title: A colorimetric assay for estimation of polyethylene glycol and polyethylene glycolated protein using ammonium ferrothiocyanate.
abstract: A colorimetric method for quantitative assay of polyethylene glycol (PEG) described here is based on partitioning of a chromophore present in ammonium ferrothiocyanate reagent from an aqueous to a chloroform phase in the presence of PEG. The method is simple, reproducible, and can detect PEG in amounts as low as 5 microg. It gives a linear response over a range of 5-100 microg. The absence of any interference by proteins makes the assay equally suitable for the estimation of PEG in PEG-protein conjugates. The method was employed to monitor the separation profile of a mixture of free and PEG-5000 coupled to bovine serum albumin during purification through a gel filtration column. In this report we have also demonstrated for the first time an assay method which permits a critical evaluation of pharmacokinetic properties of any PEG-protein conjugate under in vivo conditions.
authors.affiliation: Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021, India.
authors.forename: A
authors.initials: A
authors.lastname: Nag
authors.forename: G
authors.initials: G
authors.lastname: Mitra
authors.forename: P C
authors.initials: PC
authors.lastname: Ghosh
mesh_terms: D000818:Animals; D002417:Cattle; D003124:Colorimetry / Q000379:methods*; D005069:Evaluation Studies as Topic; D007202:Indicators and Reagents; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008297:Male; D051379:Mice; D011092:Polyethylene Glycols / Q000032:analysis* / Q000493:pharmacokinetics; D011506:Proteins / Q000032:analysis* / Q000493:pharmacokinetics; D012710:Serum Albumin, Bovine / Q000032:analysis / Q000493:pharmacokinetics; D013861:Thiocyanates
chemical_list: D007202:Indicators and Reagents; D011506:Proteins; D013861:Thiocyanates; C025244:ammonium ferrothiocyanate; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols