Sulfur compound types were determined in asphalts from the SHRP Materials Reference Library. Sulfoxides were determined by infrared spectrophotometry (IR); sulfides were measured via oxidation to sulfoxides with tetrabutylammonium periodate followed by I R thiophenes were determined by difference (total sulfur minus other types). Compound types were determined in whole asphalts as well as for fractions from each asphalt obtained using nonaqueous ion exchange liquid chromatography (NIELC). Results from the individual NIELC fractions were compared against those for the corresponding whole asphalt. In addition, results from this analysis were compared against those obtained by other workers utilizing X-ray (XANES) techniques. The neutral fraction from NIELC was further fractionated into saturated hydrocarbon, neutral-aromatic (contains thiophenic sulfur types), and sulfide classes using liquid chromatographic (LC) techniques. The distribution of sulfur types obtained from the LC separation of neutrals was compared with that obtained from the above instrumental methods. Generally, results from the IR-oxidation techniques were in good agreement with those from LC separations and XANES analysis, except that the latter include aromatic or other sulfide types in with total sulfides, whereas the oxidation-IR approach appears to be specific for aliphatic sulfides, per se. Considerable variation of sulfur types within NIELC fractions was observed. Compounds with one or more acidic groups plus a sulfoxide group constitute a significant proportion of the total amphoteric compounds present in most asphalts.

SummaryThe GC-MS characteristics of carboxylic acid esters prepared from fluorine-containing alcohols were compared to those of methyl esters. The GC retention of 2,2,2-trifluoroethyl (TFE) esters was less than, and 2,2,3,3,4,4,4-heptafluoro-l-butyl (HFB) esters was approximately equivalent to that of methyl esters. Mass spectra of TFE and HFB aliphatic esters show significantly more intense molecular and key fragment ions than those of methyl esters. Also, owing to their significantly higher molecular weights, TFE or HFB ester molecular ions and most fragment ions of interest occur at significantly higher m/z values than most potential interfering ions.Data for about 70 individual TFE and HFB esters are reported. Application of the methodology to a petroleum-derived carboxylic acid concentrate resulted in identification of straight chain, isoprenoid, methyl-substituted straight chain (2-, 3-, 5-,lo-, 12-positions along chain), and dimethyl-substituted straight chain acids containing from 11 to 22 carbons. Benzoic acid and homologs with up to 3-carbons in alkyl substitutents were minor components in the sample.The procedure provided for forming TFE and HFB esters from free acids requires less time and effort than a previously reported method, while retaining its capability for achieving essentially quantitative conversion. Free hydroxyl groups in alcohols and phenols are converted to trifluoroacetate esters concurrently with formation of TFHHFB carboxylic acid esters. The reaction products, including compounds with two functional groups (diacids, salicylic acid, etc.), chromatograph well on conventional nonpolar GC stationary phases.

The GC-MS characteristics of trifluoroacetate esters of phenolic compounds are discussed. Linear temperature programmed retention indices and total ion current MS response factors of over 120 phenolic esters are reported.The main GC advantages from analysis of trifluoroacetate esters as compared to plain phenols are enhanced volatility and improved resolution. For example, the elution temperature of a given phenol is typically 50 "C greater than that of the corresponding trifluoroacetate ester. Also, while retention of compounds with two trifluoroacetate groups is only moderately greater than mono esters, underivatized dihydroxy compounds are very difficult to elute from any GC column. Complete resolution of isomeric Co-, Ci-and Cn-alkylphenol esters is readily achieved on conventional fused silica GC columns; resolution of the corresponding underivatized compounds requires specialized GC columns with low temperature limits.In general, mass spectra of trifluoroacetate esters are more characteristic of a given structure than those of the corresponding phenols and may be more rigorously interpreted towards structural elucidation. A table in the report summarizes some of the more important spectral features used in compound identification.Example applications in analysis of coal-, shale-and petroleum-derived materials are presented. Selected ion monitoring is used to determine individual phenolic components in whole distillates; reconstructed ion chromatograms are used to illustrate distributions of selected species as a function of fuel storage and thermal stress.

Oxygen-containing functional groups (hydroxyl and carboxyl) In fuels or crude oils, or fractions thereof, are determined by IR spectroscopy. The approach Is based on chemical derivatization followed by measurement of IR bands of the corresponding derivatives. The chemical derivatization procedure Involves two steps: (1) esterification of carboxylic acids with 2,2,2-trlfluoroethanol and (2) acylation of alcoholic and phenolic hydroxyls with trifluoroacetyl chloride. The aryl trlfluoroacetates absorb at 1800 cm'1; the 2,2,2-trlfluoroethyl esters absorb In the region 1760-1740 cm'1. Variation of molar absorptivity of the derivatives as a function of structure Is determined by using pure compounds and well-defined fractions from actual fuel samples. The overall accuracy, precision, sensitivity, and range of applicability to petroleum and related sample types are discussed.

SummaryAn analytical method for differentiation of primary, secondary, and tertiary amines using exhaustive trifluoroacetylation prior to GClMS has been developed. Using the conditions described in the report, most primary amines add two and secondary amines add one trifluoroacetyl group. In general, tertiary amines do not react. GC retention indices and relative GClMS total ion current response factors for 102 trifluoroacetyl derivatives are reported. Examples of the application of the method to petroleum and coal liquid products are provided. Because of the limited thermal stability of the derivatives of primary amines, the method is applicable only to distillates boiling below 370 "C (700 OF).