Indirect Determination of Pyrrolizidine Alkaloids by Flame Atomic Absorption Spectrometry

Abstract

This paper studies the formation and extraction of ion pairs of some alkaloids derived from pyrrolizidine. The substances studied are Nemorensine, Platyphylline, Senecionine and Seneciphylline, and the ion pairs studied and extracted are formed with Bil₄. The method consists of extracting an ion pair between the organic base and the inorganic complex, the metal is measured in the organic phase (1,2 dichloroethane) by Flame AAS. The optimal experimental conditions, pH, concentration of BiI₄ ^?, shaking time, phase ratio, number of extractions, and the range of calibration are studied for these substances. The linear range in organic phase is 0.13–1.91 mg.mL^?1. The standard deviation of the method varies between 2.4–3.2%, depending on the substance analyzed. The interferences produced by various substances are studied.     

Simultaneous Determination of Senecionine,Senlciphylline, and Senecionine N-Oxide in Gynura segetum by RP-HPLC

Abstract

A rapid reversed-phase high-performance liquid chromatographic (RP-HPLC) method was established for simultaneous determination of senecionine, senlciphylline, and senecionine N-oxide in a famous traditional Chinese medicine, Gynura segetum, which has been commonly used for hemostasis. The HPLC assay was performed on a Kromasil KR100-5 C₁₈ column (25 cm × 4.6 mm, 5 µm) with mobile phase composed of acetonitrile and 0.2% phosphoric acid–triethylamine within 40 min. The detection wavelength was 220 nm. All the compounds showed good linearity (r² > 0.9997). The method was reproducible with intra- and interday variation less than 2.82%. The recovery of the assay was in the range of 96.55–103.88%. The method was successfully applied to the quantification of three constituents in 15 Gynura segetum samples collected from different metropolis. The results indicated that the developed assay could be considered as a suitable quality-control method for Gynura segetum.     

Reverse Phase Isolation of Pyrrolizidine Alkaloids

Abstract

A new liquid chromatography method for the isolation of pyrrolizidine alkaloids has been developed. The use of reverse phase high pressure liquid chromatography with a methanol - .01 M KH₂ PO₄ (pH 6.3) solvent system is discussed. Pyrrolizidine alkaloids from Senecio vulgaris, S. longilobus, and S. jacobaea have been isolated and identified.     

Determination of Dexamethasone in Cosmetics by MEKC

A rapid and reliable method based on micellar electrokinetic capillary chromatography has been developed for the determination of dexamethasone in cosmetics. Effects of buffer composition, concentration and pH, the detection wavelength, separation voltage, and injection time were systematically investigated. The optimum conditions were: 30 mM borax buffer containing 20 mM sodium dodecyl sulfate at pH 9.0, detection at 254 nm, injection time 10 s at a height of 10 cm, and a separation voltage of 15 kV. Under these conditions, the analysis of dexamethasone in cosmetics was carried out within 6 min. The method was validated for stability, precision, linearity and accuracy. Excellent linearity was obtained in the range of 50–1,000 μg mL⁻¹, and acceptable precision, in intra-day and inter-day analysis, was also obtained with relative standard deviation in the range of 0.19–0.86 and 2.50–4.90% for migration time and peak area ratio, respectively. The method was used to analyse eight cosmetic samples purchased locally.     

Preparative Isolation of Pyrrolizidine Alkaloids Derived from Senecio Vulgaris

Abstract

A large scale method for the isolation of pyrrolizidine alkaloids has been adapted from a previously published analytical method. This method is a reverse phase high pressure liquid chromatography technique, utilizing a .005 M KH₂ PO₄ (pH 6.3) — methanol solvent system. The pyrrolizidine alkaloids derived from Senecio vulgaris (common groundsel) have been utilized in this system.     

Determination of 2,4-D and Dicamba in food crops by MEKC

Summary The determination of 2,4-D (2,4-dichlorophenoxyacetic acid) and Dicamba (2-methoxy-3,6-dichlorobenzoic acid) residues in sugar cane, rice and corn was performed by a supercritical fluid extraction (SFE) method using CO₂/acetone as extraction mix and an SFE apparatus developed in our laboratory. The extracts were cleaned up after extraction by both liquid-liquid partition and a Florisil column. Micellar electrokinetic capillary chromatography (MEKC) coupled with ultraviolet on-column detection was used for the analysis of these pesticides. The detection limits were improved by the preparation of a special detection cell with an increased pathlength that gave detection limits of ca. 0.6 pg for 2,4-D and Dicamba. Our results demonstrated that capillary electrophoresis can be a powerful new analytical tool for pesticide residue analysis.     

Determination of rupatadine in pharmaceutical formulations by a validated stability-indicating MEKC method

A stability-indicating MEKC was developed and validated for the analysis of rupatadine in tablet dosage forms, using nimesulide as internal standard. The MEKC method was performed on a fused-silica capillary (50 microm id; effective length, 40 cm). The BGE consisted of 15 mM borate buffer and 25 mM anionic detergent SDS solution at pH 10. The capillary temperature was maintained at 35 degrees C and the applied voltage was 25 kV. The injection was performed using the hydrodynamic mode at 50 mbar for 5 s, with detection by photodiode array detector set at 205 nm. The method was linear in the range of 0.5-150 microg/mL (r2=0.9996). The specificity and stability-indicating capability of the method were proven through degradation studies inclusive by MS, and showing also that there was no interference of the excipients and no increase of the cytotoxicity. The accuracy was 99.98% with bias lower than 1.06%. The LOD and LOQ were 0.1 and 0.5 microg/mL, respectively. The proposed method was successfully applied for the quantitative analysis of rupatadine in pharmaceutical formulations, and the results were compared to a validated RP-LC method, showing non-significant difference (p>0.05).     

Determination of pentachlorophenol and tribromophenol in sawdust by ultrasound-assisted extraction and MEKC

An ultrasonic bar-assisted extraction and CE separation procedure for the determination of pentachlorophenol (PCP) and 2,4,6-tribromophenol (TBP) residues in sawdust was developed and applied. For this purpose, micellar electrokinetic capillary chromatography (MEKC) was used and compared with a GC/MS methodology. This methodology allowed the quantification of PCP and TBP in a concentration range of 2.5-12.0 mg/kg for TBP and 2.8-12.0 mg/kg for PCP. Different sample treatment processes were evaluated in order to extract these compounds from sawdust. Better results were obtained when the residues were extracted with ultrasound-assisted hexane, filtered, evaporated, dissolved in Na(2)CO(3), and injected into the CE equipment. The optimal option for GC/MS was extraction with Na(2)CO(3 )followed by a derivation using acetic anhydride and liquid-liquid extraction with hexane. This method allowed the quantification of TBP and PCP in sawdust in a concentration range of 0.19-12.00 mg/kg and 0.14-12.00 mg/kg, respectively. The CE method was compared with the GC/MS as reference method. The results were shown to be statistically similar by both methods for PCP as well as for TBP.     

Determination of triptonide by cloud point extraction combined with MEKC

A method has been developed for the determination of triptonide in the traditional Chinese herb Tripterygium wilfordii Hook F. by micellar electrokinetic capillary chromatography combined with cloud point extraction. The analyte was extracted at pH 3.0 by micelles of the nonionic surfactant polyoxyethylene 7,5-octylphenyl ether (Triton X-114). A 250-muL aliquot from the extracted surfactant-rich phase was diluted to 400 muL with ethanol to reduce its viscosity before separation by MEKC. Under optimum conditions, an enrichment factor of 25 is obtained and the determination limit of triptonide is found to be 3.15 x 10(-7) mol/L. The proposed method has been successfully applied to the determination of triptonide in T. wilfordii tablet and spiked urine matrix, demonstrating the feasibility and reliability of the proposed method.     

选择性远程DEPT技术用于吡咯里西啶类生物碱的结构测定和核磁共振研究

本文从峨眉千里光(Sencic Fubcri Hensl)中分得二个吡咯里西啶类生物碱。经测定,一个为阔叶千里光碱(1),另一个为新阔叶千里光碱(2)。它们的~(1)H NMR研究尚未见报道。两者的~(13)C NMR研究已有报道,但1的许多~(13)C谱峰归属,不同的作者所得的结果不一致,而2的~(13)C谱峰归属与本文的二维NMR实验结果不一致。这二个化合物的NMR谱较为复杂,部分谱峰相互重选,其归属用一般方法不易确定。本文采用最近由我们提出的选择性远程~(13)CDEPT技术对这二个化合物的结构及其     

Determination of mercury ion by MEKC with on-column derivatisation and LIF detection

A simple and automatic method for the determination of mercury ion by MEKC with on-column derivatisation and LIF detection is described in the present paper. In this method, solutions of a nonfluorescent rhodamine derivative and mercury ion were injected individually and mixed by applying a short voltage. Subsequently, the mercury ions reacted with the nonfluorescent rhodamine derivative to produce strongly fluorescent product. The resulting product was then removed by EOF and micelles towards the detection window and detected by LIF detector. The experimental conditions in terms of the concentration and injection volume ratios between mercury ion and derivatisation reagent, the mixing time and waiting time for the on-column reaction were optimised. The optimal conditions were determined as follows: the concentration and injection volume ratios between mercury ion and derivatisation reagent were 1:20 and 10:1, respectively; the mixing time was 40 s under the applied voltage of 5 kV; the waiting time was proved unnecessary. The detection limit for mercury ion was 5 x 10(-8) M, and the total analysis time was less than 10 min.     

Determination of antitubercular drugs by micellar electrokinetic capillary chromatography (MEKC)

A method for the determination of isoniazid (ISO), pyrazinamide (PYR) and rifampicin (RIF) in pharmaceutical products, by micellar electrokinetic capillary chromatography (MEKC) with ultraviolet detection is described. The influence of pH, concentration of surfactants, buffer and organic solvents, over the separation were studied as experimental variables. The optimal separation was carried out at 30 degrees C and 20 kV, using a 40 mM borate buffer and 100 mM sodium dodecylsulphate (SDS) adjusted to pH 8.5. Under these conditions, the analysis is accomplished in about 8 min. The method was applied to the determination of these compounds in different pharmaceuticals with good results when compared with a reference liquid chromatographic (LC) method.     

Determination of phenylenediamine isomers in hair dyes by coal cinders micro-column extraction and MEKC

A new micellar electrokinetic chromatography (MEKC) method using beta-cyclodextrins (β-CDs) and 1-butyl-3-methylimidazolium hexafluorophosphates (ionic liquids) as additives was successfully developed for determination of para-, meta-, and ortho-phenylenediamines isomers (p-P, m-P, and o-P) in hair dyes. To improve the sensitivity of the MEKC-UV, a simple and cheap flow injection (FI) technique using a micro-column packed with coal cinders (the by-products from combustion in a boiler) as solid-phase extractant was also investigated. In the presence of 20 mmol L(-1) phosphates at pH 5.5, addition of 12 mmol L(-1) ionic liquids and 8 mmol L(-1) β-CDs greatly improved the separation efficiency. The three analytes could be quantitatively adsorbed by coal cinders, and desorbed readily with 0.15 mL of 0.01 mol L(-1) NaOH. Under the optimum conditions, an enrichment factor (EF) of 33.3 was obtained, and determination limits of p-P, m-P, and o-P were 1.97?×?10(-7), 0.99?×?10(-7), and 0.61?×?10(-7) mol L(-1), respectively. The adsorption capacities of the coal cinders micro-column for p-P, m-P, and o-P were all 1.20 mg g(-1). The presented procedure was successfully applied to the determination of p-P, m-P, and o-P in hair dyes with satisfactory results.     

气相色谱-质谱法测定主流烟气中的植物碱

采用气相色谱-质谱法测定主流烟气中的烟碱、降烟碱、麦斯明、假木贼碱和新烟草碱。捕集有总粒相物的剑桥滤片加入内标后,用50g·L-1氢氧化钠溶液将植物碱游离出来,经乙酸乙酯萃取后,在DB-35MS色谱柱上分离,采用选择离子扫描模式。5种植物碱的浓度与峰面积在一定范围内呈线性关系。烟碱的检出限(3S/N)为12μg·支-1,其他4种植物碱的检出限(3S/N)为0.30~2.5μg·支-1。5种植物碱的加标回收率在86.5%~108%之间,测定值的相对标准偏差(n=6)在1.7%~4.5%之间。     

Simultaneous Determination of Four Alkaloids in Gan-Yan-Ling Injection by GC-MS

A new separation and quantification method based on GC-MS in the selective ion mode for simultaneous determination of four alkaloids in Gan-Yan-Ling injection was developed. The calibration curves are linear over the range of 0.0125–0.555 mg mL^?1 for cytisine, 0.009455–1.008 mg mL^?1 for sophocarpine, 0.04739–1.516 mg mL^?1 for matrine and 0.01135–1.211 mg mL^?1 for sophoridine. Eleven different batches of Gan-Yan-Ling injections were analyzed and the results indicated that the method was sensitive and reliable for the determination of four alkaloids and could be used to control the quality of the preparation.     

Quantitative Determination of Three Protoberberine Alkaloids in Jin-Guo-Lan by HPLC-DAD

An accurate and simple HPLC method for the simultaneous determination of three protoberberine alkaloids (columbamine, jatrorrhizine, and palmatine) contained in Chinese medicine Jin-Guo-Lan (Tinospora sagittata Oliv. and Tinospora capillipes Gagnep) is presented in this study. The herb samples from six main origins and three herb markets were investigated. The separation was performed on a YMC-C₁₈ ODS column at 30°C with a gradient elution program. Acetonitrile and phosphate buffer (0.02 mol L⁻¹ sodium dihydrogen phosphate and 0.01 mol L⁻¹ triethylamine, pH 3) were used as mobile phases and the flow rate was set at 1 mL min⁻¹. The recovery of the method was in the range of 99.43–100.96%, and all the alkaloids showed good linearity (r ² > 0.9997) in the relatively wide concentration ranges. The developed method was applied to the determination of these alkaloids in the collected herb samples, and the results showed that the contents of these components in Jin-Guo-Lan varied greatly from habitat to habitat. It was demonstrated that the proposed method was helpful for the quality evaluation of Chinese medicine Jin-Guo-Lan.     

Spectrofluorimetric Determination of Opium Alkaloids by Mixed Anhydride Reagent

Abstract

The spectrofluorimetric determination of five major opium alkaloids by malonic acid-acetic anhydride reagent is reported. The fluorescence characteristics of various alkaloidal systems and the effect of different parameters like temperature, time of heating and diluent on the fluorescence intensity are described. The interference of various foreign substances has also been checked.     

Determination of Betamethasone and Dexamethasone in Human Urine and Serum by MEKC After an Experimental Design

A simple and reliable micellar electrokinetic capillary chromatography method has been presented for the simultaneous determination of betamethasone (BM) and its epimer dexamethasone (DM) in human urine and serum. A three level full factorial experimental design was employed to search for the optimum conditions. Rapid and baseline separation of BM and DM was obtained within 7 min with the optimum conditions of 30 mM borax buffer, 30 mM sodium dodecyl sulfate at pH 10.0, separation voltage at 18 kV, injection time 15 s at a height of 10 cm, using sodium sorbate as internal standard. The proposed method was validated with respect to stability, precision, linearity and accuracy. Good relationship between peak area ratio and analyte concentration was linear over 30–1,000 µg mL^?1 for BM and DM with correlation coefficients ≥0.9993. Relative standard deviations of the method were all less than 4.50% in the intra-day and inter-day analysis. The developed method was applied to assay spiked human urine and serum samples containing both compounds with recoveries in the range of 97.5–100.5%.     

Determination of Organophosphorus P sticides in Water, Vegetables and Grain by Automated SPE and MEKC

A sensitive method for the multi-residue analysis of organophosphorus pesticides in environmental samples has been developed. It involves an automated solid phase extraction procedure using a Gilson ASPEC XLi and capillary electrophoresis analysis with UV detection. Acephate, methamidophos, dichlorvos, dicrotophos and malathion could be separated by micellar electrokinetic capillary chromatography using an electrophoretic electrolyte containing 20 mM phosphate buffer (pH 7.5) and 75 mM sodium dodecyl sulphate. A linear relationship between concentration and peak area was obtained within the range 0.2–450 g mL^?1 with correlation coefficients greater than 0.996 and detection limits between 7 and 150 ng mL^?1. Intra- and inter-day precision values of about 0.8–2.3% RSD (n=11) and 0.9–3.0% RSD (n=15), respectively were obtained. When the preconcentration step was used, an enrichment factor of 250 was easily achieved in the analysis of water samples, making it possible to determinate pesticide residues at concentration levels as low as 0.04 ng mL^?1. In analyses of vegetables and grains, the sensitivity levels were about 0.03 μg^?1.