Use of ultrafiltration and chromatography to assess aluminum speciation inserum after deferoxamine administration

Deferoxamine effectively chelates aluminum by forming aluminoxamine, a low- molecular-weight compound removable by dialysis, However, aluminum-bound sp ecies other than aluminoxamine might be present in serum after the administ ration of deferoxamine. To study aluminum speciation after the administrati on of deferoxamine, high-performance liquid chromatography (HPLC) and ultra filtration techniques were used. Samples of serum were obtained from six di alysis patients 44 hours after the administration of a single dose of defer oxamine, HPLC and ultrafiltration studies were performed. In the HPLC studi es, samples underwent ultrafiltration, the filtrate was injected into the c hromatographic system, and detection was performed by UV light and atomic a bsorption spectrometry, Unknown species of aluminum other than aluminoxamin e were found in the early elution fractions. In the ultrafiltration studies , the same samples of serum from the six patients underwent ultrafiltration using membranes with different molecular-weight cutoff values from 1 to 30 kd, The percentages of aluminum found by ultrafiltration using membranes w ith cutoff values of 5, 10, and 30 kd were greater (64.4% +/- 2.5%, 63.5% /- 3.7%, and 65.6% +/- 4.3%, respectively) than the percentages obtained wi th membranes with a 1-kd cutoff value (38.7%), suggesting that the unknown species of aluminum have a molecular weight between 1 and 5 kd. The unknown species of aluminum cannot be aluminoxamine because they behaved in a diff erent way with HPLC. (C) 2000 by the National Kidney Foundation, Inc.