Capillary electrochromatography-applicability to the analysis of pesticides and compounds of environmental concern and the theory of electroosmosis

Summary The applicability of capillary electrochromatography to the automated analysis of pesticides and phthalate esters that are of environmental concern was assessed. Reversed phase packing materials were compared. Column to column and run to run reproducibility was established. Peak height with an internal standard gave the best reproducibility. Faster analysis than alternative HPLC methods was demonstrated for a mixture of the insecticide pirimicarb and related pyrimidines. The relationship between the concentration of an analyte in a sample and at the detector was determined by the use of radio-labelled¹⁴C-pirimicarb. The volume fraction of the liquid zone was 0.64. The possibility of electroosmosis through the pores is discussed with reference to the Rice-Whitehead model for electroosmotic flow in a capillary. A new parameter, the effective pore size is used in equations for electroosmosis through porous packings.     

Permeation liquid membrane for trace metal speciation in natural waters. Transport of liposoluble Cu(II) complexes

In this paper, the transport of Cu(II) in the presence of lipophilic Cu(II) organic complexes through permeation liquid membranes (PLMs) have been investigated. In natural waters, small organic compounds, which form liposoluble neutral complexes with Cu(II), are potentially toxic and bioavailable. Hence, to understand the role of liposoluble Cu(II) complexes in natural waters, four organic ligands: phthalic acid, bipyridyl, pyrocatechol and hydroxyquinoline, which form uncharged or lipophilic Cu(II) complexes, were tested. The results showed that the transport of lipophilic Cu(II) complexes through PLM depends on the lipophilicity of the complex. Applications of PLMs in natural waters are presented.     

Synthesis and Structure of Environmentally Relevant Perfluorinated Sulfonamides

Alkylated perfluorooctanesulfonamides are compounds of environmental concern. To make these compounds available for environmental and toxicological studies, a series of N-alkylated perfluorooctanesulfonamides and structurally related compounds were synthesized by reaction of the corresponding perfluoroalkanesulfonyl fluoride with a suitable primary or secondary amine. Perfluoroalkanesulfonamidoethanols were obtained from the N-alkyl perfluoroalkanesulfonamides either by direct alkylation with bromoethanol or alkylation with acetic acid 2-bromo-ethyl ester followed by hydrolysis of the acetate. N-Alkyl perfluorooctanesulfonamidoacetates were synthesized in an analogous way by alkylation of N-alkyl perfluoroalkanesulfonamides with a bromo acetic acid ester, followed by basic ester hydrolysis. Alternatively, N-alkyl perfluoroalkanesulfonamides can be alkylated with an appropriate alcohol using the Mitsunobu reaction. Perfluorooctanesulfonamide was synthesized from the perfluorooctanesulfonyl fluoride via the azide by reduction with Zn/HCl. All perfluorooctanesulfonamides contained linear as well as branched C₈F₁₇ isomers, typically in a 10:1 to 30:1 ratio. The crystal structures of N-ethyl and N,N-diethyl perfluorooctanesulfonamide show that the S-N bond has considerable double bond character. This double bond character results in a significant rotational barrier around the S-N bond (ΔG^≠ = 62-71 kJ mol⁻¹) and a preferred solid state and solution conformation in which the N-alkyl groups are oriented opposite to the perfluorooctyl group to minimize steric crowding around the S-N bond.     

Passive sampling and/or extraction techniques in environmental analysis: a review

The current state-of-the-art of passive sampling and/or extraction methods for long-term monitoring of pollutants in different environmental compartments is discussed in this review. Passive dosimeters that have been successfully used to monitor organic and inorganic contaminants in air, water, sediments, and soil are presented. The application of new approaches to the determination of pollutants at the sampling stage is discussed. The main milestones in the development of passive techniques for sampling and/or extraction of analytes, and in biomonitors used in environmental analysis, are summarized in this review. Passive samplers and biomonitors are compared.     

Multi-Residue Analysis of Some Polar Pesticides in Water Samples with SPE and LC–MS–MS

In the present study a multi-residue analytical method was developed for monitoring some polar pesticides such as acephate, methamidophos, carbofuran, isoproturon, dimethoate in water with SPE (solid-phase extraction) and LC–MS–MS. Acetochlor was taken as surrogate, and alachlor as internal standard. SPE with different types of columns was compared with LLE (liquid-liquid extraction). Further, the breakthrough volume for different pesticides was determined. The results showed that the selected pesticides can be determined very sensitively with LC–MS–MS. The minimum detectable quantity (MDQ) for each pesticide was about 1.0 ng. To date, SPE cartridge studies showed that the Oasis HLB cartridges were suitable for further studies. However, for Oasis HLB cartridge, different pesticide showed different breakthrough volume. The results showed that for acephate and methamidophos, the breakthrough volume was about 30 mL of water sample, much less than the breakthrough volume of other pesticides studied. Because of the higher vapor pressure and higher Henry's constant of methamidophos, dimethoate and carbofuran, much attention should be paid on their losses in the evaporation step of the experiment. This analytical method can be applied to determine pesticide contamination in environmental water samples. Revised: 12 September 2005 and 21 October 2005     

Regulation of plastic from a circular economy perspective

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Electroanalytical sensors for nonconducting media based on electrodes supported on perfluorinated ion-exchange membranes

Electroanalytical sensors, suitable for the analysis and monitoring of electroactive analytes present in gaseous phase or low-conductive liquid media, and based on electrodes in close contact with perfluorinated ion-exchange polymers are reviewed. The basic operative mechanism of these sensors, in which ion-exchange polymers act as solid polymer electrolytes (SPE's), is thoroughly discussed, while stressing the fundamental reasons why their behavior differs from that of conventional membrane electrodes. The procedures for preparing composite working electrodes by coating one side of ion-exchange membranes with stable porous films of conductive materials are described, along with the most common strategies followed to assemble this type of sensors. Useful examples of measurements in electrolyte-free media of inorganic and organic electroactive species of interest mainly for environmental analysis are given. Future prospects for the development of these sensors are also discussed.     

酚类环境雌激素的色谱分析方法

综述了近年来酚类环境雌激素的色谱分析研究进展,包括气相色谱和气质联用,高效液相色谱和各种检测器联用技术。比较了使用气相色谱和液相色谱两种方法的优缺点,并对环境雌激素样品预处理作了介绍。     

Preconcentration of lead,cadmium, copper and zinc in water at the pg g−1 level by non-boiling evaporation

An evaluation of the non-boiling evaporation technique for the preconcentration of Pb, Cd, Cu, Zn at the pg g^?1 level in water samples is presented. Various improvements were made to allow efficient control of contamination problems at these extremely low concentrations. They include the choice of FEP Teflon for the evaporation containers and the use of sophisticated cleaning, ageing and pre-conditionning procedures. Detailed calibration graphs were obtained down to the sub-pg g^?1 level by processing ultra-low concentration standards. This technique was then applied to the determination of these four metals in snow samples collected in Greenland and Antarctica.     

Screen-printed electrochemical hybridization biosensor for the detection of DNA sequences from the Escherichia coli pathogen

An electrochemical biosensor for the specific detection of short DNA sequences from the E. coli pathogen is described. This hybridization device relies on the immobilization of a 25-mer oligonucleotide probe, from the E. coli lacZ gene, onto a screen-printed carbon electrode. Chronopotentiometric detection of the Co(bpy)₃⁺³ indicator is used for monitoring the hybridization event. Numerous variables of the assay protocol, including those of the probe immobilization step, the hybridization event, and the indicator association/detection, are characterized and optimized. Hybridization times of 2- and 30-min are sufficient for detecting 300- and 50 ng/mL, respectively, of the E. coli DNA target. Applicability to analysis of untreated environmental water samples is illustrated. Such single-use electrochemical sensors hold great promise for decentralized environmental and food testing for the E. coli pathogen.