Alan Townshend

Handbook on toxicity of inorganic compounds

This text consists of a total of 74 chapters of which 68 are devoted to individual elements and derived substances. The introductory chapter contains general definitions and describes the manner in which each elemental chapter is organized. For each of these chapters the points covered include chemistry and distribution, technological uses, physiological processes, detoxification mechanisms, levels of tolerance, summary of ecotoxicity, and analytical chemistry as well as a list of references. In addition to the elements, a chapter is also devoted to radiotoxicity. Aside from a discussion of individual elements, the second chapter covers the chemistry of inorganic compounds from the point of view of essentiality in biological systems and the properties and interdependency of these compounds. The third chapter is a very brief description of general principles used in toxicology, with emphasis on metals. The fourth chapter deals specifically with the collection, storage, and handling of biological materials for subsequent analysis. This is followed by chapters on the individual elements. The final chapter is a summary containing various tables describing values for threshold limits, biological tolerance, and acceptable intake.

Use of the term "recovery" and "apparent recovery" in analytical procedures (IUPAC Recommendations 2002)

The terms recovery and apparent recovery are recommended to avoid confusion caused by the use of the term recovery to cover two distinct situations. These situations deal with: (a) the yield of a preconcentration or extraction stage of an analytical process (where recovery is recommended) and (b) the quantity observed value/reference value, obtained using an analytical procedure that involves a calibration graph (where apparent recovery is recommended).

Determination of glucose in blood by flow injection analysis and an immobilized glucose oxidase column

Abstract A flow-injection system for glucose determination is described. Glucose oxidase is immobilized on controlled porosity glass (CPG) and used in a glass column (2.5 mm diameter × 2.5 cm). The hydrogen peroxide produced by the enzymatic reaction (⩾ 1 × 10 −6 M) is detected by the current produced in a flow-through cell, with two platinum electrodes having a potential difference of 0.6 V. Glucose (0–20 mmol l −1 ) can be determined in blood plasma either with a dialyser in the system or, better, by incorporating a column of copper(II) diethyldithiocarbamate on CPG before the enzyme column. The results compared well with those obtained by a conventional analyser system. The glucose oxidase column showed little change in activity over a 10-month period.

Hair analysis : applications in the biomedical and environmental sciences

This book reviews the theory and practice of using hair as a biopsy tissue for trace elements and discusses the pros and cons of this methodology. The authors examine in detail past and present use of hair trace-element levels as indicators of nutritional status, disease, heavy-metal poisoning and environmental exposure. This book also describes methods for collecting and preparing hair samples for determining their trace-element content. The authors also discuss the various theories explaining the biological incorporation of trace elements into hair and the external factors that may affect trace-element absorption.

Solution chemiluminescence—some recent analytical developments. Plenary lecture

Some recent developments in analytical solution chemiluminescence (CL) are described. These include various approaches for monitoring CL, especially flow injection, applications based on luminol and peroxyoxalate CL, direct determinations based on the CL of the analyte, and the uses of CL for liquid chromatographic detection.

Flow injection analysis for monitoring chemiluminescent reactions

Abstract Various coiled flow cells are tested for monitoring the chemiluminescence produced by the cobalt-catalysed oxidation of luminol by hydrogen peroxide and the fluorescein-sensitized oxidation of sulphide by sodium hypochlorite. When a 6-coil cell is used, 1O −3 –1OO ng of Co 2+ and 1–1000 ng of S 2 can be determined in 10- and 100-μl samples, respectively.

Determination of morphine by flow injection analysis with chemiluminescence detection

Chemiluminescence detection has been used in combination with flow injection analysis to determine 1 fmol of morphine by its reaction with permanganate in an acidic tetraphosphate solution. Structurally similar narcotics can also be determined by the same procedure. A mechanism for the chemiluminescent reaction is suggested.

Flow-injection determination of paraoxon by inhibition of immobilized acetylcholinesterase

Abstract Two flow-injection methods (continuous-flow and stopped-flow) are proposed for the determination of paraoxon, applying the dual-injection technique and spectrophotometric detection. They are based on the inhibition of the acetylcholinesterase-catalysed hydrolysis of α-naphthyl acetate and subsequent reaction of the α-naphthol produced with p-nitrobenzenediazonium fluoroborate. For the continuous-flow system the calibration graph was linear from 5 × 10−7 to 1.5 × 10−5 M, the relative standard deviation (r.s.d.) (n=6) for an 8 × 10−6 M standard was 1.4%, the limit of detection (3σ) was 4 × 10−7 M and the sample throughput was ca. 60 h−1. For the stopped-flow system the linear range was from 1 × 10−8 to 4 × 10−7 M, the r.s.d. for a 2.5 × 10−7 M standard was 0.9%, the limit of detection was 8 × 10−9 M and the sample throughput was 30 h−1.

Flow injection chemiluminescence determination of sulphite

A comparison is made of the use of riboflavin and 3-cyclohexylaminopropanesulphonic acid (CAPS) to increase the sensitivity of the determination of sulphite in a flow injection procedure based on the chemiluminescence produced by permanganate oxidation in an acidic solution. Both procedures give linear calibration graphs for 5–60 ng of sulphite, but the CAPS procedure has a lower detection limit (1.2 ng) and better relative standard deviation (RSD)(2.5% for 40 ng, n=10). Riboflavin enhancement arises from energy transfer, but the reason for the CAPS enhancement could not be identified with certainty.

Simultaneous determination of sucrose and glucose in mixtures by flow injection analysis with immobilized enzymes

Abstract Sucrose is determined in a flow-injection system by using a manifold comprising columns of invertase/mutarotase and glucose (immobilized on controlled-pore glass) in sequence, and amperometric detection of the hydrogen peroxide produced. The system can be modified to allow the sequential determination of sucrose and glucose (10−4–10−2 M) by incorporating a controlled bypass around the invertase column, thus allowing one sample to traverse both columns (giving a response from glucose and sucrose) and the next to pass through only the glucose oxidase column (glucose response only). Further modification allows a single sample to be split between the two flow paths, so that two peaks are obtained in sequence (sucrose/glucose, and glucose). Both procedures are rapid and precise.