Determination of chlorine containing species in explosive residues using chip-based isotachophoresis

A new method has been developed to allow the determination of the chlorate, chloride and perchlorate anions in inorganic explosive residues to be made using isotachophoresis (ITP). To enable a good separation of these species to be achieved the method involves the use of two complexing agents. Indium(III) is used to allow the determination of chloride whilst using nitrate as the leading ion and alpha-cyclodextrin is used to allow the separation of chlorate and perchlorate. Separations were carried out using a miniaturised poly(methyl methacrylate) (PMMA) separation device. The method was applied to analysing both model samples and actual inorganic explosive containing residue samples. Successful determinations of these samples were achieved with no interference from other anions typically found in inorganic explosive residues. Limits of detection (LOD) for the species of interest were calculated to be 0.80 mg l(-1) for chloride, 1.75 mg l(-1) for chlorate and 1.40 mg l(-1) for perchlorate.     

Natural radionuclides as dirt tracers in sugar cane consignments

The limit of detection (LOD) improvement in TLC determination of uranium and thorium in presence of other metal ions is presented in this paper. The mobile phase system contains iso-propyldithiophosphotic acid (i-PrDTP), as a complexing agent, in order to differentiate the studied species by modifying their retention. The paper reports the successful separation and the quantitative determination of uranium and thorium in the presence of other metal ions in the concentration range 2.5–30 μg/μl.     

Analysis of nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in water, particularly waste water

Summary Two chromatographic techniques can be considered for the detection of the complexing agents NTA, EDTA and DTPA in water: gas chromatography (GC) and liquid chromatography (HPLC). GC is capable of detecting all three compounds in concentrations of as little as 0.001 mg/l. However, this requires a complex and time-consuming sample preparation (enrichment, derivatization). HPLC represents a possible alternative for detecting EDTA and DTPA. Without enrichment it is possible to reach a detection limit of 0.1 mg/l, i.e., while this method is rather less sensitive, it provides results in a much shorter time. If the sample concentrations are high enough, this method is more suitable for conducting routine monitoring of emissions of EDTA and DTPA in waste water. Simple matrices such as surface water or drinking water can be enriched on a pre-column to reduce the detection limit.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

整体柱高效液相色谱法测定草甘膦原药中甲醛含量

建立了衍生化-高效液相色谱法对草甘膦原药中痕量甲醛含量进行测定的方法。样品中残留甲醛经超声波水浴提取，与2，4-二硝基苯肼衍生反应，生成的2，4-二硝基苯腙用反相整体柱色谱进行快速分离，在360nm紫外波长下检测，外标法定量。该分析方法在2．0～200mg/L浓度范围呈良好线性，添加回收率在88％～105％之间，相对标准偏差小于5％。样品中甲醛的最小检测浓度为0．5mg/kg。比较了整体色谱柱和常规C18反相柱分离效果，表明整体色谱柱可在1．5min内实现衍生化产物的快速分离并进行定性定量，同时发现相对于常规柱，采用整体柱提高了检测灵敏度约10倍。     

Two-dimensional nano-liquid chromatography-mass spectrometry system for applications in proteomics

Transient isotachophoresis-capillary zone electrophoresis with artificial seawater as the background electrolyte (BGE) was improved to further lower the limit of detection (LOD) for determination of nitrite and nitrate in seawater. By lowering the pH of BGE, the difference between effective mobility of nitrite and that of nitrate increased, thereby permitting increased sample volumes to be tolerated and their LOD values to decrease. Artificial seawater with pH adjusted to 3.0 using phosphate buffer was adopted as the BGE. To reverse electroosmotic flow (EOF), a capillary was flushed with 0.1 mM dilauryldimethylammonium bromide for 3 min before the capillary was filled with the BGE. Limits of detection (LODs) for nitrite and nitrate were 2.7 and 3.0 microg/l (as nitrogen), respectively. The LODs were obtained at a signal-to-noise ratio of 3. Values of the relative standard deviation (RSD) of peak area for these ions were 2.0 and 0.75%, respectively, when nitrite concentration was 0.05 mg/l and that of nitrate was 0.5 mg/l. The RSDs of peak height were 4.4 and 2.3%. The RSD values of migration time for these ions were 0.19 and 0.17%. The proposed method was applied to determination of nitrite and nitrate in a proposed certified reference material for nutrients in seawater, MOOS-1, distributed by the National Research Council of Canada. Results agreed with the assigned tolerance interval. This method was also applied to determination of these ions in seawater collected around Osaka Bay. Results nearly agreed with those obtained by a conventional spectrophotometric method.     

络合萃取-在线衍生土壤酸性除草剂条件选择与优化

以Na4EDTA为络合剂,以五氟苄基溴为衍生试剂,采用快速溶剂萃取仪萃取,同时实现土壤酸性除草剂的络合萃取在线衍生,并以气相色谱-质谱(NCI源)进行检测。对络合条件、衍生条件、萃取条件、离子源选择进行了优化。方法的回收率为75%～95%、相对标准偏差为6.7%～13%、检测限2.8～8.4μg/Kg。     

Determination of phenolic disinfectant agents in commercial formulations by liquid chromatography.

Using liquid chromatography (LC), a convenient and versatile method was developed for the assay of disinfectant products containing the commonly used phenolic agents, alone or in combination, including phenol, 2-phenylphenol, 4-t-amylphenol, 4-chloro-3,5-dimethylphenol (PCMX), 2-benzyl-4-chlorophenol, and triclosan. The procedure involves a simple dilution or dissolution of the product aliquot or portion followed by membrane filtration and LC. The method was applied to 19 different products representing 17 manufacturers and containing from one to 4 phenolic agents. Chromatography was performed using a Zorbax SB-C18 column, acetonitrile-0.05M KH2PO4 (55 + 45, v/v) pH 3.00, as mobile phase and UV detection at 280 nm. The intralaboratory precision of the product assays ranged form 0.34-5.35% (n = 5) and recoveries via fortification varied from 96.1-103.8%. The limits of quantitation (LOQ) and detection (LOD) ranged from 5.58 x 10(-5) to 2.50 x 10(-4) mg/mL and from 1.76 x 10(-5) to 0.67 x 10(-4) mg/mL, respectively, for the 6 analytes. The response for all analytes was observed to be linear for at least a 50-fold range in concentration (0.001-0.05 mg/mL). The proposed method provides an efficient means for the isolation and quantitation of these phenolic compounds.     

超高效液相色谱-串联质谱法检验腐败血中吗啡和6-单乙酰吗啡

采用改良的QuEChERS前处理方法，建立了同时检验腐败血中吗啡和6-单乙酰吗啡的超高效液相色谱-串联质谱（UPLC-MS/MS）方法。腐败血中加入乙腈-水（4：1，v/v）混合溶液、30 mg NaCl和60 mg MgSO₄盐析促进相分离，最后经25 mg N-丙基乙二胺（PSA）和25 mg MgSO₄净化。选用ZORBAX Eclipse Plus C₁₈色谱柱分离，0.01%（v/v）氨水和乙腈作为流动相进行梯度洗脱，电喷雾电离正离子（ESI⁺）模式扫描，多反应监测（MRM）模式检测。结果表明，吗啡和6-单乙酰吗啡在5~200 μg/L范围内线性关系良好，相关系数（r²）≥ 0.9957，检出限（S/N=3）均为1 μg/L，定量限（S/N=10）均为5 μg/L。3个加标水平（5、100和200 μg/L）下，吗啡和6-单乙酰吗啡的平均加标回收率分别为81.84%~103.44%和81.03%~104.46%，日内和日间精密度（RSD）均小于12%，基质效应为83.04%~107.61%。方法简便、灵敏、可靠，可实现腐败血中吗啡和6-单乙酰吗啡的快速定性定量检验。     

Trace and ultratrace analysis methods for the determination of phosphorus by flow-injection techniques

Trace (≤1 mg/l or 30 μM) and ultratrace (≤1 μg/l or 30 nM) analysis methods for phosphorus determination by flow-injection analysis are reviewed. Most of the methods cited in this review are fundamentally based on the reaction of orthophosphate with molybdate to form heteropoly acids, such as molybdenum yellow and molybdenum blue, and some of the methods are based on the formation of such secondary reactions as ion associates and their aggregates with bulky cations, such as cationic dyes and quaternary ammonium ions. The heteropoly acids themselves can be measured by spectrophotometry, and the ion associate formed with a cationic dye, Malachite Green (MG), can be measured based on the coloration of MG. Light scattering detection methods can be used for measuring the aggregates of ion associates formed with bulky cations. Highly sensitive detection of phosphorus can be accomplished by fluorophotometry; Rhodamine B (RB) and its analogues react with molybdophosphate to form ion associates, which shows fluorescence quenching of RB: LOD is about 5 nM. The detection method based on the chemiluminescence of luminal oxidized with molybdophosphoric acids is probably the most sensitive of all the detection methods reported so far: LOD of the method is as low as 1 nM. The LOD of the molybdenum blue method can be improved by using a liquid core waveguide: LOD is 0.5 nM.     

Enantioselective separation and determination of the dinotefuran enantiomers in rice,tomato and apple by HPLC

An effective chiral analytical method was developed for the resolution and determination of dinotefuran enantiomers in rice, tomato and apple samples. Dinotefuran enantiomers were baseline‐separated and determined on a novel chiral column, ChromegaChiral CCA, with n‐hexane–ethanol–methanol (85:5:10, v/v/v) as the mobile phase at a flow rate of 1.0 mL/min with UV detection at 270 nm. The resolution of dinotefuran enantiomers was about 1.8. The first eluted enantiomer was (+)‐dinotefuran and the second eluted one was (?)‐dinotefuran. The effects of mobile‐phase composition and column temperature on the enantioseparation were evaluated. The method was validated for linearity, repeatability, accuracy, LOD and LOQ. LOD was 0.15 mg/kg in rice and tomato, 0.05 mg/kg in apple, with an LOQ of 0.5 mg/kg in rice and tomato, 0.2 mg/kg in apple. The average recoveries of the pesticide from all matrices ranged from 75.8 to 92.9% for all fortification levels The precision values associated with the analytical method, expressed as RSD values, were <16.5% for the pesticide in all matrices. The methodology was successfully applied for the enantioselective analysis of dinotefuran enantiomers in real samples, indicating its efficiency in investigating the environmental stereochemistry of dinotefuran in food matrix.     

Direct determination of fourteen underivatized amino acids from Whitmania pigra by using liquid chromatography-evaporative light scattering detection

A new reversed phase high performance liquid chromatography-evaporative light scattering detection (RP-HPLC-ELSD) method has been developed for the direct determination of fourteen amino acids in Whitmania pigra, a commonly used traditional Chinese medicine (TCM). Simultaneous separation of these fourteen amino acids was achieved on a Prevail C18 column. Under the condition of gradient elution, the fourteen amino acids were separated within 25 min. The drift tube temperature of ELSD was set at 115 degrees C, and with the nitrogen flow rate of 2.5 l/min. All calibration curves showed good linear regression (r > 0.9975) within test ranges. The recoveries ranged from 94.8% to 104.4%. The limit of detection (LOD) for each compound was more than 20 mg/l at a signal to noise ratio (S/N) of 3. The validated method was successfully applied to quantify fourteen amino acids from Whitmania pigra, which provides a new basis of overall assessment on quality of Whitmania pigra.     

Rapid chloride analysis using miniaturised isotachophoresis

A new design of miniaturised separation device for performing isotachophoresis (ITP) has been produced. The device contains a simple arrangement of channels comprising a single separation channel with a 'double T' injection geometry. The device was produced in poly(methyl methacrylate) and incorporates an on-column conductivity detector. A new electrolyte system was developed to enable the rapid determination of chloride to be made. This electrolyte system uses a leading ion of 3.5 mM nitrate at pH 3.0 with 0.5 mM indium(III) added as a complexing agent. Use of this electrolyte system with the new separation device allowed chloride samples to be analysed in under 100 s, with a limit of detection (LOD) calculated to be 2.2 mg l(-1).     

高效液相色谱法测定番茄酱中辛硫磷残留

建立了高效液相色谱(HPLC)法测定番茄酱中辛硫磷残留量的方法。番茄酱样品经乙腈提取盐析,弗罗里硅土固相萃取小柱净化,样液浓缩过滤膜后用乙腈溶解定容。采用C18色谱柱,流动相为体积比4∶1的乙腈∶0.15%甲酸水溶液,检测波长285nm,外标法定量。结果表明:在0.01～1mg/kg范围内辛硫磷的线性关系良好(r=0.9999)。方法检出限为0.01mg/kg,平均回收率为86.1%～102.7%,相对标准偏差为2.0%～6.5%。该法简便、快速、灵敏、准确,各项技术指标均满足农药残留检测的要求。     

A low-cost flame atomic absorption spectrometry method for determination of trace metals in aqueous samples

A simple and fast method for the extraction into xylene of sub mug l(-1) concentrations of metals using ammonium diethyldithiophosphate (DDTP) as a complexing reagent and their subsequent determination by flame atomic absorption spectrometry is described. The method was tested in sea water spiked with Au at a concentration of 3.0 mug l(-1). The extraction was carried out until the aqueous to organic phase ratio achieved a 1000-fold preconcentration of metal. Optimisation of extraction parameters and the effect of Fe interference was investigated. Sea water samples spiked with Au produced an average recovery of 95% and the detection limit (3sigma) in deionized water was 2.9 ng l(-1). High enrichment factors could be obtained due to the small final volume (mul) of organic solvent.     

Trace humic and fulvic acid determination in natural water by cloud point extraction/preconcentration using non-ionic and cationic surfactants with FI-UV detection

A preconcentration and determination method for humic and fulvic acids at trace levels in natural water samples was developed. Cloud point extraction was successfully employed for the preconcentration of humic acid (HA) and fulvic acid (FA) prior to the determination by using a flow injection (FI) system coupled to a spectrophotometric UV-Vis detector. The quantitative extraction of HA and FA within the pH range 1-12 was obtained by neutralization of the anionic charge on the humic substances with a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB). This generated a hydrophobic species that was subsequently incorporated (solubilized) into the micelles of a non-ionic surfactant polyethylene glycol, tert-octylphenyl ether (Triton X-114). The FI method for HA and FA determination was developed by injection of 100 microl of the extracted surfactant-rich phase using an HPLC pump with spectrophotometric detection at 350 nm. A 50 ml sample solution preconcentration allowed an enrichment factor of 167. The limit of detection (LOD) obtained under the optimal conditions was 5 microg l(-1). The precision for ten replicate determinations at 0.2 mg l(-1) HA was 3.1% relative standard deviation (RSD), calculated from the peak heights. The calibration using the preconcentration system for HA and FA was linear with a correlation coefficient (r2) of 0.9997 at levels near the detection limits up to at least 1 mg l(-1). The method was successfully applied to the determination of HA and FA in natural water samples (river water).     

Chiral determination of a novel acaricide cyflumetofen enantiomers in cucumber,tomato, and apple by HPLC

A simple chiral analytical method was developed for the enantiomeric determination of cyflumetofen in cucumber, tomato, and apple by normal‐phase HPLC. The effects of mobile phase composition and column temperature on the enantioseparation were evaluated. Excellent separation was achieved at 25°C on a Chiralpak AD‐H column, with a mixture of n‐hexane and 2‐propanol (95:5, v/v) as mobile phase at a flow rate of 1.0 mL/min detecting at 234 nm. The resolution of cyflumetofen enantiomers was up to 5.5. The elution order of the enantiomers was determined by an online OR‐2090 detector, which was performed under the same chromatographic conditions. The first eluted enantiomer was (–)‐cyflumetofen and the second eluted one was (+)‐cyflumetofen. The method was validated for linearity, repeatability, accuracy, LOD, and LOQ. LOD ranged from 0.1 to 0.15 mg/kg, with the LOD varying from 0.33 to 0.5 mg/kg for each enantiomer, respectively. The average recoveries of the pesticide ranged from 71.4 to 102.0% at all fortification levels. The precision values associated with the analytical method, expressed as RSD values, were below 14.8% in all matrices. The method was then successfully applied to detect cyflumetofen enantiomers in real samples.     

柱前衍生-高效液相色谱法测定调制乳粉中左旋肉碱的含量

建立了柱前衍生-高效液相色谱(HPLC)测定乳制品中左旋肉碱含量的方法。试样经0.1 mol/L盐酸超声提取后,采用阳离子交换固相萃取柱净化,在三乙胺和氯甲酸丁酯的催化下与L-丙酰胺-β-萘胺发生取代反应,使用配有二极管阵列检测器(DAD)的高效液相色谱仪测定,外标法定量。该方法在0.250~50.0 mg/L范围内线性关系良好,线性方程为y=164.4x-11.3,相关系数为0.9998,加标回收率为84.3%~86.0%,相对标准偏差为1.93%~3.18%。该方法的检出限为10 mg/kg,定量限为25 mg/kg。运用该方法对国内20个实际乳粉样品中的左旋肉碱含量进行测定,20个样品中均检出了左旋肉碱,含量为53~163 mg/kg。该方法快速、简便、准确,适用于乳品中左旋肉碱含量的检测。     

Use of miniaturised isotachophoresis on a planar polymer chip to analyse transition metal ions in solutions from metal processing plants

An electrolyte system, using malic acid as a complexing agent, has been developed to allow the determination of transition metal cations using miniaturised isotachophoresis. The method allowed the simultaneous determination of Mn2+, Cr3+, Fe2+, Co2+, Zn2+ and Ni2+ to be made without interference from other common ions. Limits of detection were calculated to be in the range 0.5-1.0mg l(-1) for Mn2+, Cr3+ Co2+ and Zn2+ and 2.0 mg l(-1) for Fe2+ and 4.7 mg l(-1) for Ni2+. The successful analysis of five industrial samples, containing a range of these metal ions, obtained from metal processing plants were achieved in under 13 min. The separations were performed on a poly(methyl methacrylate) chip with integrated platinum wire conductivity detection electrodes.     

手性高效液相色谱法测定板蓝根中表告依春和告依春含量

采用Chiralpak IC手性柱(250 mm×4.6 mm, 5 μm),建立了正相高效液相色谱测定板蓝根中表告依春(R-告依春)和告依春(S-告依春)含量的方法。考察了流动相组成、流速和柱温对分离度的影响。经优化后的实验条件: 以正己烷-异丙醇(体积比为90:10)为流动相,流速为0.8 mL/min;检测波长为245 nm,柱温为20 ℃。在此优化条件下,表告依春和告依春分离度为3.4,检出限为2.0 mg/L,在0.02～2.0 g/L范围内有良好的线性关系,平均回收率为101%,相对标准偏差(RSD)小于3.0%(n=6)。本方法可将具有抗病毒活性的表告依春与其对映体告依春基线分离并测定,专属性强,能有效控制板蓝根的质量。     

Development of an ion-pair reversed-phase HPLC method with indirect UV detection for determination of phosphates and phosphites as impurities in sodium risedronate

A method based on RP-HPLC with indirect UV detection was developed for the determination of phosphates and phosphites as impurities in sodium risedronate. RP separation of the phosphates and phosphites was achieved by adding tetrabutylammonium hydroxide as an ion-pairing agent in the mobile phase. Potassium hydrogen phthalate was added to the mobile phase as an ionic chromophore in order to obtain high background absorption of the mobile phase. Separation was performed on a C18 column using a mixture of pH 8.2 buffer (containing 0.5 mM tetrabutylammonium hydroxide and 1 mM phthalate) and acetonitrile (95 + 5, v/v) as the mobile phase, with indirect UV detection at 248 nm. The validation of the method included determination of specificity/selectivity, linearity, LOD, LOQ, accuracy, precision, and robustness. The LOD was 0.86 microg/mL for phosphates and 0.76 microg/mL for phosphites. The LOQ was 2.60 microg/mL for phosphates and 2.29 microg/mL for phosphites. The developed method is suitable for quantitative determination of phosphates and phosphites as impurities in QC of sodium risedronate.