Simultaneous micellar electrokinetic chromatography and liquid chromatography of adriblastina and tarabine PFS Their application to some biological fluids

The current work presents analytical procedures for simultaneous determination of tarabine PFS and adriblastina by micellar electrokinetic chromatography (MEKC) and liquid chromatography (LC). For MEKC analysis, separations and identifications were accomplished using uncoated fused-silica capillary with hydrodynamic injections in the presence of 50mM borate/phophate pH 8.7 and 100mM SDS. The migration times of tarabine PFS and adriblastina were found to be 2.70 and 6.40min, respectively. Calibration curves were established for 10-300ng/mL (r=0.998) tarabine PFS and for 8-120microg/mL (r=0.999) adriblastina. For LC analysis, separations were performed on teicoplanin stationary phase with reversed mobile phase containing methanol:buffer pH 4.05 (20:80%, v/v) at 285nm. The retention times of tarabine PFS and adriblastina were 5.18 and 7.20min, respectively. Calibration curves were established for 3-90microg/mL (r=0.998) tarabine PFS and for 10-120microg/mL (r=0.999) adriblastina. Both MEKC and LC methods were applied for the simultaneous determination of analytes in urine samples.     

Simultaneous determination of cefepime and L-arginine by micellar electrokinetic chromatography and applications to commercial injections

A simple micellar electrokinetic chromatography (MEKC) with UV detection is described for simultaneous analysis of cefepime and L-arginine. The determination of cefepime and L-arginine in pharmaceutical preparations was performed at 25degreesC using a background electrolyte consisting of Tris buffer with sodium dodecyl sulfate (SDS) as the electrolyte solution. Several parameters affecting the separation of the drugs were studied, including the pH and concentrations of the Tris buffer and SDS. Under optimal MEKC conditions, good separation with high efficiency and short analysis times is achieved. Using cefazolin as an internal standard, the linear ranges of the method for the determination of cefepime and L-arginine were over 5-100 microg/mL; the detection limits of cefepime (signal to noise ratio = 3; injection 3.45 kPa, 3 s) and L-arginine (signal to noise ratio = 3; injection 3.45 kPa, 3 s) were 2 microg/mL and 4 microg/ mL, respectively. Applicability of the proposed method for the determination of cefepime and L-arginine in commercial injections was demonstrated.     

Simultaneous determination of digoxin and digitoxin by micellar electrokinetic chromatography and application to drug formulations

A simple micellar electrokinetic chromatographic method is described for simultaneous determination of digoxin and digitoxin. The simultaneous analysis of digoxin and digitoxin was performed in Tris buffer (10 mM; pH 9) with 90 mM sodium dodecyl sulfate and 10% isopropyl alcohol as an anionic surfactant and organic modifier. Under these conditions, good separation with high efficiency is achieved in short analysis times. Several parameters affecting the separation of the drugs were studied, including the pH and concentrations of the Tris buffer and sodium dodecyl sulfate. The linear range of the method for the determination of digoxin and digitoxin was over 0.01–0.3 mg/mL; the detection limit (signal to noise ratio = 3; injection 3.5 kPa 3 s) was 4 and 6 μg/mL, respectively. Application of the proposed method to the determination of digoxin in commercial tablets and in injections proved to be feasible.     

离子液体对胶束电动色谱胶束微结构以及分离效果的影响

考察了离子液体对胶束电动色谱胶柬微结构以及分离效果的影响.研究结果表明,离子液体使胶束的表面电荷密度变小、粒径变大及其内核极性增大.以泼尼松、氢化可的松和泼尼松龙为分析对象,氢化可的松与泼尼松龙在十二烷基硫酸钠(SDS)胶束体系中不能实现分离.而在SDS-离子液体混合介质(20 mmol/L SDS-10 mmol/L...     

高效液相色谱法同时测定水体中的环丙沙星和氟甲喹

为了满足实验室测试和野外测试需要,也为其他学者研究不同抗生素之间的相互作用提供相关的资料,本研究选用环丙沙星(CIP)和氟甲喹(FLU)作为代表,建立了一种简单、稳定、易普及的高效液相色谱法用于同时快速测定水体中两种氟喹诺酮类抗生素的含量,并讨论了不同流动相及其比例和水样中几种常见阴、阳离子(Ca²⁺、Mg²⁺、Fe³⁺、Al³⁺、SO₄^2-和HCO₃^-)对抗生素测定的影响。结果表明:三乙胺对改善柱效有明显效果;低浓度离子对测试影响不大,但Fe³⁺和Al³⁺可能与固定相的表面羟基或测试组分发生配合作用,造成基线不稳。实验结果对其他研究者对于流动相的选择与优化具有借鉴意义。     

高效液相色谱法同时测定化妆品中的呋喃妥因和呋喃唑酮

建立了一种同时检测化妆品中呋喃妥因和呋喃唑酮的高效液相色谱法(HPLC)。乳液、膏霜、化妆水、散粉、唇膏类等不同类型的化妆品样品由乙腈-甲醇(体积比为1∶1)混合溶液超声提取后进行HPLC分析。采用Kromasil C18色谱柱,以乙腈-0.4%乙酸溶液(体积比为30∶70)为流动相,流速1.0 mL/min,采用二极管阵列检测器检测,检测波长为365 nm;采用外标法定量,呋喃妥因和呋喃唑酮检测的线性范围为0.1～20 mg/L,相关系数为0.9999,最低检出限为1.2 mg/kg;在0.2,1.0,10.0 mg/L加标水平下,平均回收率为88.0%～104.6%,相对标准偏差为0.5%～4.8%。该方法快速准确,可用于化妆品中呋喃妥因和呋喃唑酮的同时测定。     

毛细管胶束电动色谱法分离测定中药半枝莲中的7种有效成分

建立了毛细管胶束电动色谱同时分析检测中药半枝莲药材及其膏剂中黄芩素、柚皮素、汉黄芩素、野黄芩苷、芹菜素、木犀草素和原儿茶酸7种有效成分的方法。半枝莲样品中7种有效成分经甲醇超声提取。实验考察了运行缓冲溶液的pH值和浓度、添加剂、检测波长、分离电压和进样时间等重要参数对目标物分离的影响。得到的优化条件为: 运行缓冲液50 mmol/L硼砂-0.20 mol/L硼酸溶液(pH 8.4),含8.5 mmol/L十二烷基硫酸钠(SDS),分离电压25 kV,检测波长260 nm和335 nm。在此条件下,7种组分于12 min内达到基线分离。各组分在8×10~6～3.2×10~4mol/L范围内呈良好的线性关系,相关系数(r2)为0.9965～0.9999;检出限为7.0×10~8～2.0×10~6mol/L;回收率均大于85%。该方法提取简便、准确可靠、重复性好、灵敏度高,可以用于中药半枝莲中7种有效成分的定量检测。     

Strategies for the on-line preconcentration and separation of hypolipidaemic drugs using micellar electrokinetic chromatography

Three strategies were investigated for the simultaneous separation and on-line preconcentration of charged and neutral hypolipidaemic drugs in micellar electrokinetic chromatography (MEKC). A background electrolyte (BGE) consisting of 20 mM ammonium bicarbonate buffer (pH 8.50) and 50 mM sodium dodecyl sulfate (SDS) was used for the separation and on-line preconcentration of the drugs. The efficiencies of sweeping, analyte focusing by micelle collapse (AFMC), and simultaneous field-amplified sample stacking (FASS) and sweeping, were compared for the preconcentration of eight hypolipidaemic drugs in different conductivity sample matrices. When compared with a hydrodynamic injection (5 s at 50 mbar, 0.51% of capillary volume to detection window) of drug mixture prepared in the separation BGE, improvements of detection sensitivity of 60-, 83-, and 80-fold were obtained with sweeping, AFMC and simultaneous FASS and sweeping, respectively, giving limits of detection (LODs) of 50, 36, and 38 μg/L, respectively. The studied techniques showed suitability for focusing different types of analytes having different values of retention factor (k). This is the first report for the separation of different types of hypolipidaemic drugs by capillary electrophoresis (CE). The three methods were validated then applied for the analysis of target analytes in wastewater samples from Hobart city.     

高效液相色谱法同时测定发酵液中赤藓糖醇和L-赤藓酮糖的含量

建立了采用高效液相色谱(HPLC)同时测定发酵液中底物赤藓糖醇和产物L-赤藓酮糖含量的方法。采用Lichrospher 5-NH2色谱柱(250 mm×4.6 mm),柱温30 ℃,以乙腈-水(体积比为9:1)为流动相,流速1.0 mL/min。用示差折光检测器检测赤藓糖醇,检测器温度为35 ℃。用紫外检测器在室温下检测L-赤藓酮糖,检测波长为277 nm。所得赤藓糖醇的线性范围为1.00～100.00 g/L,相关系数为0.9985,检出限为0.10 g/L,定量限为0.45 g/L;所得L-赤藓酮糖的线性范围为1.00～100.00 g/L,相关系数为0.9958,检出限为0.50 g/L,定量限为0.87 g/L;赤藓糖醇的日内和日间相对标准偏差(RSD)分别小于3.28%和5.30%, L-赤藓酮糖的日内和日间RSD分别小于2.16%和2.25%;回收率均大于99%。取不同时间的发酵液样品分别用上述方法测定,结果表明所建立的HPLC法不受发酵液中其他组分的影响,可同时测定底物赤藓糖醇和产物L-赤藓酮糖的含量。     

Simultaneous determination of nine flavonoids and qualitative evaluation of Herba Epimedii by high performance liquid chromatography with ultraviolet detection

A simple high performance liquid chromatographic method has been developed for the determination of nine flavonoids in Herba Epimedii, including quercetin-3-O-glucoside, epimedin A, hexandraside A, epimedin B, epimedin C, icariin, icariside I, icariside II, and icaritin. The chromatographic separation was performed on a Diamonsil C(18) column (5 microm, 250x4.6 mm) with gradient elution by acetonitrile-0.5% acetic buffer (adjusted to pH 5.00 with triethylamine). Methodological validation gave acceptable linearities (r(2) >0.9992) and recoveries (ranging from 98.9 to 102.4%). The limits of detection of these flavonoids ranged from 16.3 to 83.3 ng. The results indicated that the contents of flavonoids in Herba Epimedii varied significantly from habitat to habitat with contents ranging from 0.05 to 39.0 mg/g. Twenty five Herba Epimedii samples prepared from five different botanical materials were investigated by the established method, and the results showed the influence of the botanical material and the habitat on the quality of Herba Epimedii. The proposed method is simple, effective, and suitable for the evaluation of this traditional Chinese medicine.     

高效液相色谱法同时分离检测食品添加剂

建立了一种同时分离检测没食子酸丙酯(PG)、特丁基对苯二酚(TBHQ)、二丁基羟基甲苯(BHT)和苯甲酸等食品添加剂的高效液相色谱(HPLC)分析方法.通过对流动相、流速、柱温、检测波长等色谱条件的优化,确定了最佳的分离检测条件:甲醇(B)和水(A)(0.1%的乙酸溶液)作为流动相,梯度洗脱:0~6 min,60%B,流速0.3 m L/min;6~9 min,60%~100%B,流速0.6 m L/min,柱温维持在25℃,检测波长280 nm(PG、TBHQ、BHT),230 nm(苯甲酸).在最佳的色谱条件下,方法的线性范围分别为1~200、2~400、2~400、0.5~400 mg/L,检出限(LOD)为0.02~0.06 mg/L,相关系数(R2)均大于0.999 4,加标回收率在77.76%~106.27%之间.该方法还成功应用于话梅、薯片、方便面实际样品中食品添加剂的分析检测.     

高效液相色谱法同时测定厚朴温中胶囊中的7种有效成分

建立了同时测定厚朴温中胶囊中山姜素、甘草酸、和厚朴酚、小豆蔻明、木香烃内酯、去氢木香内酯及厚朴酚含量的反相高效液相色谱法。固定相为Scienhome C18柱(250 mm×4.6 mm,5 μm),流动相为甲醇-乙腈-0.06%磷酸溶液(体积比为38∶27∶35),流速为1.0 mL/min,柱温为30 ℃,检测波长为235 nm。在上述条件下,山姜素、甘草酸、和厚朴酚、小豆蔻明、木香烃内酯、去氢木香内酯及厚朴酚的质量浓度分别在0.885～17.7,107～2140,8.85～17.7,1.035～20.7,4.85～97,5.9～118和17.5～350 mg/L时与色谱峰面积之间的线性关系良好;回收率分别为96.9%～101.1%,96.0%～100.5%,100.3%～100.8%,97.7%～101.4%,100.4%～102.3%,96.0%～102.3%和96.2%～100.6%。该方法简便、快速、准确,可用于厚朴温中胶囊的质量控制。     

Combination of hollow fiber-based liquid-phase microextraction with sweeping techniques in micellar electrokinetic chromatography for the determination of Strychnos alkaloids in human urine

A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextraction (LPME) based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinetic chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL-1 for both strychnine and brucine in human urine sample. The detection limits (S/N=3:1) for strychnine and brucine were 1 ng mL-1 and 2 ng mL-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.     

Simultaneous determination of some organophosphorus pesticides by high performance liquid chromatography

An HPLC method for the simultaneous detection of six organophosphorus pesticides (Dimethoate, Ethion, Malathion, Phorate, Phosalone and Parathion) on a Zorbex ODS column using methanol + water (80:20) as solvent is described.     

Separation and determination of acrylamide in potato chips by micellar electrokinetic capillary chromatography

A simple and rapid method using micellar electrokinetic capillary chromatography (MEKC) was developed for the separation and determination of acrylamide in potato chips at low levels for the first time. The experimental conditions for the separation and quantification of acrylamide were optimized at first. The optimized conditions were: 50 mmol/L Na₂B₄O₇ and 40 mmol/L SDS at pH 10.0, 12 kV applied voltage, 76 cm total length (67 cm effective length) and 75 μm i.d. capillary, 198 nm wavelength, 15 cm high 25 s hydrodynamics sample injection, 20 °C air-cooling. The linear response of acrylamide concentration ranges from 0.5 to 100 μg/mL with high correlation coefficient (r = 0.9986, n = 9). The LOD and LOQ were estimated to be 0.1 and 0.33 μg/mL based on S/N = 3 and 10. The precision values (expressed as R.S.D.) of intra- and inter-day were 0.86-4.35% and 2.61-9.65%, respectively. Recoveries spiked at levels 2, 20, 60 μg/mL ranged between 90.86% and 99.6% with R.S.D. less than 6.5%. Finally, the developed method has been applied to the analysis of real samples and has achieved satisfactory results. All of these indicated that it was a reliable method for the quantification of acrylamide in potato chips.     

Separation of fifteen quinolones by high performance liquid chromatography: application to pharmaceuticals and ofloxacin determination in urine

A simple chromatographic method is described for assaying 15 quinolones and fluoroquinolones (pipemidic acid, marbofloxacin, enoxacin, ofloxacin, norfloxacin, ciprofloxacin, danofloxacin, lomefloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, nalidixic acid, flumequine and piromidic acid), in urine and pharmaceutical samples. The determination was achieved by LC using an RP C18 analytical column. A mobile phase composed of mixtures of methanol-ACN-10 mM citrate buffer at pH 3.5 and 10 mM citrate buffer at pH 4.5, delivered under an optimum gradient program, at a flow rate of 1.5 mL/min, allows to accomplish the chromatographic separation in 26 min. For detection, diode-array UV-Vis at 280 nm and fluorescence detection set at excitation wavelength/emission wavelength: 280/450, 280/ 495, 280/405 and 320/360 nm were used. Detection and quantification limits were between 0.3-18 and 0.8-61 ng/mL, respectively. The method was validated in terms of interday (n = 6) and intraday (n = 6) precision and accuracy. The procedure was successfully applied to the analysis of human and veterinary pharmaceuticals. Also, ofloxacin was determined in human urine samples belonging to a patient undergoing treatment with this active principle, among others.     

Development and validation of a method to determine amoxicillin in physiological fluids using micellar liquid chromatography

A simple and robust method was developed for the routine identification and quantification of amoxicillin by micellar LC. Amoxicillin, a beta-lactamase inhibitor, is one of the most commonly prescribed drugs in the treatment of urine and skin structure infections. In this work, amoxicillin was determined in urine samples without any pretreatment step in a phenyl column using a micellar mobile phase of 0.10 M SDS and 4% butanol at pH 3. A UV detection set at 210 nm was used. Amoxicillin was eluted at 5.1 min with no interference by the protein band or endogenous compounds. Linearities (r >0.9998), intra- and interday precisions were determined (RSD (%) 0.4-2.7% and 0.3-5%, respectively, in micellar media, and 0.14-2.6% and 0.13-6%, respectively, in urine), and robustness was studied in the method validation. LOD and LOQ were 0.04 and 0.1 microg/mL in micellar media and 0.14 and 0.34 microg/mL in urine, respectively. Recoveries in the urine matrix were in the range of 95-110%. The validated method proved to be reliable and sensitive for the determination of amoxicillin in urine samples.     

Development and validation of new methods for the determination of melatonin and its oxidative metabolites by high performance liquid chromatography and capillary electrophoresis,using multivariate optimization

Melatonin (N-acetyl-5-metoxytriptamine, MEL) has focused a lot of attention as consequence of its multiple functions. MEL is a potent endogenous antioxidant and a free radical scavenger that reacts with several sort of radicals generating various metabolites. Two of them are N1-acetyl-N2-formyl-5-methoxykynurenine (AFMK) and N1-acetyl-5-methoxykynurenine (AMK). These compounds are important because they have also antioxidant actions as well as other important biological properties. In the present work, we develop two methods to detect and quantify these compounds (MEL, AFMK and AMK) in the same sample. For this purpose we used an experimental design, and utilized high performance liquid chromatography (HPLC-DAD) and micellar electrokinetic chromatography (MEKC) techniques with diode array detector in both of them. The limit of detection/quantification for MEL, AFMK and AMK were respectively 44/94, 18/38 and 23/51 ng mL⁻¹ by using HPLC and 13/44, 37/124 and 47/156 ng mL⁻¹ by using MEKC. This is the first time that these compounds have been separated in the same chromatogram or electroferogram. The time of analysis was faster using MEKC. Furthermore, this technique showed better resolution but HPLC offered better limit of detection and quantification for metabolites. Both methods were validated and correlation coefficients were higher than 0.999 and the range of recovery of those methods were 99.6–103.7%. Precision was evaluated as repeatability and intermediate precision with relative standard derivation <5%. When a 5 μg mL⁻¹ solution of these compounds were analyzed with both methods we do not observed any statistically significance differences. Moreover, we analyzed 3COHM (cyclic-3-hydroximelatonin), another known metabolite of melatonin, by using the same methods. The employment of these methods will offer a useful tool to contribute to answer the role of MEL, AFMK and AMK in biological system and both methods can be used in routine analysis for these compounds.     

Extraction of nitrofurantoin and its toxic metabolite from urine by supercritical fluids. Quantitation by high performance liquid chromatography with UV detection

A procedure is described for the determination of nitrofurantoin and its toxic metabolite in urine from patients with urinary infection using supercritical fluid extraction (SFE) and liquid chromatography. The standard solution of toxic metabolite (radical anion) was obtained by electrochemical reduction of nitrofurantoin in an aprotic medium and chemical reoxidation with oxygen. In our initial SFE studies to find the adequate extraction parameters, drug solutions were impregnated onto filter paper. Quantitative extractions were achieved when the experiments were carried out under 2500 psi of pressure at a temperature of 80 °C (oven and restrictor) after 20 min of static extraction and 5 min of dynamic extraction. The modifier used was acetonitrile (2.0 ml in a 10 ml extraction column). Nitrofurantoin and its toxic metabolite were detected in urine samples. Both compounds were quantified in the extracts by high performance liquid chromatography (HPLC) with detection at 310 nm. The calibration graph of these compounds in acetonitrile was linear between 10.9 and 378.0 μM (R=0.9995) for nitrofurantoin and between 3.0×10⁻³ and 21.0 μM (R=0.9992) for the metabolite. The detection limits (LOD) were 12.1 and 0.9 μM, respectively. The drug was administered to two patients during 7 days, and all the urine eliminated between 1 day before and 2 days after administration was analyzed. One patient consumed the drug in the form of microcrystals and the other as macrocrystals.     

Simultaneous separation of nitrofuran antibiotics and their metabolites by using micellar electrokinetic capillary chromatography

Mixtures comprising nitrofuran antibiotics (NFA) and nitrofuran metabolites (NFM) were resolved for the first time by using MEKC. Sodium deoxycholate (SDC) was chosen as the micelle-forming surfactant. Optimization of separation conditions was achieved by using a central composite experimental design (CCD) approach. Experimental parameters such as concentration ratio of borate to phosphate in the buffer, pH of the running electrolyte and voltage were investigated. The effect of concentration of the surfactant on resolution was significant. Under optimal conditions of 80 mM SDC, pH 9.0, (20 mM borate + 20 mM phosphate) and 16 kV, the resolution between eight consecutive peak pairs ranged from 1.9 to 11.8. Due to the absence of a UV-active chromophore in the metabolites, they were derivatized with 2-nitrobenzaldehyde (2-NBA). In order to mimic a proposed extraction procedure for the analysis of both NFA and/or derivatized NFM in a sample, aqueous samples (prederivatized with 2-NBA) were extracted by using C(18) SPE cartridges. After washing with H(2)O, the cartridges were eluted with a small portion of organic solvent with weak elution characteristics to remove excess 2-NBA (hexane was chosen). Target analytes were then recovered with ACN. Excellent reproducibility of migration time (t(mig)) was achieved for all analytes using the developed MECC approach, with absolute t(mig) <1% RSD and t(mig) ratio <0.2% RSD, and peak area ratio was 4% RSD. The LOD for each compound, calculated by extrapolating to an S/N of 3, were found to be 0.19-2.0 microg/mL.