Continuous flow configuration for total grease and surfactant determination in industrial degreasing baths

A simple and robust continuous system for the sequential determination of total grease and surfactant contents in industrial degreasing baths has been developed. The two families of compounds are extracted from the samples by liquid–liquid extraction and aliquots of 250 μl of the organic extract are automatically passed through a silica sorbent column for surfactants retention while the greases are directed to the evaporative light scattering detector for fraction monitoring. Complete separation of both families of compounds in the continuous flow system and right peak assignment was corroborated by ATR-FTIR analysis. The proposed method exhibits an adequate linear ranges and excellent precision, which makes it suitable for the determination of both parameters in these industrial samples. Finally, 15 real samples obtained from pre-cleaning and cleaning baths from a production line of one of these industries were analyzed by the proposed continuous flow analyzer and by a reference gravimetric method with satisfactory results.