DETERMINATION OF LEAD LEVELS IN

1
DETERMINATION OF LEAD LEVELS IN CANNED FOOD
SAMPLES BY GFAAS ANDREW HOFF, MELISSA LIFFICK,
AND ZACK SEYMOUR Department of Chemistry, Earlham
College, Richmond, IN
Results
Microwave Digestion Procedure Using the CEM 2000
System
ABSTRACT
Lead concentrations
EXPERIMENTAL METHOD
Blank corrected Soln. Value (ppb)
Lead, a toxic substance that occurs naturally in
food, soil, water and air is of public health
interest because of several dangerous effects
that it causes to humans, especially in young
peoples. Lead poisoning can affect many systems
of the body due to its toxicity after
accumulation in multiple organs. Food is a
constant source of lead and recently the F.D.A.
became concerned with the elements unnatural
occurrence in some canned foods. Soldering of
cans was thought to be the determining factor in
lead levels in food. From the late 70s to the
late 80s, lead soldering of cans for food was
decreased 86 and lead soldering was prohibited
in the United States as of 1995. A method using
Graphite Furnace Atomic Absorption Spectroscopy
(GFAAS) was developed to measure the trace levels
of lead in several canned food sample matrices.
The samples tested were canned tomatoes and
canned pineapples. All samples were below
detection limit except for the oldest canned
tomatoes which had a significant amount of lead.
Wet Wt Value (ppb)
Dry Wt Value (ppb)
Stage 1 2 3 4 Power
50 50 50 50 PSI
20 40 85
100 Time (min) 1000 1000
1000 1000 TAP (min) 500
500 500 500
Sample separation using filtration
Sample
IGA Peeled Tomatoes
15.45 ? 0.80
1924 ? 93
163.5 ? 7.9
Freeze dry sample
Below D.L.
FAME Sliced Tomatoes
Below D.L.
Below D.L.

Below D.L.
Below D.L.
Below D.L.
IGA Chunk Pineapple
Weigh0.5g sample

• Detection limit 6.66 ppb in solution

GFAAS Method

• Temperature Program
• Step ramp time(s) hold time(s) temp(C) Ar
  flow
• 1 5 55 120 300 Drying
• 2 5 30 900 300 Ashing
• 3 1 10 20 300
• 4 0 6 1600 0 Atomizing
• 5 1 5 2500 300

Microwave Digestion
Calibration Curve
GFAAS Analysis

INTRODUCTION
Perkin Elmer 5100 Graphite Furnace Atomic
Absorption Spectrometer

• Goal To determine concentrations of lead found
  in canned foods matrix using Graphite Furnace
  Atomic Absorption Spectroscopy (GFAAS)
• The samples are from IGA Peeled California
  Tomatoes of an unknown date (at least 5 years
  old), FAME Slice Stewed Tomatoes (1998), and IGA
  Chunk Pineapple (2000).
• GFAAS should yield trace levels (ppb) of lead
  found in the canned food samples.

• Wavelength 283.3 nm
• Lamp Current 10 mA
• Slit Width 0.70 nm
• Read Time 6.00 sec
• Read Delay 0.0 sec
• BOC Time 2.00 sec
• Sample Size 2 x 20 ?L

Conclusions
GFAAS with Zeeman Background Correction

• Amounts of lead could only be detected in IGA
  Peeled California Tomatoes, the oldest canned
  food tested.
• Lead was not found in newer canned foods, which
  fits with FDA regulation of lead soldered cans.
• Future research greater precision can be
  achieved with more standards and replicates.

Graphite furnace
Monochromator
Magnet
Canned Food Samples
Zeeman absorption profile
Background plus atomic absorption
Acknowledgments
Background only
Adapted template from Tim Heinke Earlham
College Chemistry Department
Electronics