Evaluation of Heavy Metals Concentration in Milk Products by using Atomic Absorption Spectroscopy

E-ISSN: 2720-9326 P-ISSN: 2716-0459 DOI: 10.20885/EKSAKTA.vol2.iss2.art7 Research Article Evaluation of Heavy Metals Concentration in Milk Products by using Atomic Absorption Spectroscopy Nurul Auni Zainal Abidin1*, Nur Sofiah Abu Kassim 1, Sheikh Ahmad Izaddin1, Sheikh Mohd Ghazali1, Noor Hidayah Pungot2, Siti Sufiana Kamni2 1 2 * Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Cawangan Negeri Sembilan, Kampus Kuala Pilah, 72000 Kuala Pilah, Negeri Sembilan, Malaysia Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia Corresponding author: Received: 21 September 2021; Accepted: 23 September 2021; Published: 28 September 2021 Abstract: Milk products are essential food in the human diet because it contains many essential trace minerals such as calcium, magnesium, copper, zinc, sodium, potassium and phosphorous. The utilization of, milk is increasing at a large scale throughout the world. It is essential to maintain the good quality of milk during production and manufacturing because the presence of toxic metals in the milk becomes the cause of health disturbance in human life. Therefore, the present investigation was carried out to determine concentrations of lead, nickel, iron, copper, and chromium in powdered milk and fresh milk products by Atomic Absorption Spectroscopy. Different milk samples of products (two fresh milks and two powdered milks) were purchased from the local market. For the decomposition of the organic substances in milk samples, wet digestion was used with a mixture of nitric acid and sulfuric acid in volume proportions 1:3 (v/v). The analytical curve for all metals covered the linear range from 0.5 to 4.0 ppm with correlation coefficients higher than 0.9994. The limit of detection (LOD) for Pb, Ni, Fe, Cu, and Cr were found to be 0.25, 0.023, 0.012, 0.0067, and 0.073 ppm, respectively. While the limit of quantification (LOQ) in the range of 0.02 to 0.76 ppm. Of all the metals determined, Pb, Ni, and Fe were the most abundant with concentrations between 1.233 and 1.677 ppm while Cr was not detected in all the samples. The results showed that fresh milk samples have a higher concentration of heavy metals compared to powdered milk samples. Keywords: Heavy metals, milk products, Atomic Absorption Spectroscopy, correlation coefficients, limit of detection Introduction Increasing in population around the world from modern technology led to the rises of environmental pollution. Environmental pollution can occur because of many factors and one of the factors is because of the contamination of heavy metals. Heavy metals are referring to any metallic chemical element that is higher in density and toxic or poisonous at low concentrations [1]. Heavy metal can enter the body through food consumption in daily life. As for children, heavy metal s entered the body through milk that they consumed for their growth and development during infancy. Daily consumption of milk products shows evidence that it provided a unique balance of nutrients to the human body. Milk can be described as a vital component that gives benefits to the human diet. Milk has been categories as a complete food to human because contained important nutrients such as protein, vitamins, minerals, and essential fatty acid [2]. There are two groups of metal contents in milk which are essential elements and non-essential elements. Iron, copper, and zinc are essential elements while lead and cadmium are non-essential elements. Nowadays, there are many improvised milk productions that have been made by people such as powdered milk, fresh milk, and other dairy products such as yogurt and cheese. The heavy metals may enter the powdered milk through different machines that are involved in the processing and distribution and it also can contaminated powdered milk either through foodstuff and water or through manufacturing and packaging processes [3]. EKSAKTA journal.uii.ac.id/eksakta 136 August 2021, Volume 2, No. 2, 136-141 E-ISSN: 2720-9326 P-ISSN: 2716-0459 The excess presence of heavy metals in milk can give side effects on human health. Heavy metals in the body may cause drawbacks such as the damages of skeletal and cell, renal failure, osteoporosis, blood and lung cancer, hormonal disturbances, gastrointestinal problems, and anemia [3]. Plumbum (Pb) can cause the disorder of the central nervous system, damages to kidneys, liver, heart, and blood vessels, the immune system, and the development of cancer. Besides, Cadmium (Cd) may give side effects when it accumulates in tissues like the liver and kidneys. Cadmium (Cd) is carcinogenic especially in the lungs and prostate and caused the development of tumors. The determination of trace inorganic constituents in milk is a challenging task due to their complex emulsions like matrices and low concentration levels of the metal ions [4]. Many digestion procedures to oxidize organic matrices of different samples have been reported in the literature [5,6]. The acid digestion procedures are the most popular sample pre-treatment techniques for elemental determination in biological and environmental samples. The determination of heavy metals can be performed by several instrumental techniques [7] including indirect photometric chromatography [8], ion chromatography [9], flame atomic absorption spectrometry [10], and flame atomic absorption spectrometry [11]. One of the instruments that provide an accurate result is atomic absorption spectrophotometry (AAS). Due to the high sensitivity, this technique authorizes the establishment of sequential and simultaneous methods for determinati ons of many elements with efficient background correction [12]. Thus, this study aims to determine the heavy metal contents such as lead (Pb), chromium (Cr), nickel (Ni), copper (Cu), and iron (Fe) in different types of powdered milk and fresh milk product s by using atomic absorption spectrophotometry. Materials and Methods The chemicals used in this study are nitric acid (HNO 3), sulphuric acid (H2SO4), deionized water, and the standard solution of Pb, Ni, Fe, Cu, and Cr. Atomic Absorption Spectrometer Analyst (Perkin Elmer) 700 equipped with high-intensity deuterium arc lamp for the correction of non-specific background and WinLab32 software for atomic absorption provides maximum productivity and compliance (Figure 1). Two different brands of milk which are fresh milk (A and B) and powdered milk (C and D) were purchased from the local market. Figure 1. Basic atomic absorption spectrometer setup. For the preparation of powdered milk sample, 0.5 g of sample was weighed by using an analytical balance. The sample was transferred into 100 mL round bottom flask and mixed with 5 mL of HNO 3 and 15 mL of H2SO4 with volume ratio of 1:3 (v/v). These mixtures were digested at 210 ℃ for 2 hours and 30 minutes in a Kjeldahl digested apparatus fitted with reflux condenser. Then, the digested sample was allowed to cool (...truncated)