Analytical chemistry in Belgium: an historical overview

The people, places and political influences of importance in the history of chemistry in Belgium have been reviewed with particular reference to analytical chemistry. Correspondence: D. Thorburn Burns, The Science Library, The Queen’s University of Belfast, Belfast, BT9 5AG Northern Ireland, UK     

前言

The 6th International Conference on Environmental Catalysis(6th ICEC)was held in Beijing from September 12 to September 15,2010.The ICEC is a series of con- ferences that was initiated in Pisa(1995)and followed up in Miami Beach(1998),Tokyo(2001),Heidelberg(2005) and Belfast     

Green Solvents for Catalysis

Vom 13. bis 16. Oktober vergangenen Jahres fand in Bruchsal das von der Dechema organisierte Symposium „Green Solvents for Catalysis ‐ Environmentally Benign Reaction Media”︁ statt. Die wissenschaftliche Koordination lag in den Händen von Walter Leitner (RWTH Aachen und MPl für Kohlenforschung, Mülheim/Ruhr), Kenneth R. Seddon (Queen's University, Belfast) und Peter Wasserscheid (RWTH Aachen). Zehn Hauptvorträge, 19 Kurzvorträge und 71 Poster bildeten ein anregendes Forum für den wissenschaftlichen Austausch zwischen 220 Wissenschaftlern aus 24 Nationen.     

Development of a green chromatographic method for determination of colorants in food samples

A green chromatographic analytical method for determination of Tartrazine, Brilliant Blue and Sunset Yellow in food samples is proposed. The method is based on the modification of a C18 column with a 0.25% (v/v) Triton X-100 aqueous solution at pH 7 and in the usage of the same surfactant solution as mobile phase without the presence of any organic solvent modifier. After the separation process on the chromatographic column, the colorants are detected at 430, 630 and 480 nm, respectively. The chromatographic procedure yielded precise results and is able to run one sample in only 8 min, consuming 15.0 mg of Triton X-100 and 38.8 mg of phosphate. When the flow rate of the mobile phase is 1 ml min⁻¹ the retention times are 2.1, 3.6 and 7.0 min for Tartrazine, Brilliant Blue and Sunset Yellow, respectively; and all peak resolutions are ca. 2. The analytical curves present the following linear equations: area = 7.44 10⁵ + 2.71 10⁵ [Tartrazine] (R = 0.998, n = 7); area = 1.09 10⁵ + 3.75 10⁵ [Brilliant] (R = 0.9995, n = 7) and area = −7.34 10⁴ + 2.33 10⁵ [Sunset] (R = 0.998), n = 7) and, the limits of detection for Tartrazine, Brilliant Blue and Sunset Yellow were estimated as 0.125, 0.080 and 0.143 mg l⁻¹. When the proposed method is applied to food samples analysis, precise results are obtained (R.S.D. < 5%, n = 3) and in agreement with those obtained by using the classical spectrophotometric method. The traditional usage of organic solvent as mobile phase in HPLC is not used here, which permits to classify the present method as green.     

Distinguished People and Places Important in the History of Portuguese Analytical Chemistry

The people and places of importance in the history of chemistry in Portugal have been reviewed with particular reference to analytical chemistry.     

HPLC and NMR quantification of bioactive compounds in flowers and leaves of Brassica rapa: the influence of aging

Abstract

Several members of the Brassicaeae family are known to possess beneficial properties which positively impact human diet, thanks to the presence of antioxidants, bioactive polyphenols and amino acids. B. rapa, one of the most widespread and economically relevant species, represents an outstanding example. The aim of this study is to investigate, at the molecular level, the effect of plant aging on the concentration of some biologically relevant compounds in different parts of the plant. Using HPLC and NMR techniques, the quantification of polyphenolic species (caffeic acid, quercetin and rutin), succinic acid and alanine was performed in flowers and leaves of young and mature B. rapa plants.     

Unique green chromatography method for the determination of serotonin receptor antagonist (Ondansetron hydrochloride) related substances in a liquid formulation,robustness by quality by design-based design of experiments approach

Serotonin receptor antagonist drug Ondansetron hydrochloride injectable formulation containing all related substances was identified and quantified by a single, simple, sensitive, eco-friendly, and green high-performance liquid chromatography method. The disseverment of all impurities was achieved with the Discovery Cyano (250 × 4.6) mm, 5 μm column. The gradient program was composed of pH 5.7 phosphate buffer as mobile phase A and acetonitrile as mobile phase B. The flow rate, column compartment temperature, and detection wavelengths were 0.9 mL/min, 30°C, and 216 nm, respectively. The method was validated as per current regulatory guidelines. The obtained %relative standard deviation for the precision results was between 0.55 and 2.72% for all impurities. The correlation coefficient values from the linearity experiment for impurities and analyte were more than 0.995. The accuracy results were obtained between 88.4 and 113.0% for all impurities. Both sample and standard solutions showed 24 h stability at benchtop and refrigerator conditions. All impurities and analytes met the specificity and mass balance for all forced degradation conditions. Quality-by-design-based design of experiments was utilized to establish the method's robustness. Method greenness was assessed by using the current advanced tool green analytical procedure index, National Environmental Methods Index, and analytical eco-scale.     

Development of a single-run liquid chromatography-mass spectrometry analysis for the detection of 11 multiclass contaminants of emerging concern using a direct filtration method

In toxicological analysis, the analytical validation method is important to assess the exact risk of contaminants of emerging concern in the environment. Syringe filters are mainly used to remove impurities from sample solutions. However, the loss of analyte to the syringe filter could be considerable, causing an underestimate of the analyte concentrations. The current study develops and validates simultaneous liquid chromatography-mass spectrometry analysis using a direct filtration method to detect four groups of contaminants of emerging concern. The adsorption of the analyte onto three different matrices and six types of syringe filters is reported. The lowest adsorption of analytes was observed in methanol (16.72%), followed by deionized water (48.19%) and filtered surface lake water (48.94%). Irrespective of the type of the matrices, the lowest average adsorption by the syringe filter was observed in the 0.45 μm polypropylene membrane (15.15%), followed by the 0.20 μm polypropylene membrane (16.10%), the 0.20 μm regenerated cellulose (16.15%), the 0.20 μm polytetrafluoroethylene membrane (47.38%), the 0.45 μm nylon membrane (64.87%) and the 0.20 μm nylon membrane (71.30%). In conclusion, the recommended syringe filter membranes for contaminants of emerging concern analysis are polypropylene membranes and regenerated cellulose, regardless of the matrix used.     

Thermoanalytical investigations of the decomposition course of copper oxysalts

The thermal decomposition course of copper acetate monohydrate (CuAc) was examined on heating up to 600°C at various rates, by TG, DTA and DSC. Non-isothermal kinetic and thermodynamic parameters were determined in air or nitrogen. SEM was used to describe the decomposition course and the solid products were identified by IR and XRD analysis. The results indicated that CuAc was dehydrated at 190°C and then partially decomposed at 220°C, giving rise to CuO in addition to a minor portion of Cu₂O and Cu₄O₃. The last two oxides seemed to facilitate the decomposition of the rest of the anhydrous acetate. Cu₂O and Cu₄O₃ were oxidized in air at >400°C, in a process that did not occur in nitrogen.It is a pleasure to thank the Queen's University of Belfast, particularly the staff of the Electron Microscope Unit for assistance in obtaining the electron micrographs. Thanks are also due to the Egyptian Government for the granted fellowship.     

Analysis of trace elements and their physico-chemical forms in natural waters

Trace elements in natural waters can be present in different physico-chemical forms, varying in size, charge and density properties. Knowledge of speciation is essential for understanding the transport, distribution, and biological uptake of trace elements in the environment. The development of techniques to provide reliable information on physico-chemical forms has, therefore, become a challenge within Analytical Chemistry.When selecting analytical methods for the determination of total concentrations or fractions of trace elements in natural waters, no exclusion of species should occur, or at least it must be accounted for. Furthermore, the determination limits must be sufficiently low to allow the actual concentrations to be determined with reasonable precision and accuracy. For very low concentrations, preconcentration techniques are applicable, provided the chemical yield of the spike represents that of the original species present. For methods meeting these criteria, the suitability for routine analysis should be considered.When the physico-chemical forms of trace elements are to be determined, the fractionation should take placein situ or shortly after sampling. As the concentrations involved in speciation studies may be extremely low, there is an increasing awareness of potential sources of errors influencing analytical results. Sample collection and separation/fractionation/concentration procedures prior to analysis are, therefore, essential within Analytical Chemistry, and the whole procedure must be taken into account when interpreting the results. There are, however, several requirements which should be met by techniques applicable for speciation purposes. In general, size fractionation techniques (e.g.in situ hollow fibre ultrafiltration) should be applied prior to the addition of any chemical reagents (charge fractionation techniques).     

Interlaboratory exercises to compare analytical method performances

Three intercomparison exercises on simulated rainwater were held in the period 1991–93 involving 72 to 99 laboratories in Europe and South America. The exercises required the analysis of pH, conductivity, main anions (Cl^–, NO ₃ ^– and SO ₄ ^2– ) and main cations (Ca²⁺, K⁺, Mg²⁺, Na⁺ and NH ₄ ⁺ ). The concentrations of the single ions ranged between 5 and 150 moll^–1. Results were used to evaluate and compare the precision of the analytical methods. A general improvement in precision was observed in the course of the exercises.     

Is good laboratory practice necessarily good analytical practice? Is GLP necessarily GAP?

According to the chemical legislation in force in most of the industrialized nations to protect man and the environment from the harmful effects of hazardous substances and preparations, a product must be subjected to a large number of mandatory tests before it may be marketed, to demonstrate that it shows no adverse effects on man or the environment when properly handled. To ensure that the results of tests are comparable and above all verifiable, the OECD has drawn up a set of guidelines for Good Laboratory Practice, GLP, on the request of the FDA and EPA authorities in the USA. The application of these guidelines is now mandatory for all the tests specified by the chemical legislation, also for analytical methods. These methods not only apply to the stipulated determination of physical and chemical parameters they also apply to toxicological and ecotoxicological tests. Comprehensive documentation of all stages of these tests from preparatory work to reporting is designed to make the results verifiable. Agreement with the principles of GLP means that the procedures used in a test have been documented in such a manner as to be verifiable. However, does compliance with GLP necessarily guarantee accurate analytical values and thus correct test results? Is GLP necessarily also Good Analytical Practice, GAP? In the following the authors try to provide the answer.     

Tetravalent Pseudomonas aeruginosa Adhesion Lectin LecA Inhibitor for Enhanced Biofilm Inhibition

A potent divalent ligand of the Pseudomonas aeruginosa adhesion lectin LecA was elaborated into a tetravalent version. A polyethylene glycol (PEG) spacer was introduced to link two divalent galactosides. Each of the two divalent ligands contained a rigid spacer with a central phenyl group that is bridged by the PEG moiety. The resulting tetravalent ligand was found to bind LecA in the nanomolar range involving all of its sugar (sub)ligands. Analytical ultracentrifugation studies clearly showed that the tetravalent ligand was capable of aggregation the LecA tetramers in contrast to the divalent ligands. The aggregator behavior was found to be of importance in P. aeruginosa biofilm formation inhibition. Despite the weaker affinity it was a considerably better biofilm inhibitor with half inhibitory values around the 28 micromolar range.     

Multicriteria Decision Analysis and Grouping of Analytical Procedures for Phthalates Determination in Disposable Baby Diapers

This study presents the application of one of the tools from the multicriteria decision analysis set (MCDA), the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). Selected green analytical chemistry metrics were used to rank analytical procedures for the phthalate determination in disposable baby diapers. Nine analytical procedures were assessed in order to find one that has the lowest environmental impact and the best analytical figures of merit. Nine different criteria, where weighting was based on the experts’ evaluation, were used in the procedures’ assessment. With the use of TOPSIS, an easy and straightforward technique, selection of the most appropriate procedure was made.     

Determination of Melamine in Dairy Products and Melamine Tableware by Inhibition Electrochemiluminescent Method

An electrochemiluminescent (ECL) method has been developed for the determination of melamine based on the inhibition of luminol ECL. A significant luminol ECL can be found at 1.47 V in the phosphate buffer solution at high pHs and low potential scan rates, this ECL signal can be inhibited obviously by melamine. The decrease of ECL intensity was linearly proportional to the logarithm of melamine concentration in the range of 1–100 ng/mL (R²=0.9911) and with the detection limit of 0.1 ng/mL. The method has been applied successfully to determine melamine in dairy products and melamine tableware, the recoveries were in the range of 98.5%–103.7% and 95.5%–106.0%, respectively. The mechanism of the inhibition effect was also proposed, the active oxygen (O₂^{· −}) generated from the electrooxidation of OH⁻ reacted with luminol anion (L^{· −}) to generate light emission, and the present of melamine can eliminate the active oxygen, which cause the decrease of the ECL intensity.     

The U.S. Department of Energy (DOE) Sampling and Analytical Chemistry Guide: Doe Methods for Evaluating Environmental and Waste Management Samples

Abstract

DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) is a guidance/methods document to support sampling and analysis activities at DOE sites. DOE Methods is intended to supplement existing guidance documents (e.g., EPA's Test Methods for Evaluating Solid Waste, SW-846), which generally apply to low-level or nonradioactive samples. DOE Methods targets the complexities of DOE radioactive mixed waste and environmental samples. The document contains quality assurance (QA), quality control (QC), safety, sampling, organic analysis, inorganic analysis, and radioanalytical guidance as well as sampling and analytical methods. An addendum is distributed every six months (April and October) with updated guidance and additional methods.

DOE Methods provides a vehicle for technology transfer within the environmental restoration (ER) and waste management (WM) (collectively known as EM) community. As DOE Methods evolves, its usefulness and applicability are anticipated to grow to meet the demands of the DOE/EM mission. At the present time, DOE Methods contains methods and guidance information supplied by DOE sites. Because the EM activities in DOE are not unique to the United States, the international environmental community could benefit from the information gathered for the DOE program. This information could provide additional resources for their EM activities.     

Determination of chlorpyrifos and acephate in tropical soils and application in dissipation studies

A rapid and accurate method for the extraction and determination of the two organophosphorus insecticides, chlorpyrifos and acephate in top- and subsoil materials of three tropical clayey soils from Sarawak has been developed. Soil samples were extracted with ethyl acetate and the pesticides were determined by GC-FPD. High recoveries of 76–102% and 76–100% were obtained for acephate and chlorpyrifos respectively, at fortification levels of 0.01, 0.1 and 1 mg kg^?1 with standard deviations below 9.0%. The addition of water prior to the extraction was important for obtaining high and reproducible recoveries. The method did not require clean-up of the extracts prior to GC analysis and could be detected down to 0.01 mg kg^?1. A field study was conducted using the modified method to measure the degradation kinetics and migration of acephate and chlorpyrifos in one of the soils over a period of 84 days. The degradation of acephate and chlorpyrifos were rapid with half-lives of 3.3 and 8.7 days, respectively. Both pesticides were detected in subsoils 2 h after application at the deepest (50 cm) soil layers examined and at concentrations up to 5.42 mg kg^?1. Subsoil concentrations of acephate were higher than for chlorpyrifos, and subsoil concentrations of acephate peaked after it had started to degrade in the top soil. The subsoil concentrations of the pesticides were attributed to transport with soil particles (chlorpyrifos) and via solution (acephate) through pores and cracks present in the soil profiles. The study demonstrates the high mobility of even strongly retained and fast degrading pesticides under tropical humid conditions.     

Green procedure using limonene in the Dean-Stark apparatus for moisture determination in food products

In the past 10 years, trends in analytical chemistry have turned toward the green chemistry which endeavours to develop new techniques that reduce the influence of chemicals on the environment. The challenge of the green analytical chemistry is to develop techniques that meet the request for information output while reducing the environmental impact of the analyses. For this purpose petroleum-based solvents have to be avoided. Therefore, increasing interest was given to new green solvents such as limonene and their potential as alternative solvents in analytical chemistry. In this work limonene was used instead of toluene in the Dean-Stark procedure. Moisture determination on wide range of food matrices was performed either using toluene or limonene. Both solvents gave similar water percentages in food materials, i.e. 89.3 ± 0.5 and 89.5 ± 0.7 for carrot, 68.0 ± 0.7 and 68.6 ± 1.9 for garlic, 64.1 ± 0.5 and 64.0 ± 0.3 for minced meat with toluene and limonene, respectively. Consequently limonene could be used as a good alternative solvent in the Dean-Stark procedure.     

Analytical tools for urocanic acid determination in human samples: A review

Urocanic acid is a chromophore found in the skin that has been identified as an important immunosuppressant and carcinogenesis mediator through its photoisomerization from trans to cis form induced by ultraviolet radiation. Research on analytical methods that explore urocanic acid isomerization is indispensable to fully understand the deleterious effects mediated by this biomarker. In this context, the current relevant analytical methods for determination of these isomers in human samples are summarized in this review. The methods presented here are applicable to human samples collected by noninvasive methods (or minimally invasive), encompassing an array of analytical techniques, including high‐performance capillary electrophoresis, confocal Raman spectroscopy, gas chromatography, high‐performance liquid chromatography, and mass spectrometry, among others. Developed high‐performance liquid chromatography methods have proven to be advantageous, allowing noninvasive collections for in vivo analysis and the confocal Raman, specially, for real‐time analysis. Among all these methods, high‐performance liquid chromatography is the most investigated one with mass spectrometry or ultraviolet detector, and the mass spectrometry detector being the most studied in the last years, demonstrating high sensitivity, very low detection limits, and accurate identification, especially for clinical investigations.