It is widely known that toxic metals can be found in some foods because they are naturally present in the Earth’s crust and can be released as pollutants into the water and soil used to grow food and through the food manufacturing and packaging processes. Exposure to these metals at an early age has been linked to developmental problems, behavior issues, and attention deficit hyperactivity disorder. The levels of toxic metals in baby foods are therefore more of a concern and require strict safety controls from raw materials to finished products. In this work, we explore and discuss the applicability of the Shimadzu inductively coupled plasma-mass spectrometer (Shimadzu ICPMS-2030) to the quantification of As, Cd, Hg and Pb in selected baby foods at this very low limit ranges.

1. Determination of Heavy
Metals in Baby Foods by
ICP-MS
Shimadzu Scientific Instruments, Columbia, MD

2. Introduction
It is widely known that toxic metals can be found in some foods because they are naturally
present in the Earth’s crust and can be released as pollutants into the water and soil used to
grow food and through the food manufacturing and packaging processes. Exposure to these
metals at an early age has been linked to developmental problems, behavior issues, and
attention deficit hyperactivity disorder.
The levels of toxic metals in baby foods are therefore more of a concern and require strict
safety controls from raw materials to finished products.

3. Introduction
A report issued by an investigative committee in the U.S. House of Representatives in February
2021 showed that many baby foods sold in U.S. markets contained significant levels of arsenic
(As), cadmium (Cd), lead (Pb) and mercury (Hg). These findings raised great public concerns
and attention, which led to the Baby Food Safety Act in March 2021. This act sets limits of toxic
elements in infant and toddler food as shown in Table 1.
In this work, we explore and discuss the applicability of the Shimadzu inductively coupled
plasma-mass spectrometer 2030 (Shimadzu ICPMS-2030) to the quantification of As, Cd, Hg
and Pb in selected baby foods at this very low limit ranges.
Element
Action Levels (ppb)
Non-cereal Cereal
Inorganic As 10 15
Cd 5 10
Hg 2 2
Pb 5 10
Table 1. Proposed action levels of metals in
infant and toddler foods

4. Experimental
Sample Preparation
 Apple juice, puffs, and rice cereal purchased from local grocery store were selected as
representative of baby food products.
 Approximately 0.5 g of each sample (2 g for apple juice) was weighed into a sealed TeflonTM
reaction vessel that contained 4.5 mL of 70% HNO3 and 0.5 mL of 35% HCl. The sample was
allowed to sit in the fume hood for 15 minutes for pre-digestion and then digested with a CEM
MARS 6 microwave digestion system using the pre-set food method: ramp time of 20 min to
210 oC and hold time of 15 min before cooling down.
 A blank sample consisting only of the reagents was also prepared for quality control. Fortified
samples were prepared by spiking stock standard solution into the reaction vessels before
digestion to confirm the quantitative recovery of the analytes.
 Digested samples were diluted to contain 4.5% HNO3 and 0.5% HCl before measurements.
Calibration standards also contained 4.5% HNO3 and 0.5% HCl for matrix match.
 Reagents including HNO3, deionized water, and certified reference materials are provided by
MilliporeSigma. The HNO3 and deionized water are ultra-pure trade metal grade.

5. Instrumentation
 The ICPMS-2030 was automatically tuned to adjust torch position, lens voltage and mass
resolution to optimize the signal intensity.
 Scandium (Sc), indium (In) and bismuth (Bi) were selected as internal standard elements. The
internal standard solution was added to the calibration standards and samples using an
internal standard automatic addition kit, which utilizes a T-shaped glass tube and a peristatic
pump for mixing the analysis sample with the internal standard sample and introducing the
mixture to the nebulizer.
 Digested diluted samples were analyzed with a Shimadzu ICPMS-2030 coupled with a CETAC
ASX-280 autosampler.
 Quality control samples including initial calibration verification standard (ICV), continuing
calibration verification standards (CCV), method blank, and matrix spiked samples were run to
ensure the validation of the calibration curve, the accuracy and precision of quantification, and
the drift of instrument within acceptable range. The ICV was run right after the calibration
standards. The CCV was run before and after the sample sequence, and every 10 samples.
Experimental

6. Table 2. Operating conditions of Shimadzu ICPMS-2030
Parameter Setting Parameter Setting
Radio Freq. Power 1.20 kW Mix Gas 0.00 L/min
Sampling Depth 5.0 mm Cell Gas 6.0 mL/min
Plasma Gas 9.0 L/min Cell Voltage -21 V
Auxiliary Gas 1.10 L/min Energy Filter 7.0 V
Carrier Gas 0.70 L/min Chamber Temp. 5 oC
Experimental
 The ICPMS is equipped with a collision cell that uses helium (He) to discriminate polyatomic
interferences based on kinetic energy. Data were collected with He gas on to minimize the
polyatomic interferences. Table 2 lists the operating conditions used for the ICPMS-2030.
Analytical elements and their corresponding measurement parameters are listed in Table 3.

7. Experimental
Table 3. Analytical elements and their corresponding measurement parameters
Elem.a Mass ITSD
Calib. Range
(µg/L)
Corr. Coeffic.
R2
Instrument Limits
(µg/L)b
Calculated Limits
(µg/L)c
Spiked
Concen.
(µg/L)d
DL LOQ DL LOQ
As 75 Sc (45) 0.025-1 1.0000 0.00304 0.0101 0.00157 0.00522 0.5
Cd 111 In (115) 0.0125-0.5 0.9997 0.000524 0.00175 0.000297 0.000989 0.25
Hg 200 Bi (209) 0.0045-0.18 1.0000 0.000388 0.00129 0.000704 0.00235 0.1
Pb 208 Bi (209) 0.0125-0.5 0.9999 0.000673 0.00224 0.000430 0.00143 0.25
a. For all elements, integration time is 4 sec, No. of Scan 10, Repeat No. 3, helium cell gas on;
b. Detection limits (DL) and limits of quantification (LOQ) provided by the instrument software;
c. DL and LOQ based on the standard deviation of 10 repeated blank samples;
d. Spiked concentration is the spiked concentrations of different elements in the final measurement solutions after dilution.

8. Results and Discussion
• Calibration curves for the target elements are shown in Figure 1. All of the calibration curves
show excellent linearity across the respective calibration range.
Figure 1. Calibration curves for As, Cd, Hg and Pb.
0.00 0.25 0.50
Concentration (ug/L)
0
50
100
150
Pb 208 (DBG)
0.0 0.5 1.0
Concentration (ug/L)
0
10
20
30
40
As 75 (DBG)
0.00 0.25 0.50
Concentration (ug/L)
0
25
50
Cd 111 (DBG)
Intensity
Intensity
Intensity
Intensity
0.0 0.1 0.2
Concentration (ug/L)
0.0
2.5
5.0
7.5
10.0
Hg 200 (DBG)

9. Results and Discussion
• All the different baby foods were completely decomposed, leaving clear solutions after
digestion.
• Table 4 shows the concentrations of elements in ppb in digested solutions of original and
fortified samples for different baby foods as well as blank sample. All of the four target
elements are below the detection limit for the blank sample.
• Relative standard deviations (RSD) are mostly below 5, indicating the high precision of the
instrument. All initial calibration verification sample (ICV), continuing calibration verification
samples (CCVs), and spiked samples show recoveries in the range of 90-110%, further
validating the methodology and the accuracy of the Shimadzu ICPMS-2030.

10. Results and Discussion
Table 4. Concentrations of elements in digested solutions of original and fortified samples as well as recovery yields
75As 111
Cd 200Hg 208
Pb
Blank
Mean value (µg/L) n.d.a n.d. n.d. n.d.
RSD (%, n=4)b --- --- --- ---
Fortified blank
Mean value (µg/L) 0.508 0.244 0.0956 0.264
RSD (%, n=4) 3.56 1.96 1.87 2.44
Recovery (%) 102 98 96 106
Apple juice
Mean value (µg/L) 0.0440 n.d. n.d. 0.0189
RSD (%, n=4) 3.85 --- --- 6.11
Fortified apple juice
Mean value (µg/L) 0.550 0.247 0.101 0.283
RSD (%, n=4) 1.50 2.17 3.25 3.67
Recovery (%) 101 99 101 106
Puffs
Mean value (µg/L) 0.638 0.0697 n.d. 0.113
RSD (%, n=4) 2.38 4.81 --- 2.09
Fortified Puffs
Mean value (µg/L) 1.12 0.314 0.101 0.364
RSD (%, n=4) 1.69 2.13 1.83 1.13
Recovery (%) 96 98 101 100
Rice cereal
Mean value (µg/L) 0.534 0.0541 0.00855 0.0480
RSD (%, n=4) 1.80 5.08 3.38 2.79
Fortified rice cereal
Mean value (µg/L) 1.03 0.302 0.112 0.310
RSD (%, n=4) 1.45 2.61 4.07 3.22
Recovery (%) 100 99 104 105
a. n.d. = not detected;
b. RSD, relative standard deviation of four separate measurements.

11. Results and Discussion
• Table 5 shows concentrations of target elements in raw materials. All three baby foods
contained As and Pb, and some contained detectable Cd and Hg. The puffs and rice cereal
contained 124 and 106 µg/kg of As, respectively, significantly higher than the maximum levels
of As in baby foods proposed in Baby Food Safety Act.
Table 5. Concentrations of toxic elements in baby foods (in µg/kg
matrix), back-calculated for dilution and initial mass of matrices
As Cd Hg Pb
Apple juice 2.21 n.d. n.d. 0.949
Puffs 124 13.6 n.d. 22.0
Rice cereal 106 10.8 1.70 9.57

12. Shimadzu ICPMS-2030 provides excellent sensitivity, precision, accuracy, tolerance, fast time
response and high sample throughput for determination of multiple elements in baby foods at
extremely low levels.
Conclusions
References
• “Baby Foods Are Tainted with Dangerous Levels of Arsenic, Lead, Cadmium, and Mercury”,
Subcommittee on Economic and Consumer Policy, Committee on Oversight and Reform, U.S. House
of Representative, February 4, 2021
• “Baby Food Safety Act of 2021”, Committee on Health, Education, Labor, and Pensions, U.S. House of
Representative

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