N-Paraffin distribution

Gas chromatography was used to determine n-paraffin distribution in the oil and wax samples. An F and M Instrument Company Model 500 chromatograph was used with an uncompensated single column, a helium carrier gas flow rate of 25 ml/min., and a thermal conductivity detector. The column was 4.8 mm in diameter and 3.3 m in length, and was packed with 3% Dexil 300 on Chromo-sorb P. The block and injection port temperatures were maintained at 673 K. The column was temperature-programmed from 348 K to 673 K at a rate of 5.7 K per minute. Peak identification was aided by the use of internal standards of decane, dodecane, and hexadecane. The baseline was determined by heating without sample injection. Response values were not available for the various areas on the traces, so the analyses were reported as % by area. 

Generally, the most apparent is the n-paraffin distribution that has proved to be useful in differentiating the main types of pollutant samples (cmde oils, fuel oils and tank washings [102] or even types of cmde oils [103,104], although in this case the method involves the quantification of the previously isolated n-paraffins, therefore lengthening the analysis time. 

---