title: Efficacy of an extraction solvent used to quantify albumin deposition on hydrogel contact lens materials.
abstract: OBJECTIVE
  Extracting proteins from conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials using a mixture of trifluoroacetic acid/acetonitrile (TFA/ACN) is a well-established procedure for quantifying individual and total protein deposited on contact lenses. The purpose of this study was to determine the efficacy of TFA/ACN in extracting albumin from SH and a CH group IV lens material using an in vitro model.
  
  
  METHODS
  One CH group IV lens material (etafilcon A) and five different SH lens materials (lotrafilcon A, lotrafilcon B, balafilcon A, galyfilcon A, and senofilcon A) were incubated in both simple albumin solution and a complex artificial tear protein solution containing 125I-labeled albumin. All the lens materials were incubated for 14 days at 37 degrees C with constant rotations. Following the incubation period, radioactive counts were determined and the lenses were placed in an appropriate volume of the extraction solvent. After the specified time, the lenses were removed and radioactive counts were determined again to calculate the amount of albumin remaining on the lenses post-extraction.
  
  
  RESULTS
  Extraction efficiencies for albumin from the artificial tear protein solution were 97.2% +/- 2 for etafilcon A, 77.3% +/- 6.2 for lotrafilcon A, 73.5% +/- 5.6 for lotrafilcon B, 81.5% +/- 5.8 for balafilcon, 91.2% +/- 3.4 for galyfilcon A, and 89.2% +/- 3.4 for senofilcon A. Results were similar for the albumin extracted after incubating in the simple albumin solution.
  
  
  CONCLUSIONS
  Although TFA/ACN is efficient at extracting albumin deposited on etafilcon lenses, it does not extract all the albumin that is deposited on SH lenses and alternative extraction procedures should be sought.
authors.affiliation: Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, ON, Canada. lnagapat@uwaterloo.ca
authors.forename: Lakshman N
authors.initials: LN
authors.lastname: Subbaraman
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Glasier
authors.forename: Heather
authors.initials: H
authors.lastname: Sheardown
authors.forename: Lyndon
authors.initials: L
authors.lastname: Jones
mesh_terms: D000097:Acetonitriles / Q000592:standards*; D000418:Albumins / Q000302:isolation & purification*; D003263:Contact Lenses, Hydrophilic; D004338:Drug Combinations; D006801:Humans; D020100:Hydrogels; D066298:In Vitro Techniques; D009883:Ophthalmic Solutions / Q000737:chemistry; D012997:Solvents / Q000592:standards*; D014269:Trifluoroacetic Acid / Q000592:standards*
chemical_list: D000097:Acetonitriles; D000418:Albumins; D004338:Drug Combinations; D020100:Hydrogels; D009883:Ophthalmic Solutions; D012997:Solvents; D014269:Trifluoroacetic Acid; C032159:acetonitrile