Comparison between proton-induced X-ray emission (PIXE) and total reflection X-ray fluorescence (TXRF) spectrometry for the elemental analysis of human amniotic fluid

A comparison between use of proton-induced x-ray emission (PIXE) and total reflection x-ray fluorescence (TXRF) techniques in relation to the elementa l analysis of amniotic fluid (AF) was carried out by measuring the concentr ations of Cl, K, Ca, Fe, Cu, Zn and Br, For 10 AF samples analyzed, the agr eement between PIXE and a TXRF measurements was 100% for K, 60% for Cl and Ca, 80% for Fe and 50% for Cu, For Zn, although there was only a 20% agreem ent, the measured concentrations ranged between 0.1 and 1 mu g/ml with a TX RF standard deviation as high as 0.070 mu g/ml. For Br, a factor of 1.8 +/- 0.2 was obtained between TXRF and PIXE measurements, suggesting a systemat ic error between experiments. This work indicates that further investigatio n is required to determine the experimental conditions, e.g. sample prepara tion and irradiation, which lead to complete agreement between TXRF and PIX E when a complicated organic sample such as amniotic fluid is analyzed, Cop yright (C) 1999 John Wiley & Sons, Ltd.