Determination and speciation of methyl mercury and total mercury in fish tissue samples by gold-coated W-coil atom trap cold vapor atomic absorption spectrometry

•A new in-atomizer trapping technique was developed for Hg determination.•Selective, simple, robust and low-cost method was improved.•With using a conventional AAS, achieved ng/L detection level.•With using trap method, effect of interfering elements was reduced or eliminated.