Triple-quadrupole mass spectrometry (MS/MS) has been used to compare nitroaromatic emissions from two different types of diesel engines, a direct-injection, single-cylinder engine and an indirect-injection V-8 engine. The low level of nitropyrenes/ nitrofluoranthenes in exhaust extracts may be due in part to the low pyrene content of the reference fuel used. Addition of pyrene to reference fuel resulted in increased pyrene in exhaust extracts, but only minor differences in mutagenicity. Only about 1/1000 of the total mutagenicity from complete reaction with N02 appeared to have occurred during diesel exhaust and soot collection on filters. Fractionation with Me2SO was found to be useful in separating aliphatic hydrocarbons from mutagenic activities and in concentrating nitroaromatic compounds for MS/MS analysis.Concentration of certain nitroaromatic compounds was necessary for isobutane chemical ionization MS/MS, while atmospheric pressure MS/MS appeared capable of detecting nitroaromatic compounds even in unfractionated extracts. MS/MS comparisons of concentrated samples of differing mutagenicities showed the main differences were increased ion intensities of dinitro compounds in more mutagenic samples. It is concluded that the polynitro compounds may be of more significance than mononitro compounds in the mutagenic activities that have been found associated with diesel soot.

The effect of 10% or 20% Intralipid on lipid clearing enzymes, plasma lipids and apoproteins was investigated during the first 5 days after birth in 37 premature infants maintained on total parenteral nutrition; 21 infants received 20% and 16 received 10% Intralipid, respectively. Lipid was infused over a 20-h period at rates of 1, 2 and 3 g/kg/day on consecutive days. Plasma lecithin: cholesterol acyltransferase (LCAT) activity was low and increased significantly (p<0.05) only during infusions of 3 g/kg/day in both groups of infants. Plasma lipolytic activity was generally not affected by the regimen or preparation (10% or 20%) of Intralipid infused, except for higher (p<0.05) levels at 3 g/kg/day of 20% compared with prelipid infusion. Plasma triglyceride concentrations wer similar after 10% or 20% Intralipid, whereas plasma total cholesterol was significantly higher during infusion of 2 and 3 g/kg/day of 10% compared with 20% Intralipid. The efficient clearing of 20% Intralipid might be related to the lower lecithin: triglyceride ration which is compatible with the low LCAT activity of premature infants.

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