GILMARTIN and REVELANTE: CONCENTRATION OF METALS IN TWO ADRIATIC FISH 



the Center for Marine Research in Rovinj, weighed 

 and their standard length determined. Each 

 fish was then dissected into component parts, 

 e.g. skin (including scales), gills, muscle. These 

 components were then pooled according to type, 

 weighed, dried to a constant weight at 110°C, 

 ground to homogeneous meal in a porcelain 

 mortar, and stored in a glass desiccator until 

 analyzed. 



Analytical Methods 



Standard chemical procedures (Christian and 

 Feldman 1970; Fletcher 1970; Uthe et al. 1970; 

 Stainton 1971) as modified by Knauer and Martin 

 (1972) were used. For all elements except mer- 

 cury, two 1-g aliquots of sample plus 10 ml 

 70% redistilled HNO3 were added to 30-ml 

 beakers, which were covered with watch glasses 

 and refluxed at 90°C for 2 h, followed by evapora- 

 tion to dryness. After charring, the samples were 

 redissolved in 5 ml 70% HNO3, followed by the 

 dropwise addition of 30% H2O2 until the samples 

 remained clear. At this point the samples were 

 evaporated to 5 ml, cooled, and diluted to 25 ml 

 with distilled water. 



All samples were analyzed on a Perkin-Elmer 

 303 atomic absorption spectrophotometer.^ Var- 

 ious combinations of fuels and oxidants, as 

 recommended in the Perkin-Elmer manual, were 

 used for each element. Small differences between 

 signal and base line in some of the Cd, Ni, 

 and Ag analyses may have introduced error. 



Procedures for mercury differed slightly. 

 Approximately 0.2-0.4 g dry weight of sardine 



^Reference to trade names does not imply endorsement by 

 the National Fisheries Service, NOAA. 



and anchovy tissues were weighed into 20-ml 

 Neutraglas disposable ampoules, followed by the 

 addition of 3 ml of a 2:1 solution of concentrated 

 H2SO4 and HNO3. Samples were heated on a hot- 

 plate overnight at 80°C, cooled in ice, followed 

 by the addition of 8 ml 6% KMn04 until the 

 solution just turned pink. Subsequently 2 ml of 

 sample digest were drawn into a 10-ml disposable 

 syringe, followed by the addition of 2 ml reductant, 

 and partitioning. The mercury was partitioned 

 between liquid and air on a vortex mixer by 

 drawing the syringe back to 10 ml (leaving a 

 6-ml air space). The vapor was then injected 

 into a specially constructed 3-ml (total volume) 

 glass absorption cell which had been mounted on 

 the burner assembly of a Perkin-Elmer 303 

 atomic absorption spectrophotometer. A Westing- 

 house hollow cathode mercury lamp was used as 

 an energy source. Three sets of blanks and three 

 sets of standards consisting of ,10, 20, and 30 ng 

 mercury (HgCl2) in triplicate were interspersed 

 within a given sample run. 



Calibration 



During the analyses, aliquots of National 

 Bureau of Standards Orchard Leaves No. 1571 

 were routinely analyzed for each element (Table 

 2). Similar standardizations conducted by Knauer 

 (1972) during his study of metals in the northern 

 anchovy, Engraulis mordax, and an interlabora- 

 tory calibration using both the destructive 

 analytical techniques with atomic absorption 

 spectrophotometry and non-destructive activa- 

 tion analysis (Knauer 1972; Goldberg 1972), in- 

 dicate that our standardizations compare well 

 with other laboratory analyses for these elements 

 (Table 2). 



Table 2. — Comparative standardizations of elemental concentrations in National 

 Bureau of Standards Orchard Leaves No. 1571 in micrograms per gram (Hg in nanograms 

 per gram). 



'Flameless atomic absorption spectroscopy. 

 ^Neutron activation analysis. 



195 



