Analysis of feed blends containing microencapsulated 2‐ethyl‐1‐hexanol: Verification of homogeneity and stability

Abstract

2‐ethyl‐1‐hexanol (2‐EH) was nominated for carcinogenicity testing by the National Toxicology Program because it is a high‐volume chemical and a major metabolite of di(2‐ethylhexyl)phthalate, a known hepatocarcinogen and a known contaminant in blood storage bags. In addition to uses as an intermediate in the manufacture of plasticizers, 2‐EH is also used as a solvent, a lubricant and as a finishing compound for paper and textiles. The preferred route of administration for the carcinogenicity studies was oral via the diet. However, feed blends containing neat 2‐EH were not sufficiently stable for feed studies. Dosed feed blends prepared with neat 2EH retained only 86% of the theoretical concentration after blending, and 46% of theoretical after storage for 2 days in a rat cage environment. Feed blends containing microencapsulated 2‐EH were sufficiently stable for toxicity studies: no losses of 2‐EH were observed after blending, feed blends stored for 7 days in a rat cage retained 99% of the theoretical concentration and blends stored in sealed containers at room temperature for 21 days retained 97% of the theoretical concentration. These studies demonstrate the potential for microencapsulation technology to eliminate dose formulation problems associated with volatile chemicals.