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PO-CON1795E Analysis of toxic elements in processed milk products using ICP-MS ASMS 2017 TP 195 Mangesh Pawar 1 , Amol Shinde 1 , Sampada Khopkar 1 , Ankush Bhone 1 , Ajit Datar 1 , Pratap Rasam 1 , Jitendra Kelkar 1 Shimadzu Analytical (India) Pvt. Ltd., 1 A/B Rushabh Chambers, Makwana Road, Marol, Andheri (E), Mumbai-400059, Maharashtra, India.
2 Analysis of toxic elements in processed milk products using ICP-MS Introduction Milk is considered as complete food as it provides all essential macro and micronutrients. Macronutrients consist of protein, carbohydrate and lipids, whereas micronutrients consist of elements, vitamins and enzymes [1][2] . Milk as an excretion of the mammary gland can carry numerous xenobiotic substances that constitute a technological risk factor for milk and milk products. Toxic elements like Arsenic (As), Cadmium (Cd), Lead (Pb) and Mercury (Hg) have caused adverse effects on human health. These can be transferred from contaminated soil to plants and grass, causing accumulation of these toxic metals in cattle, but also in humans consuming milk. Milk processing may also cause contamination of milk products with toxic elements. The objective of this study is to develop a sensitive, selective, accurate and reliable method using Shimadzu ICPMS-2030 to determine the risk of toxic heavy metals in milk product. Methods and Materials Commercially available milk products e.g. toned milk and cheese (Figure 1) were used for the extraction of toxic heavy metals in this study. Recovery studies were established by spiking milk product samples with standard solution of elements. The extracts obtained were analysed on Shimadzu ICPMS-2030. Figure 1 Milk and processed milk products The samples were digested using microwave digestion system (Anton Paar). Sample Preparation: Transfer 1g of milk/ cheese in microwave digester PTFE vessel Add 5mL nitric acid, 1mL perchloric acid, 1mL hydrogen peroxide Sample digestion in microwave digester as per programme (Table 1) & volume make up to 20mL
3 Figure 2 Shimadzu ICPMS-2030 Inductively coupled plasma mass spectrometer Figure 3 Newly developed Collision Cell Analysis of toxic elements in processed milk products using ICP-MS 1 2 3 4 10 10 10 10 Steps Ramp (min) 100 150 180 200 Temp (°C) 05 10 10 10 Hold time (min) Table 1: Microwave digester programme Inductively coupled plasma mass spectrometer ICPMS-2030 by Shimadzu (shown in Figure 3), sets a new benchmark in ICP-MS technology with minimum consumption of Argon gas. This system ensures highest quality of data, with very high degree of reliability. The newly developed collision cell (shown in Figure 3) based on UFsweeper technology uses high purity Helium gas for removal of polyatomic interferences. The mini-torch design allows the operation of ICPMS at low RF power without compromising the sensitivity. Key features of ICPMS-2030 The extracts obtained were analysed on Shimadzu ICPMS-2030. Analysis was done using plasma generated by specially designed mini torch as an ionization source. ICPMS LabSolutions software and special features like Profile integration time and Total mass measurement were used for identification, detection and quantitation. NIST traceable standards were used for quantification of elements at low level in QuantBase mode (used for quantitation purpose).
4 Analysis of toxic elements in processed milk products using ICP-MS Torch : Mini torch Radiofrequency : 1.2 kW Sampling depth : 5 mm Plasma gas (L/min) : 8.0 Auxiliary gas (L/min) : 1.1 Carrier gas (L/min) : 0.7 Cell voltage : -21 V Cell gas (mL/min) : 6.0 Energy Filter : 7V Chamber temp. : 5 ˚C Number of scans : 10 Integration time : 2sec Peristaltic pump speed : 60 r.p.m.- High 20 r.p.m.- Low Isotopes monitored = 75 As, 111 Cd, 208 Pb, 202 Hg Internal standard = 89 Y Analytical Conditions (ICPMS-2030) Linearity data for elemental standards in the concentration range of 0.1 μg/L to 10 μg/L for toned milk and cheese is shown in Figure 4 and Figure 5. Figure 4 Standard linearity curves for 0.1-10μg/L for Milk 0 5 10 Concentration (ug/L) 0 25 50 75 100 As 75 (DBG) 0 5 10 Concentration (ug/L) 0 25 50 75 100 Cd 111 (DBN) 0 5 10 Concentration (ug/L) 0 250 500 750 Pb 208 (DBN) 0 5 10 Concentration (ug/L) 0 25 50 75 Hg 202 (DBN) Intensity Intensity Intensity Intensity 3s = 0.011695 (μg/L) 10s = 0.038984 (μg/L) 3s = 0.001505 (μg/L) 10s = 0.005018 (μg/L) 3s = 0.004171 (μg/L) 10s = 0.013905 (μg/L) 3s = 0.000051 (μg/L) 10s = 0.001706 (μg/L) r= 0.99995 r= 0.99991 r= 0.99997 r= 0.99749
5 Analysis of toxic elements in processed milk products using ICP-MS Not detected Not detected 5.6 1.6 Toned milk (μg/L) Cheese (μg/L) 5.0 Not detected Not detected 1.2 Table 2 Average elemental results obtained for processed milk products (n = 6 replicates) As Cd Pb Hg Elements Figure 5 Standard linearity curves for 0.1-10μg/L for Cheese 0 5 10 Concentration (ug/L) 0 25 50 75 100 As 75 (DBG) 0 5 10 Concentration (ug/L) 0 25 50 75 100 Cd 111 (DBN) 0 5 10 Concentration (ug/L) 0 1000 2000 3000 4000 5000 Pb 208 (DBG) 0 5 10 Concentration (ug/L) 0 25 50 75 Hg 202 (DBN) Intensity Intensity Intensity Intensity 3s = 0.034835 (μg/L) 10s = 0.116118 (μg/L) 3s = 0.009937 (μg/L) 10s = 0.033125 (μg/L) 3s = 0.012816 (μg/L) 10s = 0.042722 (μg/L) 3s = 0.005946 (μg/L) 10s = 0.019822 (μg/L) r= 0.99993 r= 0.99999 r= 0.99999 r= 0.99998 Results Extracts were analysed on ICPMS-2030 in QuanBase mode. The elements were further quantified using calibration curves plotted from analytical standards (Merck). Measurements were made using an off axis Collison cell system which helped to remove neutrals and photon interferences. The results obtained were evaluated for statistical parameters like accuracy and linearity. Accuracy in terms of recovery was found to be between 70 to 120% for pre-spiked samples. The results showed good linear response with correlation coefficient ≥ 0.995.. The results obtained for toned milk and cheese are given in Table 1. RSD and % recoveries for toned milk and cheese are shown in Table 2 and Table 3 respectively. The RSD of six replicates was within 7%, showing good precision of the method.
First Edition: December, 2017 © Shimadzu Corporation, 2017 Analysis of toxic elements in processed milk products using ICP-MS 95-108 87-98 75-106 100-110 %Recovery (Accuracy) 96-117 92-97 99 -115 101-107 %Recovery (Accuracy) Cheese Toned milk %RSD 6.8 2.2 6.3 2.4 %RSD 5.4 1.6 2.1 0.9 Table 3 Average accuracy results at 0.25 μg/L of for toned milk & cheese sample (n = 6 replicates) As Cd Pb Hg Elements Conclusion ICPMS-2030 was found to be best technique for the determination of toxic heavy metals at very low concentration. The above methodology proved to be selective, sensitive, accurate and reliable. Disclaimer: Shimadzu ICPMS-2030 and application in this poster are intended for Research Use Only (RUO). Not for use in diagnostic procedures. Not available in the USA, Canada and China.