QUANTITATIVE-ANALYSIS OF N-METHYL-2-PYRROLIDINONE RETAINED IN COAL EXTRACTS BY THERMAL EXTRACTION GC-MS

N-methyl-2-pyrrolidinone (NMP) is widely used for coal extractions. It is well known that extraction solvents are retained in the coal extracts even after extensive drying procedures. The amount of NMP retained will affect the accuracy of the extraction yield and the character of the extracts. Thermal extraction gas chromatography-mass spectrometry (g.c.-m.s.) has been applied to quantify the amount of NMP retained in coal extracts. Several NMP related compounds are found in the coal extracts, but not in the whole coals. NMP was added to activated carbon and this material used as a standard to produce a linear calibration curve. The detection limit (S/N = 5) is estimated to be 0.015 mu g NMP, and the relative standard deviation was 5.73% for a 0.093 mg standard sample containing 0.016 mu g NMP. Nine NMP soluble coal extracts and two blended coal extracts were analysed by this method, and the weight percentages of the retained NMP varied from 0.71 to 4.61%, with deviations (n = 3) ranging from 0.01 to 0.11%.