I belive your instrument is working without loosing intensity. If so try this.

Volatile hydrides can be generated by adding acidified aqueous solution of the sample to a small volume (1%) of sodium borohydride in glass container. This would convert all your metal to the metalhydride which would increase the signal intensity.

Hello.

I really don't think furnace is the best way to analyse Pb by AAS. Like Udaya said, try hydride generation to enhance. You can get signal gains up to 100 X (dpending on the matrix).

Cheers

Hello

I think that it is possible to analyse Pb in water.

Please, let me know some answers:

1) Did you study the pyrolis and atomization curves using standard solution? Firstly without modifier.

2) As you said, there is a very low signal when you injected the volume of sample in GF AAS. However, It was in the best temperature conditions? Which was the pyrolisis temperature?

3) Finally, try 2 ug of Pd in your best temperature. Probably, your signal will be better.

Cheers

Frederico

Referencing the book 'graphite furnace AAS source book' on page 109, you can use ammonium hydrogen phosphate. See paper by Manning et al (1983) in Applied Spectroscopy titled 'the determination of trace elements in natural waters using a stabilized temperature platform furnace'.

I recommend to you using of matrix modifier mixture (Magnesium Nitrate + Ammonium dihydrogen phosphate)

Note with using matrix modifier the furnace temperature program must be changed ashing and atomization temperatures must be increased