Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The size of the literature on As is therefore formidable. The heart of this review consists of two tables: one is a compilation of principal official documents and major review articles, including the toxicology and chemistry of As. This includes comprehensive official compendia on As speciation, sample treatment, recommended procedures for the determination of As in specific sample matrices with specific analytical instrument(s), procedures for multi-element (including As) speciation and analysis, and prior comprehensive reviews on arsenic analysis. The second table focuses on the recent literature (2005–2013, the coverage for 2013 is incomplete) on As measurement in aqueous matrices. Recent As speciation and analysis methods based on spectrometric and electrochemical methods, inductively coupled plasma-mass spectrometry, neutron activation analysis and biosensors are summarized. We have deliberately excluded atomic optical spectrometric techniques (atomic absorption, atomic fluorescence, inductively coupled plasma-optical emission spectrometry) not because they are not important (in fact the majority of arsenic determinations are possibly carried out by one of these techniques) but because these methods are sufficiently mature and little meaningful innovation has been made beyond what is in the officially prescribed compendia (which are included) and recent reviews are available.     

Alternative measures of environmental technology structure in DEA: An application

The nonparametric data envelopment analysis (DEA) literature on environmental efficiency (EE) considers handling undesirable outputs in two alternative ways: either in their original forms with the assumption that these are weakly disposable or in various translated forms with the assumption that these are strongly disposable. Choosing a particular approach implies adoption of a particular, distinct treatment of undesirable outputs, and hence yields a distinct set of EE estimates. To explore the effects of the interplay between choice of EE measure and specific treatment of undesirable outputs, this paper attempts to generate all possible output-oriented EE measures based on these two alternative approaches. Furthermore, guided by the argument that slacks are important in identifying properly the efficiency behavior of firms, it proposes two new alternative, slacks-based formulations of EE: one based on the range directional model, and the other on the generalized proportional distance function model. Using a confected data set of ten firms and a real-life data set of 22 OECD countries, our empirical analysis reveals that: first, EE scores are influenced not only by the choice of disposability assumption for undesirable outputs but also by the way these are treated in various translated forms; second, the choice of any particular treatment of undesirable outputs plays no role in influencing the rankings of firms; and third, our two new alternative EE formulations are, at the least, viable alternatives to existing EE measures in ranking firms according to their eco-efficiency behavior.     

Supercritical fluid extraction of microbial phospholipid fatty acids from activated sludge

Supercritical carbon dioxide (scCO₂) extraction was applied for the determination of microbial phospholipid fatty acids (PLFA) in activated sludge. Quantification was performed by using gas chromatography–mass spectrometry (GC–MS). The highest extraction yields of PLFA, at a concentration of 7.28 nmol/mg-dry activated sludge, was obtained at a temperature of 80 °C, pressure of 25 MPa and 10% (v/v) methanol for a 15-min extraction time. ScCO₂ extraction results obtained in these conditions were comparable with those obtained by liquid organic solvent extraction (LSE) based on diversity and equalibility indices. The repeatability test showed that the relative standard deviation values were less than 13%. The experimental results show that the scCO₂ extraction saves time and uses much less organic solvent. In addition, scCO₂ extraction is a promising and alternative method for the analysis of microbial community structure in environmental assessment using the PLFA profile.     

Reference materials in environmental trace organic analysis

 The paper reviews the application of reference materials (RMs) in environmental analysis of trace organic pollutants. The problems related to RM preparation, stability, use, etc. are critically discussed. Importance of analytical quality assurance and the role RMs play in the process are emphasised. Received: 18 May 1999 · Accepted: 27 December 1999     

Sequential Automated Focused Microwave-Assisted Soxhlet Extraction of Compounds with Different Polarity from Marine Sediments Prior to Gas Chromatography Mass Spectrometry Detection

An extraction method based on the use of a focused microwave-assisted Soxhlet extractor with subsequent gas chromatography separation and mass spectrometry detection is proposed for the analysis of environmental pollutants from marine sediments collected at the outflow of an urban wastewater treatment plant to the sea. For the extraction of compounds with different polarity, sequential extraction with dichloromethane and water was performed on each sample. The experimental variables were optimized by the experimental design methodology for both the organic and aqueous extractant. The total time required for quantitative extraction of triclosan, bisphenol A, estrone, estradiol, oxyfluorofen and permethrin was 75 min, a short time as compared with the 24 h Soxhlet extraction (diethylstilbestrol, 4-octylphenol, procymidone and 2,7/2,8-dichlorodibenzo-p-dioxin isomer pair).Revised: 10 March and 18 April 2005     

Thermal relaxation in excited electronic states of d and d metal complexes

Photophysical kinetic results have played an important role in assessing excited state relaxation pathways in transition metal complexes. The applicability of a kinetic analysis is critically dependent on the quality of the individual decay rates, the temperature range examined, and the model used to extract the activation parameters. The extensive literature describing the temperature dependence of excited state depopulation in d³ and d⁶ complexes permits an evaluation of both the power and limitations of kinetic arguments in assessing the mechanism of excited state relaxation.     

荧光法直接测定环境水中痕量苯酚

研究了荧光分光光度通过控制酸度直接测定环境水中苯酚的新方法。在pH＝1时，直接测定苯酚的含量，波长为λex／λem＝270／297nm，检出限为4．0g/mL，线性范围为0－3．2μg/mL。回收率为99％－101％。     

Solubilization of active molecules in microemulsions for improved environmental protection

Various industries including food and pharmaceuticals are sharing increasing interest in microemulsions. Also, one can demonstrate that solubilization of active materials within the core or interface of microemulsions may have environmental benefits.

In this work, we report three examples of new microemulsion formulations specially designed to be capable of solubilizing active materials and protecting the environment from the emission of hazardous matter or protecting sensitive molecules from the detrimental effects of the environment.

In the first example, fire-resistant ingredients were incorporated in hydraulic fluids based on water-in-oil (W/O) microemulsions and their typical characteristics were described. In the second example, five-component oil-in-water (O/W) microemulsions were designed to solubilize lycopene and protect it from exposure to light. In the third example, a friendly solvent (butyl lactate) was microemulsified to form nanosized liquid droplets capable of solubilizing bromine-based bactericide formulations of sophisticated wood preservatives.

The new vehicles exhibit a very significant solubilization capacity and can be applied in aqueous media. In the last example, the active matter may be triggered when demanded and the release will be followed by film formation.     

A new certified reference material for the quality control of palladium, platinum and rhodium in road dust, BCR-723

Certified Reference Materials (CRMs) represent a key tool for the quality control of chemical analyses. The demand for environmental materials is constantly increasing in complex analytical fields, and the European Commission (EC) (through the Measurements & Testing Generic Activity) is responding to the urgent needs for materials requiring collaborative efforts at the international level. This paper describes the preparation of a new road-dust material (BCR-723), along with homogeneity and stability studies and the analytical work performed for the certification of the contents of palladium, platinum and rhodium, under the EC's PACEPAC project, PACEPAC being the acronym for “Production And CErtification of a road dust reference material for Platinum, palladium and rhodium used in Automotive Catalytic converters”.     

The Chlorofluorocarbon/Ozone Theory—A Scientific Status Report

In 1974 Professors Rowland and Molina of the University of California at Irvine developed a theory concerning the possible adverse impact of chlorofluorocarbons on the earth's ozone shield. These compounds are the working fluids responsible for the safety and efficiency of almost all air-conditioning and refrigeration equipment and are used as propellants in many types of aerosol products.—The present article is divided into five sections. The first is an historical perspective of the scientific situation up to the end of 1974. The second section examines the various findings and observations on which the theory is founded and outlines new knowledge gained in this sector since early 1975. The third section is devoted to the possible consequences of ozone depletion while the fourth and fifth sections consider the question of the risk taken in delaying a decision to stop production of certain halocarbons.