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Analytical and Bioanalytical Chemistry (v.368, #6)
Analytical chemistry and the law: Progress for half a millennium by D. Thorburn Burns (pp. 544-547).
Chemistry has been used for the detection of adulteration since the earliest times of recorded history going back at least 31/2 millennia. Since the invention of printing the subject is easier to follow. Aspects of law and its application via chemistry in regard to precious metals, food, drink and medicinal materials are reviewed over the last half millennium with particular reference to the U.K.
The position of the analyst as expert: Yesterday and today by W. Fresenius (pp. 548-549).
The interrelation between law and analytical chemistry 150 years ago is outlined, showing that similar problems to today already existed at that time. Examples of present-day cases of judicial investigations are given and consequences for the duty of the analytical chemist are discussed.
Historical development of expertise in forensic chemical analysis by W. Vycudilik (pp. 550-552).
The history of forensic chemical analysis shows a development from the mere quotation of a concentration value to an expert opinion which helps to explain manifold circumstances of the case under consideration. The development of forensic expertises on chemical problems connected to forensic medicine reveals two essential stages: 1. A period, when sensual perceptions were the only means of investigation and 2. a period, when developments in chromatographic separation and spectrometric identification have permitted objectified results.
Proving beyond all reasonable doubt – Analytical aspects by M. C. Walsh (pp. 553-556).
An overview is presented of the problems and challenges facing the analyst who is asked to provide data to support the law. Factors that the analyst should consider include: the legal reasons for performing the analysis; situations where analytical data should and should not be used in support of litigation; the scientific basis for the legislation; and the sample source and method of sampling.
Fact finding beyond all reasonable doubt – Legal aspects by W. H. Rechberger (pp. 557-560).
A description is provided of the European (esp. German and Austrian) legal concept of “fact finding beyond all reasonable doubt”. The uncontested principle of the free evaluation of evidence is closely connected with the dispute about the “probative standard” (= this means the degree of the judge’s conviction which is necessary for the fact finding). There can neither be a purely subjective nor a purely objective theory of the probative standard. Because of the human limits of possible perception and of the subjective cognitive faculties the total conviction of truth as demanded by the “conviction-of-truth-theory” could never mean absolute certainty. It is sufficient if “no other reasonable man with a clear view of the conditions of life would be convinced”. On the other hand, the objective theory, which sees the judge’s task only in consideration of probabilities, becomes more and more important. As a third principle, there is the preponderance principle influenced by the Anglo-American system.
Aggravation of licensing procedures by doubtful thermodynamic data by G. Meinrath; S. Hurst; R. Gatzweiler (pp. 561-566).
Environmental prognosis by geochemical modelling is a scientific approach to several open questions of general public interest. Two prominent fields where geochemical modelling holds an important share are the remediation of contaminated former uranium mining areas and safety assessment of radioactive waste repositories in the geosphere. In both fields, application of geochemical modelling is stipulated by public authorities. The enormous complexity of models that can be handled by computers rises the awareness on the meaningfulness of a modelling result and demands for provision of an estimate of the dependability of a calculation output by the computers. It is obvious that bias, over- and underestimation of uncertainty in input data reduces the relevance of the calculation output. Chemistry contributes important data to geochemical modelling, both from field analysis and in the fundamental physico-chemical quantities enclosed into the thermodynamic data base. Some examples will be given where progress in quality assessment of chemical data may further the predictive power of geochemical modelling.
“Demonstration” vs. “designation” of measurement competence: the need to link accreditation to metrology by P. De Bièvre; P. D. P. Taylor (pp. 567-573).
Formal acceptance of the results of chemical laboratories is increasingly organized through a) accreditation of measuring laboratories nationally and b) mutual recognition of accreditation internationally (through formal Multilateral Recognition Agreements, MRAs). However, real comparability of results of measurements is realized by using common (internationally agreed) measurement scales which make these results traceable to this scale, i.e. “traceable” to the same (internationally agreed) value of the unit of that scale. In addition, the criterion against which the evaluation is done, should be “external” to the measurement laboratories which are being evaluated. This is realized in IRMM’s International Measurement Evaluation Programme (IMEP) where evaluation is performed against values which are anchored using “metrology”, the science of measurement with its own rules, which offers a sound foundation for measurement in all scientific disciplines. It is argued in this paper that the demonstration of measurement capability against values on such scales provides a result-oriented rather than a procedure-oriented evaluation. Thus, competence can be “demonstrated” rather than just “designated” and this can be shown to both customers and regulators. It inspires more confidence.
Comparability of thermodynamic data – a metrological point of view by G. Meinrath (pp. 574-584).
In order to compare and to interpret chemical measurements, compliance with general rules of metrology is compulsory. Such rules are the more important the more the chemical measurements are applied under circumstances where material assets and goods or immaterial values like health may be affected. Metrology of chemical measurements attempts to define rules for achieving comparability and for guaranteeing quality of analytical data. Thermodynamic data are commonly derived from a set of analytical measurements. Comparability among thermodynamic data is an important issue especially for those data to be applied in politically sensitive issues of environmental prognosis, long-term safety assessment of nuclear waste repositories in deep geological formations and assessment of environmental impact of technical intervention in the geosphere. Taking the data evaluation step in the traceability chain of thermodynamic data as an example, the existing thermodynamic data is shown to be affected by deficiencies in comparability and quality that may severely limit its dependability in environmental prognosis. The need for a metrologically acceptable approach is demonstrated. Statistical concepts improving a reliable assignment of meaningful measurement uncertainty to a thermodynamic datum are presented. Unresolved issues, i.e. measurement uncertainty of a pH measurement, hampering the construction of a traceability chain are outlined.
Inverse vs. classical calibration for small data sets by J. Tellinghuisen (pp. 585-588).
In classical calibration, the statistically uncertain variable y is regressed on the error-free variable x for a number of known samples, and the results are used to estimate the x value (x 0) for an unknown sample from its measured y value (y 0). It has long been known that inverse calibration – regression of x on y for the same data – is more efficient in its prediction of x 0 from y 0 than the seemingly more appropriate classical procedure, over large ranges of the controlled variable x. In the present work, theoretical expressions and Monte Carlo calculations are used to illustrate that the comparison favors the inverse procedure even more for small calibration data sets than for the large sets that have been emphasized in previous studies.
Estimation of the uncertainty of CRMs in accordance with GUM: Application to the certification of four enzyme CRMs by T. P. J. Linsinger; J. Pauwels; H. Schimmel; A. Lamberty; A. M. H. van der Veen; G. Schumann; L. Siekmann (pp. 589-594).
Uncertainties of four enzyme-CRMs that have recently been certified in a co-operation between the IRMM and the International Federation for Clinical Chemistry were estimated. Estimation was based on the sum of the uncertainties of characterization, homogeneity and stability. Data from the certification collaborative study were used to estimate laboratory uncertainties, which form the basis for the uncertainty of characterization. Estimations for the uncertainty of homogeneity were derived from classical homogeneity studies. The estimations of uncertainty of stability caused the most difficulties. Realistic uncertainties fitting the needs of customers while being derived from measurement data based on theoretical considerations were obtained.
Simultaneous spectrophotometric determination of La, Ho, Mn 5-Br-PADAP complexes using multivariate calibration with partial least-squares (PLS) data evaluation by R. E. Ferreyra; J. M. Camiña; E. Marchevsky; J. M. Luco (pp. 595-600).
A simple and fast analytical pocedure is proposed for the simultaneous spectrophotometric determination of lanthanum, holmium and manganese in synthetic ceramics, (La(0.8–x) Hox Sr0.2 MnO3), by using the partial least-squares (PLS) method. As chromogenic agent 5-Br-PADAP [2-(5-bromo-2-pyridylazo)-5-diethylaminophenol] was used, which form colored complexes with the three elements studied. To avoid metal hydrolysis, a mixture ¶of ethanol and Triton X-100 at pH 9.5 was used for all ¶experiments. A set of 17 calibration solutions measured throughout the 400–700 nm wavelength range was used in the calibration step. The concentration range for Mn(II) was 1–12 × 10–6 mol L–1, while the range for the rare earth elements La(III) and Ho(III) was 2–8 × 10–6 mol L–1. In order to demonstrate the applicability of the proposed method, a set of artificial samples containing the three analytes in variable proportions was prepared and analyzed. The analytical results obtained were quite acceptable with relative errors not greater than 7% in most cases.
Strategy for water analysis using ICP-MS by J. L. Fernández-Turiel; J. F. Llorens; F. López-Vera; C. Gómez-Artola; I. Morell; D. Gimeno (pp. 601-606).
The developed strategy permits determination in three steps of sixty-seven elements using inductively coupled plasma mass spectrometry (ICP-MS). Sodium, Mg, Si, S, Cl, K, and Ca are determined in a first step; ¶B, Al, P, Cr, Fe, Mn, Ni, Cu, Zn, As, Se, Ag, Cd, Sb, Ba, Hg, and Pb are determined in a second step; and Li, Be, Ti, V, Co, Ga, Ge, Br, Rb, Sr, Y, Zr, Nb, Mo, Sn, Te, I, Cs, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Pt, Au, Tl, Bi, Th, and U are analyzed in a third step. The figures of merit obtained are adequate to carry out water quality monitoring and other hydrochemical studies, such those based in the application of hydrochemical fingerprinting to water management.
X-ray fluorescence analysis of trace metal ions following a preconcentration of metal-diethyldithiocarbamate complexes by homogeneous liquid-liquid extraction by A. Takahashi; S. Igarashi; Y. Ueki; H. Yamaguchi (pp. 607-610).
A homogeneous liquid-liquid extraction method for 36 metal ions with diethyldithiocarbamate was studied. As a result, 11 metal ions were extracted as metal-chelates. Under the experimental conditions, the maximum concentration factor was 500 (i.e., 0.1 mL of sedimented liquid phase was produced from 50 mL of aqueous phase). Moreover, the proposed method was utilized as a preconcentration method for X-ray fluorescence analysis of these metals. The recovery of each metal was ca. 97–100%. All calibration curves were linear over the range of 5.0 × 10–7 mol L–1 to 1.0 × 10–5 mol L–1. The detection limits were at the ¶10–8 mol L–1 levels and the relative standard deviations were below 5% (5 determinations). When the proposed method was used for the determination of contaminants in a synthetic sample (Al-based alloy model) and of components in an Au-Pd alloy, the results were satisfactory.
Development of a voltammetric method for the determination of iron(III) in Zn-Fe alloy galvanic baths by R. Favaron; L. M. Aleixo (pp. 611-615).
A square wave voltammetric method whith a static mercury drop electrode (SMDE) was developed for the quantitative determination of iron (III) in Zn-Fe alloy galvanic baths. Real alloy bath samples were analyzed by the standard addition method and recovery tests were carried out. 0.50 mol L–1 sodium citrate (pH 6.0) or 0.20 mol L–1 oxalic acid (pH 4.0) were applied as supporting electrolytes resulting in both cases in a peak potential of about –0.20 V vs. Ag|AgCl (saturated KCl). The iron (III) concentration in the alloy bath was 9.0 × 10–4 mol L–1. A good correlation (r = 0.9999) was achieved between the iron (III) concentration and the peak current in the electrolytes studied, with linear response ranges from 1.0 × 10–6 to 1.2 × 10–4 mol L–1. Interference levels for some metals such as copper (II), lead (II), chromium (III) and manganese (II) that can hinder the Zn-Fe alloy deposition were evaluated; only copper (II) interferes seriously.
Determination of organophosphorus insecticides in natural waters using SPE-disks and SPME followed by GC/FTD and GC/MS by D. Lambropoulou; T. Sakellarides; T. Albanis (pp. 616-623).
Two methods for the analysis of ten organophosphorus insecticides in natural waters using solid phase extraction disks containing C18 and SDB and solid phase microextraction fibers containing polyacrylate (PA) are developed. Bromophos ethyl, bromophos methyl, dichlofenthion, ethion, fenamiphos, fenitrothion, fenthion, malathion, parathion ethyl and parathion methyl were determined by GC/MS and GC/FTD. The SPE-disks require only 1000 mL of sample and provide a method limit of detection in the range of 0.01–0.07 μg/L and recovery rates from 60.7 to 104.1%. The solid phase microextraction (SPME) technique requires 2–5 mL of water sample and provides a method limit of detection in the range of 0.01 to 0.05 μg/L for all detectors and the recoveries compared to distilled water ranged from 86.2 to 119.7%. The proposed methods were applied to the trace level screening determination of insecticides in river water samples originating from different Greek regions.
Rapid liquid chromatographic determination of residual penicillin G in milk by N. Furusawa (pp. 624-626).
A simple and rapid high-performance liquid chromatographic (HPLC) method for determination of residual penicillin G (benzylpenicillin, PCG) in milk was developed. The sample preparation was performed by stirring with ethanol and reacting with 5 M 1,2,4-triazole-mercury (II) chloride solution at 65 °C for 10 min followed by an ultra centrifugation step. The HPLC separation was carried out using a Mightysil® RP-4GP column, a mobile phase of acetonitrile and 0.1 M phosphate buffer (pH 6.5) (35:65, v/v) and a photo-diode array detector. The average recoveries from spiked PCG (0.004, 0.01, 0.05 and 0.1 μg/mL) were above 86% with coefficients of variation between 1.2 and 4.5%. The limit of detection was 0.004 μg/mL. This value corresponds to the maximum residue limit (MRL) in milk (0.004 μg/mL, EU and Japan). The total time required for the analysis of one sample was below 40 min.
ETAAS method for the determination of Cd, Cr, Cu, Mn and Se in blood fractions and whole blood by C. Prohaska; K. Pomazal; I. Steffan (pp. 627-632).
An electrothermal atomic absorption method (ETAAS) for the direct determination of trace elements (Cd, Cr, Cu, Mn, Se) both in blood fractions (erythrocytes, plasma and lymphocytes) and whole blood was developed. Zeeman background correction and graphite tubes with L’vov platforms were used. Samples were ¶diluted with HNO3/Triton X-100 and pipetted directly ¶into the graphite tube. Ashing, pretreatment and atomization steps were optimized carefully for the different fractions and elements applying different matrix modifiers ¶for each element. For the lymphocyte fraction a multi-fold injection technique was applied. Low detection limits ¶of the ETAAS method (Cd 0.13 μg/L, Cr 0.11 μg/L, ¶Cu 0.52 μg/L, Mn 0.13 μg/L, Se 0.7 μg/L of whole blood) combined with small quantities of sample necessary for analysis allow determination of trace elements in this matrix. Verification of possible differences in the trace element status of humans was performed with statistical significance (P < 0.05). In addition, a contribution to the determination of normal values of essential elements was achieved. The method was applied for determination of trace elements in human blood and blood fractions of two groups (n = 50) different in health status.
Microwave assisted extraction for trace element analysis of plant materials by ICP-AES by J. Borkowska-Burnecka (pp. 633-637).
Application of microwave assisted extraction for the decomposition and dissolution of plant samples for trace metal determination by ICP-AES was examined. Dried onion, leaves of spinach beet and three reference materials CTA-OTL-1, CTA-VTL-2 and CL-1 were analyzed. Water, EDTA and hydrochloric acid (0.01, 0.10 and 1.0 M, respectively) were used as leaching solutions. The extraction efficiency was investigated by comparison of the results with those obtained after microwave wet digestion. HCl was found to be very suitable for quantitative extraction of B, Ba, Cd, Cu, Mn, Ni, Pb, Sr and Zn from the samples. For reference materials, the measured concentrations are well consistent with the certified values. The use of EDTA led to a complete extraction of B, Cd, Ni, Pb, Sr and Zn. Water was found to be a good leaching solution for boron. For extraction with HCl and EDTA, the RSD values for the concentrations measured were below 8% for most of the elements.
Study of the adsorption behavior ¶of heavy metal ions on nanometer-size ¶titanium dioxide with ICP-AES by Pei Liang; Yongchao Qin; Bin Hu; Chunxiang Li; Tianyou Peng; Zucheng Jiang (pp. 638-640).
A new method using nanoparticle TiO2 as solid-phase extractant coupled with ICP-AES was proposed for simultaneous determination of trace elements. The adsorption behavior of nanometer TiO2 towards Cu, Cr, Mn and Ni was investigated by ICP-AES, and the adsorption pH curves, adsorption isotherms and adsorption capacities were obtained. It was found that the adsorption rates of the metal ions studied were more than 90% in pH 8.0∼9.0, and 2.0 mol L–1 HCl was sufficient for complete elution. Nanometer TiO2 possesses a significant capacity for the sorption of the metal ions studied which is higher than the capacity of silica, the commonly used extractant. The method has been applied to the analysis of some environmental samples with satisfactory results.