APPENDIX 



DETERMINATION OF OIL EVAPORATION BY 

 GAS CHROMATOGRAPHY 



Gas chromatography can be used to estimate the losses of volatile 

 components from fuel oils or crude oils. The following calculations 

 form the basis for the brief discussions in the body of the report. 



If it is assumed, as a simplification, that a mass of oil, M, is 

 composed of a volatile portion, M^., and a ''nonvolatile'' portion, M^j, then 



M = M + M (1) 



v n 



If the nonvolatile portion is sufficiently volatile to be gas-chromato- 

 graphed readily, and if the above masses are proportional by a factor, a, 

 to the respective areas, A, in the gas chromatogram of the original oil,°, 

 then 



o o o . o , u , ,U /«■. 



M = M + M = aA = aA + aA (2) 



V n V n 



Because of the slightly different sample size and column conditions, a 

 different factor, b, will apply to the gas chromatogram of the weathered 

 oil, w, and 



M = M + M = bA = bA + bA C3) 



V n V n 



If the nonvolatile portion does not change appreciably on weathering, then 

 mO = M^, and since M^ = aA^ , and >^ = bA^ , 



aA" = bA" (4) 



and 



(5) 



The portion of oil, P, remaining on weathering is 



14 



