Читать книгу X-Ray Fluorescence in Biological Sciences - Группа авторов - Страница 84

Lead (Pb) enters the body primarily by absorption through the gastrointestinal tract or by inhalation. It is estimated that about 11% of Pb in adults and 25–48% in children has been absorbed from the gastrointestinal track. After entering the body it infiltrates different bodily organs unequally. Pb concentrations in bone tissue rises from 8% to 90% after just 20 hours after entering in the body. Blood is the media responsible for transporting Pb throughout the body, and hence Pb can be monitored by measuring Pb concentrations in blood serum (S─Pb), blood plasma (P─Pb) or whole blood (W─Pb) samples. However, blood serum and blood plasma do not give a full indication of blood‐Pb level in a human body; therefore measurement Pb levels in whole blood is preferable to S─Pb or P─Pb measurements. According to Donald Smith et al. [14], Plasma Pb levels are approximately 0.29% on average of whole‐ blood Pb level.

Atomic absorption spectrometry (AAS), inductively coupled plasma‐atomic emission spectroscopy (ICP‐AES), polarography, and inductively coupled plasma mass spectroscopy (ICP‐MS) have been used for determining blood Pb levels in S─Pb or P─Pb for years. But this poses problems, namely that all these techniques require large volumes of samples. Moreover they cannot measure whole blood samples, as these contain fat bodies. However, collection of biological samples in large volumes is very complicated. On the other hand sample preparation for those instruments requires special attention and is thus time‐consuming. In this case EDXRF is the only suitable tool for measuring Pb concentrations in whole blood samples as it requires only small amounts of sample material, and is nondestructive and versatile in comparison with other techniques.