Limitations of ZAF correction factors in the determination of calcium/phosphorus ratios: important forensic science considerations relevant to the analysis of bone fragments using scanning electron microscopy and energy-dispersive x-ray microanalysis.
J Forensic Sci
; 35(3): 560-8, 1990 May.
Article
em En
| MEDLINE
| ID: mdl-2348174
ABSTRACT
A series of calcium phosphate standards having calcium/phosphorus (Ca/P) molar ratios of 0.50, 1.00, 1.50, and 1.67, respectively, was prepared for bulk specimen analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXA). The standards were mounted on carbon planchettes as either pure crystals or crystals embedded in epoxy resin. Ten different samples of each embedded and non-embedded standard were analyzed in a JEOL 100 CX electron microscope interfaced with a Kevex 8000 EDXA system using a lithium-drifted silicon detector and a multichannel analyzer. The Ca/P ratios were determined by calculating both net peak intensities without matrix corrections and atomic kappa-ratios using the MAGIC V computer program with ZAF correction factors for quantitative analysis. There was such extensive absorption of phosphorus X-rays in standards embedded in an epoxy matrix that the observed Ca/P ratios were statistically compatible with four different standards ranging in theoretical Ca/P ratios from 1.0 to 1.67. Although the non-embedded crystals showed a greater separation in the Ca/P ratios, both methods of preparation produced serious flaws in analysis. Direct application of the discovery of this caveat to the identification of suspected bone fragments for forensic science purposes is discussed.
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Base de dados:
MEDLINE
Assunto principal:
Fósforo
/
Osso e Ossos
/
Cálcio
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Idioma:
En
Revista:
J Forensic Sci
Ano de publicação:
1990
Tipo de documento:
Article