The objective of the current project is to develop methodology for quantitative analysis of low level aluminum in injectable biological products that contain aluminum, either, as a result of inadvertent contamination or through intentional addition. In developing methodology, the current project will utilize improvements in graphite furnace electrothermal atomizer design. Several limitations were often associated with earlier designs, the most important being, that the temperature distribution along the atomizer was not always uniform due to contact of atomizer tube ends with water cooled contact cylinders. Inevitably, this would cause memory effects as a result of matrix condensation at the cooler ends of the atomizer tube. A more recent atomizer design, as will be utilized in the current study, consists of a transversally heated graphite tube as opposed to a longitudinally heated one. This design will provide a more uniform temperature distribution over the entire tube length, i.e., the atomizer tube ends will reach the same temperature as the tube center during the atomization stage. Under these conditions, the formation of free atoms will be optimal, molecular formation from atoms will be decreased, the loss of atoms will be minimized, and condensation at the cooler tube ends, which can produce memory effects, will be substantially eliminated. In evaluating the new atomizer, method development will focus primarily on three areas of experimental investigation. These areas include: 1) initial sample preparation (digestive vs non-digestive techniques), 2) instrumental parameter optimization, which involves, temperature ramping, drying time and temperature, thermal pretreatment time and temperature, atomization temperature and time, gas flow rate optimization, and 3) matrix modification, which is a technique to give better separation of the analyte from matrix components by making the matrix more volatile and/ or stabilizing the analyte. Method validation will be accomplished by determining the accuracy, precision, specificity, detection limit, quantitation limit, linearity and range when determining the aluminum content of various inter-laboratory and intra-laboratory reference materials as well as various low level aluminum containing biological products.
