Ether-insoluble substances, olive oil production as a result of bad or faulty operations in the oil and volatile substances insoluble in petroleum ether is the name given to the total foreign matter. Among these are sand, soil and similar substances, as well as oxidized fatty acids, nitrogenous substances, mineral substances, carbohydrates and some resin and calcium residues.

In 2014, the Ministry of Food, Agriculture and Livestock issued the Turkish Food Codex Communiqué on Methods for Analysis of Olive Oil and Olive Oil (Communiqué no: 2014 / 53). This Communiqué specifies the methods of analysis for olive oil and pomace oils. Numerous analysis methods are included in the annexes of the Communiqué. Similar methods are used for determination of ash with insoluble foreign matter in ether.

A certain weight sample is placed in the apparatus, a certain amount of ether is added and shaken off. After standing for about half an hour at 20 degrees, it is filtered through a tared ashless filter paper. The filter paper is washed with a small amount of ether until no oil remains. The filter paper is removed from the device and the solvent is evaporated. Then 103 degree is kept in the oven. It is then weighed with cooling. If ash is found in the filtrate, the solvent is removed by careful evaporation and the residue is incinerated in a tared vessel and the remaining ash is weighed. The amount of ash is calculated as a percentage.

In authorized laboratories, within the framework of chemical tests determination of ash and insoluble foreign matter in ether. In these studies, the standards issued by domestic and foreign organizations are complied with. The standard used in these studies is as follows:

• TS EN ISO 663 Animal and vegetable fats and oils - Determination of insoluble impurity content

This international standard describes the method for the determination of peroxide value in animal and vegetable fats and oils by iodometric method.