R.M. Dagnall

Molecular emission characteristics of various fluorides in a low-temperature-hydrogen diffusion flame

A capillary burner supporting a nitrogen/hydrogen diffusion flame has been evaluated as a possible means of detection for several volatile fluorides after their gas-chromatographic separation. The fluorides of As, B, C, Ge, I, Mo, P, Re, S, Sb, Se, Si, Te and W were formed by the reaction of the element with chlorine trifluoride, and the intense molecular emission given by each was recorded. An attempt was made to identify the emitting species.

Electronic modulation of microwave-excited electrodeless discharge lamps for use in atomic-fluorescence spectrometry

Electronic modulation of electrodeless discharge lamps has been investigated with respect to frequency of operation and modulation waveform. The optimal frequency of operation was found to be ca. 20,000 Hz, using a square waveform, and modulation was best achieved by adding the modulation waveform to the reference of the stabilizing element in the microwave power supply. Optimal operating conditions have been established for d.c. and a.c. modes of operation for several sources.

Analytical applications of ternary complexes—IV: Titration of macro- and micro-amounts of cyanide

The use of a 1,10-phenanthroline/Bromopyrogallol Red indicator system is proposed for the visual and photometric titration of cyanide with silver nitrate in the range 10(-1)-10(-4)M and 10(-4)-10(-5)M respectively. Sharp, well-defined end-points are observed and the titration succeeds at low concentrations where the Liebig-Dénigès method is inapplicable. The results obtained agree well with those of the conventional method. EDTA may be used as a mass-masking agent for most cations.

Determination of iodine by atomic-absorption spectrometry using the platinum-loop technique

The use of a platinum-loop atomizer and an electrodeless discharge lamp has been applied to the atomic-absorption determination of mercury at the 183.0-nm resonance line. Oxygen was flushed from the light-path with argon, giving adequate readiation transmission characteristics and a sensitivity of 9 ppm of iodine for 1% absorption. The method is prone to both cationic and anionic interferences, but the use of cation-exchange and solvent-extraction procedures overcomes some of the problems.

Atomic Absorption and Emission Spectrometry of Mercury at 184.9nm

Abstract We have previously described qualitative measurements concerning the feasibility of atomic absorption spectrometry of mercury at 184.9nm (1). This communication describes the analytical utility of such measurements together with some atomic emission studies using a conventional monochromator system purged with an inert gas to prevent absorption of radiation by oxygen.

Some considerations on spectral line profiles of microwave-excited electrodeless discharge lamps.

The problems of line broadening in microwave-excited electrodeless discharge lamps for the more volatile elements, P, S, I, Se, Zn, Cd and Hg are discussed in relation to their use in atomic-absorption and fluorescence spectrometry. Both theoretical and practical implications are considered.

Some intense sources of radiation for the alkali and alkaline earth elements

Abstract Five new methods are described for the preparation of intense narrow line sources of resonance radiation for the alkali and the alkaline earth elements. Optimum conditions for their preparation and operation are described and their suitability for atomic fluorescence spectrometric purposes has been investigated. The most successful method involves a discharge in flowing atmospheric pressure argon in a quartz tube. A small quantity of the element (or element halide) of interest is suspended in a quartz cup in the discharge stream. The resulting source is applicable to a wide range of relatively involatile elements and, although it is somewhat short lived, it may be recharged readily. Microwave excitation of hollow cathode lamps was not found to be very useful for analytical purposes.

Comparison of a modification of the Ellman method to measure carbamate inhibition of acetylcholinesterase in plasma. Erythrocytes and brain tissues in Sprague Dawley rats using two analytical systems

Inhibition of the enzyme acetylcholinesterase (AChE) using a carbamate compound was measured in 30 Crl: CD(R)BR Sprague Dawley rats. Erythrocyte, plasma, and brain tissues were analyzed using modifications of the Ellman technique(1) on two different clinical chemistry analyzers. Both EDTA and heparin anticoagulated whole blood were used for the erythrocyte and plasma tests. Results demonstrated similar inhibition of the enzyme in all three tissues between the control and dosed groups using the two technique modifications and instruments. Final inhibition of plasma and erythrocyte AChE for the control vs. treated groups (males and females combined) was 89.5% vs. 82% and 39% vs. 38% for the Technicon AutoAnalyzertrade mark vs. the Boehringer Mannheim Hitachitrade mark 704, respectively. Inhibition of the left and right brain segments for the control vs. treated groups (males and females combined) was 35% vs. 39% and 33.2% vs. 29% for the Technicon and the Hitachi, respectively. All inhibitions were significant at the 5% level using two tailed Dunnetts t-Test. Hemolysates prepared from EDTA whole blood packed cells gave more consistent results on the Hitachi 704.

Application of photon-counting in atomic-absorption spectrophotometry

An analysis is given of the statistics of photon-counting as a means of making measurements in atomic-absorption spectrometry. It is concluded that the simple application of Poisson counting statistics may give an over-optimistic estimate of the error, since other sources of error, such as flame flicker and variable nebulization rate, may be more significant.