This report presents completed sealed tube stability test results for the following eight refrigerant/lubricant mixtures: R-22/mineral oil; R-124/alkylbenzene; R-134a/pentaerythritol (PE) ester (mixed acid); R- 134a/PE (branched acid); R-134a/ PE (100 cSt viscosity); R- 142b/alkylbenzene; R-143a/ PE (branched acid); R-152a/alkylbenzene. Partial results are shown for an additional eight refrigerant-lubricant mixtures. Though work is in progress, no data are available at this point in time for the five remaining test mixtures. Reported are: visual observations on aged sealed tubes, gas chromatographic analyses on the vapor phase contents of the tubes, chloride ion contents of HCFC containing mixtures or fluoride ion contents of HFC mixtures, and total acid number values and infrared analysis results for mixtures containing ester lubricants.

Our originally stated objectives included: (1) development of a quantitative source function for colloid mobilization to groundwater, and (2) assessment of the most important colloidal phases to which nonpolar compounds sorb. We have been pursuing a series of studies to elucidate the roles of colloidal phases in subsurface environments. Most notably, we have discovered the critical role of secondary cementitious phases like goethite. We developed a new procedure for measuring surface iron oxides'' which is a great improvement over earlier methodologies. Currently, we are developing a unifying model with which we can predict the mobilization of colloids to groundwater flowing through such porous media. Also, we have been able to show that groundwater samples contain colloidal phases in sufficient quantities and of suitable properties to enhance the mobile load of toxic compounds like polycyclic aromatic hydrocarbons. Finally, we have synthesized our varied field investigations from sites in Massachusetts, New Jersey, Delaware, Nevada, Connecticut, and New York to yield a protocol for other researchers interested in evaluating colloids in groundwater. These accomplishments are discussed in more detail below. Through these efforts, we have become increasingly convinced of the central role played by colloidal phases in numerous subsurface phenomena controlling contaminant fates.