Скачать книгу

development and function, and also interfere with the normal functioning of other bodily organs and systems. Exposure to Pb can pose a substantial risk to nervous, immune, renal, skeletal, and hematopoietic systems of both adult and children. Neurological, physiological, and behavioral disorders in children due to Pb exposure, are very common. According to the US Centers for disease control and prevention (CDC), 10 μg/dl or higher concentration of Pb in blood is considered as “elevated” or a “level of concern.” However, it has been shown that even blood Pb concentrations below 10 μg/dl are inversely associated with children's intelligence quotient (IQ) scores at three to five years of age. As a result of these findings, the CDC has recommended changes for the threshold of acceptable elevated blood Pb concentrations to 5 μg/dl.

      6.3.2 Role of EDXRF in Diagnosis of Blood Lead Level

      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.

      6.3.3 Collection of Blood Sample and Preparation

      Five milliliters of venous whole blood was drawn by disposable syringe. The blood sample was transferred immediately into a labeled container and stored in an ultra‐freezer at −20 °C to avoid any microbial growth. Blood samples should be collected in plastic containers prior to pretreatment and kept in a 20% nitric acid solution for 24 hours, properly rinsed with deionized water, and dried. The empty weight of all containers were taken before being stored in a plastic covering. The total weight of blood with containers was taken at room temperature. Subtracting the empty weight of the container gave the weight of the fresh sample. The samples were dried in an oven at 60–70 °C for four to six days. The dried samples were powdered in a carbide mortar with the help of a pestle and preserved in desiccators until subsequent analysis [15].

      6.3.4 Preparation of Pellets from Powdered Sample

      6.3.5 Sample Irradiation

Photo depicts pellet of blood sample. Photo depicts energy dispersive X-ray fluorescence (EDXRF) system.

      6.3.6 Precision and Accuracy of the Result

Скачать книгу


Elements Elemental concentration in Orchard leaf/NIST 1571 (mg/kg) Mean SD Certified value Orchard leaf/NIST 1571 RE (%) CV (%)