Zinc in peripheral blood

Peripheral blood is the most widely sampled body tissue because of the ease of access by venesection. The concentration of zinc in whole blood is about 6-7 mg Zn/L The concentration in the erythrocyte is about 10 mg Zn/L. The white cells individually contain some 25 times as much zinc as a red cell, but the concentration varies with the different types isolated from whole blood. Milne et al. (1965) have evaluated different 

The concentration of zinc in plasma/serum is lower than in the cellular components of blood, and for healthy persons is around 1 mg/L. 

This is by far the most commonly used test of zinc status. 

Plasma/serum samples require to be diluted before determination by flame AAS. The uptake rate of the nebuliser system is lower when dilute protein solutions are aspirated compared to aqueous calibration standards. This effect differs between instruments of different manufacture, being dependent upon nebuliser tube diameter and the gas flow and pressure. The effect can be overcome in a number of ways. At dilutions of plasma/serum of greater than 1 in 20, the viscosity of the diluted solution approaches that of water. This reduces the concentration of zinc in the test solution to around 0.05 mg/L and requires considerable scale expansion and a specially modified instrument (Dawson and Walker, 1969). 

A suitably viscous but inert fluid such as glycerol can be added to the calibration standards at a concentration which equalises the uptake rates. This is the basis of a Proposed Selected Method (Smith et al., 1979). This has been criticised by Kelson (1980) 

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G., and Rink, L., Flow cytometric measnrement of labile zinc in peripheral blood mononuclear cells, Analyt. Biochem. 352, 222-230, 2006. 

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