Abstract: Reformulated and other automotive motor gasolines may be analyzed to detect adulteration with gasolines containing a Rhodamine B base marker dye by mixing a small sample of the suspected fuel in a vial containing a small quantity of unbonded flash chromatography-grade silica. The presence of such marker dye in the suspect sample will color the silica red. The coloration may be detected in fuel samples which also contain red or blue grade identification dyes, detergent additives and oxygenates such as ethanol and MTBE.

Abstract: Aged and/or colored diesel fuels and similar petroleum distillates may be analyzed for the presence of an anthraquinone marker dye such as DuPont Chemicals Oil Blue B Liquid dye by passing a sample of the fuel through an unbonded silica solid phase extraction column which retains the color-forming agents on the column and which will provide for visual detection of the substantially nonretained marker dye in the column. A sufficiently nonpolar elution solvent such as dichloromethane or toluene may be passed through the column to elute the marker dye without removing the color-forming agents from the column. The solvent may be spectrophotometrically analyzed to detect presence of the dye.

Abstract: The concentration of detergent additives and the like in motor gasoline and similar liquid petroleum fuels is measured by evaporating a sample of the fuel and passing the sample through a light-scattering detector to measure the concentration of unevaporated particles of high molecular-weight, low volatility material present in the additive concentrate. A gasoline sample may be passed through the detector by a transport medium comprising one of heptane and iso-octane. Photo detector signals generated by the additive-containing sample are compared with signals detected with samples not containing any additive. The sample and the transport medium are condensed after analysis. The method is fast, does not require venting of volatile hydrocarbon fluids to atmosphere and may be carried out using a minimal quantity of fuel product as the sample.

Abstract: Marker dyes are detected in aged and dirty or "brown" gasolines by passing a sample of gasoline through plural solid phase extraction columns including a first column having a strong anion exchange phase bonded to a silica substrate. A color-forming reagent is added to the first column after elution of the gasoline sample therethrough. The marker dye colored complex and colored bodies not retained on the first column are eluted into a nonpolar solid phase extraction column with methane-sulfonic acid and the marker dye colored complex is eluted through the second column and into and through a third column containing unbonded silica. The color bodies of the gasoline will remain on the columns and the marker dye will be detectable at the bottom of the third column as evidenced by a pink color for marker dyes such as Morton International Mortrace MP marker dye and the like.

Abstract: A method for analyzing marker dye present in the parts per million range in gasoline is provided using a solid-phase extraction technique with formation of the colored complex in the extraction column as well as a method for detecting the adulteration of gasoline containing the marker.