双酶水解-高效液相色谱法测定肉松中淀粉含量的研究

本文采用双酶水解-高效液相色谱法,建立了一种肉松中淀粉含量的测定方法。研究结果表明,在选定条件下,α-淀粉酶和淀粉葡萄糖苷酶可将肉松中淀粉专一彻底水解成葡萄糖,采用高效液相色谱法测定样品中葡萄糖含量,在0.5~50.0 mg/mL浓度范围内呈现良好的线性关系,线性相关系数为0.9999。采用不同浓度加标所得回收率为93.7%~99.8%,方法检出限为0.36%,定量限为1.2%,相对标准偏差(RSD)均小于5%。     

五味保肝丸生产工艺分析

目的建立五味保肝丸定性定量质量标准。方法薄层色谱法定性鉴别五味子和丹参的存在，高效液相色谱法确定降酶丸中五味子甲素含量。结果定性鉴别五味子和丹参，方法简便，图谱清晰；高效液相色谱法测定含量，结果准确，阴性无干扰。结论该实验方法可作为降酶丸的定性定量质量标准指标。     

同位素稀释质谱法测定α-淀粉酶的蛋白质含量

利用同位素稀释质谱法测定了盐溶液中α-淀粉酶的蛋白质含量.在含有α-淀粉酶的盐溶液中加入适量的苯丙氨酸标记物后进行酸水解,水解后的氨基酸经过高效液相色谱(HPLC)分离,质谱检测采用选择离子模式,分别监测苯丙氨酸(m/z=166)和标记苯丙氨酸(m/z=174)的离子,根据苯丙氨酸的含量计算α-淀粉酶的蛋白质含量,因此在测定中只需要氨基酸的标准物质就可以保证蛋白质含量测定结果的溯源性.实验中优化了酸水解的时间,采用HPLC-MS和MALDI-TOF质谱证明了淀粉酶已完全水解,并对测定结果的不确定度进行了评估.该方法可以准确测定溶液中蛋白质含量,并可用于蛋白质含量标准物质的定值.     

脲铵氮肥中缩二脲测定方法的研究

HG/T 4214-2011《脲铵氮肥》中规定,测定脲铵氮肥中缩二脲含量的依据为GB/T 22924—2008《复混肥料(复合肥料)中缩二脲含量的测定》。本文对分光光度法和高效液相色谱法两种方法进行比较。试验结果为分光光度法由于其他离子干扰太多,检测结果偏高;用液相色谱法测定快捷干扰小,加标回收率达到98.2%~101.5%,检测方法更准确可靠。     

高效液相色谱法测定异麦芽低聚糖的组分

采用高效液相色谱法(HPLC),以Zorbax C_(18)柱来分离柱,水为流动相,示差折光仪为检测器,一次进样可同时测定葡萄糖、异麦芽糖、异麦芽三糖和潘糖、异麦芽四糖等。本法对双酶协同作用制取异麦芽低聚糖工艺研究中的低聚糖进行测定,所得结果良好,变异系数为0.28％-1.66％,线性相关系数为0.9996-1.000,低聚糖的检出限在微克级。     

高效液相色谱色谱法测定牛奶及乳制品中维生素A的研究分析

维生素A为一种重要的脂溶性物质,现阶段对该物质的含量测定方法主要有:薄层色谱法、分光光度法、液相色谱法、气相色谱法等,高效液相色谱法为一种操作简单、快速、灵敏、准确的测定维生素A的方法,本文从样品处理、色谱分离以及检测等几个方面对高效液相色谱色谱法测定牛奶及乳制品中维生素A的研究进行综述。     

茶叶中糖类物质分析方法综述

在全面检索1907年以来国内外所有关于糖类物质分析方法研究文献的基础上,介绍了茶叶中的糖类物质及其分析方法现状,对糖类物质的主要分析方法进行了系统地介绍,并对化学分析法、气相色谱法、离子交换色谱法、凝胶色谱法、高效液相色谱法、毛细管电泳法、质谱法等主要分析方法进行了评述,并提出了用高效液相色谱法建立茶叶中糖类物质测定的标准方法。     

反相高效液相色谱法测定饮用水中的酚类化合物

介绍了反相高效液相色谱法测定饮用水中的酚类物质。该法采用的固相萃取预处理法操作简便,节省溶剂,且稳定性好,回收率高。实验以ODS柱为分离柱,采用梯度洗脱,可编程紫外检测器进行样品检测。方法准确,重现性好,杂质干扰少,检出限低。     

教科书中荧光增白剂VBL的分析方法研究

利用高效液相色谱-荧光检测器法对教科书中VBL荧光增白剂进行了测定。具体方法为用岛津LC-20AD高效液相色谱系统,Eclipse-C18柱(250 mm×4.6mm,5.0μm)色谱柱,流动相A为甲醇,B为8mmol/L乙酸铵水溶液,流速0.5mL/min,激发波长350nm,发射波长430nm,进样量1μL。外标法测定教科书中VBL荧光增白剂的含量,检测线性关系R~2=0.9985,回收率为92.5%～94.5%之间,相对标准偏差为0.81%(n=6)。研究结果表明,高效液相色谱-荧光检测器法操作简便,结果准确,不受木质素和其他荧光物质的干扰,具有较好的重现性与稳定性,可用于教科书中VBL荧光增白剂含量的测定。     

改进调经祛斑胶囊质量标准的研究

目的改进调经祛斑胶囊的质量标准。方法采用显微镜法对处方中红花、手参、白芍进行显微鉴别;用薄层色谱法对女贞子、当归、枸杞子、黄芪进行鉴别;用高效液相色谱法测定制剂中芍药苷的含量。结果显微鉴别、薄层色谱鉴别专属性强;建立的测定芍药苷含量的HPLC法符合研究要求。结论该方法简便、准确、重现性好,可作为控制调经祛斑胶囊质量标准的方法。     

Carcass chilling-experimental investigation of weight loss from lean meatLa réfrigération de la viande-recherches expérimentales sur les pertes de masse de la viande maigre

Weight loss histories have been determined for slabs of warm, pre-rigor sheep meat, trimmed free of fat, cooled for up to 24 h by chilled air in a wind tunnel. Evaporation from a lean meat surface is seen to proceed in three stages. In a short first stage evaporation proceeds as if the meat surface were fully wetted. In the second stage the meat surface progressively dries, with the evaporation rate falling to as little as 35% of the fully wetted surface value. In the third stage the meat surface progressively rewets. Experimentally determined moisture profiles showed that drying occurred only in a thin layer near the meat surface. These results indicate that in the early stages of chilling, diffusional transport of water through a partly dried surface layer controls the flow of water to the meat surface and thereby the rate of evaporation weight loss.     

Carcass chilling-experimental investigation of weight loss from lean meat

Weight loss histories have been determined for slabs of warm, pre-rigor sheep meat, trimmed free of fat, cooled for up to 24 h by chilled air in a wind tunnel. Evaporation from a lean meat surface is seen to proceed in three stages. In a short first stage evaporation proceeds as if the meat surface were fully wetted. In the second stage the meat surface progressively dries, with the evaporation rate falling to as little as 35% of the fully wetted surface value. In the third stage the meat surface progressively rewets. Experimentally determined moisture profiles showed that drying occurred only in a thin layer near the meat surface. These results indicate that in the early stages of chilling, diffusional transport of water through a partly dried surface layer controls the flow of water to the meat surface and thereby the rate of evaporation weight loss.     

Vitamin C Spray Drying: Study of the Thermal Constraint

Temperature variation in the spray drying method has no effect on the ascorbic acid molecule. No chemical interaction between the colloidal silica and the ascorbic acid could be determined, but a physicochemical interaction “absorption” was determined. Colloidal silica improved the final yield of spray drying in proportion to its concentration. No polymorphic forms could be determined in the spray-dried ascorbic acid. Drug release from the ascorbic acid spray dried was found to be dependent on the Aerosil content: highest release rates were obtained with Aerosil.     

快速水解法测定羽毛及其降解物中的色氨酸

通过提高水解温度,减少水解时间的前处理方法,用氨基酸自动分析仪测定羽毛及其降解物中色氨酸的测定值。分析结果表明,采用4mol/LLiOH、145℃、水解5h的快速水解法与常规前处理方法所测得色氨酸含量基本一致,方法回收率91%,变异系数2.24%。可缩短分析时间,且不影响分析结果的准确度。     

Combined partial acid hydrolysis and electrospray ionization-mass spectrometry for the structural determination of oligosaccharides

A general oligosaccharide acid hydrolysis method, amenable to electrospray ionization mass spectrometry (ESI-MS), is described that allows for hydrolysis of glycosidic bonds for both hexose- and N-acetylhexosamine-containing oligosaccharides. The partial acid hydrolysis of oligosaccharides is obtained by using an acid-exchange resin as the acid catalyst. A ladder sequence of the glycan is produced in solution that is directly analyzed by ESI tandem mass spectrometry, employing both ion trap and Fourier transform ion cyclotron resonance mass spectrometers, to provide sequence and linkage information. Unlike traditional acid hydrolysis procedures, there is minimal degradation of monosaccharide residues or deacetylation of N-acetylhexosamines by employing this technique. It is further demonstrated that the stereochemistry of the released monosaccharides and the anomeric configuration within disaccharides is determined by direct derivatization of the hydrolysate with Zn(dien)-Cl2 followed by ESI-MS/MS.     

Processing effect on structural changes of high acid-catalysed silica gel

The structure of silica gels prepared by hydrolysis of tetraethoxysilane (TEOS) with high acid content has been investigated. The gels were obtained by varying the nitric acid contents at a constant H₂O/TEOS molar ratio of 10. The molar compositions were TEOS: H₂OHNO₃ =110: x(x=0.1–1.0). The effects of acid content and drying temperature on structural changes in the gels were examined. In addition, the surface area, pore volume, pore size distribution, and the microstructure were determined. The results showed that the pore structure changed to larger pore sizes and broader size distributions as a result of increasing the drying temperature. However, at a constant drying temperature, a higher acid content yielded a higher pore volume. The gels dried at lower temperatures had slit-shaped micropores and a narrow pore size distribution; whereas, the gels dried at higher temperatures had ink bottle-shaped pores and a relatively broad size distribution.     

Specific determination of As(V) by an acid phosphatase-polyphenol oxidase biosensor

An original amperometric biosensor based on the simultaneous entrapment of acid phosphatase (AcP) and polyphenol oxidase (PPO) into anionic clays (layered double hydroxides) was developed for the specific detection of As(V). The functioning principle of the bienzyme electrode consisted of the successive hydrolysis of phenyl phosphate into phenol by AcP, followed by the oxidation of phenol into o-quinone by PPO. The phenyl phosphate concentration was, thus, monitored by potentiostating the biosensor at -0.2 V vs Ag/AgCl to detect amperometrically the generated quinone. The detection of As(V) was based on its inhibitory effect on AcP activity toward the hydrolysis of phenyl phosphate into phenol. The As(V) can be specifically determined in pH 6.0 acetate buffer without any interferences of As(III) or phosphate, the detection limit being 2 nM or 0.15 ppb after an incubation step for 20 min.     

Specific distribution of sialic acids in animal tissues as examined by LC-ESI-MS after derivatization with 1,2-diamino-4,5-methylenedioxybenzene

Simultaneous analysis of sialic acids has been a challenging target, because sialic acids having N- or O-acetyl, glycolyl, and sulfonic acid ester groups are labile during their release from carbohydrate chains and analytical procedures. In the present paper, we propose a method using high-performance liquid chromatography coupled with eletrospray ionization mass spectrometry (HPLC-ESI-MS). The method was evaluated by applying to the analysis of sialic acids in various tissues, especially digestive organs in mice and rats. The method was based on the in situ precolumn derivatization of sialic acids after releasing them by hydrolysis. The sialic acids were derivatized with 1,2-diamino-4,5-methylenedioxybenzene to form highly fluorescent quinoxaline derivatives. By using two different hydrolysis conditions (i.e., with 2 M acetic acid and with 0.1 M hydrochloric acid), both total sialic acids and sialic acid distributions were easily determined. We found that sialic acids showed characteristic distributions in the tissues of mice and rats. Further, HPLC-ESI-MS revealed that all the tissues examined in mice and rats commonly contained highly acetylated sialic acids and 8-O-sulfated N-acetylneuraminic acid.     

Bioactivity of wollastonite/aerogels composites obtained from a TEOS–MTES matrix

Organic–inorganic hybrid materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS), methyltrimethoxysilane (MTES), synthetic wollastonite powders and polydimethylsiloxane (PDMS) in an ethanol solution. Aerogels were prepared from acid hydrolysis of TEOS and MTES with different volume ratio in ethanol, followed by addition of wollastonite powder and PDMS in order to obtain aerogels with 20 wt% of PDMS and 5 wt% of CaO of the total silica. Finally, when the wet gels were obtained, they were supercritically dried at 260 °C and 90 bar, in ethanol. In order to obtain its bioactivity, one method for surface activation is based on a wet chemical alkaline treatment. The particular interest of this study is that we introduce hybrid aerogels, in a 1 M solution of NaOH, for 30 s at room temperature. We evaluate the bioactivity of TEOS–MTES aerogel when immersed in a static volume of simulated body fluid (SBF). An apatite layer of spherical-shaped particles of uniform size smaller than 5 microns is observed to form on the surface of the aerogels after 25 days soaking in SBF.