3-1. Sample preparation
About 500 mg of sample was weighed in microwave vessels. Samples were kept for
10 minutes of pre-digestion after carefully adding 3 mL of suprapure nitric acid (HNO
3
) and
2 mL of ultra pure water. The vessels were then heated in microwave digestor under
controlled temperature program (Table 2).
After digestion, samples were left to cool at ambient temperature and filled up using ultra-
pure water in a 50 mL volumetric flask. Pre-spiked recovery studies were carried out at
limit of quantifications LOQ & 10 x LOQ levels by spiking samples with standard stock
solution. The LOQ level was set as per EC 836/2011. Table 3 shows the (LOQs) which
were achieved in the present study.
Estimation of heavy metals in processed fruit products using Shimadzu inductively coupled plasma mass spectrometry
Sampada Khopkar , Mangesh Pawar, Amol Shinde, Ajit Datar, Jitendra Kelkar and Pratap Rasam
Shimadzu Analytical (India) Pvt. Ltd., 1 A/B Rushabh Chambers, Makwana Road, Marol, Andheri (E), Mumbai-400059, Maharashtra, India
2. Introduction
Commercially available fruit jams, juices and concentrates (Figure 1) contain different
physiologically and nutritionally important compounds, e.g. bioactive phytochemicals
(phenolic, flavonoids, carotenoids etc.) and vital nutrients (proteins, carbohydrates and
vitamins).
An increased popularity and demand for these food items is due to increased awareness
about healthcare and average life expectancy in society. All these reasons make fruit
products very widely consumed in both developed and developing countries by different
age groups. Apart from nutritional and functional compounds, fruit juices contain many
major (macro elements like Ca, K, Mg etc.), minor (micro elements like Cu, Fe, Mn, Zn
etc.) and trace elements (As, Cd, Cr, Pb, Hg, Se etc.).
Figure 1. Typical processed fruit items
Copper plays an important role in hemoglobin synthesis. Zinc is essential for many
enzymes involved in several physiological functions such as protein synthesis and energy
metabolism. Lead is highly toxic element that accumulates in biological systems and it
leads to deficits in psychological functions such as intelligence and learning ability in
humans. Even though macronutrients are required for many biological functions, their
excess presence in human body leads to health hazards. The main sources of the
elements in such samples may be water, fruit, soil, manufacturing process, container and
environmental contamination due to fertilizers, pesticides, raw materials etc.
Considering the nutritional value associated with essential elements indispensable for life
maintenance on one hand, and the health hazard of toxic elements on other hand,
elemental analysis of these food items is of importance. It becomes particularly important
for fruit products, due to high seasonal variability in their elemental composition. Their
regular examination with respect to elemental content can bring valuable information
about their suitability for consuming. Reliable information on the elemental content of jam,
fruit juice, and concentrates can help producers to improve the overall quality of these
products by identifying sources of contamination with toxic elements. It is also important
for consumers in view of the nutritional value of processed fruit products.
The present work aimed to develop an ICPMS method for determination of heavy
elements in jam, juice and concentrates samples as per FSSAI limits.
The elemental content in all matrices was found to be below LOQ. Table 6 shows the results
obtained for % recoveries at LOQ and 10 x LOQ level. Using ICPMS-2030, excellent spike
recoveries were achieved for most of the elements in spiked samples. Recoveries were within
80 to 120 % for all elements.
5. Conclusion
The macronutrient as well as toxic elements specified by FSSAI were measured in sub ppb to ppm
range. The spiked recoveries shows reliability of the method. The results demonstrate suitability of
the Shimadzu ICPMS-2030 for routine analysis of jam, juice and concentrate samples.
The calibration standard solutions showed good linearity with correlation coefficient ≥ 0.995. The
internal standards used were Bi and Y. The selection of internal standard was as follows; for Pb
and Hg, Bi was used and for As, Cd, Cu, Sn and Zn, Y was used as internal standard. The
concentration of internal standard was 20 ppb. The memory effect of mercury was alleviated by
adding 100 ppb gold into the standards and samples.
ThP 175
Figure 2. ICPMS-2030 with auto sampler AS-10
4. Results
Disclaimer: The products and application in this poster are intended for Research Use Only (RUO). Not for use in diagnostic
procedures.
Table 2. Microwave digestion program used in present study
Ramp (min)
Temperature (°C)
Hold (min)
10
120 5
10
180 30
Table 3. LOQs for processed fruit products
Element LOQ in ppm
As 0.02
Cd 0.02
Hg 0.2
Pb 0.2
Cu 1.4
Sn 50
Zn 1
3-2. Calibration standard preparation
Sigma Aldrich 1000 ppm individual certified reference standards were used for preparation of
intermediate stock solution. Calibration standard solutions were prepared by diluting
intermediate stock solution. Yttrium and Bismuth were used as internal standards. Internal
standards were aspirated using online internal standard addition kit. The instrumental
configuration and analytical conditions are given in Table 4. The concentrations of linearity
standards are given in Table 5.
Table 4. Instrumental Parameters
Plasma torch Mini torch
Radiofrequency 1.2 kW
Sampling depth 5 mm
Plasma gas flow 10 L/min
Auxiliary gas flow 1.1 L/min
Carrier gas flow 0.7 L/min
Collision gas Helium
Collision gas flow 6.0 mL/min
Cyclone Chamber temp.
5 °C
Figure 3 Linearity curves for targeted elements
Calibration level As Cd Hg Pb Cu Sn Zn
Level 1 0.1 0.1 1 1 7 25 5
Level 2 0.2 0.2 2 2 14 50 10
Level 3 0.5 0.5 5 5 35 125 25
Level 4 1.0 1.0 10 10 70 250 50
Level 5 2.0 2.0 20 20 140 500 100
Level 6 2.5 2.5 25 25 175 625 125
Table 5 Concentrations (in ppb) of linearity levels used in present work
Elements
Jam Juice Concentrate
% Recovery at
LOQ
% Recovery at
10 X LOQ
% Recovery at
LOQ
% Recovery at
10 X LOQ
% Recovery at
LOQ
% Recovery at
10 X LOQ
As
91.8 91.7 92.5 95.2 102.3 99.8
Cd
97.4 95.4 92.3 93.8 99.1 95.6
Hg
94.9 92.7 95.2 92.3 97.3 91.7
Pb
101 97.4 97.4 96.2 103 102.4
Cu
99.5 94.4 103.3 99.6 109.9 107.7
Sn
96.1 100.9 96.1 97.5 98.6 104.7
Zn
107.1 94 96.8 94.9 108.6 96.7
Table 6. Average % recoveries obtained at LOQ and 10 X LOQ (n=4)
1. Overview
In the present work, an inductively coupled plasma mass spectrometry (ICPMS) method
for elemental analysis of processed fruit products with ICPMS-2030 was developed.
Commercially available samples from local market were used for this experiment.
The Maximum Residual Limits (MRL’s) of elements as per Food Safety Standards Authority
of India (FSSAI) guidelines are shown in Table 1. The analysis was performed on
Shimadzu ICPMS-2030 (Figure 2) coupled to an autosampler.
3. Method
Element FSSAI Limit in ppm
Arsenic (As) 0.1*
Cadmium (Cd) 0.1*
Mercury (Hg) 1
Lead (Pb) 1
Copper (Cu) 7
Tin (Sn) 250
Zinc (Zn) 5
Table 1. FSSAI limits for heavy element in processed fruit products
*Due to nonavailability of FSSAI limits, they were taken arbitrarily.
