共查询到20条相似文献,搜索用时 140 毫秒
1.
离心萃取-紫外光谱法测定可乐饮料中咖啡因的含量 总被引:3,自引:0,他引:3
建立了一种快速、准确,溶剂消耗少的测定可乐饮料中咖啡因含量的紫外光谱分析方法,并将大相比离心萃取应用于仪器分析样品微制备过程。该方法将2mL三氯甲烷直接加入装有100μL可乐饮料的离心试管中,离心萃取3min后取清液在278nm处进行紫外光谱测定,操作简单、快速,重现性好,相对标准偏差小于3%;在3种可乐饮料中加入不同浓度的咖啡因标准溶液,回收率在96.6%~106.1%之间。线性范围为0.5~30mg/L,相关系数为0.9999;检出限为0.001mg/L。将本方法应用于市售可乐饮料中咖啡因含量分析,取得了满意的结果。 相似文献
2.
本文建立了饮料中咖啡因含量的快速检测方法。采用拟反相色谱法,以极性硅胶柱配以高水量的流动相,所测9种饮料样品均能在4min内快速完成分离测定。系统研究了影响咖啡因保留的多种因素,优化后的最佳测定条件为:采用Inertsil100-5SIL色谱柱(150×4.6mm i.d.,5μm),以乙腈-0.03mol·L-1甲酸钠溶液(pH=2.9)(体积比5∶95)为流动相,检测波长274nm。将其用于饮料中咖啡因的测定,线性范围为0.2~1 000μg·mL-1(r=0.9995),检出限(S/N=3)为0.05μg·mL-1。回收率为92.3%~105.7%,精密度(RSD)<3.5%。同时还对咖啡因的保留机理进行了探讨。 相似文献
3.
微波消解-端视ICP-AES测定茶叶中微量重金属元素 总被引:6,自引:0,他引:6
采用微波消解-端视等离子体原子发射光谱(ICP-AES)测定茶叶中微量重金属元素Pb、As、Cd、Cu、Fe,并对ICP-AES工作参数及条件进行了优化和选择。Pb、As、Cd、Cu、Fe的检出限分别为2.9×10-3μg/mL、5.2×10-3μg/mL、0.056×10-3μg/mL、0.55×10-3μg/mL、0.59×10-3μg/mL,线性范围为0~10000μg/L,相对标准偏差为1.7%~8.5%;回收率为90%~104%。该方法与国标法比较,结果无显著性差异。本法能用于茶叶测定。 相似文献
4.
5.
HPLC法同时测定茶叶中多酚、咖啡因和维生素C 总被引:1,自引:0,他引:1
采用高效液相色谱法(HPLC)建立了同时检测茶叶中咖啡因、没食子酸、烟酸、绿原酸和维生素C含量的方法。色谱条件为:Lichrospher C18反相柱(250 mm×4.6 mm,5μm),以甲醇和0.2%甲酸水溶液为流动相,梯度洗脱,流速为1.0 m L/min,测定温度为35℃,检测波长为275nm。咖啡因、没食子酸、烟酸、绿原酸和维生素C在0~70μg/m L浓度范围内被测组分浓度对被测组分面积呈良好的线性关系,其相关系数均在0.9995以上;加标回收率在95.10%~104.82%之间;相对标准偏差均在1.3%~5.5%之间。该方法可作为评价茶叶及其相关产品的质量控制提供参考依据。 相似文献
6.
《理化检验(化学分册)》2015,(7)
采用超声辅助分散液相微萃取技术结合高效液相色谱法测定蜂蜜中的咖啡因。将样品用水溶解配制成100g·L-1样品溶液,取7.5 mL样品溶液,加入三氯甲烷120μL和甲醇1.5mL,混匀后超声5min,离心后吸取5μL沉积相,在WondasilTM C18色谱柱上分离,以甲醇(1+1)溶液为流动相进行洗脱,紫外检测波长为274nm。咖啡因的线性范围为10.0~500μg·L-1,检出限(3S/N)为9μg·L-1。测定值的相对标准偏差为2.7%~4.1%,加标回收率在96.6%~104%之间。 相似文献
7.
建立了同时测定酚氨咖敏片中对乙酰氨基酚、氨基比林、咖啡因和马来酸氯苯那敏4组分含量的毛细管气相色谱法。采用SE-30大口径毛细管色谱柱(30 m×0.53 mm,1.0μm),柱温190℃,汽化室温度220℃,检测器为FID,检测温度250℃,载气为高纯N2,分流比为1∶6,内标为盐酸麻黄碱,以无水乙醇为溶剂,样品无需衍生化处理,直接进样测定。样品中各组分完全分离,辅料无干扰,对乙酰氨基酚、氨基比林、咖啡因和马来酸氯苯那敏分别在20~2000μg/mL、15~1500μg/mL、10~500μg/mL和20~100μg/mL范围内线性关系良好(r0.999),各组分的平均回收率在99.6%~101.2%范围内,RSD2%。 相似文献
8.
9.
10.
《分析试验室》2015,(10)
将包裹了三(2,2'-联二吡啶)二氯化钌(Ⅱ)配合物(Ru(bpy)32+)的二氧化硅纳米粒子(Ru(bpy)32+@Si O2)通过Nafion膜修饰在玻碳电极上,并研究了咖啡因在此电极上的电化学发光行为。在单因素实验的基础上,结合响应面分析法对实验条件进行了优化,建立了一种检测咖啡因的新方法。在最佳的实验条件下,咖啡因浓度在5.0×10-3~20μmol/L范围内与其相对发光强度呈良好的线性关系(r2=0.9996),检出限(S/N=3)为1.3×10-3μmol/L。连续平行测定1μmol/L的咖啡因溶液5次,相对发光强度的RSD为3.8%。方法用于可乐样品的实际测定,回收率为93.7%~103.8%。 相似文献
11.
12.
Martinavarro-Domínguez A Boseb D Durgbanshi A Gil-Agustí M Capella-Peiró ME Broch SC Esteve-Romero J 《Journal of chromatography. A》2005,1073(1-2):309-315
A procedure was developed for the determination of caffeine and theophylline using a C18 column (5 microm, 250 mm x 4.6 mm) and micellar liquid chromatography using hybrid mobile phases containing sodium dodecyl sulfate (SDS) and propanol, butanol or pentanol as modifiers. Detection was performed with a variable wavelength UV-vis detector at 272 nm. After the application of an interpretative strategy for the selection of the optimimum mobile phase, caffeine and theophylline can be resolved and determined in serum samples by direct injection, using a mobile phase made up of 50 mM SDS-2.5% (v/v) propanol-10 mM KH2PO4, pH 7, with an analysis time below 5 min. Calibration was linear in the range 0.05 to 50 microg mL(-1) with r > 0.999. The statistical evaluation of the method was examined by performing intra-day (n = 6) and inter-day calibration (n = 7) and was found to be satisfactory, with highly accurate and precise results. The proposed method was suitably validated and applied to the determination of caffeine and theophylline in serum samples of patients treated with bronchodilators. 相似文献
13.
Mengjia Li Junyi Zhou Xue Gu Yan Wang Xiaojing Huang Chao Yan 《Journal of separation science》2009,32(2):267-274
A quantitative CE (qCE) system with high precision has been developed, in which a 4‐port nano‐valve was isolated from the electric field and served as sample injector. The accurate amount of sample was introduced into the CE system with high reproducibility. Based on this system, consecutive injections and separations were performed without voltage interruption. Reproducibilities in terms of RSD lower than 0.8% for retention time and 1.7% for peak area were achieved. The effectiveness of the system was demonstrated by the quantitative analysis of caffeine, theobromine, and theophylline in real samples, such as tea leaf, roasted coffee, coca cola, and theophylline tablets. 相似文献
14.
Capillary zone electrophoresis is employed for the determination of caffeine using end-column amperometric detection with a carbon fiber microdisk array electrode at a constant potential of 1.45 V versus a saturated calomel electrode. The optimum conditions of separation and detection are 0.1 52mM NaH2PO4-0.648mM Na2HPO4 for the buffer solution, 20 kV for the separation voltage, 5 kV for the injection voltage, and 10s for the injection time. The limit of detection is 2.9 x 10(-4)mM or 1.2 fmol (signal-to-noise ratio = 2). The relative standard deviation is 0.68% for the migration time and 2.3% for the electrophoretic peak current. The method is applied to determining caffeine in human serum and a cola drink. 相似文献
15.
Zahra Talebpour Saeed Maesum Mehdi Jalali-Heravi Mojtaba Shamsipur 《Analytical sciences》2003,19(7):1079-1082
A 1H-NMR procedure based on an analysis of its data by a multivariate calibration method was conducted for the simultaneous determination of theophylline and caffeine in synthetic and real samples. Partial least squares regression (PLS) was chosen as the calibration method. The methyl signals of theophilline at 3.36 and 3.54 ppm that overlapped with those of caffeine were significant characteristics which were employed in this study for their analyses. The proposed method was successfully applied to recovery studies of theophylline and caffeine from real tablet samples. 相似文献
16.
Ohyama K Wada M Lord GA Ohba Y Nakashima MN Nakashima K Akiyama S Lim CK Kuroda N 《Electrophoresis》2005,26(4-5):812-817
A capillary electrochromatography (CEC) method has been developed for the separation of caffeine and its two metabolites 1-methylxanthine (1-MX) and 1,7-dimethylxanthine (1,7-DX). The stationary phase was 3-(1,8-naphthalimido) propyl-modified silyl silica gel (NAIP) and the best separations were achieved with 4.0 mM citrate buffer (pH 5.0) containing 80% methanol at an applied voltage of 25 kV. The compounds were completely separated in less than 3.5 min with good repeatability, which was approximately 3-times less than that in high-performance liquid chromatography (HPLC) with NAIP. The proposed method coupled with microdialysis was successfully applied to the monitoring of caffeine concentration in rat brain with detection limits of 1.11 microg/mL. 相似文献
17.
Summary A new method based on reversed-phase ion-interaction HPLC is described for the identification and quantitation of theobromine, theophylline and caffeine in beverages. The interaction reagent used is octylamine orto-phosphate which also constitutes the mobile phase. The stationary phase is a microparticulate reversed-phase C-18 packing. With spectrophotometric detection at 274 nm, detection levels of 0.15, 0.30 and 0.40 ppm were achieved for theobromine, theophylline and caffeine, respectively.Quantitative analysis was performed by the standard addition method for theobromine and caffeine contents in tea, espresso-coffee, decaffeinated coffee, decaffeinated tea and cola-beverages. 相似文献
18.
Summary An HPLC procedure is described for the determination of caffeine in pharmaceutical preparations. A Spherisorb octadecylsilane ODS-2 C18 analytical column and spectrophotometric detection at 273 nm were used. The chromatographic behaviour of caffeine with different micellar eluents containing sodium dodecyl sulphate (SDS) is described. The determination of caffeine in pharmaceutical preparations was performed by use of a mobile phase containing 0.05 M sodium dodecylsulphate (SDS) and 1.5% propanol at pH7. At a 6.0 g mL–1 concentration level the peak area and peak height repeatability were 2.6 and 2.4%, respectively. The application of the proposed method to the analysis of five pharmaceutical formulations, using peak heights as the dependent variable, gave recoveries between 85 and 104% of the values declared by the manufacturers. The proposed procedure for the determination of caffeine is rapid (15 min per sample), reliable and free from interferences. 相似文献
19.
M.A. Rostagno N. Manchón M. D’Arrigo E. Guillamón A. Villares A. García-Lafuente A. Ramos J.A. Martínez 《Analytica chimica acta》2011,(2):10584
A fast HPLC method with diode-array absorbance detector and fluorescence detector for the analysis of 19 phenolic acids, flavan-3-ols, flavones, flavonols and caffeine in different types of samples was developed. Using a C18 reverse-phase fused-core column separation of all compounds was achieved in less than 5 min with an overall sample-to-sample time of 10 min. Evaluation of chromatographic performance revealed excellent reproducibility, resolution, selectivity and peak symmetry. Limits of detection for all analyzed compounds ranged from 0.5 to 211 μg L−1, while limits of quantitation ranged between 1.5 and 704 μg L−1. The developed method was used for the determination of analytes present in different samples, including teas (black, white, green), mate, coffee, cola soft drink and an energetic drink. Concentration of the analyzed compounds occurring in the samples ranged from 0.4 to 314 mg L−1. Caffeine was the analyte found in higher concentrations in all samples. Phytochemical profiles of the samples were consistent with those reported in the literature. 相似文献
20.
茶叶中咖啡因的超临界流体分析 总被引:6,自引:0,他引:6
用超临界流体法 (SFC)测定茶叶中的咖啡因 ,在二氧化碳流动相中加入体积分数为 5 %的甲醇后 ,得到了良好的分离效果。该方法具有样品前处理简单 ,共存组分不干扰测定 ,分析速度快等优点 ,可以用于茶叶中咖啡因的快速分析。 相似文献