title: Evaluation of water-soluble DBS for small proteins: a conceptual study using insulin as a model analyte.
abstract: OBJECTIVE
  Water-soluble sampling materials for DBS have been introduced to solve some of the common challenges of DBS.
  
  
  METHODS
  Carboxymethyl cellulose (CMC) as water-soluble material was evaluated for small proteins using insulin as model analyte. 15 µl of whole blood was deposited and dried on a sheet of CMC prior to dissolvation of the whole spot, matrix precipitation with acetonitrile and LC-MS/MS analysis.
  
  
  RESULTS
  CMC was shown to promote matrix precipitation resulting in cleaner extracts than precipitation without CMC present. The recovery of insulin from the spot was 68 ± 4%, and the spotted samples were stable for at least 1 week in room temperature.
  
  
  CONCLUSIONS
  Water-soluble DBS showed promising performance also in analysis of small proteins.
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, Norway.
authors.forename: Cecilie
authors.initials: C
authors.lastname: Rosting
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, Norway.
authors.forename: Christine Østvik
authors.initials: CØ
authors.lastname: Sæ
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, Norway.
authors.forename: Astrid
authors.initials: A
authors.lastname: Gjelstad
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, Norway.
authors.forename: Trine Grønhaug
authors.initials: TG
authors.lastname: Halvorsen
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D001800:Blood Specimen Collection / Q000379:methods; D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D011232:Chemical Precipitation; D002853:Chromatography, Liquid / Q000379:methods; D059788:Dried Blood Spot Testing / Q000379:methods*; D006801:Humans; D007328:Insulin / Q000097:blood*; D057230:Limit of Detection; D012995:Solubility; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D007328:Insulin; D014867:Water; D002266:Carboxymethylcellulose Sodium; C032159:acetonitrile
keywords: DBS; LC–MS; carboxymethyl cellulose; insulin; precipitation; protein analysis