Determination of insecticide pymetrozine by differential pulse polarography/application to lake water and orange juice

A simple, fast and sensitive differential pulse polarographic method (DPP) for the determination of pymetrozine insecticide in pure form, agrochemical formulation, natural water and orange juice samples is proposed. The polarographic behavior of pymetrozine exhibited a double well-defined polarographic peaks at -580 and 950mV (versus SCE), respectively. The peak potentials were strongly pH-dependent in that they shifted to more negative values with increasing pH. The polarographic reduction corresponding to the first peak at pH 2.0 (B-R buffer solution) showed quantitative increments with the additions of standard pymetrozine solution under the optimal conditions and the corresponding peak current was linearly proportional to pymetrozine concentration in the range of 4.97x10(-7) to 7.35x10(-5)molL(-1). The limit of detection (LOD) and limit of quantification (LOQ) were obtained as 1.48x10(-7) and 4.93x10(-7)molL(-1), respectively. The mean recoveries of the 5.0x10(-6)molL(-1) pymetrozine spiked to lake water and orange juice were (4.89+/-0.23)x10(-6) and (4.97+/-0.19)x10(-6)molL(-1) at 95% confidence level, respectively. The method was extended to the determination of pymetrozine in agrochemical insecticide formulation Plenum and accuracy was in agreement with that obtained by HPLC comparison method. Influences of some interfering ions and some other pesticides were also investigated. The mechanistic study was not pursued.     

气相色谱法测定茶色素中的乙酸乙酯残留量

本文建立了一个气相色谱法测定茶色素中的乙酸乙酯残留量的方法。方法的回收率为100.1％～101.1％,相对标准偏差为2.0％,检测限为2ng(S/N≥3).测定结果表明:方法具有简单、可靠、快速、准确等特点。     

Comparison of immobilisation of air pollution control residues with cement and with silica

Cement as agent for immobilising Pb from air pollution control residues is compared with the use of different silica-containing materials. The DIN 38414-S4 leaching test was used to control Pb leachability and to compare obtained Pb leachate concentrations with the landfill limit of 2 mg/l for Pb. Firstly, one scrubber residues was treated with cement and micro-silica. With cement, the Pb leachability could be reduced with a factor ranging from 3 to 50 depending on the type and amount of cement used and depending on the curing time. The landfill limit of 2 mg/l was, however, never attained. From all tested silica-containing additives, aerosil could reduce the initial Pb leaching (101.3mg/l) to below the detection limit at a dosage of 0.13 g aerosil/g residue. Second best and an economically preferable silica-containing additive was micro-silica: a reduction from 101.3 to 0.7 mg/l was observed at a dosage of 0.4 g micro-silica/g residue. The formation of Ca-silicates was found to be responsible for the decreased Pb leachability. To generalise the findings, the Pb leachability of five cement-treated and five micro-silica-treated air pollution control residues were compared. For three scrubber residues, 2-20 times lower Pb leachate concentrations were measured for micro-silica-treated samples (cured for 5 weeks) than cement-treated samples. For a fly ash and a boiler ash the difference was, respectively, 48 and 17 times. pH-dependent leaching tests showed that at pH=2.5, Pb leaching is 250 times lower for the micro-silica-treated residue than for the cement-treated residue and almost seven times lower at pH 12.4.     

Solid phase extraction of lead on octadecyl bonded silica membrane disk modified with Cyanex302 and determination by flame atomic absorption spectrometry

A simple, reliable and rapid method for preconcentration and determination of lead using octadecyl bonded silica membrane disk impregnated with Cyanex302 and flame atomic absorption spectrometry is presented. The influence of aqueous phase pH, type of eluent, flow rates of sample solution and eluent, volume of eluent and amount of extractant has been investigated. The break through volume is greater than 4.0 dm(3) with an enrichment factor of more than 400 and a detection limit of 1.0microg dm(-3). The method developed for determination of lead is good as six replicate determinations using 100cm(3) solution containing lead in the range 1-4900microg provides a relative standard deviation (R.S.D.) of 0.4%. The selectivity of the proposed method was confirmed from the interference studies. The developed procedure was successfully applied for the determination of lead in spiked sea water, USGS standard soil sample, sludge and industrial effluents, medicinal formulation, plant, some food products and wine.     

A sol-gel based solid phase microextraction fiber for analysis of aromatic hydrocarbons

A sol-gel based solid phase microextraction fiber for headspace sampling (HP-SPME) and GC determination of benzene, toluene, ethylbenzene and xylenes (BTEX) is introduced. The influences of fiber composition, microextraction conditions such as temperature and time on the fiber performance and desorption temperature and time were investigated. Under optimal conditions, the use of proposed fiber was thermally stable up to 250 degrees C and demonstrated high sensitive and fast sampling of BTEX from gaseous phase. Depending on the analysed substance, the linear range for a selected fiber and the applied GC-FID technique was from 4 to 80 ng mL(-1)with limit of detection (LOD) 0.2-0.7 ng mL(-1) and 100-1000 ng mL(-1) with LOD 8-20 ng mL(-1) for gaseous and soil samples, respectively. HP-SPME-GC analysis was highly reproducible-relative standard deviations (R.S.D.) were between 5.0 and 7.9%. The proposed fiber was successfully used for BTEX sampling from indoor air and headspace of soil samples.     

Quantitation of 4-(4-Chl0R0Phenyl)-2-Pyrr0Lidin0Ne in Baclofen Powder and Tablets

Abstract

A high-pressure liquid chromatography method to quantify 4-(4-chlorophenyl)-2-pyrrolidinone which is present as an impurity in baclofen powder and its dosage forms has been developed. The USP-NF method for the determination of 4-(4-chlorophenyl)-2-pyrrolidinone in powder is based on TLC and is only qualitative. The developed method was successfully used to quantify 4-(4-chlorophenyl)-2-pyrrolidinone in powder (USP-NF limit 1%) and in tablets (USP-NF limit 5%). The method is accurate and reproducible with a percent error of 4% for powder and 3% for tablets.     

Development of a dispersive liquid-liquid microextraction method for the determination of polychlorinated biphenyls in water

A very simple and powerful microextraction procedure, the dispersive liquid-liquid microextraction (DLLME), was used for the determination of the content of 10 polychlorinated biphenyls (PCBs) in water samples, using gas chromatography coupled with electron-capture detection (GC-ECD). The appropriate amount of acetone (disperser solvent) and chlorobenzene (extraction solvent) at the microlevel volume was used for this procedure. The conditions for the microextraction performance were investigated and optimized. The optimized method exhibited a good linearity (R(2)>0.996) over the studied range (0.005-2mugL(-1)), illustrating a satisfactory precision level with R.S.D. values between 4.1% and 11.0%. The values of the detection limit (S/N=3) were found to be lower than 0.002mugL(-1). Furthermore, a large enrichment factor for the analytes (up to a 540-fold) was achieved in a very short time for only a 5.00-mL water sample. The effectiveness of the method towards real samples was tested by analyzing well, river and seawater samples. The relative recoveries of the well, river and seawater samples, which had been spiked with different levels of PCBs were equal to 92.0-114.0%, 97.0-102.0% and 96.0-103.0%, respectively. The attained results demonstrated that DLLME combined with GC-ECD was a fast and inexpensive technique for the PCBs determination in water samples.     

流动注射化学发光法测定杀扑磷

基于杀扑磷对过氧化氧和鲁米诺在碱性条件下化学发光有抑制作用,本文建立了一种杀扑磷的流动注射化学发光（FI-CL）检测方法。杀扑磷在1．0×10^-7-1．0×10^-3g／mL范围内与发光强度呈良好的线性关系,检测限（S/N=3）为7．3×10^-8g,／mL,测定相对标准偏差（RSD）为1．26％,对柑橘样品进行加标回收率测定,回收率在89．5％-92．6％之间。     

土壤中多氯联苯的快速测定

研究了土壤中多氯联苯的最佳提取方法和HPLC的快速测定方法,该方法的最低检出限为0.001mg/kg,PCBs含量在0.05—0.2mg/kg范围内,土壤中PCBs的回收宰均在80—104%之间,本法操作简便,准确度高、精密度好,土壤中其它杂质基本不干扰测定。     

Automatic on-line pre-concentration system using a knotted reactor for the FAAS determination of lead in drinking water

An automatic on-line pre-concentration system is proposed for lead determination in drinking water using flame atomic absorption spectrometry (FAAS). Lead(II) ions are retained as the 1-(2-pyridylazo)-2-naphthol (PAN) complex in the walls of a knotted reactor, followed by an elution step using 0.50molL(-1) hydrochloric acid solution. Optimisation involving the sampling flow rate, pH and buffer concentration factors was performed using a Box-Behnken design. Other factors were established considering results of previous experiments. The procedure allows the determination of lead with a 0.43microgL(-1) detection limit (3sigma/S) and precisions (expressed as relative standard deviation) of 4.84% (N=7) and 2.9% (N=7) for lead concentrations of 5 and 25microgL(-1), respectively. The accuracy was confirmed by the determination of lead in the NIST SRM 1643d trace elements in natural water standard reference material. The pre-concentration factor obtained is 26.5 and the sampling frequency is 48h(-1). The recovery achieved for lead determination in the presence of several ions demonstrated that this procedure could be applied to the analysis of drinking water samples. The method was applied for lead determination in drinking water samples collected in Jequié City, Brazil. The lead concentration found in 25 samples were always lower than the permissible maximum levels stipulated by World Health Organization.     

流动注射化学发光法测定伏杀硫磷

基于伏杀硫磷对过氧化氢和鲁米诺在碱性条件下化学发光有抑制作用,本文建立了一种伏杀硫磷的流动注射化学发光(FI-CL)检测方法。伏杀硫磷在1.0×10-7-1.0×10-5g/mL范围内与发光强度呈良好的线性关系,检测限(S/N=3)为3.1×10-8g/mL,相对标准偏差(RSD)为1.21%,对甘蓝样品进行加标回收率测定,回收率在90.2%-97.4%之间。     

土壤界限含水率自动检测系统设计研究

为了解决传统土壤界限含水率检测中存在的需人工现场操作、耗时久、数据采集困难、数据传输实时性差等问题,设计了一种土壤界限含水率自动检测系统。该系统以西门子S7-200PLC为控制核心,由传送带、正方体容器、搅拌容器、电子秤、抹平系统、圆锥仪和加热箱等组成,使用MCGS组态软件进行数据监控,并采用采样烘干法测定含水率,液-塑限联合测定法测定液、塑性指数。实际应用中,该系统能够完成自动搅拌、多组数据同时测定和数据实时传送,基于含水率和液、塑性指数实现土体的分类以及地基土承载力的估算。该系统具有自动化程度高、操作简单及成本低廉的特点,能够广泛应用于各种土壤界限含水率的测定,对农业工程的设计和实施具有一定的参考价值。     

Simultaneous spectrophotometric determination of iodate and bromate in water samples by the method of mean centering of ratio kinetic profiles

A new and very simple kinetic-spectrophotometric method was developed for the simultaneous determination of binary mixtures of iodate and bromate in water samples, without prior separation steps. The method is based on the mean centering of ratio kinetic profiles, allows rapid and accurate determination of bromate and iodate. The analytical characteristics of the method such as detection limit, accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) for the simultaneous determination of binary mixtures of iodate and bromate were calculated. The results show that the method was capable of simultaneous determination of 0.05-1.50 microg mL(-1) each of iodate and bromate. The results allow simultaneous determination with the ratio 30:1-1:30 for iodate-bromate. The proposed method was successfully applied to the simultaneous determination of iodate and bromate in several water samples.     

超高效液相色谱串联质谱法测定鸡肉中吡虫啉残留量的研究

本文介绍了利用超高效液相色谱串联质谱(UPLC/MS/MS)快速检测鸡肉中吡虫啉残留量的方法。样品通过乙腈-水(体积比为9:1)溶液提取,饱和乙腈的正己烷净化。采用电喷雾电离,正离子模式,多反应监测扫描。该方法的最低检出限为0.1μg/kg,在0.1~100μg/kg的线性范围内,相关系数r为0.9978,三种不同加标浓度,7次平行实验平均回收率为87.47%～98.85%,相对标准偏差(RSD)为3.09%～5.29%,该方法具有前处理简单,灵敏度高,分析时间短等优点,适用于鸡肉中吡虫啉农药残留的快速检测。     

An on-line pre-concentration system for determination of cadmium in drinking water using FAAS

In the present paper, a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) is proposed as pre-concentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. The optimization step was performed using two-level full factorial design and Doehlert matrix, involving the variables: sampling flow rate, elution concentration, buffer concentration and pH. Using the established experimental conditions in the optimization step of: pH 8.2, sampling flow rate 8.5 mL min(-1), buffer concentration 0.05 mol L(-1) and elution concentration of 1.0 mol L(-1), this system allows the determination of cadmium with detection limit (LD) (3sigma/S) of 20.0 ng L(-1) and quantification limit (LQ) (10sigma/S) of 64 ng L(-1), precision expressed as relative standard deviation (R.S.D.) of 5.0 and 4.7% for cadmium concentration of 5.0 and 40.0 microg L(-1), respectively, and a pre-concentration factor of 158 for a sample volume of 20.0 mL. The accuracy was confirmed by cadmium determination in the standard reference material, NIST SRM 1643d trace elements in natural water. This procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. For five samples analyzed, the achieved concentrations varied from 0.31 to 0.86 microg L(-1).     

高效液相色谱法检测食品接触材料中三聚氰胺的残留量

建立了一种用液相色谱技术检测分析食品接触材料中三聚氰胺残留量的方法。样品采用0.1 mol/L盐酸作为提取溶液,70℃水浴超声提取。色谱分离采用NH2柱,流动相为V(乙腈):V(5mmol/L磷酸盐缓冲溶液,pH 6.5)=75:25,二极管阵列检测器检测。在优化条件下,三聚氰胺浓度在0.2-100 mg/L范围内与其峰面积线性关系良好,检出限(S/N=3)为0.02 mg/L。在100μg的添加水平下,三聚氰胺的回收率在80-99%之间,相对标准偏差(RSD)为2.80-4.32%。揭示了原料中三聚氰胺残留量与成型品的三聚氰胺迁移量的正相关关系。结果表明,该法简便、快速,可准确测定食品接触材料中三聚氰胺残留量。     

Adsorption equilibrium and kinetics of polyvinyl alcohol from aqueous solution on powdered activated carbon

In this study, powdered activated carbon (PAC) was used to remove polyvinyl alcohol (PVA) from the aqueous PVA solution. The adsorption kinetics has been studied pertaining to various initial PVA concentration and PAC dosage. The rates of adsorption were found to conform to the second-order kinetics with good correlation. Boyd plot confirmed that external mass transfer was the rate-limiting step in the sorption process. The adsorption isotherm obtained resembled with H-type of isotherm, which indicated a high affinity of the solute for the sorption sites. The Freundlich model appeared to fit the isotherm data better than the Langmuir model. The thermodynamic parameters such as Delta H degrees , Delta S degrees and Delta G degrees were evaluated from the slope and intercept of linear plot of log Kc against (1/T) x 1000. The change in entropy (DeltaS degrees ) and heat of adsorption (Delta H degrees ) of PAC was estimated as 1.45 kJ mol(-1)K(-1) and 365 kJ mol(-1), respectively. The free energy of the adsorption at all temperatures was negative indicating a spontaneous process. The maximum PVA removal of 92% was obtained at a pH of 6.3 and contact time of 30 min for an adsorbent dose of 5 g/L.     

Preparation of a modified flue gas desulphurization residue and its effect on pot sorghum growth and acidic soil amelioration

A modified flue gas desulphurization residue (MFGDR) was prepared and its effects on sorghum growth and acidic soil amelioration were evaluated in this paper. The MFGDR was prepared by calcining a mixture of dry/semi-dry flue gas desulphurization (FGD) residue from a coal-fired power plant, sorted potash feldspar and/or limestone powder. The available nutrients from the MFGDR were determined with 4.91 wt% K⁺, 1.15 wt% Mg²⁺, 22.4 wt% Ca²⁺, 7.01 wt% Si⁴⁺ and 2.07 wt% SO₄²⁻-S in 0.1 mol L⁻¹ citric acid solution. Its pH value was held at 9.60 displaying slightly alkaline. The results of sorghum pot growth in both red and crimson acidic soil for 30 days indicated that adding the MFGDR at a dosage of 2 g kg⁻¹ in total soil weight would increase the growth rate of biomass by 24.3-149% (wet weight basis) and 47.3-157% (dry weight), the stem length and thickness increase by 5.75-22.1% and 4.76-30.9% in contrast with CK treatment for two test cuttings, respectively. The effect on sorghum growth was attributed to the increase of available nutrients, the enhancement of soil pH value and the reduction of aluminum toxicity in acidic soil due to the addition of the MFGDR. The experimental results also suggested that the MFGDR could be effectively used to ameliorate the acidic soil which is widely distributed throughout the southern China.     

Determination of trace nickel in water samples by cloud point extraction preconcentration coupled with graphite furnace atomic absorption spectrometry

A new method based on the cloud point extraction (CPE) preconcentration and graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of trace nickel in water samples. When the micelle solution temperature is higher than the cloud point of surfactant p-octylpolyethyleneglycolphenyether (Triton X-100), the complex of Ni2+ with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) could enter surfactant-rich phase and be concentrated, then determined by GFAAS. The main factors affecting the cloud point extraction were investigated in detail. An enrichment factor of 27 was obtained for the preconcentration of Ni2+ with 10 mL solution. Under the optimal conditions, the detection limit of Ni2+ is 0.12 ng mL(-1) with R.S.D. of 4.3% (n = 10, c = 100 ng mL(-1)). The proposed method was applied to determination of trace nickel in water samples with satisfactory results.     

Study on solid phase extraction and graphite furnace atomic absorption spectrometry for the determination of nickel, silver, cobalt, copper, cadmium and lead with MCI GEL CHP 20Y as sorbent

A solid phase extraction and graphite furnace atomic absorption spectrometry (GFAAS) for the determination of nickel, silver, cobalt, copper, cadmium and lead with MCI GEL CHP 20Y as sorbent was studied. Trace amounts of chromium, nickel, silver, cobalt, copper, cadmium and lead were reacted with 2-(2-quinolinil-azo)-4-methyl-1,3-dihydroxidobenzene (QAMDHB) followed by adsorption onto MCI GEL CHP 20Y solid phase extraction column, and 1.0molL(-1) HNO(3) was used as eluent. The metal ions in 300mL solution can be concentrated to 1.0mL, representing an enrichment factor of 300 was achieved. The recoveries of analytes at pH 8.0 with 1.0g of resin were greater than 95% without interference from alkaline, earth alkaline and some metal ions. When detected with graphite furnace atomic absorption spectrometry, the detection limits in the original samples were 1.4ngL(-1) for Cr(III), 1.0ngL(-1) for Ni(II), 0.85ngL(-1) for Ag(I), 1.2ngL(-1) for Co(II), 1.0ngL(-1) for Cu(II), 1.2ngL(-1) for Cd(II) and 1.3ngL(-1) for Pb(II). The validation of the procedure was performed by the analysis of the certified standard reference materials, and the presented procedure was applied to the determination of analytes in biological, water and soil samples with good results (recoveries range from 89 to 104%, and R.S.D.% lower than 3.2%. The results agreed with the standard value or reference method).