Collected papers on the use of inductively coupled annular plasmas in atomic spectroscopy

The author's international reputation as an atomic spectroscopist commenced with the publication of the first paper, and subsequent patents, describing the use of the inductively coupled annular plasma as an emission source. Prior to this he had achieved recognition for other innovative papers [3-7, 10] in the field of analytical chemistry. The accompanying collection of papers refer to the period after the author's entry into the field of atomic spectroscopy with high temperature plasmas. [Continues.

Improvements relating to atomic spectroscopic methods and apparatus incorporating an inductively-coupled plasma

Improvements relating to atomic spectroscopic methods and apparatus incorporating an inductively-coupled plasm

Book Reviews

THE ASSAULT ON PRIVACY. By Arthur R. Miller. Ann Arbor: University of Michigan Press, 1971. Pp. xiv, 333. $7.95. TRIAL DIPLOMACY. By Alan E. Morrill. Chicago: Court Practice Institute, 1971. Pp. xxix, 1174.$17.50 (Paperback)

Atomiser, Source, Inductively Coupled Plasmas in Atomic Fluoresence Spectrometry (ASIA): A Study of Chemical and Ionisation Interference Effects

The effects of phosphate, aluminium, sodium and potassium on the atomic fluorescence of calcium at 422.7 nm and the ionic fluorescence at I:393.4-396.8 nm have been studied. When the operating conditions are optimised for maximum fluorescence signal from a solution containing no interferents, interference effects are observed which may be interpreted in terms of stable compound formation, ionisation suppression and fluorescence quenching. These effects may be removed by optimising the operating parameters for minimum interference

Comparison of Alternating Variable Search and Simple Methods of Optimisation for Inductively Coupled Plasma Optical Emission and Atomic Fluorescence Spectrometry

The performance of several cyclic alternating variable search (AVS) optimisation methods are compared with two simplex methods with respect to the number of changes of variable required to search a model two-factor response space. The roles of the initial step size and of the variable step size are discussed, and the information produced concerning the shape of the factor space is evaluated. An AVS method which starts with a fixed step size and then changes to a variable step size on second and subsequent cycles is compared with a variable step size simplex for the optimisation of an inductively coupled plasma optical emission spectrometer and of the atomiser, source inductively coupled plasmas in atomic fluorescence spectrometry (the ASIA system). The order in which the variables are taken in the AVS method does not affect the value of the optimum eventually found. Both methods perform satisfactorily for the optical emission work, although the AVS method provides information about the shape of the factor space which is easier to interpret than in the simplex method. However, the simplex method was not always able to satisfy the conditions for termination in the case of the atomic fluorescence studies and was much slower to implement than the AVS method as the latter used direct visual feedback from the output of the lock-in amplifier as a measure of the figure of merit (total fluorescence signal)

A Comparison of Boosted-Discharge Hollow Cathode Lamps and an Inductively Coupled Plasma (ICP) as Excitation Sources in ICP Atomic Fluorescence Spectrometry

Copper, nickel and lead boosted-discharge hollow cathode lamps, run at recommended currents, have been compared with a high-powered inductively coupled plasma (ICP) as excitation sources in atomic fluorescence spectrometry (AFS). A similar comparison was made with a copper lamp run at higher currents. It was found that for lead and nickel, the fluorescence spectra differed in the relative intensities of the transitions observed with the two sources. No evidence was found for a difference in radiances between the two sources when the lamp was overrun. Although the lamps gave rise to lower blank standard deviation values, detection limits were worse because of poorer sensitivity due to the inability of the circular source to illuminate the required atom cell volume in the atomiser. It was concluded that the ICP was the better source, when the criterion is detection limits, but the lamps may be more convenient in some circumstances

Model-based evaluation of the long-term cost-effectiveness of systematic case-finding for COPD in primary care

Introduction'One-off' systematic case-finding for COPD using a respiratory screening questionnaire is more effective and cost-effective than routine care at identifying new cases. However, it is not known whether early diagnosis and treatment is beneficial in the longer term. We estimated the long-term cost-effectiveness of a regular case-finding programme in primary care.MethodsA Markov decision analytic model was developed to compare the cost-effectiveness of a 3-yearly systematic case-finding programme targeted to ever smokers aged ≥50 years with the current routine diagnostic process in UK primary care. Patient-level data on case-finding pathways was obtained from a large randomised controlled trial. Information on the natural history of COPD and treatment effects was obtained from a linked COPD cohort, UK primary care database and published literature. The discounted lifetime cost per quality-adjusted life-year (QALY) gained was calculated from a health service perspective.ResultsThe incremental cost-effectiveness ratio of systematic case-finding versus current care was £16 596 per additional QALY gained, with a 78% probability of cost-effectiveness at a £20 000 per QALY willingness-to-pay threshold. The base case result was robust to multiple one-way sensitivity analyses. The main drivers were response rate to the initial screening questionnaire and attendance rate for the confirmatory spirometry test.DiscussionRegular systematic case-finding for COPD using a screening questionnaire in primary care is likely to be cost-effective in the long-term despite uncertainties in treatment effectiveness. Further knowledge of the natural history of case-found patients and the effectiveness of their management will improve confidence to implement such an approach

Circular dichroism spectroscopy of membrane proteins

Circular dichroism (CD) spectroscopy is a well-established technique for studying the secondary structures, dynamics, folding pathways, and interactions of soluble proteins, and is complementary to the high resolution but generally static structures produced by X-ray crystallography, NMR spectroscopy, and cryo electron microscopy. CD spectroscopy has special relevance for the study of membrane proteins, which are difficult to crystallise and largely ignored in structural genomics projects. However, the requirement for membrane proteins to be embedded in amphipathic environments such as membranes, lipid vesicles, detergent micelles, bicelles, oriented bilayers, or nanodiscs, in order for them to be soluble or dispersed in solution whilst maintaining their structure and function, necessitates the use of different experimental and analytical approaches than those employed for soluble proteins. This review discusses specialised methods for collecting and analysing membrane protein CD data, highlighting where protocols for soluble and membrane proteins diverge