Micromethodfor DeterminingTotal Iron-BindingCapacity by FlamelessAtomicAbsorptionSpectrophotometry

Because of the large quantities of venous blood required, assays of total iron-binding capacity (TIBC) and serum iron are often omitted in diagnostic tests involving small children. As an alternative to the conventional method of assessing TIBC, we developed a micromethod based on flameless atomic absorption spectrophotometry (flameless AAS). Additionally, the standard microproc#{233}dure for determining serum iron was modified so that iron concentration could be estimated from the same iron standards used to calculate TIBC. With these procedures, only 20 MI of serum is required to prepare protein-free supernate for measurement of TIBC or serum iron with an atomic absorption spectrophotometer equipped with a graphite furnace and a recorder. The resulting TIBC, serum iron, and computed transferrin saturation values Compared well with those obtained by conventional flame atomic absorption spectrophotometry. The correlation was statistically significant at the 99% confidence level. These flameless AAS micromethods provide an accurate and sensitive means of determining both TIBC and serum iron in a totalof 40 MI of serum, a quantity easily collected from a fingertip puncture, and hence are appropriate for routine laboratory work in pediatric clinics and for large-scale nutrition surveys.