高效液相色谱法测定粮食作物中的色氨酸

用ＨＰＬＣ法测定粮食作物中的色氨酸,实验采用阳离子交换柱,以０．１ｍｏｌ／ＬＣＨ３ＣＯＯＮＨ４为流动相,荧光检测器中ｅｘ２８０ｎｍ,ｅｍ３４０ｎｍ检测,色氨酸和酪氨酸分离很好,回收率在９５％以上。     

HPLC-PAD法优化乌骨鸡活性肽分离纯化

乌骨鸡是一种具有药用价值的鸡种,乌骨鸡的鸡肉蛋白通过酶促水解后可获得多肽产物乌骨鸡活性肽,营养价值高,分离纯化活性肽是研究乌骨鸡应用价值的基础。利用装置C18反相色谱柱或TSKgel凝胶色谱柱的高效液相色谱仪进行乌骨鸡活性肽的分离优化,针对流动相、流速进行优化的同时,参考波长、进样量,以出峰数为主,结合分离度等考察分离效果。结果表明:C18柱的出峰数随甲醇含量及流速的降低而增加;三氟乙酸或磷酸盐作缓冲液时出峰数基本一致,但分离度不同;综合因素得pH 6.0磷酸盐/6%甲醇/水体系的流动相、0.2 mL/min的流速为该实验下的最佳分离条件。TSKgel柱的乙腈分离效果优于甲醇,梯度洗脱效果较好;综合因素得出0.1%三氟乙酸/(10%～25%)乙腈/水体系的流动相、0.5 mL/min的流速为该实验下的最佳分离条件。     

伊枯草菌素A发酵过程中游离氨基酸的HPLC分析

建立一种快速、高效测定游离氨基酸含量的异硫氰酸苯酯(PITC)柱前衍生高效液相色谱法,并利用此方法分析检测iturin A发酵过程中游离氨基酸的动态变化。以异硫氰酸苯酯(PITC)为衍生化试剂,采用Venusil-AA(4.6 mm×250 mm,5μm)氨基酸分析专用柱,并优化HPLC检测色谱条件。结果表明:梯度洗脱程序、流动相pH值、色谱柱温对分析时间、色谱峰分离及峰型具有重要影响。当最优色谱条件为:流动相A为0.1 mol/L无水乙酸钠缓冲溶液(pH6.4±0.1)-乙腈(66∶5),流动相B为乙腈-水(4∶1),流速1.0 mL/min,检测波长254 nm,色谱柱温40℃,梯度程序洗脱,35 min内可完全分离16种氨基酸,且各氨基酸在一定浓度范围内线性关系良好(R2均大于0.9986),加标回收率在83.84%-108.02%之间,RSD值均小于2.77%。该方法耗时短、操作简便、准确可靠,具有良好的精密度和稳定性。通过此方法研究分析伊枯草菌素A发酵过程中各游离氨基酸含量变化规律,发现其氨基酸浓度变化规律大致分为三类。     

分析紫杉醇与三尖杉宁碱的简易方法

以粒径单分散聚苯乙烯反相色谱填料为色谱柱固定相,即采用MKF-DK-RP型分析柱(300mm×7.8mm,8μm),流动相为乙腈-水溶液,流速为1.0mL/min,检测波长为229nm,建立了一种分析紫杉醇与三尖杉宁碱的简易方法。结果表明,本方法可使紫杉醇与三尖杉宁碱达到有效分离,且紫杉醇的检测浓度在0.0625~2.0mg/mL范围内线性关系良好(r=0.9999)。本方法简单,重复性好。     

反相液相色谱法分析芦荟制品中有机酸

提出了一种反相液相色谱法分析芦荟制品中有机酸的含量。采用C18 RP为色谱分离柱,磷酸盐溶液与乙腈作流动相;芦荟制品经简单处理后直接进行分离定量,在10min内把其中的苹果酸、乳酸和富马酸等完全分离定量,各种酸的回收率均大于98％。经多次实验证明：该方法是测定芦荟制品中有机酸的快速、准确和有效的定量方法。     

白屈菜药材HPLC指纹图谱研究

本文建立了白屈菜药材的HPLC指纹图谱。采用DiamonsilC 18柱 (迪马公司 )为分析柱 ,以乙腈 0 0 1MKH2 PO4 梯度洗脱为流动相 ;柱温 35℃ ;流速 1ml/min :检测波长 2 90nm。在上述条件下可以很好的分离白屈菜的各类成分 ,得到的色谱图可作为白屈菜药材专属性的指纹图谱。     

高效液相色谱-柱后光化学衍生法测定变性淀粉中黄曲霉毒素含量的研究

本文采用高效液相色谱-柱后衍生法对变性淀粉中的黄曲霉毒素G2、G1、B2和B1含量进行测定.样品采用乙腈-水(84:16,v/v)提取,经免疫亲和柱净化,C18色谱柱分离,以乙腈-甲醇-水(10:30:60,v/v)为流动相进行洗脱,用HPLC光化学衍生-荧光检测器检测样品含量.结果表明,4种黄曲霉毒素的标准曲线线性均...     

双歧杆菌发酵果蔬汁中低聚果糖的高效液相色谱法分析

目的采用高效液相色谱法（HPLC）对双歧杆菌发酵果蔬汁中的低聚果糖进行分析。方法 HPLC分析条件为：ZORBAX NH2 Analytical色谱柱,乙腈∶水（75∶25）为流动相,柱温35℃,流速为1.0ml/min,示差折光检测器（RID）。结果果蔬汁中的低聚果糖及几种主要糖类均得到有效分离。此分离方法的加标回收率和精密度（RSD）均较高。结论分析结果表明双歧杆菌发酵果蔬汁中含有较丰富的功能性低聚果糖,尤其是蔗果三糖含量很高。     

同规格不同生产厂家的色谱柱对胸腺法新有关物质测定结果的影响

目的:通过比较同规格不同生产厂家的色谱柱对胸腺法新有关物质测定结果的影响,对中国药典2010年版二部收录的胸腺法新有关物质测定法进行探索研究。方法:选用十八烷基硅烷键合硅胶为填充剂的色谱柱(4.6mm×250mm,5μm);流动相A:乙腈-水-磷酸(140:860:1);流动相B:乙腈-水-磷酸(250:750:1),采用梯度洗脱;流速:1.0mL/min;紫外检测波长:210nm;进样量:20μl;柱温:室温。结果:针对碱破坏样品,同规格不同厂家的色谱柱间测试结果存在明显差异。结论:在使用《中国药典》2010年版二部收录的胸腺法新有关物质检测项下检测方法,对胸腺法新及其制剂进行有关物质检查时,应先进行色谱柱的筛选。采用Thermo scientific Hypersil GOLD C18(250×4.6mm、5?m)、GRACE AlltimaHP C18(250×4.6mm、5μm)色谱柱检测,主峰与峰前邻近杂质峰的分离度好,结果准确可靠,可用于注射用胸腺法新有关物质的测定。     

坚龙胆环烯醚萜甙的HPLC分析

应用HPLC分析方法,建立了坚龙胆中5个主要环烯醚萜甙的含量测定方法。在ZORBAXSB—C18色谱柱,乙腈-0．2％磷酸水溶液为流动相,梯度洗脱,流速1．0mL/min,柱温为40℃,检测波长254nm的色谱条件下,化合物得到良好的分离,并具线性相关。本方法操作简便,重现性好,灵敏度高。对不同产地的样品进行比较分析的结果表明,产地对坚龙胆中环烯醚萜甙的组成和含量有显著的影响。     

Chiral separation of tryptophan enantiomers by liquid chromatography with BSA-silica stationary phase

The separation of tryptophan enantiomers was carried out with medium-pressure liquid chromatography using BSA (bovine serum albumin)-bonded silica as a chiral stationary phase. The influence of various experimental factors such as pH and ionic strength of mobile phase, separation temperature, and the presence of organic additives on the resolution was studied. In order to expand this system to preparative scale, the loadability of sample and the stability of stationary phase for repeated use were also examined. The separation of tryptophan enantiomers was successful with this system. The data indicated that a higher separation factor (α) was obtained at a higher pH and lower temperature and ionic strength in mobile phase. Addition of organic additives (acetonitrile and 2-propanol) in mobile phase contributed to reduce the retention time of L-tryptophan. About 30% of the separation factor was reduced after 80 days of repeated use.     

Optimum operational conditions for chiral separation of tryptophan enatiomers using ligand exchange liquid chromatography

A simple and precise method for chiral separation of tryptophan enantiomers using high performance liquid chromatography with aligand exchange mobile phase was developed. Chiral separation was performed on a conventional C₁₈ column, using a mobile phase that consisted of a water-methanol solution (88∶12, v/v) containing 10 mmol/Ll-leucine and 5 mmol/L copper sulfate as a chiral ligand additive at a flow rate of 1.0 mL/min. This method allowed baseline separation of two enantiomers with a resolution of 1.84 in less than 30 min. The effect of various conditions, including concentration, type of ligand, organic modifier, pH, flow rate, and temperature, on enantioseparation were evaluated and chiral recognition mechanisms were investigated. Thermodynamic data (ΔΔH and ΔΔS) obtained by van't Hoff plots revealed that enantioseparation is an enthalpy-controlled process.     

Chiral HPLC Separation and Modeling of Four Stereomers of DL‐Leucine‐DL‐Tryptophan Dipeptide on Amylose Chiral Column

Chiral high‐performance liquid chromatography (HPLC) separation and modeling of four stereomers of DL‐leucine‐tryptophan DL‐dipeptide on AmyCoat‐RP column are described. The mobile phase applied was ammonium acetate (10 mM)‐methanol‐acetonitrile (50:5:45, v/v). The flow rate of the mobile phases was 0.8 mL/min with UV detection at 230 nm. The values of retention factors for LL‐, DD‐, DL‐, and LD‐ stereomers were 2.25, 3.60, 5.00, and 6.50, respectively. The values of separation and resolution factors were 1.60, 1.39, and 1.30 and 7.76, 8.05, and 7.19. The limits of detection and quantitation were ranging from 1.0–2.3 and 5.6–14.0 μg/mL. The simulation studies established the elution orders and the mechanism of chiral recognition. It was seen that π–π connections and hydrogen bondings were the main forces for enantiomeric resolution. The reported chiral HPLC method may be applied for the enantiomeric separation of DL‐leucine‐DL‐tryptophan in unknown matrices. Chirality 28:642–648, 2016. © 2016 Wiley Periodicals, Inc.     

A procedure for the separation and quantitation of tryptophan and amino sugars on the amino acid analyzer

Tryptophan, 5-methyl tryptophan, glucosamine, and galactosamine can be separated from each other and hydrolysis products including lysinoalanine by chromatography on a 6 × 260-mm column of W-3H resin. The column is developed at 70°C for 20 min with pH 3.95 (0.4 Na⁺) buffer, followed by pH 6.4 (1 Na⁺) buffer for 55 min using a Beckman 119 CL amino acid analyzer. The recovery of the internal standards, 5-methyl tryptophan and galactosamine, can then be used to correct for tryptophan and glucosamine losses, respectively. The procedure uses the column and buffers normally employed for protein hydrolysate analysis and does not require additional resin columns, special buffers, or flow rate changes.     

Analysis of oligogalacturonic acids with 50 or fewer residues by high-performance anion-exchange chromatography and pulsed amperometric detection

Underivatized oligogalacturonic acids with a degree of polymerization (DP) ranging from 2 to 50 have been separated for the first time on a high-performance CarboPac PA1 pellicular anion-exchange stationary phase column. Baseline separation of these pectic fragments was accomplished using a nonlinear gradient of pH 6 potassium oxalate buffer as the mobile phase. Acetate buffer linear gradients were also useful as mobile phases, but only for separations of oligogalacturonic acids that were soluble in this solvent (DP less than 20). Additionally, oligogalacturonic acid separations were accomplished on a lower capacity AS4A stationary phase column. Triple pulse amperometric detection was selective, sensitive, and reproducible, nevertheless, oligogalacturonic acid response factors were affected by DP and compositional changes in the mobile phase.     

Tryptophan Metabolism in Ochromonas malhamensis

Tryptophan enhanced the growth of Ochromonas malhamensis at concentrations up to 0.4 mg/ml; higher concentrations inhibited, the growth inhibition being reversible by tyrosine and adenine. The presence of a tryptophan synthetase system in vitro was demonstrated. Tyrosine and phenylalanine stimulated the activity of this enzyme. The uptake of exogenous tryptophan was accompanied by an increase in the free tryptophan pool which in turn suppressed the tryptophan synthetase system, thus pointing to a controlled mechanism. Incorporation of tryptophan in the growth medium enhanced the biosynthesis of folate-active compounds. An elucidation of the mode of action of tryptophan is attempted on the basis of known metabolic pathways.     

Simultaneous determination of dibucaine and naphazoline in human serum by monolithic silica spin column extraction and liquid chromatography-mass spectrometry

A simple, sensitive, and specific liquid chromatography-mass spectrometry (LC-MS) method for simultaneous determination of dibucaine and naphazoline from serum was developed and validated. The extraction procedure was performed using a monolithic silica spin column. Chromatographic separation of dibucaine and naphazoline was achieved on a C(18) reverse phase column with a mobile phase gradient (mobile phase A: 10mM ammonium formate and mobile phase B: acetonitrile) at a flow rate of 0.2mL/min. LC-MS was operated under the selective ion monitoring mode using the electrospray ionization technique in the positive mode. The retention times for naphazoline, dibucaine, and the internal standard (IS) were 6.7, 7.8, and 8.0min, respectively. A linear graph was obtained for dibucaine and naphazoline with correlation coefficients >0.998 for all analytes by this method. The limit of quantification of dibucaine and naphazoline was 10 and 25ng/mL, respectively. The mean recoveries were greater than 70%. Both compounds were stable under conditions of short-term storage, long-term storage as well as after freeze-thaw cycles. Monolithic spin column extraction and LC-MS analysis enabled the separation of dibucaine and naphazoline within 20min.     

色氨酸操纵子研究进展

色氨酸只能由微生物和植物合成。催化色氨酸分支途径的酶由色氨酸操纵子编码。生物体内色氨酸合成受到严格调控,色氨酸操纵子发挥重要作用。本文综述色氨酸代谢途径及其调节,并对途径工程在色氨酸操纵子改造中的应用进行回顾。     

色氨酸对海水处理下长春花生物碱含量的影响

以长春花为(Catharanthus roseus(L.)G.Don)材料进行温室实验,研究了不同浓度色氨酸对20%海水处理下长春花幼苗生物碱含量的影响,发现20%海水中加入色氨酸,长春花中色氨酸脱羧酶(TDC)活性提高,吲哚生物总碱以及长春碱、长春质碱、文多灵、长春新碱含量显著增加.其中加入500 mg/L的色氨酸最有利于生物碱含量的增加.