1998. settings or samples for skills screening generally have high lipid material. The presence of excessive lipids in these sera is definitely objectionable because of the unaesthetic appearance, difficulty in rehydration after lyophilization, and possible interference in the nontreponemal checks for syphilis. Traditionally, chloroform has been the preferred method for delipidization of human being or animal sera used in the developing of diagnostic or control reagents. Although chloroform efficiently removes lipids, its use is not advisable because of environmental issues. Chloroform is classified like a carcinogen and requires both monitoring of staff exposure time and hazardous waste disposal. Chloroform use is also inconvenient due to the amount of labor and time required for emulsification and separation. Cleanascite HC consists of moderately hydrophobic silica which has been wetted or triggered so that it will disperse in aqueous press. This permits effective connection with lipophilic biomolecules, presumably from the launch of water from the surface. The surface structure has also been revised by a proprietary process in order to minimize nonspecific relationships with proteins (4). Cleanascite HC is supplied like a finely distributed, solid-phase suspension (33% centrifuged NSI-189 volume/total volume) in saline. When human being sera are treated with Cleanascite HC, lipids are eliminated at a percentage much like or better than that acquired with chloroform, with only a minimal loss of reactivity of the antisera due to immunoglobulin G (IgG) or IgM binding. The purpose of this study was to evaluate Cleanascite HC treatment as an alternative to chloroform treatment for the removal of lipids from freezing, banked sera. New serum samples from syphilis individuals were not included in this initial study. As part of the evaluation, we identified the decreases in the amounts of total lipid and protein and any effect on the reduction of reactivity in the treponemal and nontreponemal checks for syphilis. MATERIALS AND METHODS Serum sample treatment. Twenty-one separate human being serum samples which had been stored in bulk at ?20C for 1 to 18 years were treated with either Cleanascite HC (Affinity Technology, Inc., Fairfield, N.J.) or chloroform. Fifteen of the serum samples contained both treponemal and nontreponemal antibodies. The remaining six serum samples were nonreactive in all checks for syphilis. We added 1 ml of Cleanascite HC to each of 21 glass test tubes (12 by 75 mm) and centrifuged them at 1,000 for 20 min. The supernatant was decanted, and 2 ml of the serum to be treated was added to the Cleanascite HC pellet. These tubes were vortexed to suspend the pellet and were then incubated at 2 to 8C over night with constant mild agitation at approximately 27 rpm on a tabletop rocker platform. Following incubation, the samples were centrifuged at 1,000 for 45 min. The treated sera were decanted into another set of correspondingly labeled glass test tubes (12 by 75 mm). The sera were then filtered through 0.45-m-pore-size filter membranes (Gelman Sciences, Ann Arbor, Mich.) to remove any broken polymer particles that might be in the suspension. For chloroform extraction, 1 ml of each serum sample was added to a second set of glass test tubes. One milliliter of chloroform was then added to each tube and the tube was vigorously vortexed until a solid emulsion was acquired. The tubes were then centrifuged at 1,000 for 30 min. The supernatant NSI-189 was removed from the lipid-chloroform coating by decanting it into correspondingly labeled microcentrifuge tubes (39 by 10 mm; Sarsted, Newton, N.C.), NSI-189 which were then centrifuged at 10,000 for 45 min. The supernatant was cautiously decanted into related glass test tubes (12 by 75 mm) (10). Sample screening. Total lipid dedication was made for all the CSF2RB serum samples, including the pretreatment sample, by two different methods. Total cholesterol was identified enzymatically by a modification of the method of Allain et al. (1). Triglycerides were measured by using a quantitative enzymatic means of determination of the glycerol level, as revised by McGowan et al. (8). Total serum lipid levels (indicated as milligrams per deciliter) were calculated by using the method TL = 2.27 TC + TG + 0.623, where TL is the total lipid level, TC is the total cholesterol level, and TG is the.