Reversed-Phase HPLC Analysis of Steviol Glycosides Isolated from Stevia rebaudiana Bertoni

High Performance Liquid Chromatography (HPLC) experiments have been performed on nine steviol glycosides namely rebaudioside A, steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A isolated from the leaves of Stevia rebaudiana using Reversed-Phase (RP) column. Using RP-HPLC method, the individual retention times for nine naturally occurring ent-kaurane diterpene glycosides of S. rebaudiana reported in JECFA have been determined at four different temperatures: 20℃, 40℃, 60℃, and 79℃. Also, calculated the relative retention times of the eight steviol glycosides steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A against the major steviol glycoside rebaudioside A. HPLC results suggested that temperatures 40℃ and 60℃ would be ideal conditions for better separation of steviol glycosides.

Single-run reversed-phase HPLC method for determining sertraline content,enantiomeric purity,and related substances in drug substance and finished product

A direct enantio-,diastereo-,and chemo-selective high-performance liquid chromatographic method was developed for determining the content,enantiomeric purity,and related substances of the chiral antidepressant drug sertraline HCl in a single chromatographic run.The separation was achieved on a chiral stationary phase based on amylose tris(3-chloro-5-methylphenylcarbamate)under reversed-phase conditions.The method was optimized by evaluating the influence of the temperature and mobile phase composition on the retention and selectivity.The application of the single-run approach allowed to baseline resolve all investigated species in less than 15 min,without using buffers or tandem-coupled columns.The chromatographic method was validated according to the guidelines of the Official Medicines Control Laboratory and applied to control the content of sertraline HCl and related chiral substances in a generic antidepressant formulation.

A Sensitive Reversed-Phase High-Performance Liquid Chromatography Method for the Quantitative Determination of Milk Xanthine Oxidase Activity

A new reversed-phase high performance liquid chromatography method was developed to quantitate the activity of xanthine oxidase involved in milk fat globule membrane with xanthine as the substrate and the separation of product (uric acid). The increment of uric acid in the reaction system was used to calculate the total activity of XO. The optimized assay conditions, linearity of detection, recovery of uric acid and chromatogram were developed in text, indicating this method is simple, rapid and efficient. It is an alternative potential method for the determination of the activity of XO in milk.

INTERSECTION POINT RULE OF THE RETENTION VALUE AND NORMAL BOILING POINT OF THE HOMOLOGUES IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

In this paper, a linear relationship between the logarithm of capacity factor k and normal boiling point to of the homologues has been derived, based on the basic retention equation of liquid chromatography according to statistical thermodyoamics proposed by professor Ln Peizhang and others, This equation has been verified by a large number of experimental data, all the strsight lines of lnk- of bumologues for different mobile phass coaiposltion cross each other at the same point, So the intereection point equation van proposed, wbich was used to prodict the retention valu, the result was satisfactory.

INTERSECTION POINT RULE OF THE RETENTION VALUE AND MOBILE PHASE COMPOSITION OF THE HOMOLOGUES IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Based on the intersection point rule of the retention value and normal boiling point of homologues in reversed-phase high-performance liquid chromatography(RPLC), the intersection point rule of the retention value of homologues and mobile phase composition has been derived, and was testified by a lot of experimental data from the literature. With this newly proposed equation, we can use the retention value of the compound in one mobile phase composition to predict its retention value in any other mobile phase composition. For fourteen groups of homologues in five mobile phase compositions on five Kinds of columns, the overall average absolute error of 721 data sets is 2.8%.

Actional Mechanism of Trifluoroacetic Acid for the Separation of Biopolymers by Reversed-phase Liquid Chromatography

The present paper covers the actional mechanism of trifluoroacetic acid for the separation of biopolymers investigated by using the parameters of stoichiometric displacement model for retention(SDM-R) in reversed-phase liquid chromatography. It was found that the trifluoroacetic acid(TFA) may participate in, or stimulate the association among displacing agent molecules in mobile phase, and decrease the affinity of both the associate molecules of the displacing agent and the TFA-protein ion-pairing. The former dominates over the separation selectivity of biopolymers as the concentration of TFA is lower than a given value, and the two contrary functions partly offset to each other and the latter dominates as its concentration is greater than the given value.

Quantitative analysis by reversed-phase high-performance liquid chromatography and retinal neuroprotection after topical administration of moxonidine

AIM:To determine moxonidine in aqueous humor and iris-ciliary body by reversed-phase high performance liquid chromatography(RP-HPLC),and to evaluate the retinal neuroprotective effect after topical administration with moxonidine in a high intraocular pressure(IOP)model.METHODS:The eyes of albino rabbits were administered topically and ipsilaterally with 0.2%moxonidine.A RPHPLC method was employed for the identification and quantification of moxonidine between 2 and 480 min,which presented in the aqueous humor and iris-ciliary body.Flash electroretinography(F-ERG)amplitude and superoxide dismutase(SOD)level were measured between day 1 and day 15 after topical administration with moxonidine in a rabbit model of high IOP.Histological and ultrastructural observation underwent to analyze the changes of retinal morphology,the inner retinal layers(IRL)thickness,and retinal ganglion cell(RGC)counting.RESULTS:Moxonidine was detectable between 2 and 480 min after administration,and the peak concentration developed both in the two tissues at 30 min,0.51μg/m Lin aqueous humor and 1.03μg/g in iris-ciliary body.In comparison to control,F-ERG b-wave amplitude in moxonidine eyes were significantly differences between day 3 and day 15(P<0.01)in the high IOP model;SOD levels were significantly higher at all time-points(P<0.01)with a maximum level of 20.29 U/mgprot at day 15;and RGCs were significantly higher(P<0.05).CONCLUSION:Moxonidine is a viable neuroprotective agent with application to high IOP model.All layers of retina,including RGC layer,retinal nerve fiber layer and INL,are more preserved after moxonidine administration.SOD plays a neuroprotective role in ocular hypertension-mediated RGC death.

STUDY ON THE SEPARATION AND EXTRACTION MECHANISM OF RARE EARTH ELEMENTS BY MEANS OF REVERSED-PHASE PAPER CHROMATOGRAPHY

Reversed-phase paper chromatography technique is used for study on the extraction mechanism and sep- aration of rare earth elements.As the stationary phase,chromatographic paper strips are impregnated with a solution of monomyristyl phosphoric acid (MPA) in chloroform.Mineral acids are used as developers. The effect of concentration of acids and/or salts upon R_f has been investigated.According to the re- sults of R_f values for a given rare earth element in various acids,the order of extraction ability is HCl>HNO_3>H_2SO_4.A tetrad effect is clearly observed.for the R_f value of rare earth elements.The effects of other parameters on the R_f value,such as the quantities of extractant retained by the paper and the temperature are also examined.Based on the determination of the molar ratio of MPA to rare earth elements and the number of H^+ ions released in extraction reaction,a reasonable mechanism is proposed.The mutual separation of heavy rare earth elements will be better than that of the light rare earth group because of the larger separation coefficient of the former.A mixture of Ho-Er-Tm-Lu is successfully separated by the present method.

Determination of isotretinoin in pharmaceutical formulations by reversed-phase HPLC

The development of facile and rapid quantification of biologically active biomolecules such as isotretitoin in therapeutic drugs contained in many generic formu- lations is necessary for determining their efficiency and their quality to improve the human health care. Isotretritoin finds its applications in the maintenance of epithelial tissues. Different processes to date such as normal phase HPLC, or gas chromatrography am- ong others are able to separate and quantify isote- troin. However, the extraction is quite complex and in the case of HPLC, the analysis requires long retention times. In such context, an isocratic reversed- phase high-performance liquid chromatography (HP- LC) technique coupled with an UV-vis detector is described here for easy separation and quantification of 13-cis-retinoic (isotretinoin) from soft gelatin capsule formulations. The isotretinoin was extracted from three different commercial drug samples with tetrahydrofuran (THF) solvent by a procedure that can be completed in less than 10 minutes. Subsequent separation and quantification were accomplished in less than 5 minutes under isocratic reversed-phase conditions on a Lichrospher RP18 column and a mobile phase consisting of 0.01% TFA/acetonitrile (15/85, v/v) at a flow rate of 1.0 mL/min. Isotretoin was detected for the three samples via its UV-vis absorbance at 342 nm. The method was validated and the results showed good linearity, precision and accuracy for sensitive and selective quantitative determination of isotretinoin in the different pharmaceutical formulations. We found that the average isotretinoin content in two of the three commercial pro- ducts fell outside the 90-110% United States Pha- rmacopeia specifications. Consequently, the facile extraction and the precise method for the biomole- cule quantification open up tremendous possibilities in improving the quality control of drugs which can exist as different generic brands.

评估三种不同品牌的新型冠状病毒抗原洗脱液对甲型/乙型流感病毒抗原检测盒的性能影响

目的:评估三种品牌新型冠状病毒抗原洗脱液对雅培(上海)诊断产品销售有限公司生产的Clearview甲型/乙型流感病毒抗原检测盒的性能影响,探讨研究使用一个样本同时进行新型冠状病毒抗原和甲型/乙型流感病毒抗原两种检测的可行性。方法:选取江苏大学附属医院就诊的102例患者,每人采取两根鼻拭子。按照各自的产品说明书对同一患者采集的双份鼻拭子分别用所选的三种品牌中的一种新型冠状病毒抗原洗脱液和甲型/乙型流感病毒抗原洗脱液进行抗原洗脱、同时检测甲型/乙型流感病毒抗原检测,对检测的结果进行符合率分析。结果:广州万孚生物技术股份有限公司的新型冠状病毒抗原洗脱液的检测Clearview甲型/乙型流感病毒抗原的结果,甲型流感病毒抗原阳性符合率为100%;乙型流感病毒抗原阳性符合率、阴性符合率、总符合率均为100%。杭州艾康生物技术有限公司的新型冠状病毒抗原洗脱液的检测Clearview甲型/乙型流感病毒抗原的结果,甲型流感病毒抗原阳性符合率、乙型流感病毒抗原阳性符合率均为100%;阴性符合率为90%;总符合率为97%。浙江东方基因生物制品有限公司的新型冠状病毒抗原洗脱液的检测Clearview甲型/乙型流感病毒的结果,甲型流感病毒抗原阳性符合率、乙型流感病毒抗原阳性符合率、阴性符合率、总符合率均为100%。结论:所试验的三种品牌的新型冠状病毒抗原洗脱液适用于雅培(上海)诊断产品销售有限公司生产的Clearview甲型/乙型流感病毒抗原检测。

AS23离子色谱柱法测定地表水中碘化物

采用AS23阴离子分析柱,50 mmol/L氢氧化钾淋洗液,流速1.0 mL/min,进样量250μL,对地表水中碘化物进行检测,结果表明,该方法在8.620 min出峰,方法检测限为0.5μg/L,测定方法相关性R=0.9998,线性范围0.01~2 mg/L,适用于地表水中碘化物的测定。

甲状旁腺识别策略在终末期肾脏病患者中的应用价值

目的建立终末期肾脏病行透析治疗患者的数据模型,评价甲状旁腺超声识别策略的诊断效能和可行性。方法选取2021年1月至2021年6月行甲状旁腺超声检查的慢性肾脏病受试者43例,从中识别出疑似甲状旁腺共112枚。以超声引导下细针穿刺细胞学病理+洗脱液Tg+iPTH为诊断金标准,判断“甲状旁腺识别策略”的诊断效能。根据是否使用甲状旁腺识别策略分为试验组和对照组。比较2组判断结果的组内相关系数。结果试验组iPTH水平(2148.744±796.178)pg/mL,对照组iPTH水平(23.676±13.133)pg/ml,2组比较差异有统计学意义(t=22.954,P<0.01)。甲状旁腺识别策略法判断甲状旁腺的诊断准确率为92.857%,敏感度为93.421%,特异度为91.667%,曲线下面积0.925,阳性预测值为95.946%,阴性预测值为86.842%。试验组5名医生甲状旁腺识别结果的组内相关系数为0.814,对照组5名医生甲状旁腺识别结果的组内相关系数为0.568。结论基于本模型,甲状旁腺超声识别策略有较高的诊断效能,该方法可使不同超声医师得出准确且一致的识别结果。

草乌甲素柱层析三元体系回收洗脱液快速调节及二次利用

目的:提供一种草乌甲素柱层析三元体系回收洗脱液快速调节的方法,适用于草乌甲素回收洗脱液的二次利用。方法:通过酸碱滴定法和密度比重法的联合运用,推导出简便的计算公式,按照操作方法测定未知量带入公式,即可准确调节草乌甲素柱层析回收液中三元溶剂的比例关系。结果:通过回收洗脱液(调节后)各组分比例关系验证及洗脱效果验证,说明按照上述方法调节后的回收液能达到新配制的水平,可进行二次利用。结论:所提供的方法原理清晰,操作简单,实用性强,并且将数学计算运用到原料药研发工艺上,使过程控制更精确且可数字化,降低废液排放和生产成本。

淋洗法处理铬污染土壤研究进展

重金属铬进入土壤后不仅会污染地下水,还会在植物体内累积进而危害人体健康。淋洗技术具有操作简单、节约成本、效果显著等优点,是较为常用的铬污染土壤处理方法。本文整理和归纳了目前有关铬污染土壤淋洗的研究,介绍各种淋洗剂的淋洗原理、应用及存在问题,分析影响淋洗效果的因素,如土壤性质、淋洗剂性质、淋洗液pH值、淋洗时间、液固比及增强方式等,并针对铬污染土壤淋洗存在的黏性土壤中铬淋洗效率不高、淋洗后土壤的生态风险评价不足、淋洗废水处理和资源化不足等问题,提出相应建议。

离子色谱仪观测数据影响因素分析

基于压力、流量参数、样品存放时间、淋洗液、混标液配制等实验,分析装置系统、人为干扰、场地环境、自然环境等因素对离子色谱仪观测数据的影响。实验结果表明:流量和压力与观测值成反比,工作电流变化对测值影响不大;纯净水品牌、模板的准确性是产生误差的重要因素;日常观测中取样、样品处理、进样、判峰等人工操作环节会引起测量误差,需保证观测的标准化和规范性。

淋洗液自动发生-离子色谱法同时测定食品中的21种有机酸

建立了一种利用离子色谱法同时测定样品中奎尼酸、乙酸、丙酮酸、草酰乙酸、甘露酸、乳酸、琥珀酸、苹果酸、酒石酸、草酸、富马酸、抗坏血酸、α-酮戊二酸、肉桂酸、水杨酸、柠檬酸、异柠檬酸、阿魏酸、顺乌头酸、反乌头酸、β-香豆酸等21种有机酸的方法。样品经提取、脱色、过滤后用IonPac AS11分离柱分离，以EG40自动淋洗液发生器生成的5～34mmol／L KOH为淋洗液洗脱，抑制电导检测器检测。21种有机酸的浓度与其峰面积在一定的范围内呈良好的线性关系，检出限均低于0．188mg／L，加标回收率为91．5％～101．8％。该法用于多种食物样品中有机酸的测定，结果令人满意。

烟草中9种有机酸的梯度离子色谱法测定研究

采用淋洗液自动发生-梯度离子色谱分离,电导检测法分离测定了烟草中的甲酸、乙酸、乳酸、丙酸、丁酸、苹果酸、丙二酸、草酸和柠檬酸,并研究了9种有机酸在阴离子交换色谱中的保留行为。以淋洗液自动发生器生成的KOH为淋洗液,样品经提取、过滤稀释后,在IonPac AS11-HC阴离子交换色谱柱上分离,抑制电导检测器进行检测,一次进样可同时分离烟草中的常见有机酸。9种有机酸在优化条件下线性良好,相关系数r≥0.998 6,检出限(S/N=3)为0.013～0.065μg/L,相对标准偏差(RSD)为0.7%～3.0%,加标回收率为93%～103%。方法简单、准确、灵敏度高,能够满足实际样品的测试要求。

淋洗液浓度对痕量低分子量脂肪族胺离子色谱分离度的影响

采用阳离子交换柱分离,以甲基磺酸为淋洗液,建立了检测水体中痕量甲胺和二甲胺的离子色谱法,并分析了淋洗液浓度对被测物分离度的影响。结果表明:当淋洗液浓度为3mmol/L,流速为1.1mL/min,应用电导检测时,甲胺和二甲胺在5.0～100μg/L浓度范围内具有良好的线性,方法检出限分别低至8.29ng/L(以峰面积定量)和0.69μg/L(以峰高定量),平均回收率分别为97.2%和91.6%;3个浓度水平样品(10.0,20.0,和100μg/L)的精密度均低于2.1%。本方法操作简单,检出限低,适用于检测水体中痕量存在的低分子量脂肪族胺。

阴离子交换色谱中淋洗液流速对测定灵敏度影响的讨论

研究了阴离子交换色谱法定量分析时淋洗液流速对测定灵敏度影响的规律。使用３种不同型号的阴离子交换柱，详细地研究了３种总离子浓度不同的样品中淋洗液流速对峰高和峰面积的影响。实验表明，若标准溶液和样品溶液中的阴离子总浓度相差较大，将在不同程度上影响分析结果的准确度。初步探讨了上述现象的机理。通过紫外（２１０ｎｍ）和电导检测结果的对比观察，说明灵敏度的变化不完全如文献中提到的由抑制器抑制不足或ＮＯ－２质子化所致。在相同条件下改变柱温后的实验结果表明也不是离子交换过程中离子传质速度比较慢引起离子交换不完全的原因。提出的其它机理假设仍需进一步研究证实。

淋洗剂凝胶渗透色谱法研究非缔合多组分溶液

A polyglycol solution containing different molecular weight PEG components waschosen as test solution. By comparing the results obtained by conventional gel permeation chro-matography GPC(water as eluent, sample solution as injected solution)and Eluent-GPC (PEGsample solution as eluent, the concentrated sample solution ,diluted sample solution, water, and sample solution itself as injected solution respectively), the advantage and potential practical usage of Eluent-GPC were discussed.