Preparation of an intra-laboratory reference material--determination of the aluminum content of a pooled 5% albumin (human) solution by ETAAS, MFS and ICP-AES.

Human albumin solutions as well as other biological products intended for human use may contain aluminum as a result of intentional addition due to manufacturing protocol or through inadvertent contamination occurring during the manufacturing process. Because of the implication of aluminum in human disease, it is desirable that aluminum levels in these products be monitored. To satisfy the need for a reference material that is representative of albumin products that are intended for therapeutic use, a pooled 5% human albumin solution was prepared in bulk to serve as a reference for aluminum during analytical procedures. Aliquots of the albumin pool were analyzed for their aluminum content by three independent analytical methods, namely, electrothermal atomic absorption, molecular fluorescence and inductively coupled plasma-atomic emission spectrometry. Measured values for aluminum in the albumin solution showed good agreement between the different analytical methods. The concentration of aluminum was determined to be 0.512 microgram Al/ml by the atomic absorption method, 0.502 microgram Al/ml by molecular fluorescence, and 0.498 microgram Al/ml by the inductively coupled plasma-atomic emission method. The overall average concentration was calculated to be 0.507 microgram/ml +/- 0.009 micrograms Al/ml. The preparation of the albumin reference and its subsequent aluminum analysis is described.

Dissolution of cast aluminum in different denture cleansers.

Aluminum is one type of metal base material used as an alternative to acrylic resin. This study evaluated whether commonly used denture cleansers cause leaching of the metal base into the cleaning solution. Seven cleansers (Efferdent, Polident, Clorox, Clorox/Cascade, vinegar, Tartar and Stain Remover, and Ivory soap) and two controls (tap water and distilled water) were evaluated. One hundred thirty-five wax samples (30 x 30 x 1 mm) were cast in 99.4% pure aluminum. The 135 samples were randomly assigned to the nine cleanser groups. Each sample was soaked in a cleanser for 0.5, 1, or 8 hours, and the amount of aluminum present in each cleanser was then analyzed by atomic flame-emission spectrometry. The results indicated that all cleansers leached aluminum into solution in varying amounts. Tartar and Stain Remover and Clorox caused the greatest leaching, whereas Ivory soap and Efferdent leached the least.

Aluminum content of source plasma and sodium citrate anticoagulant.

The concentration of aluminum was determined in samples of source plasma collected by the normal plasmapheresis procedure, which involves collection in anticoagulant and immediate freezing. Samples of sodium citrate anticoagulant used in the collection of source plasma were also tested for aluminum, as were empty source plasma containers and 0.9% sodium chloride infusion (USP). Samples of source plasma were collected from a geographic cross-section of the donor population in the USA by three different manufacturers. Aliquots of these samples were mixed with Triton X-100 and sulfuric acid and analyzed for aluminum by atomic absorption spectrometry using electrothermal atomization (graphite furnace) and Zeeman background correction. The arithmetic mean and standard deviation for the aluminum content of 28 samples of source plasma were found to be 25.5 +/- 8.4 ng Al/ml. The aluminum content of the individual samples of source plasma ranged from 12 to 48 ng Al/ml. The aluminum content of 6 samples from two manufacturers of the sodium citrate anticoagulant that is used in source plasma ranged from 410 to 2,080 ng/ml. Aluminum levels found in saline for infusion and nitric acid leachates from empty source plasma containers were less than 6.9 ng/ml. The level of aluminum expected in uncontaminated human blood has been estimated to be 10 ng Al/ml or less. Comparison of this figure with the present data indicates that the sodium citrate anticoagulant contributes significantly to the aluminum load of source plasma and, therefore, to the aluminum content of products such as albumin derived from source plasma.

Aluminum toxicity and albumin.

During a study of priming solutions for extracorporeal membrane oxygenation (ECMO) in the intensive care nursery, it was discovered that those solutions using certain brands of 25% albumin contained aluminum levels within the toxic range. When the brand was changed to a brand known to have a lower aluminum (Al) content, a marked drop in priming solution Al levels was measured. The heat exchanger was examined as a possible source of soluble Al. No evidence of elevated Al levels was found in fluids perfusing this heat exchanger when compared with a stainless steel heat exchanger. The Al content of various blood products was evaluated along with various brands of 5% albumin and 25% albumin.

Measurement of total calcium in biological fluids: flame atomic absorption spectrometry.

The measurement of total calcium (CaT) in biological fluids by flame atomic absorption spectroscopy (FAAS) is one of the more accurate yet practical methods available today. With attention to details at every analytical step, the imprecision of FAAS outlined above can be as low as +/- 0.01 mmol/liter at the 2.65 mmol/liter upper reference level of CaT found in the serum of healthy young adults (a CV of 0.4%). The accuracy of FAAS as judged by measurements of NBS/SRM #909, a lyophilized serum material carrying CaT values assigned by isotope dilution mass spectrometry, can be within +/- 1% (recovery of 99-101%) or less in skilled hands. As our brief section on application suggests, FAAS methods for CaT can be adopted to provide rapid and accurate results in many different biological fluids and tissues.

A survey of the concentrations of eleven metals in vaccines, allergenic extracts, toxoids, blood, blood derivatives and other biological products.

Approximately 85 samples of injectable biological products regulated by the Center for Drugs and Biologics of the United States Food and Drug Administration were surveyed for the presence of 11 elements, namely aluminum, arsenic, barium, cadmium, chromium, lead, mercury, selenium, thallium and zinc, by flame and flameless methods of atomic absorption spectrometry and flame emission spectrometry. The range of products tested included whole blood, red cells, plasma, normal serum albumin, antihemophilic factor, and other products derived from blood; allergenic extracts including honey bee venom and house dust allergenic extracts; vaccines such as measles virus vaccine and typhoid vaccine; and tetanus toxoid. The metal concentrations found in the majority of these products were low or undetectable. The metal levels varied from manufacturer to manufacturer, product and lot-to-lot of the same manufacturer's products. House dust allergenic extracts had the highest concentrations of arsenic (2.4 ppm), cadmium (0.28 ppm), chromium (0.6 ppm) and lead (1.5 ppm) found in the study. A high zinc concentration (24 ppm) in an immune serum globulin was attributed to the zinc-containing rubber stopper in contact with the product. A range of 0.36-3.30 ppm aluminum was found for seven 25% normal serum albumin samples from seven manufacturers. Values of 8.2, 17 and 18 ppm aluminum were found in one manufacturer's 25% normal serum albumin. These aluminum values appeared to be the result of an anomaly in this manufacturer's production that has not been repeated to date.

Innovations in atomic absorption spectrophotometry with electrothermal atomization for determining lead in foods.

A simple and rapid method is described for the determination of lead in foods. The samples are digested in HNO3, HF, and HClO4 and then the lead is determined by atomic absorption spectrophotometry using an electrothermal atomizer with the L'vov platform. Interferences and ways to improve the precision and accuracy of the analysis were studied. Matrix modification using 1% ammonium phosphate alleviated most interferences encountered. The precision and accuracy of the method was evaluated using NBS SRM 1570 Spinach and SRM 1566 Oyster Tissue. The values obtained are in good agreement with the certified values.

Brain destruction alone does not elevate brain aluminum.

Graphite furnace atomic-absorption spectroscopy was used to measure aluminum concentrations in brain samples from 33 patients dying from a variety of neurologic diseases. Four samples from patients dying of nonneurologic causes also were studied. Nine samples (one from each of nine patients) of Creutzfeldt-Jakob disease brain contained normal amounts of aluminum. Aluminum was increased in 9 of 18 brain specimens with seven different pathologic processes. This included three of seven Alzheimer disease, two of three Huntington disease, two of two Parkinson disease, one of one progressive supranuclear palsy, one of one acoustic neuroma, one of two cerebrovascular disease, and one of two Guamanian amyotrophic lateral sclerosis (ALS). Aluminum was normal in the remaining samples (four normal, two ALS, one multiple sclerosis, one Pick disease, and two Guamanian parkinsonism-dementia). The significance of high aluminum values is not clear, but the normal values from the Creutzfeldt-Jakob cases imply that neuronal destruction per se need not lead to accumulation of aluminum in the brain.

High-purity calcium carbonate in freshwater clam shell.

The calcium carbonate in freshwater clam shells is simlilar in purity to that designated reagent grade. A simple reprecipitation of the shell extract results in a product having less Sr and Mg than reagent grade CaCO(3). Clams are harvested commercially, and discarded shells are a high-quality raw material for the production of CaCO(3).