AAS question (1 Viewer)

[megaman64]

i have two sources of information on aas. one says that the metal ion is already known and aas is used to find its concentration. the other source says that aas is used to find what metal ion it is.

which one is it?

 

[2xL]

The first one.

 

[someth1ng]

Atomic Absorption Spectroscopy (AAS) usually refers to a known metal ion with unknown concentration.

To determine concentration of a certain metal ion, you need samples of standard solutions of known concentration to make a calibration curve - graphing absorbance against concentration. Once a calibration curve is made, you can also determine the concentration based on the extent to which specific wavelength of light is absorbed (characteristic of the metal ion tested), comparing it to the calibration curve and hence, determine an approximate concentration of a specific metal ion being tested.

Another technique called Atomic Emission Spectroscopy (AES) is used to determine the metal ions present but this is not in the core syllabus - only in the Forensic Chemistry option.

 

[megaman64]

how does aas detect which metal ions are in trace elements if it is only used to find the concentration?

 

[kingkong123]

how does aas detect which metal ions are in trace elements if it is only used to find the concentration?

The trace elements are known. AAS is just a method to detect their concentrations. Prior to AAS' development, experimental methods could not detect the presence of trace elements because they were in such low concentration. Once AAS was developed, it was found that trace elements existed in extremely small concentrations (as low as ppb) and were essential to some life forms.

 

[megaman64]

oh ok thanks