title: Determination of nickel, calcium and magnesium in xylem sap by flame atomic absorption spectrometry using a microsampling technique.
abstract: BACKGROUND
  Knowledge of xylem sap chemical composition is important to the understanding of translocation, detoxification and tolerance mechanisms. However, the small amount of sample available often hampers its characterisation. Hence, low volume consumption techniques are needed for xylem sap analysis.
  
  
  OBJECTIVE
  To develop a microsampling technique for the determination of elements in xylem sap from different plants by flame atomic absorption spectrometry (FAAS).
  
  
  METHODS
  The microsampling device was optimised in terms of sample volume and integration time. The analytical characteristics of the microsampling technique (micro-FAAS) were established and compared with those of FAAS with traditional continuous nebulisation. The method was validated by means of an independent technique.
  
  
  RESULTS
  Ca, Mg and Ni were determined in a 50 microL aliquot of xylem sap solution/element that was introduced directly into the flame via the microsampling accessory. Good precision was obtained with relative standard deviations of 1.1, 0.6 and 2.3% for Ca, Mg and Ni, respectively. Matrix effects resulting from the physical characteristics of the samples and possible chemical interferences caused by phosphate and/or sulphate were ruled out.
  
  
  CONCLUSIONS
  A simple, rapid and reproducible microsampling technique coupled to FAAS was developed and successfully applied in the determination of Ca, Mg and Ni in xylem sap.
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Lisboa, Portugal.
authors.forename: Sheila
authors.initials: S
authors.lastname: Alves
authors.forename: Maria L Simões
authors.initials: ML
authors.lastname: Gonçalves
authors.forename: Margarida M
authors.initials: MM
authors.lastname: Correia dos Santos
mesh_terms: D019607:Brassicaceae / Q000737:chemistry; D002118:Calcium / Q000032:analysis* / Q000592:standards; D002138:Calibration; D030601:Cistaceae / Q000737:chemistry; D008274:Magnesium / Q000032:analysis* / Q000592:standards; D009532:Nickel / Q000032:analysis* / Q000592:standards; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D012015:Reference Standards; D015203:Reproducibility of Results; D013054:Spectrophotometry, Atomic / Q000295:instrumentation / Q000379:methods*; D052584:Xylem / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D009532:Nickel; D008274:Magnesium; D002118:Calcium