Food Analysis / ICPMS-2030
Analysis of Trace Elements in Certified Fish
Sample with ICP-MS
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The sample used in this analysis was Fish Protein Certified
Reference Material for Trace Metals (DORM-4) from
National Research Council Canada. There were two sets of
preparation. The sample, 0.5 g, was placed in a digestion
vessel followed by addition of 5.0 mL of concentrated
nitric acid, 2.0 mL of hydrogen peroxide and 1.0 mL of
water. The mixture was digested using microwave-
assisted digestion system based on AOAC 999.10
procedure. After the digestion process, deionized water
was added to the digested sample to a final total volume
of 200.0 mL.
The calibration standards were prepared from 1000 ppm
copper (Cu), iron (Fe) and zinc (Zn) standards, and 100
ppm ICP multi-element standard solution IX, which
contains arsenic (As), cadmium (Cd), chromium (Cr),
mercury (Hg), nickel (Ni), lead (Pb) and selenium (Se). The
internal standards were prepared from 1000 ppm bismuth
(Bi), germanium (Ge), indium (In) and scandium (Sc)
standards and diluted to a concentration of 10 ppb with
pure water. The standard solutions were purchased from
Merck Millipore, Germany. Type E-1 ultra pure water with
resistivity of 18 ΩW was used. Four different calibration
ranges were prepared to cover the range of the elements
based on the certified values. The calibration standards
were acid matched to the digested samples.
Table 1. Instrument and measurement conditions
Instrument : ICPMS-2030
Radio Frequency Power : 1.20 (kW)
Sampling Depth :6 (mm)
Plasma Gas Flow Rate : 8.0 (L/min)
Auxiliary Gas Flow Rate : 1.10 (L/min)
Nebulizer Gas Flow Rate : 0.60 (L/min)
Nebulizer : Coaxial Nebulizer
Spray Chamber : Cyclone Chamber
(electronic cooling)
Plasma Torch : Mini-torch
Collision gas : He
Fish is one of the most important food resource that is widely consumed in many parts of the world due to its high
protein content, low saturated fats and omega-3 fatty acid. However, because of industrial discharges from human
activities, fish may have trace levels of heavy metals such as arsenic, cadmium, lead, mercury and nickel which are
absorbed from the surrounding waters and the foods they eat. Not only do these heavy metals accumulate in organisms
and circulate in food chain, they also remain in the sediments of the ecosystem in the long term [1]. The toxicity of these
metals poses a concern to human health through the consumption of fish. Fish are the single largest sources of mercury
and arsenic for man. Mercury is a known human toxicant and the primary sources of mercury contamination in man are
through eating fish [2]. Minamata disease is a methylmercury poisoning associated with the daily consumption of large
quantities of fish and shellfish heavily contaminated with the toxic chemical [3]. Here, Shimadzu ICPMS-2030, a
inductively coupled plasma mass spectrometer (ICP-MS) was used to conduct a simultaneous analysis of elements in fish.
In addition to being highly sensitive, the ICPMS-2030 uses a helium gas collision system that greatly reduces the spectral
interference caused by argon and chlorine.
Measurement was conducted using the Shimadzu ICPMS-
2030 ICP-MS spectrometer, equipped with the mini-torch
and helium (He) gas collision system. The mini-torch
reduces running cost associated with argon gas usage. The
helium gas collision system reduces spectral interference
caused by polyatomic ions, for example,
40
Ar
16
O that
interferes with measurement of
56
Fe,
40
Ar
35
Cl that
interferes with measurement of
75
As, and
40
Ar
38
Ar that
interferes with measurement of
78
Se. The typical
measurement conditions are shown in Table 1. The
elements, mass, and calibration ranges used are shown in
Table 2.
Introduction
Experimental
