A general computer approach for calculating rate constants from near-equilibrium kinetic studies

A general computer approach for estimating rate constants from relaxation times is described. The programme CORNEK is essentially a least-squares refinement programme applied to non-linear systems. It uses directly the differential forms of the first derivatives of mass-balance and rate equations, thus avoiding the time-consuming derivations of near-equilibrium rate equations. The programme has been tested for binary systems such as Cu-histamine, Cu-serine, and the ternary system Cu-histamine-serine.     

Improvements in the determination of eight polycyclic aromatic hydrocarbons through a stepwise interlaboratory study approach

A summarising account of a systematic stepwise approach based on interlaboratory studies carried out by a number of laboratories from European Union and EFTA countries is given. This approach has been designed to improve the analytical state of the art in the determination of selected polycyclic aromatic hydrocarbons in different environmental matrices. The approach resulted in a certification exercise to produce a sewage sludge as Certified Reference Material (CRM). The results of the programme showed that HPLC and GC are equally reliable for PAH analysis at submicrogram to microgram per gram levels in various environmental matrices. Major improvements were achieved during the programme, resulting in reduced coefficients of variation and between-laboratory differences. Several recommendations emerging from the programme experience are presented.     

Validation of accuracy by interlaboratory programme

A statistical design is proposed for assessing the accuracy of an analytical method by its application to a certified reference material in an interlaboratory programme. The validation of accuracy is based on the difference between the certified value and the overall mean of the test programme and is linked to the concept that below a certain limit this difference has no practical significance. It is shown that a certified reference material cannot be used to detect bias in a method if the bias is smaller than the confidence interval of the certified value.     

The proof of analytical chemical education lies in proficiency testing: a proficiency testing programme in polytechnic academia and vocational colleges in The Netherlands

Participation in proficiency testing schemes (PT-schemes) is an important way to prove and to improve the skills of analytical chemical students. It gives valuable information on the professional capabilities of the students and is thus an important step in the training of laboratory engineers and technicians. In the programme described three types of samples are offered to the students: chemical, environmental and clinical samples. A guiding protocol presents instructions to the participating student groups. Standard operating procedures are available, but the students are also free to select their own method. The results are methodologically and statistically judged by professional PT-organisers and are presented in the customary way: the dataset, the mean (consensus) value of all participants and the Z-scores. The final presentation of the results takes place in an annual symposium where awards are presented to the best performing student groups, and a lecture programme is presented with subjects in the area of quality assurance and quality control. A selection of results from the KILO/PT/1998-1999 and the KILO/PT/1999-2000 programme is presented.     

A user-friendly programme 'SIMKINERSQUO; for simulation of kinetics involving complex reaction mechanisms

A programme, 'SIMKINERSQUO; is developed using a semi-implicit extrapolation method (SIEM) which uses the implicit midpoint rule and extrapolation to simulate complex mechanisms based on the kinetics of homogeneous chemical systems. The chemical kinetics pre-processor code is designed to translate a user-specified system of chemical rate equations into a system of chemical kinetic differential equations. The developed programme is applied to the 13-step mechanism of the reaction between Nile blue and acidic bromate. The results obtained compare well with the curves drawn using the other method, reported in literature.     

The proof of analytical chemical education lies in proficiency testing: A proficiency testing programme in polytechnic academia and vocational colleges in The Netherlands

Participation in proficiency testing schemes (PT-schemes) is an important way to prove and to improve the skills of analytical chemical students. It gives valuable information on the professional capabilities of the students and is thus an important step in the training of laboratory engineers and technicians. In the programme described three types of samples are offered to the students: chemical, environmental and clinical samples. A guiding protocol presents instructions to the participating student groups. Standard operating procedures are available, but the students are also free to select their own method. The results are methodologically and statistically judged by professional PT-organisers and are presented in the customary way: the dataset, the mean (consensus) value of all participants and the Z-scores. The final presentation of the results takes place in an annual symposium where awards are presented to the best performing student groups, and a lecture programme is presented with subjects in the area of quality assurance and quality control. A selection of results from the KILO/PT/1998–1999 and the KILO/PT/1999–2000 programme is presented.     

Improvements in the determination of chlorobenzenes and chlorophenols through a stepwise interlaboratory study approach

A systematic quality control programme carried out by a number of laboratories from the European Union and from EFTA countries is described. The programme was designated to improve the analytical state of the art in the determination of selected chlorinated benzenes and chlorinated phenols in different environmental matrices. To that end a stepwise interlaboratory study approach was chosen, analysing, in consecutive order, a clean extract of soil, a raw extract and the soil itself. Eight analytes were selected for the study, i.e. three chlorobenzenes and five chlorophenols. During the programme significant improvements in analytical performance were achieved, as shown by a decrease in within-laboratory coeffficients of variation as well as by acceptable coefficients of variation in the mean value of laboratory means of all analytes in the final matrix analysed, i.e. a natural soil. The results of the programme prompted the European Union to embark upon a pentachlorophenol interlaboratory certification study to produce an industrial soil candidate Certified Reference Material (CRM) [1].     

Interpretation of mass spectra

A computer programme is described which calculates the mass numbers and the relative intensities of each of the lines in the cluster formed in a mass spectrometer from a single type of fragment ion which contains one or more polyisotopic elements. Many elements such as B, C, S, Cl and Br possess more than one naturally occurring isotope, and the relative abundances of the various isotopes are known. A whole series of possible fragment ions may be calculated quite readily, and the results, which are printed numerically and in the form of a histogram, facilitate the interpretation of mass spectra. Trial data, a FORTRAN listing of the programme, and a sample of the output are given. The programme requires approximately 17K of fast core, and should be implemented without difficulty on any computer with a FORTRAN IV compiler.     

On the computation of the dipole change arising from vibrational angular momentum and some inter-relationships between the elements of the atomic polar tensor

A programme is developed for the computation of the contribution of the rotation of the dipole moment to vibrational transition moments. It is argued that this return to fundamentals has much in its favour compared with earlier methods based on pseudo isotope calculations. The programme is applied to H₂O. Some discrepancies are noted with the results of the matrix method originally proposed by Biarge, Herranz and Morcillo. The existence of internal relationships between the elements of the APT is demonstrated. Such relationships are of importance in the refinement of the APT to fit experimental transition moments.     

Improvements in the determination of chlorobenzenes and chlorophenols through a stepwise interlaboratory study approach

A systematic quality control programme carried out by a number of laboratories from the European Union and from EFTA countries is described. The programme was designated to improve the analytical state of the art in the determination of selected chlorinated benzenes and chlorinated phenols in different environmental matrices. To that end a stepwise interlaboratory study approach was chosen, analysing, in consecutive order, a clean extract of soil, a raw extract and the soil itself. Eight analytes were selected for the study, i.e. three chlorobenzenes and five chlorophenols. During the programme significant improvements in analytical performance were achieved, as shown by a decrease in within-laboratory coeffficients of variation as well as by acceptable coefficients of variation in the mean value of laboratory means of all analytes in the final matrix analysed, i.e. a natural soil. The results of the programme prompted the European Union to embark upon a pentachlorophenol interlaboratory certification study to produce an industrial soil candidate Certified Reference Material (CRM) [1]. Received: 28 August 1997 / Revised: 15 October 1997 / Accepted: 21 October 1997     

A simple method for calculating enantiomer ratio and equilibrium constants in biocatalytic resolutions

A computer programme for determination of equilibrium constant (K) and enantiomer ratio (E) in biocatalytic resolutions has been developed. The programme utilises experimental data, ee_s and ee_p measured at more than one conversion, and determines both K and E no matter whether the reaction is irreversible (K=0) or reversible (K>0). An estimation of errors in the calculations indicates that errors in E does not show a Gaussian distribution, while errors in K does. The usefulness of the programme has been tested in a lipase-catalysed transesterification of 1-phenoxy-2-propanol at various concentrations of acyl donor, with different solvents and at different water activities.     

Providing a traceable assigned value in a proficiency testing programme on the determination of benzoic acid in orange juice

A proficiency testing (PT) programme on the determination of benzoic acid in orange juice was organised by the Chemical Metrology Laboratory, Health Sciences Authority, Singapore, for the local food testing laboratories. The PT programme used a metrologically traceable assigned value determined by isotope dilution mass spectrometry to assess the performance of the participating laboratories. This paper discusses the reasons and approach to applying metrological principles to determine the assigned value of a PT programme. The procedure undertaken by the Laboratory to prepare a batch of PT sample, conduct homogeneity and stability testings, as well as value assignment, is presented. The discussions also include the estimation of the measurement uncertainties arising from the characterisation, testing for homogeneity and testing for stability of the PT sample. The Coordinator of the PT programme used the assigned value and its associated measurement uncertainty, together with those of the participating laboratories to assess their performances. Statistical tools applied in the performance evaluations are also presented.     

Lie algebras in quantum chemistry: Symmetrized orbitals

The application of Lie algebras in quantum chemistry is considered. Particular attention is devoted to their application to high symmetry problems especially where icosahedral symmetry prevails. A general programme for implementing the theory of Lie algebras in the analysis of symmetry problems is outlined.     

Analytical validity of the determination of mercury in whole blood and urine – Results of the German external assurance programme for toxicological analysis in biological materials

The determination of mercury concentrations in blood and urine is currently the best way of monitoring individual uptake of organic and inorganic mercury. In Germany these determinations must be carried out under the conditions of an external quality assurance programme. The German performance evaluation, based on reference values established by reference laboratories yields success rates in percent for the participants in the intercomparison programme of about 60%. A Canadian evaluation system based on two evaluations scores, yields success rates of 25–50% for “good performance” and of 65–80% for “acceptable performance”. The determination of mercury in blood and urine is at present not carried out with the necessary reliability.     

Analytical validity of the determination of mercury in whole blood and urine--results of the German external assurance programme for toxicological analysis in biological materials

The determination of mercury concentrations in blood and urine is currently the best way of monitoring individual uptake of organic and inorganic mercury. In Germany these determinations must be carried out under the conditions of an external quality assurance programme. The German performance evaluation, based on reference values established by reference laboratories yields success rates in percent for the participants in the intercomparison programme of about 60%. A Canadian evaluation system based on two evaluations scores, yields success rates of 25-50% for "good performance" and of 65-80% for "acceptable performance". The determination of mercury in blood and urine is at present not carried out with the necessary reliability.     

Durability of polymers—material property data

Some standardisation of input data is required for material property data bases. A brief review is given of developments of data bases of relevance to polymers and particular consideration given to the requirements for durability data. The measurements to be made in the Design Data Initiative Durability programme are outlined.     

Dual standard addition for quantitative NMR analysis

A technique is described for quantitative NMR measurement which involves the use of a pair of internal standards. This procedure overcomes several of the problems encountered with only one standard material. A computer programme is described for statistical treatment of the results.     

CAPSS: A thin diaphragm capacitive pressure sensor simulator

A set of analytical equations for the calculation of two-dimensional this diaphragm deflection under pressure is derived. Based on these equations, a design simulation programme capable of calculating the device performance is developed. The simulated results for sensors fabricated on (100) silicon wafer are presented. A new technique to linearize the pressure sensitivity by electrode shaping is also proposed.     

Preliminary studies into profiling DNA recovered from a radiation or radioactivity incident

The examination and profiling of human DNA recovered from a scene of crime is an essential aspect of criminal investigations. However, it is currently not known whether DNA recovered from a scene where an ionising radiation source or radioactive contamination is present can be successfully profiled. The direct examination and analysis of radioactively contaminated DNA has not been widely explored using the current procedures employed by forensic service providers. As a result, AWE is putting in place an extensive research and development programme to better understand the effects that radiation has on the ability to profile human DNA, and assess the associated retention of different radioactive contaminants within each step of the profiling procedure. A summary will be provided on the aims of this project and progress that has been made to date; together with a discussion of the lessons that have been learnt during the course of the programme’s development.     

Isotopes and radiation technology—Indian scene

India's isotope programme is today largely self-sustaining both in terms of availability of isotope products and the range of their applications in medicine, industry, hydrology, agriculture and research. Nuclear medicine is practised by over 200 medical institutions whereas 300 organisations offer radioimmunoassay service. Tracer technology, nucleonic gauging and isotope raiography are fairly well accepted by the Indian industry for troubleshooting, NDT and process control. There are three large radiation plants for sterilisation of medical products. Radiation chemical processing with both gamma and EB shows good promise. In agriculture, sixteen mutants of various crops have been produced using gamma-radiation and distributed for commerical cultivation. A strong programme of research on radiation preservation of food has finally resulted in the clearance of some irradiated foods by the Government of India.