manual of methods of analysis of foods - Ministry of Health and ...

METALS
(Ref:- A.O.A.C 17 th edn , 2000 Official Method 999.11 Determination
of Lead , Cadmium , Copper , Iron and Zinc in Foods Atomic
Absorption Spectrophotometry after dry ashing) / Manual Methods of
Analysis for Adulterants and Contaminants in Foods I.C.M.R 1990
Page 138)
2.1 DETERMINATION OF MERCURY IN FOOD BY FLAMELESS
ATOMIC ABSORPTION SPECTROPHOTOMETRIC METHOD
Principle:
The sample is digested with HNO 3 and H 2 SO 4 and HNO 3 – HClO 4 mixture
in the presence of sodium molybdate solution. The mercury content is
estimated by flameless atomic absorption method.
Apparatus:
(i)
Atomic absorption spectrophotometer: Instrumentation Laboratory
Inc., 113, Hartwell Ave., Lexington, MA 02173, Model 253 or
equivalent, equipped with Hg hollow cathode lamp and gas flow
through cell (Fig. 1), {25 (id) × 115} mm with quartz windows
commented in place.
Operating condition: Wavelength 253.7 nm, slit with 160 µm, lamp
current 3 ma, and sensitivity scale 2.5.
13