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1.
建立了高效液相色谱(HPLC)测定毛樱桃中维生素C的主要成分L-抗坏血酸和D-异抗坏血酸的方法. 以0.05 mol/L磷酸溶液∶甲醇(体积比为98∶2)作为流动相,紫外检测波长245 nm,柱温25 ℃,流速0.70 mL/min. 获得L-抗坏血酸、D-异抗坏血酸标准曲线线性较好(r为1.0),精密度(RSD)为0.6%. L-抗坏血酸加标回收率为90.83%~92.52%,D-异抗坏血酸加标回收率为91.93%~92.99%. 试验结果表明,方法测定维生素C操作简单、提取速度快、灵敏度高、回收率好,测得L-抗坏血酸的含量为8.24 mg/100 g,D-异抗坏血酸未检测出. 方法可适用于检测其他与毛樱桃相似的果蔬中L-抗坏血酸、D-异抗坏血酸的含量. 相似文献
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《理化检验(化学分册)》2019,(11)
食品添加剂样品用含1%(体积分数,下同)甲酸的100mmol·L~(-1)甲酸铵溶液溶解,经乙腈稀释后,用0.22μm微孔滤膜过滤,采用亲水作用色谱法同时测定滤液中D-异抗坏血酸、L-抗坏血酸和二氧化硫脲的含量。以InfinityLab Poroshell 120HILIC-Z色谱柱(3.0mm×100mm,2.7μm)为固定相,以含1%甲酸的100mmol·L~(-1)甲酸铵溶液和乙腈以体积比15∶85组成的混合液为流动相,用二极管阵列检测器测定。D-异抗坏血酸、L-抗坏血酸和二氧化硫脲的质量浓度均在1.0~100mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)均为1.0%。以空白样品为基体进行加标回收试验,所得回收率为94.7%~108%,测定值的相对标准偏差(n=6)小于8.0%。 相似文献
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萃取催化光度法间接测定痕量抗坏血酸 总被引:7,自引:0,他引:7
研究了在pH5.5的HAc NaAc缓冲溶液介质中,利用抗坏血酸活化Fe(Ⅲ)催化H2O2氧化邻氨基酚的显色反应,用萃取平衡控制反应时间和水相中邻氨基酚的浓度及反应程度,通过测量424nm下有机相的吸光度,建立了萃取催化光度法间接测定痕量抗坏血酸的新方法。方法的线性范围为0~50.0μg/L,检出限为6.7×10-7g/L。方法可用于维生素C片和西红柿中抗坏血酸的测定。并对反应机理进行了探讨。 相似文献
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动力学光度法测定抗坏血酸——基于对甲苯胺蓝的还原褪色反应 总被引:3,自引:0,他引:3
探讨了快速测定食品中还原型抗坏血酸的检验方法,在0.9 mol·L-1盐酸介质中,以甲苯胺蓝为动力学指示剂,抗坏血酸还原甲苯胺蓝染料并产生褪色反应,其褪色速度与抗坏血酸浓度呈正比.采用固定时间法测定,抗坏血酸浓度在100μg/10mL以内与吸光度△A值间呈线性关系,线性回归方程△A=0.010 C-0.009(r=0.999).检出限为2.0μg/10mL,表观摩尔吸光率为1.8x104L·mol-1·cm-1.应用此方法测定了6种试样中抗坏血酸含量,所得结果与国标法测得结果相一致. 相似文献
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建立了抗坏血酸存在下离子色谱法电导检测尿液中草酸的方法。样品经稀释后用0.22μm滤膜过滤,直接进样,以15 mmol·L-1Na HCO3(p H 8.3)为淋洗液,用Ion Pac AS12A阴离子分离柱(200 mm×4mm)分离,电导检测器进行检测。实验结果表明,草酸与其他常见阴离子在16 min内能够很好地分离,在此条件下抗坏血酸能够在80 min内保持稳定,不会降解为草酸而影响测量结果。测试条件下,草酸在0.2~40mg·L-1浓度范围内呈良好的线性关系,相关系数(r)为0.999 9,检出限达0.02 mg·L-1,加标回收率为96.9%~103.3%,可用于实际样品的测试。 相似文献
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溴酸钾-溴酚蓝-锰(Ⅱ)催化体系的研究及其在测定抗坏血酸中的应用 总被引:1,自引:0,他引:1
丁素芳 《理化检验(化学分册)》2005,41(9):642-643,647
基于在pH 3.6的HOAc-NaOAc介质中,抗坏血酸对溴酸钾、溴酚蓝、锰(Ⅱ)催化体系具有显著的活化作用,建立了测定抗坏血酸的方法。线性范围为10~125μg/25 mL,检出限为3.44×10-5g.L-1,用于药品、饮料中抗坏血酸的测定,结果满意。 相似文献
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Peter M. Barna 《合成通讯》2013,43(3):207-214
Abstract Pyrophosphoric acid was first reported as a phosphorylating agent for highmolecular weight alcohols in 19341. Direct phosphorylating of sugars and sugar derivatives was first carried out by Cherbuliez2 who used polyphosphoric acid on alcohols, amines and glycols. These precedents suggested to Seegmiller and Horecker in 19513 to try tetraphosphoric (polyphosphoric) acid, as supplied by commercs, as the phosphorylating agent of carbohydrate phosphorylation. Carbohydrates can be phosphorylated when all but one of the positions is blocked by suitable protective groups, or, on rare occasions, in the unblocked, “natural” stata.? The latter method can be used only on terminal, C5 or C6 positions as the 5-phosphates of pentoses and the 6-phosphates of hexoses are more stable at low pH than other phosphates and can withstand an acidic hydrolysis of the mixture of phosphorylated sugars resulting from such phosphorylation. For the phosphorylation of easily available, cheap pentoses and hexoses in the 5- and 6-positions respectively, with cheap polyphosphoric acid, this is the method of choice. 相似文献
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建立了同时分离测定水杨酸、肉桂酸、阿魏酸和香草酸的电堆集富集-非水毛细管电泳(NACE)的新方法。运行缓冲溶液为40mmol/L乙酸钠-2.5mmol/L氢氧化钠甲醇溶液,电压-25kV,在225nm波长下紫外检测。对电压、乙酸钠浓度、氢氧化钠浓度、进样时间、样品溶液等因素对电堆集及分离的影响做了系统的研究。水杨酸、肉桂酸、阿魏酸和香草酸分别在1.4~28mg/L、0.40~8.0mg/L、0.7~18mg/L和0.7~30mg/L范围内线性关系良好(r=0.9999、r=0.9997、r=0.9994、r=0.9997);回收率分别为95.8~99.6%、96.2~98·2%、95.7~105%和98.9~103%,基于3倍信噪比(S/N=3),4种有机酸的检出限分别为0.069、0.051、0.107和0.089mg/L。 相似文献
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高效液相色谱同时测定食品中苯甲酸、山梨酸、水扬酸和糖精钠 总被引:1,自引:0,他引:1
对不同种类的食品提出了不同的试样预处理方法,并对预处理中提取各被测化合物的溶剂的选择,提取时试样溶液酸度(pH值)的选定,以及除去干扰物质的试液净化条件等因素作了较深入的试验。经预处理后的澄清试液供高效液相色谱法(HPLC)分析。分析时采用ODS C18色谱柱对被测化合物(苯甲酸、山梨酸、水杨酸及糖精钠)进行分离,所用流动相为由甲醇及0.02 mol.L-1乙酸铵溶液按9比91(体积比)混合组成的溶液。测量中用二极管阵列检测器(DAD),检测波长为230 nm,按保留时间及特征光谱图进行定性。定量测定采用外标法,测量与各化合物浓度相对应的峰面积。四种化合物的检出限均小于0.000 1 g.L-1,用标准加入法进行了回收率试验,所得结果在82.3%~109.5%之间,计算得相对标准偏差(n=8)小于10%。 相似文献
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Bruno Danieli Paolo De Bellis Laura Barzaghi Giacomo Carrea Gianluca Ottolina Sergio Riva 《Helvetica chimica acta》1992,75(4):1297-1304
Quinic acid ( 1a ), shikimic acid ( 2 ), and their derivatives were acylated in organic solvents by several lipases and by the protease subtilisin Carlsberg. The most satisfactory results were obtained with methyl (or benzyl) quinate ( 7a (or 8a )) and lipase from Chromobacterium viscosum adsorbed on Celite, which showed an overshelming preference towards the acylation of OH–C(4). Under optimized conditions, the syntehtically useful 4-O -acetylquinate 8d was isolated in ca. 90% yield. On the other hand, acylation of methyl shikimate ( 10a ) showed no regioselectivity with any of the enzymes tested. A possible rationale for the different behavior of Chromobacterium viscosum lipase towards 7a and 10a is given, comparing the conformations of these two molecules, as deducted from 1H-NMR and molecular-mechanics calculation. 相似文献
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《Analytical letters》2012,45(6):629-640
Abstract A method has been developed to simultaneously determine aspirin, salicylic acid, salicyluric acid, and gentisic acid concentrations in human plasma and urine. An extraction and dry-down step prepare the sample for resolution by reverse-phase high pressure liquid chromatography. The column effluent is monitored by both ultraviolet absorbance and fluorescence to optimize sensitivity and specificity for the compounds of interest. 相似文献
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环境样品中亚砷酸盐、砷酸盐、甲基胂酸和二甲基胂酸的测定 总被引:1,自引:0,他引:1
本文叙述了分光光度法测定环境样品中亚砷酸盐。砷酸盐、甲基胂酸和二甲基胂酸的方法。这些砷的形态通过KBH_4还原为相应的砷化氢,砷化氢和甲基胂化氢与二乙基二硫代氨基甲酸银(AgDDC)形成两种不同颜色的络合物。借分光光度法测定吸光度,建立并解联立方程式,可测得各种形态砷的含量。对于环境样品中这四种形态砷的定量检出限为1.0μg As,回收率达90~100%。 相似文献
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Jacqueline Arguello Hérica A. Magosso Thiago C. Canevari Richard Landers Yoshitaka Gushikem 《Electroanalysis》2011,23(2):334-338
Selective electroanalytical responses for ascorbic acid, dopamine and uric acid at a carbon modified electrode based on 3‐n‐propyl‐1‐azonia‐4‐azabicyclo[2.2.2]octane silsesquioxane chloride (SiDbCl) is reported. The overlapped peaks observed at an unmodified electrode are resolved into three well defined voltammetric peaks allowing the simultaneous determination of the three species. Detection limits of 37, 0.3 and 0.1 μmo L−1 of ascorbic acid, dopamine and uric acid, respectively, were calculated from calibration curves based on differential pulse voltammetric experiments performed in Britton ‐ Robinson buffer solution at pH 7.04. 相似文献
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Vesna Kuntić Maja Stanojević Ivanka Holclajtner-Antunović Snežana Uskoković-Marković Ubavka Mioč Marija Todorović Tanja Jovanović Vladana Vukojević 《Monatshefte für Chemie / Chemical Monthly》2006,137(6):803-810
Summary. Compounds of phosphotungstic acid (WPA) containing the amino acids alanine (WPA–Ala) or glycine (WPA–Gly) as counter cations were synthesized and characterized by elemental analysis, thermal analysis, and IR spectroscopy. Cellular
toxicity was assessed by the trypan blue exclusion method, and the antiviral activity of WPA and the modified WPA compounds was tested against herpes simplex viruses (HSV) type 1 and type 2. Biological assays indicate that the newly synthesized
compounds exhibit no evident cytotoxic effects on Vero cells and negligible antiviral activity against HSV-1 and HSV-2. 相似文献
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Vesna Kunti? Maja Stanojevi? Ivanka Holclajtner-Antunovi? Sne?ana Uskokovi?-Markovi? Ubavka Mio? Marija Todorovi? Tanja Jovanovi? Vladana Vukojevi? 《Monatshefte für Chemie / Chemical Monthly》2006,43(9):803-810
Compounds of phosphotungstic acid (WPA) containing the amino acids alanine (WPA–Ala) or glycine (WPA–Gly) as counter cations were synthesized and characterized by elemental analysis, thermal analysis, and IR spectroscopy. Cellular
toxicity was assessed by the trypan blue exclusion method, and the antiviral activity of WPA and the modified WPA compounds was tested against herpes simplex viruses (HSV) type 1 and type 2. Biological assays indicate that the newly synthesized
compounds exhibit no evident cytotoxic effects on Vero cells and negligible antiviral activity against HSV-1 and HSV-2. 相似文献