3.2. Flow variables
The flow of the solution of Me-BTABr and Triton X-114 was varied
in the range 2.0 to 6.0 mL min−1, to study the influence of this
parameter in the analytical signal of the on-line system. According to
the results presented in Fig. 5, there is a decrease in the analytical
signal when the flow of the solution of complex and surfactant is
greater than 3.0 mL min−1. Thus the value of 2.5 mL min−1 was
chosen for the next studies.
In the preconcentration system shown in Fig. 1, water is used as a
carrier, transporting the solution ofMn (II) to the confluence.Moreover,
the flowofwater and surfactant–reagent solution, also control the speed
of passage of the reaction mixture through the reaction coil and the
minicolumn. Then the influence of the flow of water in the preconcentration
systemwas studied. Itwas observed that therewasno significant
variation in the analytical signal for values below 7.0 mL min−1. Above
this value, a decrease of analytical signal occurred.Moreover, excessive
pressure in the systemwas observed. In subsequent experiments a flow
rate value of 7.0 mL min−1 was used, to achieve a high analytical
frequency.
The flowof eluent is a parameter that controls the rate of desorption
of Mn from the minicolumn. Moreover, this parameter influences the
speed of introductionof the analyte in the nebulizer of the spectrometer.
The flow of eluent was varied in the range 2.5 to 4.5 mL min−1. There
was a decrease in the analytical signal for values above 3.5 mL min−1. In
later studies, a flow rate of 3.5 mLmin−1 was used.