Abstract
The stabilities of the vitamin B1 derivative, cocarboxylase (TDP), in eighteen amino acid infusions were investigated by HPLC and the contents of sulfite and sulfate ions in the amino acid infusions were determined by isotachophoresis. We also investigated the relationship between the stability of TDP and the concentration of sulfite ion in amino acid infusions. The results obtained were as follows.
1) There were remarkable differences in the stability of TDP among the amino acid infusions tested. The residual amount of TDP after 24 h in the most stable case was 86% for Amiyu®, and those in the most labile cases were 28% and 23% for Kylit® AS and Teruamino®-12X, respectively.
2) TDP was stable in 0.1 N phosphate buffer (pH 3.0-7.0) in the absence of sodium bisulfite (SBS) . TDP decomposed in the presence of SBS (0.01%), and the rate of decomposition of TDP depended on both the pH of the buffer solution and the concentration of SBS. The decomposition of TDP was accelerated the most in buffer solution around pH 6.0.
3) There were the remarkable differences in the concentration of sulfite ion among the amino acid infusions tested. The highest content of initial sulfite among them was 104 mM in Teruamino®-12X, while the lowest was 0.98 mM in Klinitamin®. In general, most amino acid infusions contained SBS at 2-4 mM.
4) A relationship between the stability of TDP and the concentration of SBS in amino acid infusions was not revealed, however the decomposition of TDP in amino acid infusions was assumed to be accelerated by the combination of pH of amino acid infusions and the concentration of sulfite ion in amino acid infusions.
