Which of the following is a type of chromatograph used in the investigation of coating failures?

Gas-liquid chromatography is particularly useful in the investigation of coating failures because it allows for the separation and analysis of volatile compounds that are often present in coatings and their breakdown products. This technique involves passing a gas (the mobile phase) through a column containing a liquid stationary phase, enabling the identification and quantification of various components based on their boiling points and affinity for the stationary phase.

In the context of coating failures, gas-liquid chromatography can help identify solvents, plasticizers, and additives that may contribute to the degradation of the coating. By analyzing the composition of the coating materials and any byproducts resulting from their failure, inspectors can gain valuable insights into the causes of the failure and potential solutions to rectify the issues.

The other methods mentioned, such as high-performance liquid chromatography, capillary electrophoresis, and column chromatography, while useful in certain analytical contexts, are less commonly employed for the specific type of analysis needed in coating failure investigations. Each of these methods has its own set of applications and advantages, but gas-liquid chromatography stands out for its effectiveness in dealing with the kinds of substances usually found in coatings.