Determination of urinary 5-S-cysteinyldopamine by high-performance liquid chromatography with electrochemical detection

Summary 5-S-Cysteinyldopamine, a new metabolite of dopamine, was determined in urine by high-performance liquid chromatography with electrochemical detection. The catechol was detected in 14 of 21 melanoma patients and 7 of 21 normal subjects; the highest values were 657 μg/day for melanoma patients and 44 μg/day for normal subjects. These results suggest that the cysteine conjugate may arise from autoxidation of dopamine but tyrosinase may also participate in the oxidation.     

复合维生素片剂中泛酸钙的反相高效液相色谱法测定

用十八烷基硅烷键合硅胶为填充剂,以V（水）：V（甲醇）：V（H3PO4）=950：50：1为流动相,检测波长为210 nm,采用反相高效液相色谱法分离测定了两种复合维生素片剂中的泛酸钙,实验回收率在99.2%～103.4%之间,相对标准偏差RSD为0.6%～1.0%（n=5）,检出限为41 ng.已用于复合维生素片剂中泛酸钙的测定.     

固相萃取-高效液相色谱电化学法检测大鼠血浆儿茶酚胺

建立了一种Oasis HLB固相萃取-高效液相色谱（HPLC）电化学检测大鼠血浆儿茶酚胺（CAs）的方法。血浆样本在形成二苯基硼酸-儿荼酚胺复合物后经优化的固相提取技术,得到较高样本回收率。以Atlantis C18色谱柱为固定相,确定了各种影响色谱的参数,如流动相组成、pH范围及检测器的设定。儿茶酚胺所有组分肾上腺素（E）、去甲肾上腺素（NE）和多巴胺（DA）的平均提取回收率在90％～95％之间。E、NE和DA的质量浓度在0．25～30ng／mL时与峰面积呈良好的线性关系（r值分别为0．9989,0．9992和0．9984）;检出限为0．4pg。该法灵敏、准确、重现性好、结果可靠。     

HPLC with electrochemical detection of metal-flavonoid-complexes isolated from food

Summary The electrochemical and chromatographic behaviour of flavonoid standards and of flavonoids extracted from food (green tea, black tea and onions) is investigated with respect to metalbinding properties. It is shown that metals such as iron, copper or aluminium are complexed by flavonoids, preferrably by those having an aromatic o-dihydroxy structure. This is confirmed by cyclic voltammetry on HPLC fractions (stopped flow) and by AAS measurement of metals. As the complexing sites of flavonoids are closely related to electrochemical properties, this is used for an indirect detection of metal species at low oxidation potentials. For iron species in particular a sensitive and selective detection is possible. For copper reductive detection can also be used.     

反相高效液相色谱法测定化妆品中辅酶Q10的含量

建立一种测定化妆品中辅酶Q10含量的反相高效液相色谱方法.样品用异丙醇振荡萃取后,经C18固相萃取小柱净化.以Hypersil ODS2(5 μm,150 mm×4.6 mm i.d)作分析柱,以辅酶Q9为内标,异丙醇-甲醇(V(异丙醇)V(甲醇)=23)作流动相,在波长275 nm处进行检测.在0.5～100mg/L范围内,峰高比与质量浓度比呈良好的线性关系,化妆品中辅酶Q1o的检出限为0.76ng.方法的RSD《5%.     

Separation of epigallocatechin and flavonoids from Hypericum perforatum L. by high-speed counter-current chromatography and preparative high-performance liquid chromatography

High-speed counter-current chromatography (HSCCC) and preparative high-performance liquid chromatography (prep-HPLC) were successively used for the separation of epigallocatechin and flavonoids from Hypericum perforatum L. The two-phase solvent system composed of ethyl acetate–methanol–water (10:1:10, v/v) was used for HSCCC. About 900 mg of the crude extract was separated by HSCCC, yielding 7.8 mg of quercitrin at a purity of over 97%, 12.6 mg of quercetin at a purity of over 93%, and 38.9 mg of a mixture of hyperoside, isoquercitrin and miquelianin constituting over 97% of the fraction. A mixture of epigallocatechin and avicularin pooled from three HSCCC runs, a total amount of 54.3 mg, was further separated by prep-HPLC yielding 23.4 mg of epigallocatechin and 15.3 mg of avicularin each at a purity of over 97%.     

The analysis of ethinyloestradiol in tablets by liquid chromatography with electrochemical detection

Summary The analysis of ethinyloestradiol in tablets has been carried out by reversed phase high performance liquid chromatography (HPLC) using electrochemical detection. The drug was eluted with aqueous acetonitrile containing sodium acetate as background electrolyte. The mobile phase was used as extracting solvent, and 4-tertpentylphenol was used as internal standard.     

Simultaneous determination of four 5-hydroxy polymethoxyflavones by reversed-phase high performance liquid chromatography with electrochemical detection

Accumulating evidence has suggested the potential health-promoting effects of 5-hydroxy polymethoxyflavones (5-OH-PMFs) naturally existing in citrus genus. However, research efforts are hampered by the lack of reliable and sensitive methods for their determination in plant materials and biological samples. Using reversed-phase high performance liquid chromatography (HPLC) equipped with electrochemical (EC) detection, we have developed a fast and highly sensitive method for quantification of four 5-OH-PMFs, namely 5-hydroxy-6,7,8,3′,4′-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone, 5-hydroxy-6,7,4′-trimethoxyflavone, and 5-hydroxy-6,7,8,4′-tetramethoxyflavone. The method was fully validated in terms of linearity, accuracy and precision. The limit of detection (LOD) was determined as being between 0.65 and 1.8 ng/mL (ppb), demonstrating an over 160 times higher sensitivity in comparison with the previously reported method using UV detection. The recovery rate of the method was between 96.17% and 110.82%, and the precision for the retention times and peak areas was all below 13%. The method was successfully used to quantify 5-OH-PMFs with a wide range of abundance in the citrus products and preparations, such as orange juice, citrus peel, and dried tangerine peel. The quantification method for 5-OH-PMFs developed herein could be useful for the nutritional and pharmacological studies of these compounds in future.     

Detection of albiflorin and paeoniflorin in Paeoniae Radix by reversed-phase high-performance liquid chromatography with pulsed amperometric detection

We have developed a reversed-phase high-performance liquid chromatography-pulsed amperometric detection (RP-HPLC-PAD) method for the detection of albiflorin and paeoniflorin in Paeoniae Radix and Wu-ji-san. Albiflorin and paeoniflorin were completely separated using 10% acetonitrile in 5 mM sodium phosphate buffer (pH 3.0) as an eluent and detected by PAD under alkaline conditions after using a post-column delivery system. The limit of detection (S/N = 3) and the limit of quantification (S/N = 10) were 0.10 and 0.35 ng for albiflorin, and 0.20 and 0.50 ng for paeoniflorin, respectively. The coefficients of linear regression were 0.9995 and 0.9999 for concentrations between 0.035 and 100 μg/mL. The intra- and inter-day precision (RSDs) was less than 3.56% in Paeoniae Radix and Wu-ji-san. The average recoveries from Paeoniae Radix and Wu-ji-san were 99.01–100.94% and 99.46–100.64%. This method shows higher selectivity than HPLC–UV method for analyzing albiflorin and paeoniflorin in Chinese medicinal preparation.     

Determination of glutathione content in grape juice and wine by high-performance liquid chromatography with fluorescence detection

A modified preparation of sample was developed for the determination of glutathione content in grape juice and wine by high-performance liquid chromatography with fluorescence detection, using on-line pre-column derivatization. Ice-cold deoxygenated methanol was used to deactivate the oxidation enzymes in juices or wines and keep the glutathione stable. The optimum recovery of glutathione content in grape juice and wine was obtained when either the sample of grape juice or wine was mixed in ice-cold deoxygenated methanol in the ratio 10:90 (v:v) and further diluted in sodium acetate buffer in the ratio 1:1 (v:v). The optimized method was validated for linearity, limit of detection, limit of quantification, precision and uncertainty. According to the validation data the method is appropriate for the determination of glutathione content in grape juice and wine. Glutathione contents in grape juices made from White Muscat grapes and Sauvignon Blanc wines were analysed. The average glutathione content in 28 young Sauvignon Blanc wines was 12.5 mg L⁻¹.     

毛细管电泳电化学检测法测定蜂胶中的黄酮和酚酸

用毛细管电泳电化学检测法同时测定蜂胶中的黄酮和酚酸的含量.考察了电极电位、运行缓冲液的酸度和浓度、电泳电压及进样时间对分离和检测的影响.在最佳实验每件下,以300μm直径的碳圆盘电极为检测电极,检测电位为+0.90 V(vs.SCE),在50 mmoL/L硼酸盐(pH:9.2)缓冲液中,上述各组分在25 min内能完全...     

Trace determination of nitrated polycyclic aromatic hydrocarbons using liquid chromatography with on-line electrochemical reduction and fluorescence detection

An efficient clean-up procedure coupled with a high performance liquid chromatography (HPLC) with on-line electrochemical (EC) reduction and fluorescence detection (FLD) was developed to quantify nitrated polycyclic aromatic hydrocarbons (NPAHs) in the airborne particulate. In this process, NPAHs were extracted ultrasonically followed by analysis by using a reversed phase column with an aqueous eluent containing 70% aqueous acetonitrile and sodium monocholoroacetate as a buffer solution. The extraction efficiencies were above 83% for 1-nitropyrene and 1,3-dinitropyrene (1,3-DNP) 1,6-DNP, and 1,8-DNP, and calibration graphs were linear with very good correlation coefficients (r>0.999) and the detection limits were in the range of 1.0-2.2 pg for dinitropyrenes and nitropyrene. The proposed method provides a relatively simple and convenient procedure for determining the NPAHs samples in airborne particulate.     

高效液相色谱荧光测定及质谱鉴定分析血清中胆汁酸

利用新型荧光试剂1,2-苯并-3,4-二氢咔唑-9-乙基苯磺酸酯(BDEBS)作柱前衍生化试剂,在EclipseXDB-C8色谱柱上,采用梯度洗脱对10种胆汁酸(BAs)荧光衍生物进行了优化分离。95℃下在二甲基亚砜(DMSO)溶剂中以柠檬酸钾作催化剂,衍生反应35min后获得稳定的荧光产物,衍生反应完全。荧光激发和发射波长分别为λex=333nm,λem=390nm。采用大气压化学电离源(APCISource)正离子模式,实现了血清中胆汁酸的定性测定。分析物的定量测定采用荧光法进行。线性回归系数均在0.9996以上,检出限为22.36~44.57×10-15mol。     

Analysis of four alkaloids of Coptis chinensis in rat plasma by high performance liquid chromatography with electrochemical detection

A sensitive and precise high performance liquid chromatography (HPLC)-electrochemical detection (ECD) method has been developed for the simultaneous determination of four isoquinoline alkaloids including berberine, jatrorrhizine, coptisine and palmatine in Chinese medicine Coptis chinensis. The typical HPLC analysis was performed on WondaSil^® C18-WR column (250 × 4.6 mm, 5 μm) with the mobile phase comprising 40 mM phosphate buffer (pH 7.0)–acetonitrile (40:60, v/v) at the flow rate of 0.8 mL min⁻¹. The electrochemical detection employed a three electrode system with a bare glassy carbon electrode at +1.3 V versus the Ag/AgCl reference electrode. The limits of detection (LODs) of four alkaloids ranged from 0.01 to 0.03 μmol L⁻¹ and the LOD of berberine was 80 times lower than LOD obtained by UV detection. The rat plasma samples were assayed after oral administration of the traditional Chinese medicine Coptis chinensis by the proposed HPLC-ECD method. The recoveries of this method were ranging from 88.0 to 116%, with the relative standard deviation lower than 3.1% for intra-day precision and 5.7% for inter-day precision. These results show that HPLC-ECD is a useful tool for the quality control of herbal medicine Coptis chinensis and also for pharmacokinetic studies.     

Neurochemical studies on catecholamines and indoleamines by high-performance liquid chromatography with electrochemical detection

Summary This communication reports the HPLC separation and quantitative ECD assay of dopamine (DA) and its metabolites DOPAC and HVA, 5-HT and its metabolite 5-HIAA and the noradrenaline metabolites MHPG and VMA, in samples of rat brain extracts and human CSF. The separation is carried out by reversed-phase with a methanolic phosphate/citrate buffer as mobile phase. Response is linear within 10pg-20 ng. Rat brain homogenates of cortex plus striatum were centrifuged and 10–20 l aliquots injected in the column. CSF samples were directly injected without any further manipulation. The method has been applied to the study of the possible neuromodulating role of T on the catecholaminergic and serotonergic transmission. For this purpose rats are injected intraperitoneally (ip) with T (150 mg/kg) and killed after 30 min. Relative to control rats, the results show that for n=12, T does not affect the basal level of DA and DOPAC whereas HVA increases a 99.3% and 5HT and 5HIAA show variations of 23% and — 4.1%, respectively. Aside from the fall of 5HIAA, it is interesting to note that the turnover rate of 5HT decreases, which might prove of functional significance.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Determination of ambroxol in dog plasma by high-performance liquid chromatography and UV detection

Summary A new sensitive HPLC-UV method has been developed and validated for the determination of amboroxol in dog plasma enabling the investigation of a newly developed 75 mg ambroxol-containing retard capsule of EGIS Pharmaceuticals Ltd., Budapest, Hungary. A gradient method was used for removing the longer retained plasma components of no interest. The separation was performed on a BDS Hypersil C18 (5 μm, 250×2.1 mm) analytical column, supplied with a 10 mm guard column containing the same packing material. The detection was performed at 210 nm. The calibration curve was linear in the range 25–2000 ng·mL⁻¹. Nerisopam (EGIS-6775) was used as internal standard. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

Facile extraction of berberine from different plants,separation, and identification by thin-layer chromatography,high-performance liquid chromatography,and biological evaluation against Leishmaniosis

The extraction of berberine was carried out from Berberis vulgaris, Berberis aquifolium, and Hydrastis canadensis plants using ethanol and water (70:30, v/v). The extracted berberine was characterized by ultraviolet-visible and Fourier-transform infrared spectroscopy. The purity of berberine was ascertained by thin-layer chromatography using n-propanol-formic acid-water (95:1:4) and (90:1:9) solvents. hR_f values were in the range of 44–49 with compact spots (diameter 0.2–0.4 cm). HPLC was carried out using ammonium acetate buffer and acetonitrile in gradient mode with Zodiac (4.6 × 150 mm, 3 μm) column. The flow rate was 1.0 mL/min and detection was at 220 nm. The values of separation and resolution factors of the standard and the extracted berberine were in the range of 1.13–1.16 and 1.40–1.71, respectively. A comparison has shown that both thin-layer chromatography and high-performance liquid chromatography (HPLC) methods found applications in different situations and requirements. The extracted berberine samples were used to treat Leishmaniosis and the results showed better activity of berberine in comparison to the standard drug Amphotericin B. Briefly, the reported research is a novel and may be used to extract berberine from plants, separation and identification of berberine by thin layer chromatography and HPLC and to treat Leishmaniosis.