Il. Garcia et al., CALIBRATION IN FLAME ATOMIC-ABSORPTION SPECTROMETRY USING A SINGLE STANDARD AND A GRADIENT TECHNIQUE, Journal of analytical atomic spectrometry, 9(4), 1994, pp. 553-561
To obtain calibration graphs, a standard solution of the analyte was p
umped using an increasing flow rate while pure water was aspirated, fo
r compensation, through a T-piece. In this way an on-line concentratio
n gradient was obtained and a constant flow was supplied to the nebuli
zer. The absorbance was monitored via a computer which facilitated dat
a acquisition and handling. In spite of the problems posed at low flow
rates by the pulsations caused by the rollers of the peristaltic pump
, this calibration strategy gave graphs comparable to those obtained b
y means of the separate measurement of several standard solutions. A c
alibration graph could be obtained in only 50 s with errors of less th
an +/-3%. The mode of operation also permits the on-line dilution of m
oderately concentrated solutions, which cannot be measured by direct a
spiration and simplifies the standard additions method.