A NEW FLOW-INJECTION SINGLE-STANDARD CALIBRATION METHOD FOR FLAME ATOMIC-ABSORPTION SPECTROMETRY BASED ON DILUTION BY MICROSAMPLE DISPERSION

A flow injection (FI) calibration method for flame atomic absorption s pectrometry was developed which involved microsampling of a single sta ndard using computer controlled stepper-motor driven peristaltic pumps . The theoretical basis for the method is given, demonstrating the fea sibility of utilizing the linear relationship between the reciprocal o f the dispersion coefficient (or analyte concentration) and sample vol ume in Fl systems with dispersion coefficients higher than approximate ly 30. The errors introduced by loss of linearity at lower dispersions are discussed. Calibration curves constructed by metering microliter volumes of a single standard into a sample loop of approximately 100 m u l were compared statistically to those obtained using a set of stand ard series within an 8 h working day. No significant differences betwe en the two calibration procedures were observed.