Chromatography of carbamates

We have attempted to stress the major areas of chromatographic techniques for carbamate analyses and also to illustrate the influence of carbamate moiety substituents on chromatographic behavior.

The remarkable versatility of chromatographic techniques, as demonstrated by their many applications to complex analyses, is apparent from the foregoing review. It has also been shown how powerful a tool chromatography is for research as well as for routine analytical work.

Thin-layer chromatography, introduced by Sthal in 1956²¹⁶, has largely replaced paper chromatography in many applications. In the past three years it has been increasingly applied to pharmaceutical and pesticidal analysis because of its simplicity of operation, rapidity and the high degree of resolution achieved. Under specified conditions, TLC lends itself to quantitation interpretation and is being used for analytical control and toxicological investigation.

Although gas chromatography was introduced only in 1952, it has seen extensive utility in many areas. However, it has not, until recent years, been widely used for either pesticidal or pharmaceutical analysis. This has been due not entirely to the expense of the equipment or the degree of operational sophistication required. A major difficulty has been the thermal instability of many of the carbamates and the necessary high operating temperatures required for compound volatilization. Derivatives of carbamates, such as trimethylsilyl¹³⁵ and acetyl²¹⁷ (successfully utilized in pesticidal gas chromatographic analysis because of the thermally stable nature of the respective compounds formed) suggest a similar feasibility for pharmaceutical carbamate analysis.

The desirability of a satisfactory selective detection system for nitrogen (alluded to in the work of Coulson¹³⁴ should greatly enhance the utility of gas chromatography to pharmaceutical and pesticidal carbamate analysis.