Determination of trace elements in squid organs by inductively coupled plasma mass spectrometry and neutron activation analysis

Abstract

With the aim for an analytical validation of the inductively coupled plasma mass spectrometry method by neutron activation analysis, squid (Todarodes pacificus) was collected from Japanese inshore during 1981 to 1996. The internal organs of squid collected in 1981 to 1988 were dried at 105°C for overnight and ashed for 48 hours at 450°C. Ashed samples were pulverized and homogenized. On the other hand, squid was collected in 1996 for the purpose of concentration factor. The squid was cautiously divided into edible, born, craw, liver, and others by using Teflon scissors and forceps. These samples were also ashed. Determination of nine elements (V, Mn, Fe, Co, Cu, Zn, Rb, Ag and Cd) in the ash and SRM 1572 citrus leaves, SRM 1577b bovine liver, and NIES No. 9 sargasso was carried out by non-destructive neutron activation analysis (INAA) at the TRIGA Mark II reactor of Rikkyo University with the flux of 5 × 1011 n cm-2 s-1. The standards were prepared by impregnating an aliquot of SPEX standard solution into filter paper. For ICP-MS, about 0.5 grams of ash samples and standard reference materials were dissolved into 7 M HNO3 and then evaporated to dryness. The residue was completely dissolved into 1 M HNO3 and diluted with pure water. Concentration of 13 elements (V, Mn, Fe, Co, Ni, Cu, Zn, Rb, Ag, Cd, Cs, Ba and Pb) was determined after an addition of internal standard to avoid any instrumental drift. The analytical results of nine elements in squid organs by ICP-MS were agree well with INAA within 10%. Analytical results of the other four elements (Ni, Cs, Ba and Pb) were also confirmed by ICP atomic emission spectrometry, atomic absorption spectrometry and flame photometry techniques. This paper describes the usefulness of ICP-MS for trace elements in squid organs, and an application to determine the concentration factors. Particularly, Co, Zn, Ag, and Cd were concentrated into liver with concentration factors of 105-106. The analysis of trace elements in squid organs was found to be a useful method for studying heavy metal or radioactive contamination in a marine environment.