DIFFERENT FIELDS OF APPLICATIONS - Total-Reflection X-Ray Fluorescence Analysis and Related Methods - page 329

The drug powder was ground ( < 10 μ m), mixed with an aqueous solution of
Triton X-100, and homogenized. Gallium was added as an internal standard
(20 μ g/ml). Finally, 10 μ l of the slurry was deposited on quartz glass, simply
dried in air, and analyzed by TXRF. The method was tested by a quantitative
analysis of the standard reference material IAEA-085“Human hair”and
found to be reliable for several elements; lead could not be detected. The
content of lead in the powder was about 17 mg/g (29 mg/g zinc and 23 mg/g tin).
Consequently, the patient ingested 80 mg lead per day and about 15 g during
6 months.
An intake of 60 μ g lead per day during a period of 1 month will cause chronic
poisoning with life-threatening symptoms (kidney, lung, bones). However, the
patient was in a very poor but not yet critical condition. Of course,
the crystalline compound of PbO can hardly be leached in a toxic form in
the gastrointestinal tract. In the patient's hair, the element lead was found with
a concentration of 17.2 mg/g. One hundred and forty persons in the region of
Brescia, Italy were checked, but only 22 persons showed lead in hair with a low
average of 1.6 mg/g.
All the examples demonstrate the suitability and versatility of TXRF for a
rapid screening of biosamples in the medical, clinical, and pharmaceutical
practice. Different samples, such as blood, serum, and other body fluids, but
also human tissue, nails, and hair as well as drugs can be analyzed in a rapid and
simple manner. Only small or even tiny samples are necessary, offering the
advantage of noninvasive and cheap clinical screening and monitoring of
patients and the possibility of time-dependent investigations.
5.4 INDUSTRIALORCHEMICALAPPLICATIONS
Because of its simplicity, multielement capability, and detection power,
TXRF is highly suitable for the analysis of industrial and mainly chemical
products. TXRF is the method of choice for quality control of ultrapure
reagents needed in the electronics, cosmetics, and pharmaceutical industry.
Some high-purity-grade acids, bases, and solvents, including high-purity
water, can be analyzed nearly directly down to the level of 0.1 ng/ml [115].
Further applications are concerned with high-purity metals like alumi-
num [116] or iron [117] and with ultrapure nonmetals like silicon [118,119]
or silica [118]. These solid products can be analyzed in the sub- μ g/g region
after an appropriate matrix separation.
The TXRF analysis of hydrocarbons and their polymers, and of mineral and
synthetic oils, is another field of industrial interest, for example, for the
petroleum refining industry and for engineering. It is especially useful for
the determination of trace metals in light and heavy crude oils [120], lubricating
oils [121-123], motor oils [124], and diesel fuels [125,126]. Light oils can be
applied to the carrier as drops but should first be diluted with chloroform [121]
or toluene [122] and then heated. Such a preparation can be highly convenient