Michael A. Mignardi

High-Resolution continuum-source atomic absorption spectrometry in an inductively coupled plasma with photodiode array detection

Abstract Atomic absorption spectrometry (AAS) is a well established technique using flames and graphite furnaces. An inductively coupled plasma (ICP), however, is an attractive alternative atom/ion reservoir. A high-resolution continuum-source atomic absorption spectrometer with a photodiode array detector and an ICP as the atomization/ionization reservoir is described. Multi-wavelength capability permits the simultaneous determination of several elements by their atomic and/or ionic transitions. Each acquired spectrum is averaged for 10 s to improve the signal-to-noise ratios. Detection limits are calculated for 14 elements and compared with literature values.

Determination of Phosphorous by ICP-AES Using Solid-Phase Hydride Generation

Abstract A reliable and sensitive analytical optical method for the determination of phosphorous in oceanographic and environmental materials does not exist. In this work, a novel hydride generation method was used to form phosphine from a sample containing phosphate mixed with 7% sodium borohydride. By heating the mixture to 500 °C, phosphine was reproducibly generated and collected in a cold trap. Phosphine was then introduced into an ICP where several atomic emission lines for phosphorous were observed. Copper emission did not spectrally interfere with phosphorous atomic emission with this hydride generation-ICP-AES method. This hydride generation method allows the use of small sample volumes (< 5 μL).

Time-Resolved Constant-Energy Synchronous Phosphorimetry

Constant-energy synchronous scanning has been combined with time resolution in order to increase the spectral selectivity in low-temperature phosphorimetry. The technique is called Time-Resolved Constant-Energy Synchronous Phosphorimetry (TRCESP). The personal computer-controlled flashlamp phosphorimeter consisted of a conventional spectrophosphorimeter with computer control of the scanning of the excitation and emission spectrometers. Temporal features such as the repetition rate, source pulse width, delay time between termination of the source pulse and the gate opening, and detector gate width were under various forms of electronic control. A discussion of the spectral resolution resulting from synchronous scanning and temporal resolution from pulsing the source and gating the detector is given. Several mixtures of phosphors are evaluated with respect to the effect of spatial resolution, temporal resolution, and combination of the two resolution approaches upon both sensitivity and selectivity measurements.

Evaluation of a pulsed flash-tube for inductively-coupled plasma atomic-fluorescence spectrometry

A pulsed continuum xenon flash-tube is used as an excitation source in ICP-AFS. The simultaneous excitation of many elements is attractive and avoids the one source per element as in conventional ICP-AFS. In this study, the pulsed continuum flash-tube is evaluated as an excitation source for multielement atomic fluorescence spectrometry in an ICP. Analytical figures of merit are given for the elements studied.

High-resolution continuum source atomic absorption spectrometry in an air-acetylene flame with photodiode array detection

A high-resolution continuum source atomic absorption spectrometer using a photodiode array detector and flame atomisation is described which provides wavelength versus absorbance spectra over a 2.5-nm spectral range. The multi-wavelength detection power allows the simultaneous determination of several elements, reduces problems caused by spectral interferences and automatically corrects for non-zero background absorbance. Each spectrum is acquired in 33 ms and many successive spectra can be averaged to improve the signal to noise ratios. Limits of detection calculated for nine elements range from 0.03 mg l–1 for magnesium to 10 mg l–1 for nickel.

Constant-energy synchronous, time-resolved, room-temperature phosphorimetry☆

Abstract The combination of constant-energy synchronous luminescence spectrometry (CESL) with a pulsed source and gated detection is used to demonstrate the analytical power of time resolution CESL in room-temperature phosphorimetry. The instrumentation is discussed. Two binary mixtures are evaluated to demonstrate the spectral simplification of this technique.

Determination of Polycyclic Aromatic Hydrocarbons in Cooked Beef by Low-Temperature Molecular Luminescence Spectrometry Using a Moving Sample Cooling Belt

Four polycyclic aromatic hydrocarbons are identified in broiled hamburger at the part per billion level by low-temperature molecular luminescence spectrometry (LT-MLS). Hamburger extracts in a Shpolskii solvent are injected onto a moving sample cooling device maintained at 15 K in a vacuum. Results obtained by the present system are compared with those obtained by constant energy synchronous luminescence spectrometry (CESLS) at 77 K and by high-performance liquid chromatography (HPLC) with multiwavelength detection.

Constant energy synchronous, time-resolved phosphorimetry☆

Abstract The combination of constant energy synchronous luminescence spectrometry (CESLS) with a pulsed source-gated detector is used to demonstrate the analytical power of time-resolved CESLS in phosphorimetry. Several binary mixtures are evaluated to demonstrate the spectral simplification of this approach.

On the Observation of an Atomic Fluorescence Double-Resonance Excitation Process in an ICP Induced by a Spectral Continuum Source

Double-resonance fluorescence refers to a process in which atoms (or molecules) are excited into the fluorescence state in a stepwise manner with two lasers tuned at appropriate atomic (or molecular) energy levels. The analytical advantage of such excitation processes as compared to that involving only one step (single-resonance fluorecence) lies in its increased spectral selectivity without a significant loss of sensitivity if both excited state transitions are saturated. Several analytical studies performed with tunable lasers in atmospheric-pressure atomizers have been reported in the literature.

Evaluation of a cryogenic miniature refrigeration system for low-temperature molecular luminescence spectrometry

Abstract A small cryogenic refrigeration system is presented as a means for cooling samples in low-temperature molecular luminescence spectrometry. Analytical figures of merit are shown for three compounds adsorbed on filter paper. The results are used to compare the system to other sample cooling systems. The advantages and disadvantages of using the commercially available refrigerator as a sample cooling device are discussed.