ISO 28198:2009 specifies a method for the determination of the content of toluene insoluble matter (TIM) in lecithin formulations, which indicates the presence of impurities such as protein, carbohydrate-containing extraction residues and other solid contaminants. This method is applicable to all types of vegetable lecithin.
The purpose of the method is to enable the analysis of lecithin under several regulations. Lecithin [Codex International Numbering System for Food Additives (INS) No. 322] is a generally permitted additive and the determination of the TIM is part of many specifications. The purity requirement with regard to TIM content is based on the method specified.
Toluene is the replacement for the carcinogenic benzene, which was used in older methods.