack by nucleophiles and electrophiles at various chemical bonds have been examined, and a conclusion is reached that especially reactive patterns of reactants can be developed if the substrates contain bonds between either a hard acid and a soft base, or a soft acid and a hard base. Indeed, the arguments can be elaborated to provide two distinct Rules which should be of interest in the interpretation of metal-ion assisted reactions and in the design of novel syntheses. 相似文献
17.
Shean-Yeaw Ng Chin-Soon Phan Takahiro Ishii Takashi Kamada Toshiyuki Hamada Charles Santhanaraju Vairappan 《Molecules (Basel, Switzerland)》2020,25(22)
Members of the marine soft coral genus Xenia are rich in a diversity of diterpenes. A total of 199 terpenes consisting of 14 sesquiterpenes, 180 diterpenes, and 5 steroids have been reported to date. Xenicane diterpenes were reported to be the most common chemical skeleton biosynthesized by members of this genus. Most of the literature reported the chemical diversity of Xenia collected from the coral reefs in the South China Sea and the coastal waters of Taiwan. Although there was a brief review on the terpenoids of Xenia in 2015, the present review is a comprehensive overview of the structural diversity of secondary metabolites isolated from soft coral genus Xenia and their potent biological activity as reported between 1977 to 2019. 相似文献
18.
目的研究并探讨新辅助化疗在软组织肉瘤治疗中的应用效果。方法选取2013年1月—2016年6月期间甘肃中医药大学临床医学院收治的软组织肉瘤共80例作为研究对象,采取单盲随机分组法随机分为对照组和观察组各40例,对照组实施手术治疗,观察组在手术前实施新辅助化疗,比较两组患者的保肢率、治疗效果、术后半年复发情况。结果观察组患者的保肢手术率为77.50%,对照组患者为55.00%,差异具有统计学意义(P0.05);观察组患者的治疗总有效率明显高于对照组(P0.05);术后半年随访发现,观察组的复发率明显低于对照组(P0.05);观察组患者在新辅助化疗期间未出现严重的不良反应。结论在软组织肉瘤患者行手术治疗前实施新辅助化疗,可提高患者的保肢率,提高治疗效果,减少复发,有利于改善预后。 相似文献
19.
A novel voltammetric electronic tongue, smart tongue, was employed to monitor the growth of mold and to differentiate between four types of mold grown in liquid medium. Principal component analysis (PCA) was used to extract the relevant information obtained by the smart tongue. Reference growth curves were based on measurements of dry weight and pH. The growth detected by the smart tongue was basically consistent with that observed by the measurement of dry weight and pH. The optimal combinations of electrodes and frequencies for monitoring growth were as follows: for Aspergillus, both the Pt and Au electrodes at 1 Hz, 10 Hz and 100 Hz; for Penicillium, the Pt and W electrodes at 100 Hz; for Mucor, the Pt, Pd and W electrodes at the three frequency segments; for Rhizopus, the Pd, Ti and Ag electrodes at the three frequency segments. The Ag electrode at 10 Hz or 100 Hz frequency could differentiate well between the four types of mold for culturing 6 h in the liquid media. Therefore, the smart tongue has a promising future as a modern rapid analytical technology for the real time detection of the growth of mold and for the classification model of mold. 相似文献
20.
Shoichi Maeda Shunta Chikami Glenn Villena Latag Subin Song Norio Iwakiri Tomohiro Hayashi 《Molecules (Basel, Switzerland)》2022,27(7)
In this paper, we propose a new spectroscopic method to explore the behavior of molecules near polymeric molecular networks of water-containing soft materials such as hydrogels. We demonstrate the analysis of hydrogen bonding states of water in the vicinity of hydrogels (soft contact lenses). In this method, we apply force to hydrated contact lenses to deform them and to modulate the ratio between the signals from bulk and vicinal regions. We then collect spectra at different forces. Finally, we extracted the spectra of the vicinal region using the multivariate curve resolution-alternating least square (MCR-ALS) method. We report the hydration states depending on the chemical structures of hydrogels constituting the contact lenses. 相似文献