As all inlet liners gradually become dirty and the surface becomes active they become unsuitable for most sample analysis.
Some laboratories adopt the risky practice of cleaning and then deactivating their liners.
Regardless of whether the liner has visible deposits, charring or discolouration, the process of cleaning will involve the use of solvents such as Methanol, Methylene Chloride, and Hexane. As for deactivation, many labs use Dimethyldichlorosilance in dry Toluene. Most of those chemicals are category 1 and 2, and some of the long term exposure will cause damage to organs, reproductive toxicity, and aspiration hazards. In addition to the hazardous nature of those chemicals, they are costly to purchase and equally expensive to dispose.