Nonconventional semiautomated standard addition procedure based on membrane micropumps for flame atomic absorption spectrometry

A manifold was studied that allowed the semiautomation of the standard addition method in flame atomic absorption spectrometry by use of two computer‐controlled solenoid‐based micropumps operating in a programmed way. One of the micropumps is used to inject several consecutive plugs of the sample solution while the other, which is operated out of phase, introduces plugs of a standard solution. In this way, a variant of the conventional standard addition method results. The theoretical background of the manifold is presented, and its ability to overcome classical interferences is experimentally verified. A modification of the procedure was proved to be suitable to deal with severe interferences, such as that produced by phosphate on calcium measurement, without the need of adding releasing agents. The reliability was assessed by use of certified reference materials. The manifold presented allows both sample and standard solutions as well as time to be saved. Thus, a four‐point calibration graph can be obtained that uses 2 mL and 0.75 mL of sample and standard solutions, respectively.