Determination of Reserpine in Plasma Using High-Performance Liquid Chromatography with Fluorescence Detection

Abstract

A high-performance liquid chromatographic method for determining reserpine in plasma has been developed. The procedure involves extraction of reserpine from buffered plasma into benzene, oxidation of reserpine to a fluorophor by treatment with vanadium pentoxide in phosphoric acid, and chromatographic separation of the reserpine fluorophor on an octadecylsilane column by ion-pairing with heptanesulfonate ions. Fluorescence monitoring of the column effluent provides high sensitivity of detection and increases the specificity of the procedure. A detection limit of approximately 100 pg of reserpine per ml of plasma was obtained following analysis of 2 ml samples. Analysis of a number of samples demonstrated the applicability of this method in confirming the presence of reserpine in equine plasma specimens collected at various horse shows and in evaluating the pharmacokinetic behavior of reserpine following intramuscular administration to horses.     

Determination of Bumetanide in Human Plasma and Urine by High-Performance Liquid Chromatography with Fluorescence Detection

Abstract

This paper describes a new high-pressure liquid chromatographic method used for quantitation of bumetanide in urine and plasma. Compared to previously reported methods, this assay offers the advantages of increased sensitivity, shortened sample preparation time and decreased instrumentation requirements. After addition of the 4-benzyl derivative of bumetanide as the internal standard, both urine and plasma underwent a single extraction with ethyl acetate at an acidic pH. The organic extract was separated, evaporated to dryness, reconstituted with methanol, and chromatographed using a reversed-phase C-18 radial compression cartridge with fluorescence detection. Sensitivity limits are approximately 1 ng of bumetanide per mL of plasma, with a coefficient of variation for identical samples never exceeding 6%. The method lends itself to pharmacokinetic and pharmacodynamic studies of bumetanide in humans following single therapeutic doses.     

Persistence of Diflubenzuron on Conifer Forest Foliage in a Mediterranean-Climate Ecosystem Following Aerial Application

Dimilin 45 ODC (diflubenzuron) was applied in a Mediterranean-climate conifer forest, near Vitoria, Basque Country, Spain. Pine needles were collected at post-treatment 5-day intervals for analysis of the diflubenzuron residues. A liquid chromatography method with on-line diode-array and electrochemical detection was developed for the determination of the pesticide diflubenzuron and its main metabolites: 2,6-diflurobenzamide, 4-chlorophenylurea, 4-chloroacetanilide, 4-chloroaniline and N-methyl-4-chloroaniline in forestry matrices. Aerial application at 56.3 g AI ha^?1 resulted in deposition levels of the insecticide of 1080 ng g^?1. Within 40-65 days following treatment, 51-73% of the insecticide had been removed from the foliage. During this period, the concentration of diflubenzuron was higher than 295 ng g^?1. The only metabolite detected was 2,6-difluorobenzamide and this persisted on foliage until the first rainfalls occurred. An empirical mathematical correlation was found to express the influence of rainfall, solar radiation and temperature on the persistence of the insecticide.     

Improving the Detectability of Sequential Injection Chromatography (SIC): Determination of Triazines by Exploiting Liquid Core Waveguide (LCW) Detection

Coupling a liquid core waveguide cell to a sequential injection chromatograph improved the detection limits for determination of triazine herbicides without compromising peak resolution. Separation of simazine, atrazine, and propazine was achieved in water samples by a 25 mm long C₁₈ monolithic column. Detection was made at 238 nm using a type II LCW (silica capillary coated with Teflon® AF2400) cell with 100 cm of optical path length. Detection limits for simazine, atrazine, and propazine were 2.3, 1.9, and 4.5 µg L^?1, respectively. Reduced analysis time and low solvent consumption are other remarkable features of the proposed method.     

高效液相色谱法测定有机肥中洛克沙胂

建立了高效液相色谱(HPLC)-串联紫外检测法检测有机肥中洛克沙胂的分析方法。选用20g·L-1K2HPO4作为提取剂,于60℃温度下超声提取有机肥中的洛克沙胂,采用MAX固相萃取柱净化。结果表明,采用Symmetry ShieldTMRP 18色谱柱,以含0.1%甲酸的0.05mol·L-1 KH2PO4∶甲醇=95∶5(V/V)溶液作流动相,等度洗脱,紫外266nm检测,洛克沙胂的保留时间短,且可完全避开杂质峰的干扰;其平均加标回收率介于81.14%~82.75%之间,相对标准偏差(RSD)7.0%,检出限为20μg·L-1。方法重现性好,精密度高,操作简便,适用于有机肥中洛克沙胂检测。     

Fast and Selective Determination of Pesticides in Water by Automated On-Line Solid Phase Extraction Liquid Chromatography Tandem Mass Spectrometry

An automated on line-solid phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 17 polar pesticides in water. Minimizing sample pretreatment and using a fast chromatographic separation, the method allowed a sample to be processed in 15 minutes. The MS analysis was performed by Data Dependent Acquisition, using the triggered Multiple Reaction Mode function that provided analyte confirmation, thus enhancing selectivity without compromising sensitivity. In fact, the optimized method enabled the determination of the considered pesticides at the ultratrace level, with detection limits in the range 0.07–1.65 ng/L (propazine and atrazine-desisopropyl, respectively); the only exception was linuron that showed a slightly higher detection limit (12.2 ng/L). The optimized method was then applied to real water samples; five pesticides were determined in river water, in the range 1.17–14.2 ng/L, while four were measured in drinking water, in the range 0.91–2.25 ng/L.     

Leaching of Pesticides from Fields with Recorded Pesticide Applications

During two winter seasons, 1998/99 and 1999/2000, drainage water was sampled each fortnight from four fields with recorded pesticide application. Water was analysed for a range of pesticides used on the fields. Two of the four fields were equipped with three vertical stainless steel tubes with screens at 1-1.3 m depths. Two other fields were equipped with traditional tile drains, which solely drained the specific fields. Isoproturon, which was banned from use after 1999, was the most frequently found pesticide in the drainage water. Pendimethalin was another compound frequently found, however in low concentrations. In drainage water from a field at Silstrup the active ingredients bentazone and propyzamide appeared in the drainage water at the first sampling following treatment and during the following months. The highest concentration levels were 1.3 and 2.8 µg/L, respectively. Phenoxyacid herbicides, which had been detected at concentration levels up to 0.34 µg/L in an earlier study 10 years ago, no longer appeared in the drainage water.     

Determination of Saccharin in Plasma and Urine by High Performance Liquid Chromatography

Abstract

A sensitive and specific high performance liquid chromatographic (HPLC) assay for the determination of saccharin in plasma and urine was developed. Saccharin is extracted into diethyl ether at acid pH, evaporated, and reconstituted prior to instrumental analysis. Overall recovery of saccharin is 86.9 + 8.6% and the sensitivity limits of detection is 0.15 μg per ml of plasma or urine using a fluorescence detector. The sensitivity limit in plasma can be extended to 20 ng per ml by use of a 2 ml assay volume and detector attenuation. The assay was used for the determination of saccharin in plasma and urine of rats following oral doses of 5 mg/kg.     

Bamboo Charcoal as Solid-Phase Extraction Adsorbent for the Determination of Organophosphorus Pesticides in Water Samples by High-Performance Liquid Chromatography

In this paper, bamboo charcoal was successfully developed for the solid-phase extraction adsorbent for the determination of six organophosphorus pesticides in water samples. After the bamboo charcoal was pretreated and packed in the solid-phase extraction cartridge, the organophosphorus pesticides in water samples were carried out the solid-phase extraction. To establish a perfect solid-phase extraction procedure, the experimental conditions including the eluent, eluent volume, pH of the sample, flow rate of the sample, and loading volume of the sample were all investigated. When 100 mL water samples in the pH range of 6–7 were loaded with the flow rate of 2.5 mL · min^?1 and then eluted with 10 mL acetonitrile, the proposed extraction method was validated by the recovery, correlation coefficient (R²), repeatability (RSD, n = 7) and LODs, which were 69.6–93.4%, 0.9982–0.9998, 2.9–5.6%, and 0.08–1.04 µg · L^?1, respectively. Furthermore, the analysis of the tap, snow, and river water samples demonstrated the feasibility of the proposed SPE method for real water samples. Based on the aforementioned factors, it could be concluded that bamboo charcoal was a good solid-phase extraction adsorbent, and this proposed solid-phase extraction method was suitable for the effective enrichment and determination of the organophosphorus pesticides in water samples.     

Application of Solid-Phase Microextraction for the Determination of Organonitrogen Pesticides in Aqueous Samples by Gas Chromatography with Nitrogen-Phosphorus Detector

A method based on solid-phase microextraction and gas chromatography nitrogen-phosphorus detector for the determination of common organonitrogen pesticides (ONPs) in aqueous samples was described. Three kinds of commercially available coated fused-silica fibres were compared: 100 µm PDMS, 85 µm PA, and 65 µm CW-DVB; 65 µm CW-DVB was the most sensitive fibre coating for the analytes' determination. The extraction time, the stirring, the content of salt, and the content of organic solvents were found to have a significant influence on extraction efficiency. The optimised conditions were 65 µm CW-DVB fibre, 40 min extraction time, with rapid stirring and concentration of NaCl was fixed at 0.25 g/mL. The linear range was 0.1-100 µg/L for most of the compounds. The limits of detection (LODs) ranged from 0.02 mg/L (for trifluralin, simazine, terbuthylazine, cyanazine, and pendimethalin) to 0.08 µg/L (for terbutryn) and RSD % of repeatability were for most of the compounds below 10%. Thus the maximum level set by the European Union for pesticides and drinking waters can be verified. The recovery of spiked water samples was compared and validated with the liquid-liquid extraction one. Environmental water samples were analysed and trifluraline was detected.     

高效液相色谱-二极管阵列检测法同时测定糖果中11种脂溶性着色剂

建立了一种简单、快速同时测定糖果中苏丹橙G、甲基黄、对位红、柑桔红2号、苏丹红G、苏丹Ⅰ、苏丹Ⅱ、苏丹Ⅲ、苏丹红7B、苏丹红B和苏丹Ⅳ11种脂溶性着色剂的分析方法。样品经乙酸乙酯提取,用高效液相色谱-二极管阵列检测法(HPLC-DAD)测定,外标法定量。结果表明,11种目标着色剂在0.02~1.0mg/L范围呈良好线性,线性相关系数均大于0.999。定量限(S/N≥10)为10μg/kg,在10、20、40μg/kg 3个添加水平下的平均回收率为79.6%~97.6%,相对标准偏差为2.66%~6.76%。该方法稳定、可靠,适用于糖果中上述11种着色剂的测定。     

Determination of Plumbagin in Plant Extracts and Polyherbal Formulations by High-Performance Liquid Chromatography with Fluorescence Detection

Plumbagin, a naturally occurring naphthoquinone derivative, is known to possess various pharmacological activities. A rapid, sensitive, and specific high-performance liquid chromatographic method using fluorescence detection is reported for the determination of plumbagin in two Plumbago species and five polyherbal formulations. The method employed a reverse phase C18 column with isocratic elution using 65:35 pH 3.2 methanol and 0.1% aqueous o-phosphoric acid at a flow rate of 1.0 mL/min. Plumbagin displayed maximal fluorescence with excitation at 264 nm and emission at 605 nm. A linear calibration relationship was obtained for 1 to 10 µg/mL plumbagin with limits of detection and quantitation of 8 ng/mL and 30 ng/mL, respectively. The relative standard deviation values for intraday and interday precision were less than 2%. The recoveries were greater than 97% with relative standard deviations less than 3%. This is the first study to employ high-performance liquid chromatography with fluorescence detection for the determination of plumbagin. The method was rapid, sensitive, and accurate for the analysis of plants and polyherbal formulations.     

Analysis of Organochlorine Pesticides by Solid-Phase Microextraction followed by Gas Chromatography-Mass Spectrometry

Solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) was optimized for the analysis of hexachlorocyclohexanes, DDD, DDE, DDT and other organochlorine pesticides in aqueous samples. Higher extraction efficiency was observed with the SPME fibre coated with 100 µm polydimethylsiloxane than with the fibres coated with 85 µm polyacrylate or 65 µm polydimethylsiloxane/divinylbenzene. Equilibration times were longer than 60 min, except for the hexachlorocyclohexanes, in spite of rapid stirring of the sample. However, precise quantitative analysis could be performed also under non-equilibrium conditions: i.e. repeatability standard deviations below 20%. Salt addition had a positive effect on the response for the hexachlorocyclohexanes, whereas the extraction of the other analytes was affected negatively. The pH of the sample solution did not influence the extraction efficiency. The desorption was performed for 5 min at 275°C directly in the GC injector. At shorter desorption times or lower temperatures a significant carry-over was observed for the heavier analytes. Generally, detection limits in the ng/L range were obtainable.     

Analysis of 3-Methoxy-4-Hydroxyphenylglycol in Human Cerebrospinal Fluid by Gas Chromatography Mass Spectrometry and Electrochemical Detection Liquid Chromatography

Abstract

Gas chromatography mass spectrometry [GCMS] and liquid chromatography with electrochemical detection [LCEC] have been compared in simultaneous determination of 3-methoxy-4-hydroxy-phenylglycol [MHPG] in human cerebrospinal fluid [CSF]. Both free and sulphate conjugated MHPG have been measured in these samples. By Spearman Rank Correlation non-parametric analysis both instrumental techniques related significantly for all quantitated samples.     

Determination of Monobromobimane-Labeled Phytochelatins by High-Performance Liquid Chromatography

A new method for phytochelatins by high-performance liquid chromatography (HPLC) was developed based on a condensation reaction with monobromobimane to produce fluorescent derivatives. Glutathione, H-(γ-glutamic acid-cysteine)₂-glycine-OH, H-(γ-glutamic acid-cysteine)₃-glycine-OH, H-(γ-glutamic acid-cysteine)₄-glycine-OH, H-(γ-glutamic acid-cysteine)₅-glycine-OH, and H-(γ-glutamic acid-cysteine)₆-glycine-OH were well separated, with retention times between 14.68 and 22.0 min. The HPLC method had good linearity (r < 0.9991) between 0.1 mg L^?1 and 100 mg L^?1. The limits of quantification for the analytes (S/N = 3) were 0.08, 0.3, 0.05, 0.3, 0.5, and 0.8 mg L^?1, respectively. The recoveries were between 83.0% and 101.33% with relative standard deviations less than 2%. The reported method is simple, accurate, and suitable for the determination of phytochelatins.     

Gas Liquid Chromatographic Determination of Caffeine in Breast Milk and Blood Plasma

Abstract

An improved procedure for the determination of caffeine in the presence of bupivicaine (internal standard) using gas liquid chromatography with nitrogen phosphorous detection is described. The method is based on the extraction of caffeine from plasma with a mixture of chloroform and isopropanol (95:5). The chloroform and isopropanol mixture is evaporated to dryness and the residue dissolved in 500 μl of ethyl acetate. One to 2 μl samples are injected directly into the gas chromatograph. This extraction process doesn't give rise to troublesome interfering peaks in the chromatogram. The recovery of caffeine from plasma and breast milk is approximately 99.7% and 94.1% respectively. The coefficient variation of the assay from plasma and breast milk is 2.90% and 1.18% respectively. The limit of quantitation is 0.05 mcg/ml of plasma or breast milk. Data are presented to illustrate the practicality of the method for bioavailability and pharmacokinetic evaluation of caffeine plasma and breast milk levels after oral administration of 100 mg of caffeine to lactating mothers.     

Determination of Brassinolide Analogs by High-Performance Liquid Chromatography with Evaporative Light Scattering Detection

An efficient method based on high-performance liquid chromatography with evaporative light scattering detection was developed for the separation and determination of four brassinolide analogs [24-epibrassinolide, (22S, 23S)-24-epibrassinolide, 28-homobrassinolide, and (22S, 23S)-28-epihomobrassinolide] without prior derivatization. The optimized analysis was carried out on a C₁₈ reversed-phase column (150 mm × 4.60 mm, 3 µm) at 30°C using isocratic elution of acetonitrile and water (38:62, v/v). The drift tube temperature of the detector was 60°C and the auxiliary gas (nitrogen) pressure was 360 kPa. The regression equations revealed linear relationships (R² = 0.9984–0.9994) within the test ranges. The limits of detection and quantification were in the ranges of 0.12 to 0.17 µg and 0.24 to 0.33 µg, respectively. The fully validated method was applied to quantify the active ingredient content in technical material and formulations and provides an alternative approach for quality control.     

超声辅助分散液液微萃取-高效液相色谱法快速测定水样中的6种农药

为实现小体积环境水祥中不同农药的准确、快速、高灵敏测定,通过研究萃取剂、分散剂的种类、体积、盐浓度及超声时间对萃取效率的影响,结合分散液液微萃取与超声萃取技术,并与高效液相色谱联用,建立了快速测定环境水样中的吡虫啉、水胺硫磷、辛硫磷、毒死蜱、哒螨灵和阿维菌素6种农药的方法.在优化的萃取条件下,检测6种农药的线性范围为10～ 600 μg/L,检出限(S/N=3)为0.8～3.1 μg/L,相对标准偏差为4.7％～11.3％,富集倍数可达到58～187倍.本方法具有良好的线性、精密度和回收率,并具有较好的实用性.     

Determination of Naloxone Hydrochloride in Dosage form by High-Performance Liquid Chromatography

Abstract

A new, sensitive and rapid method for the determination of naloxone hydrochloride as drug in dosage entity and form using HPLC has been developed. Authentic naloxone hydrochloride was used to establish a calibration curve. A linear relationship was obtained for concentrations ranging from 10 μg/ml to 50 μg/ml. The column used was C₁₈, Micropak MCH-10 (monomeric) and the mobile phase was acetonitrile : 0.01 M KH₂PO₄ (70 : 30) at a flow rate of 2 ml/min. Retention time for naloxone hydrochloride was 3.3 minutes. The proposed method has been proved accurate and precise compared to other pharmacopoeia methods of assay for naloxone hydrochloride.     

Determination of Organochloride and Triazine Pesticides in Natural Waters by Solvent Bar Microextraction

A new analytical methodology based on solvent bar microextraction has been developed to preconcentrate two triazine and two organochloride pesticides in natural waters prior to analysis by gas chromatography. The method was optimized for the organic solvent, sample pH, sample agitation, length of the fiber, extraction time, and salt concentration. The optimized methodology provides high enrichment factors, ranging between 40.2 (aldrin) to 107.0 (lindane). Since no salinity effects were observed, this method may be used to analyze fresh and salt water. Thus, three real samples with different salinities were analyzed with pesticide recoveries higher than 80%. As this methodology agreed with the principles of green analytical chemistry, it offers low solvent and sample consumption, simplicity, and compatibility with current analytical techniques.