title: Determination of total protein content in white wines by solid phase spectrometry in a SI-LOV system.
abstract: Although present at low concentration in wine samples, proteins, have considerable technological importance, due to their capability of haze formation. The present work presents a methodology for the quantification of total protein in white wine in a sequential injection lab-on-valve system, exploiting the bead injection concept for solid phase extraction with spectrophotometric detection. The method is based on the retention of the proteins in the solid support, NTA (nitrilotriacetic acid) superflow beads, charged by Cu(2+). The change in the absorbance is monitored at 500nm at the surface of the beads after addition of the Folin-Ciocalteu's reagent (FCr). The developed method presented a sample consumption of 400μL per assay and a consumption of FCr and Cu(2+) solution of 25μL and 100μL per assay, respectively. It was possible to achieve a linear range up to 0.30g/L with a limit of detection and quantification of 0.03 and 0.10g/L, respectively. The proposed method was successfully applied to white wine samples.
authors: CBQF/Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal.
authors: Susana S M P
authors: SS
authors: Vidigal
authors: Ildikó V
authors: IV
authors: Tóth
authors: António O S S
authors: AO
authors: Rangel
mesh_terms: D003300:Copper / Q000737:chemistry; D017022:Flow Injection Analysis / Q000379:methods*; D005656:Fungal Proteins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification*; D008863:Microspheres; D008982:Molybdenum / Q000737:chemistry; D009571:Nitrilotriacetic Acid / Q000737:chemistry; D010940:Plant Proteins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification*; D052616:Solid Phase Extraction; D013057:Spectrum Analysis / Q000379:methods*; D017973:Tungsten Compounds / Q000737:chemistry; D014920:Wine / Q000032:analysis*
chemical_list: C029556:Folin's phenol reagent; D005656:Fungal Proteins; D010940:Plant Proteins; D017973:Tungsten Compounds; D003300:Copper; D008982:Molybdenum; D009571:Nitrilotriacetic Acid