Compatibility of calcium chloride and calcium gluconate with sodium phosphate in a mixed TPN solution.

The maximum concentrations of phosphate that will remain soluble in a parenteral nutrient solution containing various concentrations of calcium chloride or calcium gluconate were determined. Various concentrations of sodium phosphate were mixed with FreAmine II (McGaw Laboratories), and the resulting solutions were mixed with 50% dextrose solutions containing various concentrations of calcium chloride or calcium gluconate. The final solutions were sealed and stored at 30 degrees C for 24 hours and then were inspected visually for precipitate formation. It was found that higher equivalent concentrations of phosphate are attainable when calcium gluconate, instead of calcium chloride, is used as the calcium source. Factors found to influence the concentrations of calcium and phosphate that are compatible in amino acid solutions are the calcium salt used, temperature and duration of storage, dextrose concentration, amino acid composition, pH, and other additives.