Introduction: Heavy metals are present in abundance amount in soil, water, food stuffs, trash, sewage, and soft drinks as well released by industries, commercials, residentials. Presence of these metals cause exposure to the humans, animals, plant and other biotic factors like air, water and environment and make them polluted. Detection of these metals can be done by various electrochemical methods and machineries. There are several analytical testing methods for detection of heavy metals. HM contaminants in solid waste often originate from multiple sources, including natural (weathering and erosion of parent rocks) and anthropogenic sources (mining, metallurgy, manufacturing of HM-containing product, vehicle emissions), (Weiss D J, Rehkämper M, Schoenberg R, et al. 2008, 42: 655–664). The few of them are AAS (Atomic Absorption Spectrometry), AES/AFS (Atomic emission fluorescence spectrometry), ICP-MS (Inductively coupled plasma mass spectrometry), ICP-OES (Inductively coupled plasma optical emission spectrometry), NAA (Neutron activation analysis), (XRF) X-Ray Fluorescence and AVS (Anodic striping voltammetry), MP-AES (Microwave Plasma Atomic Emission Spectroscopy). In this review of literature number of research papers are to be taken as reference to study amount of heavy metals in different fields and the detection methods for them.
Key Words: Heavy metals (HM), AAS, AES, ICP-MS, ICP-OES, NAA, MP-AES, X-Ray.
Review of Studies:
Boron, Phosphorus and Molybdenum content was determined in biosludges samples using MP-AES where microwave assisted acid digestion method was utilized to extract B, P, and Mo from biosludge. The limit of quantification and detection of B, P, and Mo in the extracts were determined; the linear regression coefficient was greater than 0.998 for all the three techniques, (Srinivasulu vudugandha, Nadavalasiva kumar March 2017).
Ijaz Ahmad, 2017 used Perkin Elmer Atomic absorption (AA) spectrophotometer for determination of heavy metals like Cd, Cr, Cu, Fe, Mn, Ni, & Zn in milk of camel, sheep, cattle, buffalo. They found high levels of Zn (5.150 ± 0.021 Mg/Kg), Mn (0.094 ± 0.530 Mg/ Kg) & Fe (1.580 ±0.530 Mg/Kg) in milk of camel while higher levels of noxious heavy metals such as Cu (0.223 ± 0.010 Mg/Kg) & Cd (0117 ± 0.086 Mg/Kg) were detected from goat milk. Moreover, it can be say that camel and buffalo have equal higher concentration of heavy metals.
Acid extraction was done under microwave irradiation in closed vessels using two method MP-AES & ICP-OES. The results using MP-AES was best alternatives in compare to ICP-OES for Cd, Cr, Cu, Ni, Pb and Zn. Some elements such as Cd, Cr, Pb and Zn were not influenced by applied acid treatment. But they extracted Cr, Ni in higher rate using aqua regia in compare to nitric acid, (V.Y zapryonova and E.N. Piskova (2016, dec19)).
The heavy metals determination in 25 tea samples was done in china by (Wen-si-zhong et. al, 2015, 18 July) using continuum sourced graphite furnace atomic absorption spectroscopy for quantitative analysis. They established method for sample preparation, digestion and quantified analysis of lead content in.
The study on fishes such as Chitalachitola Barbonymus Goninatus & Tachysuras Maculatus was carried out by (Rohasliney Hashim et. al 2014) using graphite furnace atomic absorption spectrometer. They detected heavy metals Cd in Chitala (0.076 Mg/Kg) while in Barbonymus Gonionatus & Tachysuras Muchulatus were already serious levels. That Ni level in all fish sample were under permissible limit. The concentrations of those heavy metal were higher in wet season, even they compared omnivorous fish & carnivorous fish with higher concentration of Pb in carnivorous fish. Moreover, they compared fish weight with concentration of Pb & Cd which were positively correlated overall, they conducted that Kelantan river fishes not exceed the EC &FAQ or WHO guidelines.
Study on water sample &fish from Tasikmutiura, puchongo for elemental analysis using ICP-OES.Only Al, Cu, Fe and Zn were detected whereas as, Cd, Pb were below detection limit. The level of heavy metals in fish sample was serious matter compare to water sample. That could be attributed to low Dissolved Oxygen (DO) levels in the lake, (Ismaniza&Idaliza Mat Salch (2012,)).
L. Dospatliev, K. Kostadinov, G. Mihaylova, N. Katrandzhiev in the year 2012 found Heavy metals Pb, Zn, Cd and Ni in the eggplant sample in the municipality of Plovdiv. Sample preparation was done by microwave system Mileston 1200 MEGA. ICP – OES was used for the determination.
Ma Lin1, Wu Chunhua, Zhao Yang in 2012 developed a method for the determination of extractable heavy metals in leather and textiles by MP-AES. Samples were extracted by artificial perspiration. The result showed that the limit of detection was 0.3?28.8?g/L, the average recoveries ranged from 88%?108%,and the relative standard deviations are lower than 1.5%.

Study of heavy metal content in 15 cosmetic products both imported and locally manufacture products were analyzed using AAS. The concentration of Pb, Cu was higher and if such products used for long time then may pose threat to human health, (Shumaila Zubair, Muhammad Adnan and Ijaz ahmad (2013sep11)).
(M Bettinellia,G.M Beoneb, S Speziaa and C Baffib in 1 December 2000) has done the measurement of the entire substance and the entire example by the blend of nitric acid and hydrochloric acid with the molar proportion of 1:3 which is otherwise called Aqua regia is a yellow-orange fuming fluid. They consolidated the microwave absorption system with the inductively coupled plasma nuclear outflow spectrometry (ICP-OES). Notwithstanding utilizing the customary reflux framework, they utilized the closed vessel framework for the assurance of Aqua regia blend. As the CRM they have utilized the CRM 141R ‘Calcareous Loam Soil’, CRM 142 ‘Light Sandy Soil’, CRM 143 ‘Sewage Sludge Amended Soil’, CRM 277 ‘Estuarine Sediment’ and CRM 320 ‘Waterway Sediment’. The test was completed in two of the research laboratories by utilizing the microwave plasma and the ICP-OES. To check the execution of the two of the laboratories, they did the confirmatory testing of the repeatability, reproducibility and recovery. The investigation was finished by the nested plan and it was confirmed that the changeability in the outcomes were from ICP-OES and not from the Microwave Plasma assurance.
Michalski Rajmund, Muntean Edward, Konczyk Joanna, used A Microwave Plasma – Atomic Emission Spectroscopy method for the determination of selected metals and metalloids (Cr, Mn, Fe, Ni, Cu, Zn, Cd, Al, Pb, Co) in herbal tea infusions the limits of detection were in the range of 0.01-0.12 mg L-1.
The concentration of heavy metal elements of environmental significance in the leachate from landfills of urban solid wastes was determined using Inductively-Coupled Plasma Atomic Emission Spectrometry (ICP-AES). Both highly toxic elements (As, Cd, Co, Cr, Pb and V) and elements present at major concentrations (Al, B, Cu, Fe, Mn, Ni and Zn) were quantified at different levels within and under the landfill (A.Alimonti, S.Caroli, L.Musmeci determined).