Determination of Triazine and Chlorophenoxy Acid Herbicides in Natural Water Samples By Solid Phase Extraction and Quantitative Thin Layer Chromatography

Abstract

Atrazine, simazine, 2, 4-D, silvex, and 2, 4, 5-T, were determined in natural water samples at 10 ppb levels by solid phase extraction on disposable C₁₈ columns and TLC on preadsorbent silica gel layers impregnated with AgNO₃, exposure to UV light, and densitometric scanning. Recoveries ranged from 70 to 88% for the triazines and 93 to 100% for chlorphenoxy acid herbicides, with average CV values of 7 to 8%. Solid phase extraction proved to be an advantageous alternative to classical liquid-liquid partition for the analysis of water for these compounds by quantitative TLC.     

Comparison of Different Sorbents for Solid-Phase Extraction of Phenoxyalkanoic Acid Herbicides

An HPLC procedure for determination of phenoxyalkanoic acid herbicides in water samples is proposed. The analytical column Phenomenex C18(2) Luna 5 µm and UV detection at 225 nm were applied. Baseline resolution was achieved in isocratic mode with a mobile phase consisting of acetonitrile/acetic acid (40/60, v/v), adjusted to pH 2.5. SPE sorbents – C₁₈ BondElut, phenyl-silica, LiChrolut SAX and polymeric sorbents – were compared for isolation and preconcentration of 6 phenoxyalkanoic acid herbicides. Higher (above 95%) and more reproducible recoveries were obtained with polymeric and phenyl-silica sorbents using pure methanol for elution. The method was tested for river water samples with the limit of detection in the range of 2–3 µg L⁻¹ (for 50 mL sample) and a reproducibility of 5% RSD.     

Solid-Phase Extraction and Capillary Gas Chromatographic Determination of Triazine Herbicides in Water

Abstract

A facile and efficient method is described for the determination of trace quantities of triazine herbicides, terbutryn, prometryn and ametryn in water. The procedure involved preconcentration of water samples by sorption on chromatographic grade silica gel particles with chemically modified surface, being covalently bonded with a nonofunctional C₈H₁₇ group. This was followed by solvent desorption with 2-propanol. The determinative step was achieved by capillary gas chromatography on Supelcowax-10 fused silica column using a nitrogen-phosphorus detector. The limit of detection was 0.1 μg-10 μgL^?1.     

Determination of Antibiotics in Surface Water by Solid-Phase Extraction and High-Performance Liquid Chromatography with Diode Array and Mass Spectrometry Detection

A high-performance liquid chromatography method is reported for the determination of antibiotics in water. The antibiotics were simultaneously preconcentrated by solid-phase extraction. High-performance liquid chromatography was performed on a C18 modified column with gradient elution in 25?min at 40°C. The separation was performed using gradient elution with 90:10 acetonitrile:water and 0.1% aqueous formic acid. The antibiotics were identified by diode array detection and mass spectrometry. The established method was suitable for the determination of antibiotics in surface water.     

Determination of Folic Acid in Commercial Diets by Anion-Exchange Solid-Phase Extraction and Subsequent Reversed-Phase HPLC

Abstract

Folic acid at the μ/g level is determined in total nutritional diets by concentration on disposable commercial anion exchange columns followed by elution with a concentrated salt solution and subsequent reversed-phase HPLC with absorbance detection at 365 nm. The method is specific for folic acid with respect to some known degradants and electrochemically generated oxidation products.     

PAD在HPLC分析长春胺中的应用

本文报道用光电二极管阵列检测器(PAD)鉴定小蔓和大蔓长春花中的长春胺。并对经典制备方法得到的长春胺样品进行了纯度判断。利用建立的紫外光谱数据库对长春胺中的分解产物进行光谱检索和鉴定。测定了长春胺的稳定性。     

Chromatographic Fingerprint Analysis of the Flowers of Abelmoschus manihot Using HPLC with Photodiode Array Detection

Abstract

A simple and valid chromatographic fingerprint analysis method was developed using high‐performance liquid chromatography‐photodiode array detection for the quality analysis of the flowers of Abelmoschus manihot. For the first time, the feasibility and advantages of employing chromatographic fingerprint were investigated and demonstrated for the evaluation of the flowers of A. manihot by systematically comparing chromatograms with professional analytical software recommended by State Food and Drug Administration. Our results revealed that the chromatographic fingerprint combining similarity evaluation could be used efficiently for the identification and quality assessment of raw herbs of the flowers of A. manihot from different sources.     

Determination of Phenylureas Herbicides in Foodstuffs Based on Matrix Solid-Phase Dispersion Extraction and RP-LC with UV Detection

A new method for simultaneous determination of seven kinds of phenylurea herbicides (PUHs) in solid foodstuffs was established based on matrix solid phase dispersion (MSPD)–RP-LC. The procedure of MSPD is simple and not time-consuming. C₁₈-bonded silica and anhydrous alumina were, respectively, used as dispersion sorbent and purificant, and dichloromethane as extraction reagent. Under the optimum conditions, seven kinds of herbicides were separated completely within 30 min, response was a linear function of concentration over the range 2.5–500 μg L^?1 with good correlation coefficients (>0.99) and lower detection limits (0.25 and 0.5 μg L^?1). Intra-day and inter-day precision of the peak areas for seven PUHs were less than 3.7 and 5.3%. The new method was used to detect seven PUHs in four kinds of solid foodstuffs with average recoveries range from 73.1 to 101%.     

固相萃取/高效液相色谱法测定地表水中磺酰脲类农药的研究

建立了固相萃取/高效液相色谱法(SPE/HPLC)同时测定地表水中五种磺酰脲类农药的方法。研究了固相萃取提取、净化方法,优化了高效液相色谱条件并用二极管阵列检测器进行定量分析。五种磺酰脲类农药在0.1~10.0μg/mL范围内线性良好,相关系数在0.9992~0.9998之间,相对标准偏差在1.8%~4.1%之间,平均回收率为72.8%~103%。本方法中五种磺酰脲类农药的检出限在0.02~0.22 ng/mL范围。用该法分析了某水域地表水,取得满意结果,表明本方法具有一定的实用性。     

固相萃取高效液相色谱法测定人血浆中的巴洛沙星

建立了测定人血浆中巴洛沙星含量的固相萃取高效液相色谱紫外检测方法。采用pH 4.5的磷酸盐缓冲液并经Waters Oasis HLB固相萃取小柱对血浆样品进行预处理。以环丙沙星作内标,以十二烷基磺酸钠溶液(取560 mL水加入3.2 g十二烷基磺酸钠)-乙腈(体积比为56∶44,用磷酸调pH至3.0)为流动相,在Diamonsil C18色谱柱(150 mm×4.6 mm,5 μm)上进行分离。方法的线性范围为25～3200 μg/L,线性关系良好(r=0.9996);巴洛沙星的检出限（S/N≥3）为5 μg/L;方法的准确度为100.3%～103.8%;平均提取回收率为57.5%～77.0%,相对标准偏差小于5.1%。方法准确、灵敏,可满足血药浓度监测和药代动力学参数测试的需求。     

Combination of Sea Sand Disruption Method and Ion-Pair Solid-Phase Extraction for Effective Isolation and Purification of Chlorogenic Acid from Plants Prior to the HPLC Determination

Chlorogenic acid (CQA) is one of phenolics commonly found in higher plants, possessing numerous health-promoting effects on humans. Unfortunately, it is easily degraded/transformed into other substances during extraction. Therefore, its reliable analysis requires a special approach that does not involve high temperatures. This paper presents a very simple method of CQA isolation using the sea sand disruption method with subsequent purification of the extract using the ion-pair solid-phase extraction process, followed by HPLC–DAD detection. It was found that control of the ion pairing reagent concentration and sample pH is crucial to improve purification, and that the best results, with recovery exceeding 98%, were obtained for 0.05 M tetrabutylammonium bisulfate at pH 7 when the ion pairs were formed directly in the extract and eluted from the C18 sorbent using an acidified methanol–water mixture. The practical potential of the developed procedure was verified by using it for CQA isolation from different plants. The approach represents one of the contemporary analytical trends and current advances in the solid phase extraction, in which several sorption extraction techniques are combined to ensure high-quality analytical results.     

Determination of Triazine Herbicides and Metabolites by Solid Phase Extraction with HPLC Analysis

An efficient solid phase extractive preconcentration/separation method was developed for the trace determination of herbicides in aqueous samples using Amberlite XAD-4 resin as the adsorbent. The retained herbicides were eluted with methanol at a flow rate of 1.0 mL min^?1 and determined by HPLC-DAD (wavelength of 220 nm) using water (pH:4.7, phosphoric acid) and methanol (ratio 35:65) as the mobile phase with a flow rate of 1.0 mL min^?1. Quantitative recoveries of simazine, atrazine and its metabolities were achieved at optimized analysis conditions that included 0.75 g of resin; a pH of 3.0; an eluent volume of 3.0 mL; an eluent flow rate of 1.0 mL min^?1; and a sample flow rate of 4.0 mL min^?1. The limits of detection, preconcentration factor, and linear ranges for the herbicides were 0.084–0.121 µgL^?1, 1000, and 0.5–20 mg L^?1, respectively. The performance of the method was evaluated by analysis of spiked water samples. The recoveries of simazine, atrazine and their metabolities were found to be quantitative (99.6–104.8%) with RSDs of 2.2–4.8% and 2.8–4.7% for intra-day and inter-day precision, respectively. The proposed method was successfully applied for trace determination of studied analytes in waste water, apple juice, and red wine samples.     

凝胶色谱和紫外光谱法对煤四氢呋喃抽提物的分析

本实验选取大同、铁法大兴、义马和神府4种煤样,用乙腈、四氢呋喃、吡啶作溶剂连续抽提后,对其中的四氢呋喃抽提物进行了凝胶色谱及二极管阵列检测分析,以确定煤抽提物中中等极性化合物的分子量分布和结构特征。通过对样品的凝胶色谱及紫外光谱分析发现,煤四氢呋喃抽提物的分子量小于840 amu,分子量分布在840~340 amu(组分1)、340~175 amu(组分2)及175~110 amu(组分3)间的组分均为芳香族化合物。但由于芳环上有不同分子量的取代基存在,使分子量分布相差极大;分子量在110 amu以下(位于标定曲线以外)的(组分4)为小分子量的链烃或脂环烃类化合物;1、2、4组分是煤四氢呋喃抽提物主要组分;而组分3在抽提物样品中含量极少。分子量在110 amu以下的小分子化合物(组分4)除大同样品中含量(8.68%)较少外,在其余3个样品中占的比例很大(神府72.96%,义马54.05%,铁法大兴51.74%)。组分1随煤变质程度增加,相对含量增加,其它组分相对含量与煤变质程度没有直接关系。     

A Multiresidue Method for the Analysis of Carbamate and Urea Pesticides from Soils by Microwave-Assisted Extraction and Liquid Chromatography with Photodiode Array Detection

Abstract

A multiresidue approach using microwave-assisted extraction and liquid chromatography with photodiode array detection was investigated for the determination of butylate, carbaryl, carbofuran, chlorpropham, ethiofencarb, linuron, metobromuron, and monolinuron in soils. The critical parameters of the developed methodology were studied. Method validation was performed by analyzing freshly and aged spiked soil samples. The recoveries and relative standard deviations reached using the optimized conditions were between 77.0±0.46% and 120±2.9% except for ethiofencarb (46.4±4.4% to 105±1.6%) and butylate (22.1±7.6% to 49.2±11%). Soil samples from five locations of Portugal were analysed.     

Determination of 4-Hydroxyphenyllactic Acid in Human Urine by Magnetic Solid-Phase Extraction and High-Performance Anion-Exchange Chromatography with Fluorescence Detection

A novel, simple, rapid, and accurate method is reported for the determination of 4-hydroxyphenyllactic acid in human urine by high-performance anion-exchange chromatography with fluorescence detection and magnetic solid-phase extraction. The separation and pretreatment conditions for urine were optimized. The isolation of 4-hydroxyphenyllactic acid was performed with isocratic elution with 4?mmol?L^?1 sodium hydroxide at 0.45?mL min^?1. Fluorescence detection was performed at an excitation wavelength of 277?nm and an emission wavelength of 340?nm. Under the optimized conditions, the linear dynamic range and the limit of detection for 4-hydroxyphenyllactic acid were 0.05–10 and 0.020?mg?L^?1, respectively. The recovery for the analyte was from 86.5 to 105.5%, with relative standard derivations less than 4.12%. The method was used for the determination of 4-hydroxyphenyllactic acid in human urine. Statistically significant differences in the 4-hydroxyphenyllactic acid concentration in urine were obtained between healthy control and individuals with breast cancer.     

Determination of 11 Cannabinoids in Hemp Plant and Oils by Liquid Chromatography and Photodiode Array Detection

Chromatographia - Drug scheduling has directed the testing approaches for forensic laboratories since the 1970s when Cannabis (marijuana and hemp) and its psychoactive constituent,...     

Solid-Phase Extraction of Carbamazepine and Two Major Metabolites from Plasma for Analysis by HPLC

Abstract

A rapid, sensitive and simple to operate HPLC method for the simultaneous determination of carbamazepine, carbamazepine 10,11-epoxide and 10,11-dihydro-10,11-trans-dihydroxycarbamazepine in plasma is described. The drug and its metabolites are extracted from plasma using commercially available reversed-phase octadecylsilane bonded-silica columns (Bond Elut C₁₈, 2.8 ml capacity). Separation was achieved by reversed-phase chromatography, using a mobile phase consisting of acetonitrile - methanol - water (19:37:44) at a flow-rate of 1.8 ml/min in conjunction with a Waters Assoc. Nova-Pak C₁₈ column. The analytical column, in Radial-Pak cartridge form, was used in combination with a Waters Assoc. Z-module RCSS and protected by a Waters Assoc. Guard-Pak precolumn module containing a Guard-Pak μBondapak C₁₈ insert. Using ultraviolet detection at 214 nm, levels in the region of 50–100 ng/ml for CBZ and its metabolites can be measured with only 250 μl of plasma. The method has been used to determine steady-state concentrations of the drug and its metabolites in paediatric patients.     

高效液相色谱-二极管阵列检测同时测定烟草中多酚类

用高效液相色谱-二极管阵列检测器(HPLC-PDA)建立了烟草中绿原酸、莨菪亭、芸香苷同时测定的方法。烟草样品用甲醇/水(4∶1,V/V)超声萃取,过滤,上样。用Hypersil ODS(4.6 mm(i.d.)×150 mm,3μm)色谱柱,甲醇/TFA水溶液梯度洗脱,PDA光谱图辅助定性,内标法定量。该方法预处理简单,重现性好,回收率84.4%~96.4%;相对标准偏差为1.4%~6.4%。