Determination of glyphosate in water samples by multi-pumping flow system coupled to a liquid waveguide capillary cell

A simple screening method was developed for the determination of glyphosate in water samples using a multi-pumping flow system. The proposed method is based on the reaction between glyphosate and p-dimethylaminocinnamaldehyde (p-DAC), in an acid medium where the reaction product can be measured spectrophotometrically at λ(max) = 495 nm. An experimental design methodology was used to optimize the measurement conditions. The proposed method was applied to the determination of glyphosate in water samples in a concentration range from 0.5 to 10 μg mL(-1). The limit of detection and quantification were 0.17 and 0.53 μg mL(-1), respectively. The results obtained (88.5 to 104.5%) in recovery studies for the determination of glyphosate in different water samples indicated good accuracy and no matrix effect for the developed method. Samples were also analyzed by a confirmatory HPLC method, and agreement within the two set of results was found.     

Diazotized reagent for spectrophotometric determination of glyphosate pesticide in environmental and agricultural samples

A new sensitive spectrophotometric method for the determination of glyphosate herbicide in environmental and agricultural samples is developed. The reaction is based on diazotization followed by coupling of glyphosate with p-dimethyl amino benzaldehyde. The resulted complex absorption spectra was observed at λ_max = 420 nm. The effects of other metal ions and pesticides were also tested for selective determination of glyphosate. The analytical parameters were optimized and have been successfully applied for determination of glyphosate in various environmental samples such as soil, water and vegetables. This method has a lower limit detection of 6 μg of glyphosate. Beer's law is obeyed over the concentration range of 6.0 μg–24.0 μg glyphosate in 25 mL of the final solution at 420 nm. The standard deviation and relative standard deviation calculated are 0.0055 and 1.023, respectively. The molar absorptivity of the colored system is 1.91 × 10¹⁰ L mol^?1cm^?1 and Sandell's sensitivity is found 0.408 × 10^?5 μg cm^?2. The proposed method is simple, sensitive, highly reproducible and time saving as compare to those complicated time consuming methods.     

有机悬浮固化分散液-液微萃取测定水样中痕量铅

建立了以二乙基二硫代氨基甲酸钠为配位剂,十二醇为萃取剂,乙醇为分散剂的悬浮固化分散液-液微萃取—火焰原子吸收光谱法测定水样中痕量铅的方法。详细探讨了影响萃取效率的因素。优化条件为:二乙基二硫代氨基甲酸钠的用量为10-6 mol,十二醇体积为90.00μL,乙醇体积为1.00 mL,pH为7.00。在最佳条件下,铅的检出限为1.12μg/L,富集倍率为16.00,线性范围5.00～600.00μg/L,对含有20.00μg/L和600.00μg/L Pb的标准溶液平行萃取测定11次,测定结果的RSD分别为3.73%和2.62%。本方法应用于自来水、河水及海水中痕量铅的分析,加标回收率为90.10%～100.70%。     

Determination of eprosartan mesylate and hydrochlorothiazide in tablets by derivative spectrophotometric and high-performance liquid chromatographic methods

Two new simple and selective assay methods have been presented for the analysis of eprosartan mesylate (EPR) and hydrochlorothiazide (HCT) in pharmaceutical formulations. The first method is based on first-derivative ultraviolet spectrophotometry with zero-crossing measurements at 246 and 279 nm for EPR and HCT, respectively. The assay was linear over the concentration ranges 3.0-14.0 μg/mL for EPR and 1.0-12.0 μg/mL for HCT. The quantification limits for EPR and HCT were found to be 1.148 and 0.581 μg/mL, respectively, while the detection limits were 0.344 μg/mL for EPR and 0.175 μg/mL for HCT. The second method involved isocratic reversed-phase liquid chromatography using a mobile phase composed of acetonitrile-10 mM phosphoric acid (pH 2.5) (40:60, v/v). Olmesartan was used as internal standard and the substances were detected at 272 nm. The linearity ranges were found to be 0.5-30 and 0.3-15.0 μg/mL for EPR and HCT, respectively. The limits of detection were found to be 0.121 μg/mL for EPR and 0.045 μg/mL for HCT. The limits of quantification were found to be 0.405 and 0.148 μg/mL for EPR and HCT, respectively. The proposed methods were successfully applied to the determination of commercially available tablets with a high percentage of recovery and good accuracy and precision.     

直接进样超高效液相色谱-三重四极杆质谱法快速测定环境水样中草甘膦、氨甲基膦酸、草铵膦及乙烯利残留

建立了一种简便、直接进样的超高效液相色谱-三重四极杆质谱法（UPLC-MS/MS）快速测定环境水样中草甘膦、氨甲基膦酸、草铵膦及乙烯利的残留。环境水样经0.22 μm滤膜过滤或冷冻离心去除杂质后,滤液无需衍生化直接进行定量分析。4种农药通过Metrosep A Supp 5柱（150 mm×4.0 mm,5 μm）分离,以碳酸氢铵-氨水溶液为流动相进行梯度洗脱,在负离子模式下以MRM方式进行检测。结果表明,4种农药在0.50~50.0 μg/L范围内相关系数（r）均大于0.999,线性关系良好,方法检出限为0.05~0.09 μg/L。实际水样在低、中、高3种加标浓度水平下,回收率分别为76.3%~108%、83.0%~107%和87.0%~105%,相对标准偏差分别为2.0%~12.3%、2.4%~5.6%和2.7%~6.8%。使用该方法对海南省34个水样进行测定,其中30个饮用水源地水样中均未检出4种农药,槟榔园附近3个水样均检出草甘膦和氨甲基膦酸,香蕉园附近的1个水样检出草铵膦和氨甲基膦酸。与传统的衍生化方法比较,该方法操作简便,重现性好,准确性高,不受基体干扰,适用于环境水样中草甘膦、氨甲基膦酸、草铵膦及乙烯利的残留检测。     

Large volume sample stacking with EOF and sweeping in CE for determination of common preservatives in cosmetic products by chemometric experimental design

This study proposes a capillary electrophoresis method incorporating large volume sample stacking, EOF and sweeping for detection of common preservatives used in cosmetic products. The method was developed using chemometric experimental design (fractional factorial design and central composite design) to determine multiple separation variables by efficient steps. The samples were loaded by hydrodynamic injection (10 psi, 90 s), and separated by phosphate buffer (50 mM, pH 3) containing 30% methanol and 80 mM SDS at -20 kV. During method validation, calibration curves were found to be linear over a range of 5-100 μg/mL for butyl paraben and isobutyl paraben; 0.05-10 μg/mL for ethyl paraben; 0.2-50 μg/mL for dehydroacetic acid; 0.5-70 μg/mL for methyl paraben; 5-350 μg/mL for sorbic acid; 0.02-450 μg/mL for p-hydroxybenzoic acid and 0.05-10 μg/mL for salicylic acid and benzoic acid. The analytes were analysed simultaneously and their detection limits (S/N = 3) were down to 0.005-2 μg/mL. The analysis method was successfully used for detection of preservatives used in commercial cosmetics.     

Determination of chlorobenzenes in pure,tap, and sea water by static headspace gas chromatography‐electron capture detection

A simple, efficient, solvent‐free, and commercial readily available approach for determination of 11 chlorobenzenes (CBs) in water samples using the static headspace (HS) sampling and gas chromatography‐electron capture detector has been described. The proposed static HS sampling method was initially optimized and the optimum experimental conditions found were 10 mL water sample containing 20% (w/v) sodium chloride placed in a 20 mL vial and stirred at 70°C for 30 min. The linearity of the method ranged from 0.16 to 8.0 μg/L for dichlorobenzene isomers, 0.0176～0.88 μg/L for trichlorobenzene isomers, 0.004～0.2 μg/L for tetrachlorobenzene isomers, and from 0.001 to 0.05 μg/L for pentachlorobenzene and hexachlorobenzene, with correlation coefficients ranging between 0.9992 and 0.9999. The limits of detection were in the low μg/L level, ranging between 0.0002 and 0.04 μg/L. The relative recoveries of spiked CBs with external calibration or standard addition method at different concentration levels in pure, tap, and sea water samples were 83～116%, 89～108%, and 93～112%, respectively, and with relative standard deviations of 1.9～6.3%, 1.6～5.4%, and 2.5～5.7% (n = 5), respectively. It is concluded that this method can be successfully applied for the determination of CBs in pure, tap, and sea water samples.     

A new strategy to simultaneous microextraction of acidic and basic compounds

The simultaneous extraction of acidic and basic pollutants from water samples is an interesting and debatable work in sample preparation techniques. A novel and efficient method named ion pair based surfactant assisted microextraction (IP-SAME) was applied for extraction and preconcentration of five selected acidic and basic aromatic species as model compounds in water samples, followed by high performance liquid chromatography-ultraviolet detection. A mixture including 1 mL of ultra-pure water (containing ionic surfactant as emulsifier agent) and 60 μL 1-octanol (as extraction solvent) was rapidly injected using a syringe into a 10.0 mL water sample which formed an emulsified solution. IP-SAME mechanism can be interpreted by two types of molecular mass transfer into the organic solvent (partitioning and ion pairing for non-ionized and ionized compounds, respectively) during emulsification process. The effective parameters on the extraction efficiency such as the extraction solvent type and its volume, type of the surfactant and its concentration, sample pH and ionic strength of the sample were optimized. Under the optimum conditions (60 μL of 1-octanol; 1.5 mmol L(-1) cethyltrimethyl ammonium bromide (CTAB) as emulsifier agent and sample pH 10.0), the preconcentration factors (PFs), detection limits and linear dynamic ranges (LDRs) were obtained in the range of 87-348, 0.07-0.6 μg L(-1) and 0.1-200 μg L(-1) respectively. All of natural water samples were successfully analyzed by the proposed method.     

An environmentally friendly reflectometric method for ranitidine determination in pharmaceuticals and human urine

This paper describes an environmentally friendly method for quantitative determination of ranitidine using diffuse reflectance spectroscopy. This method is based on the reflectance measurements of the colored product produced from the spot test reaction between ranitidine and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, using filter paper as solid support. Experimental design methodologies were used to optimize the optimal conditions. All reflectance measurements were carried out at 590 nm and the linear range was from 1.42x10(-3) to 3.42x10(-2) mol L(-1), with a correlation coefficient of 0.997. The limit of detection was estimated to be 1.09x10(-3) mol L(-1) (R.S.D.=1.9%). The proposed method was successfully applied to the determination of ranitidine in commercial brands of pharmaceuticals and no interferences were observed from the common excipients in formulations. The results obtained by the proposed method were favorably compared with those obtained by an official procedure at 95% confidence level. Additionally, the method was also applied to the determination of ranitidine in human urine showing excellent recoveries (99.6-100.3%).     

Rapid analysis of aldehydes by simultaneous microextraction and derivatization followed by GC-MS

Ultrasound-assisted dispersive liquid-liquid microextraction (UDLLME) and simultaneous derivatization followed by GC-MS was developed for the analysis of four aldehydes including acetaldehyde (ACE), propionaldehyde (PRO), butyraldehyde (BUT) and valeraldehyde (VAL) in water samples. In the proposed method, the aldehydes were derivatized with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine (PFBHA) and extracted by UDLLME in aqueous solution simultaneously; finally, the derivatives were analyzed by GC-MS. The experimental parameters were investigated and the method validations were studied. The optimal conditions were: aqueous sample of 5 mL, PFBHA of 50 μL, 1.0 mL ethanol (disperser solvent) containing 20 μL chlorobenzene (extraction solvent), ultrasound time of 2 min and centrifuging time of 3 min at 6000 rpm. The proposed method provided satisfactory precision (RSD 1.8-10.2%), wide linear range (0.8-160 μg/L), good linearity (R(2) 0.9983-0.9993), good relative recovery (85-105%) and low limit of detection (0.16-0.23 μg/L). The proposed method was successfully applied for the analysis of aldehydes in water samples. The experimental results showed that the proposed method was a very simple, rapid, low-cost, sensitive and efficient analytical method for the determination of trace amount of aldehydes in water samples.     

草甘膦的邻硝基苯磺酰氯柱前衍生高效液相色谱分析

以邻硝基苯磺酰氯(NBSC)为衍生化试剂,建立了柱前衍生草甘膦的反相高效液相色谱紫外检测法,并对衍生化条件进行了优化.最佳衍生化条件为:衍生温度25℃,反应时间10 min,硼砂缓冲溶液浓度0.25 mol/L(pH 9.0),草甘膦与NBSC的摩尔比为1:5.HPLC分析条件为:采用Lichrospher C18柱,...     

固相萃取-分散液液微萃取-柱前衍生法测定水样中痕量雌激素

建立了碳纳米管的固相萃取-分散液液微萃取-柱前荧光衍生化(SPE-DLLME-PFD)测定水体中痕量雌三醇(E3)、双酚A(BPA)、17α-乙炔基雌二醇(EE2)及17β-雌二醇(E2)的高效液相色谱方法.采用中心复合设计和响应曲面法分析并优化SPE、DLLME及PLD条件,最佳条件为210 mL水样以2.0 mL/min的流速过固相萃取柱(碳纳米管量30 mg),甲醇洗脱,氮气浓缩并定容至0.6 mL(分散剂),将100 μL C6MIM[PF6]与分散剂的混合液注入到NaCl含量为25％的2.0 mL去离子水中,离心,移取20 μL下层有机相于样品瓶中,与4.0 mg衍生剂混合,在40℃水浴中衍生25 min;用0.1mL甲醇溶解过量的衍生剂颗粒,取20 μL进样分析.在优化条件下.4种雌激素的线性范围为0.05～5.00 μg/L,相关系数R2=0.9966～0.9999;,检出限介于0.13～6.33 ng/L(S/N=3)之间.不同加标浓度条件下,雌激素的加标回收率在83.1％～122.4％范围内(RSD=1.7％～9.6％).在实际水样中E3和BPA检出率较高.与其它方法相比,本方法虽然萃取时间长、水样量大、步骤多,但具有检出限低、操作简便、环境友好等优点.     

Determination of pirimicarb and endosulfan in commercial pesticide formulations by Fourier transform infrared spectrometry

A routine method based on Fourier transform infrared spectrometry was developed for the simultaneous determination of pirimicarb and endosulfan in commercially available pesticide formulations. The method is based on peak area absorbance measurements between 1362 and 1352 cm(-1), corrected with a baseline fixed at 1338 cm(-1), for pirimicarb and peak area absorbance measurements between 919 and 909 cm(-1) with a baseline fixed at 931 cm(-1) for endosulfan; chloroform solutions for analysis were obtained by direct dilution of emulsifiable concentrates or by solvent extraction from solid samples. Various extraction conditions and appropriate band selection were investigated, and interference studies were performed. Under the experimental conditions selected, limits of detection of 13 microg/g for pirimicarb and 150 microg/g for endosulfan were obtained that correspond to 0.13 and 1.6% (w/w), respectively, in commercial samples. Results from analyses of commercial samples by the developed method compared well with those obtained by a liquid chromatography reference method.     

Detection of propranolol in pharmaceutical formulations by diffuse reflectance spectroscopy

This paper describes an analytical reflectometric method that has an objective not only the industrial quality control but also to detect possible falsifications and/or adulterations of propranolol in pharmaceutical formulations. The method is based on the diffuse reflectance measurements of the colored product (III) of the spot test reaction between propranolol hydrochloride (I) and 2,6-dichloroquinone-4-chloroimide (II) using filter paper as solid support. Spot test conditions have been investigated using experimental design in order to identify and optimize the critical factors. The factors evaluated were DCQ concentration, propranolol solvent and DCQ solvent. The best reaction conditions were achieved with the addition of 30 microL of propranolol solution in ethanol 35% (v/v) and 30 microL of DCQ solution at 70 mg mL(-1) in acetone, in this order. All reflectance measurements were carried out at 500 nm and the linear range was from 8.45x10(-4) to 8.45x10(-2)mol L(-1) (r=0.998). The limit of detection was 1.01x10(-4)mol L(-1). No interference was observed from the assessed excipients and drugs. The method was applied to determine propranolol in commercial brands of pharmaceuticals. The results obtained by the proposed method were favorably compared with those given by the British Pharmacopoeia procedure.     

Simple and automatic determination of aldehydes and acetone in water by headspace solid-phase microextraction and gas chromatography-mass spectrometry

We describe a simple and automatic method to determine nine aldehydes and acetone simultaneously in water. This method is based on derivatization with 2,2,2-trifluoroethylhydrazine (TFEH) and consecutive headspace-solid-phase microextraction and gas chromatography-mass spectrometry. Acetone-d(6) was used as the internal standard. Aldehydes and acetone in water reacted for 30 min at 40°C with TFEH in a headspace vial and the formed TFEH derivatives were simultaneously vaporized and adsorbed on polydimethylsiloxane-divinylbenzene. Under the established condition, the method detection limit was 0.1-0.5 μg/L in 4 mL water and the relative standard deviation was less than 13% at concentrations of 0.25 and 0.05 mg/L. This method was applied to determine aldehydes and acetone in 5 mineral water and 114 surface water samples. All mineral water samples had detectable levels of methanal (24.0-61.8 μg/L), ethanal (57.7-110.9 μg/L), propanal (11.5-11.7 μg/L), butanal, pentanal (3.3-3.4 μg/L) and nonanal (0.3-0.4 μg/L). Methanal and ethanal were also detected in concentration range of 2.7-117.2 and 1.2-11.9 μg/L, respectively, in surface water of 114 monitoring sites in Korea.     

Reverse micelle-mediated dispersive liquid-liquid microextraction of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-methylphenoxyacetic acid

A supramolecular solvent consisting of reverse micelles of decanoic acid, dispersed in a continuous phase of tetrahydrofuran:water, was proposed as an efficient microextraction technique for extraction of selected chlorophenoxy acid herbicides from water samples prior to high-performance liquid chromatography UV determination. The disperser solvent (1.0 mL tetrahydrofuran) containing 20 mg decanoic acid was rapidly injected into 10.0 mL of water sample. After centrifugation, the reverse micelle-rich phase (25 ± 0.5 μL) was floated at top of the home-designed centrifuge tube. The solvent was collected and 20 μL of it was injected into high-performance liquid chromatography for analysis. The results showed that the in situ solvent formation and extraction process can be completed in a few seconds. Under the optimal conditions, limits of detection of the method for 4-chloro-2-methylphenoxyacetic acid and 2,4-dichlorophenoxyacetic acid were in the range of 0.5-0.8 μg L(-1) and the repeatability of the proposed method, expressed as relative standard deviation, varied in the range of 2.5-3.2%. Linearity was found to be in the range of 1-200 μg L(-1) and the preconcentration factors were between 148 and 157. The mean percentage recoveries exceeded 92.0% for all the spiking levels in real water samples.     

Optimization of extraction procedure and chromatographic separation of glyphosate, glufosinate and aminomethylphosphonic acid in soil

Analysing herbicides in soil is a complex issue that needs validation and optimization of existing methods. An extraction and analysis method was developed to assess concentrations of glyphosate, glufosinate and aminomethylphophonic acid (AMPA) in field soil samples. After testing extractions by accelerated solvent extraction and ultrasonic extraction, agitation was selected with the best recoveries. Water was preferred as solvent extraction because it resulted in a cleaner chromatogram with fewer impurities than was the case with alkaline solvents. Analysis was performed by FMOC pre-column derivatization followed by high-performance liquid chromatography (HPLC) on a 300 mm C(18) column which permitted enhanced separation and sensitivity than a 250 mm C(18) column and increased resistance than the NH(2) column for soil samples. This extraction and analysis method allowing a minimum of steps before the injection in the HPLC with fluorescence detection is efficient and sensitive for a clay-loamy soil with detection limits of 103 μg kg(-1) for glyphosate, 15 μg kg(-1) for glufosinate and 16 μg kg(-1) for AMPA in soil samples.     

Direct Determination of Glyphosate in Environmental Waters Using Capillary Electrophoresis with Electrospray Condensation Nucleation Light Scattering Detection

An electrospray condensation nucleation light scattering detector (ESI-CNLSD) was coupled with capillary electrophoresis (CE) for analysis of glyphosate, a chemical of agricultural interest, which is otherwise difficult to detect owing to its lack of chromophores or fluorophores. To reduce the absorption of glyphosate on the CE capillary and to reduce the separation time, an N-cetyltrimethylammonium bromide (CTAB) pre-rinsing CE method was developed here. The protocol consisted of 15 min pre-rinsing of the capillary before analysis with CTAB solution and 5 min with ammonium acetate buffer at pH 2.8. The capillary inner wall coating established by this treatment lasted up to 10 h without bleeding to interfere with CNLSD signal. Calibration data were linear over two orders of magnitude, the instrument detection limit was 0.06 µg/mL and the method detection limit was 0.2 µg/mL. The method was applied to the analysis of local (rural area) lake water and commercial herbicide samples.     

Rapid and simultaneous determination of hexapeptides (Ac-EEMQRR-amide and H2N-EEMQRR-amide) in anti-wrinkle cosmetics by hydrophilic interaction liquid chromatography-solid phase extraction preparation and hydrophilic interaction liquid chromatography with tandem mass spectrometry

A rapid method for the simultaneous determination of Ac-EEMQRR-amide and H(2)N-EEMQRR-amide in cosmetic products was developed and evaluated. This analytical procedure involved extracting samples with 0.1:0.1:85:15 (v:v) trifluoroacetic acid (TFA):formic acid:acetonitrile (ACN):water and determination by hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Samples showing serious ion suppression were further cleaned up using HILIC-SPE prior to HILIC-MS/MS analysis. Stable isotopically labeled peptides, corresponding to the above two peptides, were used as internal standards to correct for loss of recovery and matrix effects. Electrospray ionization (ESI) in the positive mode was used. The linear range was 2.0-1000 ng/mL for Ac-EEMQRR-amide and 25.0-2500 ng/mL for H(2)N-EEMQRR-amide. Thirteen commercial products were analyzed for the two peptides using this method. The amounts of Ac-EEMQRR-amide in the samples ranged from none detected to 42.3 μg/g. H(2)N-EEMQRR-amide was not detected in any of the samples. The recoveries for Ac-EEMQRR-amide and H(2)N-EEMQRR-amide ranged from 85% to 110% and 84% to 119%, respectively, at the spiking level of 30 μg/g.     

Determination of volatile chlorinated hydrocarbons in water samples by static headspace gas chromatography with electron capture detection

A simple, efficient, solvent‐free, and commercial readily available approach for determination of five volatile chlorinated hydrocarbons in water samples using the static headspace sampling and gas chromatography with electron capture detection has been described. The proposed static headspace sampling method was initially optimized and the optimum experimental conditions found were 10 mL water sample containing 20% w/v sodium chloride placed in a 20 mL vial and stirred at 50ºC for 20 min. The linearity of the method was in the range of 1.2–240 μg/L for dichloromethane, 0.2–40 μg/L for trichloromethane, 0.005–1 μg/L for perchloromethane, 0.025–5 μg/L for trichloroethylene, and 0.01–2 μg/L for perchloroethylene, with coefficients of determination ranging between 0.9979 and 0.9990. The limits of detection were in the low μg/L level, ranging between 0.001 and 0.3 μg/L. The relative recoveries of spiked five volatile chlorinated hydrocarbons with external calibration method at different concentration levels in pure, tap, sea water of Jiaojiang Estuary, and sea water of waters of Xiaomendao were in the range of 91–116, 96–105, 86–112, and 80–111%, respectively, and with relative standard deviations of 1.9–3.6, 2.3–3.5, 1.5–2.7, and 2.3–3.7% (n = 5), respectively. The performance of the proposed method was compared with traditional liquid–liquid extraction on the real water samples (i.e., pure, tap, and sea water, etc.) and comparable efficiencies were obtained. It is concluded that this method can be successfully applied for the determination of volatile chlorinated hydrocarbons in different water samples.