There are many articles on the internet (try a Google search) on analysis in seawater. Concentrations are so low (

Specially, I would like to prefer the material and method of

of Heavy metal analysis in Seawater by Flame Atomic Absorption Spectroscopy

Please check the following link

http://akademikpersonel.kocaeli.edu.tr/umurege/sci/umurege07.04.2010_10.03.50sci.pdf

Analysis of Heavy metals in water samples may need graphite furnace atomic absorption spectroscopy. The levels are normally lower than 1ppm, thus wouldn't be sensitive in flame atomizers. However, may be some sample concentration procedures may be used prior to analysis. Try Furnace, hydride generation and cold vapor atomic spectroscopy as good suggestion.

Thanks to All of you.Your best suggestions and cooperation will be helpful for my research.

For analysis of trace elements in seawater, some preconcentration step is probably necessary if you do not have another atomizer as a graphite furnace. Methods of extraction in cloud point have been used with great success in the analysis of this type of elements in highly saline samples, being methods of low cost and respecting the principles of the green chemistry. If you are interested you have this reference that analyzes several metals by ICP OES, but the same procedure can be applied to FAAS. "SILVA, FRANCISCO LUAN FONSÊCA DA; LOPES, GISELE SIMONE ; MATOS, WLADIANA OLIVEIRA . Determination of cadmium, cobalt, copper, lead, nickel and zinc content in saline produced water from the petroleum industry by ICP OES after cloud point extraction. Analytical Methods (Print), v. 23, p. 9844-9849, 2015."

after collecting the water samples you must acidify the samples then use preconcentation method or use extraction method for low concentration by strong cationic exchange resin then eluted by acid .On the other hand, you can use flame photometer is very easy and accurate .