Elemental Analysis of Environmental Samples by Total Reflection X-Ray Fluorescence: a Review

Abstract

A review of total reflection x‐ray fluorescence (TXRF) as an effective excitation mode for energy‐dispersive x‐ray spectral analysis is presented. The instrumental conditions of excitation under grazing incidence (ψ<0.1°) are emphasized and the analytical features of powerful detection and simple and reliable quantification are characterized. The applicability of TXRF to environmental analyses is illustrated by some typical examples. The analysis of pure water samples leads to detection limits at the ppt (ng/l) level. A special matrix separation is only needed for river, sea and waste waters. The analysis of air dust is directly possible with a sampling volume of 1 m3 and a sampling time of 1 h. Organ tissue can be analysed down to the lower ppm range after freeze‐cutting of μm thick sections. Plant material has to be pulverized and digested prior to analysis, e.g. with nitric acid. In combination with a chromatographic separation, speciation is made possible for small 0.5 ml fractions, e.g. for vegetable foodstuffs. For all these applications a multi‐element determination can be carried out, for about 20–25 elements simultaneously. Simple and reliable quantification is effected by internal standardization. The reliability of the method has been proved by intercomparison tests. Second‐generation instruments that are compact and user‐friendly are now commercially available.

Determination of elements in water using a total reflection X-ray fluorescence spectrometer

“…Применение эффекта полного внешнего отражения (ПВО) в рентгеновских спектрометрах позволяет существенно снизить пределы обнару-жения элементов в водах (до 1-10 мкг/л и ниже). В зарубежной практике применение РФА ПВО (ан-глийская аббревиатура − TXRF) для исследования элементного состава воды -одна из традиционных его задач [56][57][58][59][60][61][62]. Жидкие образцы считаются «удобными» объектами для РФА ПВО из-за от-носительно простой процедуры приготовления излучателя, которая заключается в высушивании фиксированного микроколичества пробы (исходной, разбавленной или после концентрирования и раз-ложения), в которую добавлен внутренний стандарт, на подложке-отражателе.…”

Depth profiles of Al impurities implanted in Si wafers determined by means of the high-resolution grazing emission X-ray fluorescence technique

“…GEXRF is based on the same physical principle as TXRF [8] which is the refraction of x-rays due to a sudden change of the refractive index. GEXRF is therefore, like TXRF, used for the analysis of thin layers to determine their thickness and density or the quantification of trace amounts of impurities on surfaces.…”

Synchrotron radiation induced TXRF

“…Total reflection X-ray fluorescence analysis is a well established analytical technique for the detection of major, minor and trace elements [1][2][3] especially suited for samples, where only small specimen mass is available. Moreover TXRF can be used to investigate wafer surface contaminations or determine depth profiles in the near surface region and determine the implantation dose when using the angular dependence of the fluorescence signal.…”