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In order to address global environmental issues, a standard-free method developed by ourselves has been successfully applied to various kinds of bio-samples. Especially, a method for untreated hairs has been applied in many polluted areas to study human exposure to toxic elements. In addition to hair, nail is expected to give us valuable information about human exposure to toxic elements. However, the analysis requires relatively large amounts of samples and laborious sample preparation techniques which necessitate internal standards. In this work, we have developed a quantitative method for untreated human-nail analysis based on the standard-free method. It requires neither large amounts of nails nor complicated target preparation procedure. Furthermore, it is perfectly free from any ambiguity in target preparation such as volatilization of certain elements and contamination of the sample during chemical ashing. The optimum conditions of irradiating nail samples are established, and accuracy and reproducibility of the present method are confirmed. It is found that ultrasonic washing in distilled water is effective for many nail samples preventing the loss of elements from the sample. It is also found that elemental concentration in nails strongly depends on their sampling positions.

Standard-free method for untreated hair samples in in-air PIXE has been developed. It is confirmed that the method gives us good sensitivity and accuracy within several minutes' measurement if more than twenty hairs are attached onto the target. Even in the case where the number of hairs is less than eight, which is regular for usual in-vacuum PIXE, 10-15 minutes measurement is found to be sufficient to achieve almost satisfactory sensitivity and accuracy for elements from Cl to Pb. As the present method allows us to carry out analyses without labor in target preparation, it is expected to be quite helpful in the studies on human exposure to toxic elements. Its availability will more and more increase when the method is combined with the method of simultaneous measurement of in-vacuum and in-air PIXE we have just developed.

A standard-free method for hoof samples taken from cattle such as cow, calf, pony and sheep has been developed in order to estimate the state of health of these animals. The standard-free method developed for human nails was confirmed to be applicable to quantitative analysis of hoof samples since the shape of continuous X-rays is almost the same for nail and hoof taken from these ungulate animals. Accuracy and sensitivity of the present standard method were examined by comparing the results with those obtained by an internal-standard method combined with a chemical-ashing method, and it is confirmed that the method is applicable to hoof samples taken from domestic animals of many species. The method allows us to quantitatively analyze untreated hoof samples and to prepare the targets without complicated preparation technique which often brings ambiguous factors such as elemental loss from the sample and contamination of the sample during preparation procedure. It is also confirmed that halogens, which are important elements for estimating the state of health and are mostly lost during chemical-ashing, can be analyzed without problem by the present method. It is found that elemental concentration of more than twenty elements can be constantly analyzed and it is expected to be quite useful in order to estimate the state of health and to make diagnosis of domestic animals. It is also confirmed that elemental concentration of essential elements in hoof is not so changed depending on the positions in the sliced sample along both horizontal and vertical axis.

The standard-free method developed by ourselves 13 years ago has been widely applied to quantitative analyses of hairs such as head hair taken from human and body hair taken from companion and domestic animals. In the present work, the standard-free method for feather and down samples taken from wild birds such as swan, waxwing, osprey, heron and crow is developed. It is found that the standard-free method developed for human hairs can be successfully applied to feather samples without essential modification since the main constituents of feather are almost the same as those for human and animal hairs and, consequently, the shape of continuous X-rays is also the same. Accuracy and sensitivity of the present method were examined by comparing the results with those obtained by an internal-standard method combined with a chemical-ashing method. The method allows us to quantitatively analyze untreated feather samples of very small quantities and to prepare the target without complicated preparation technique. It is expected that the method will become a powerful tool for the studies not only on the mode of life of wild birds but also on environmental contamination by toxic elements.