In this work a multicommuted flow system for the sequential screening/determination of dichromate,
salicylic acid, hydrogen peroxide and starch in milk samples was developed. The concept of multicommutation
in flow injection analysis was chosen, resulting in an environmentally friendly system
with minimal consumption of reagents and waste generation. The proposed approach is based on a
simple binary DETECT or NO-DETECT response, thereby making it possible to determine analytes
quickly, with high performance and easy operation. For dichromate determination, the proposed
method was based on the reaction between Cr(VI) and 1,5-diphenylcarbazide, enabling a linear working
range response, between 1.0 and 10.4 mg L1, (R ¼ 0.999). In order to determine salicylic acid, the
proposed method was based on a complexation reaction of Fe(III) and salicylic acid, with the linear
working range response from 103.6 to 414.3 mg L1 (7.5 104e3.0 103 mol L1) (R ¼ 0.999). The
hydrogen peroxide determination was based on the oxidation reaction of hydrogen peroxide with
vanadium oxide (V) in an acid environment, with a linear working range of 10.0e200.0 mg L1
(R ¼ 0.996). Starch determination was based on the complex reaction of starch and triiodide, with a
linear working range of 12.5e150.0 mg L1 (R ¼ 0.999). The mean sampling rate for the four species was
83 determinations per hour. Performance curves were used to verify the quantity of false positives and
false negatives. Addition and recovery tests were used for validation of the proposed procedures,
resulting in variation between 90.1 and 108.7% for three different samples.