title: Optimisation of a capillary zone electrophoresis methodology for simultaneous analysis of organic aliphatic acids in extracts of Brachiaria brizantha.
abstract: BACKGROUND
  Aluminum toxicity is commonly verified in acidic soils, and poses a severe limitation to plant growth and development. Therefore, Al complexation by the root system mucilage, Al complexation by organic compounds that are exuded by the roots and internal metabolic processes must be monitored by organic acids (OA), since they play a central role in these aluminum tolerance mechanisms.
  
  
  OBJECTIVE
  To optimise a capillary zone electrophoresis method able to perform simultaneous separation of acetic, citric, formic, lactic, malic, oxalic, pyruvic, succinic, tartaric and aspartic acid in plant extract solutions.
  
  
  METHODS
  Method optimisation was achieved by a chemometric approach through experimental designs. The optimal condition found was: 20 mmol/L phthalic acid buffer; 0.8 mmol/L cetyltrimethyl-ammonium bromide; pH 3.4 adjusted with tris(hydroxymethyl)aminomethane (around 16 mmol/L); -15 kV of voltage; 25 °C of cartridge temperature; indirect ultraviolet detection at 240 nm; and 25 mbar injection for 2 s, within an analysis time of 4 min.
  
  
  RESULTS
  As a repeatability test of the optimal condition, 30 replicates were carried out with the same working electrolyte, where the relative standard deviation of each peak ranged from 0.081 to 0.36% (for migration time) and from 2.4 to 4.6% (for peak area).
  
  
  CONCLUSIONS
  The methodology was successfully applied to simultaneously determine citric, malic and aspartic acid in roots and leaves extract solutions of Brachiaria brizantha, demonstrating its usefulness to study aluminum tolerance.
authors.affiliation: Department of Chemistry, Federal University of Juiz de Fora - UFJF, 36036-330, Juiz de Fora, MG, Brazil.
authors.forename: Fernando Antonio Simas
authors.initials: FA
authors.lastname: Vaz
authors.forename: Patrícia Aparecida
authors.initials: PA
authors.lastname: da Silva
authors.forename: Leônidas Paixão
authors.initials: LP
authors.lastname: Passos
authors.forename: Melina
authors.initials: M
authors.lastname: Heller
authors.forename: Gustavo Amadeu
authors.initials: GA
authors.lastname: Micke
authors.forename: Ana Carolina Oliveira
authors.initials: AC
authors.lastname: Costa
authors.forename: Marcone Augusto Leal
authors.initials: MA
authors.lastname: de Oliveira
mesh_terms: D001224:Aspartic Acid / Q000032:analysis; D035201:Brachiaria / Q000737:chemistry*; D019343:Citric Acid / Q000032:analysis; D019075:Electrophoresis, Capillary / Q000379:methods*; D005227:Fatty Acids / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D008293:Malates / Q000032:analysis; D010936:Plant Extracts / Q000032:analysis* / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D014325:Tromethamine / Q000737:chemistry
chemical_list: D005227:Fatty Acids; D008293:Malates; D010936:Plant Extracts; D014325:Tromethamine; D019343:Citric Acid; D001224:Aspartic Acid; C030298:malic acid