**2.5 Quality assurance and quality control**

Appropriate quality assurance and procedures were followed to ensure the reliability and reproducibility of the results. Glassware were dipped in chromic acid for overnight and washed 2–3 times with de-ionized water before use. Analytical grade standard chemicals and reagent blanks were used during analyses to check chemical impurities and other environmental contaminations. Always, freshly prepared solutions were standardized against primary standard for actual strength. Triplicate samples were analyzed to check precision of the analytical method and instrument. For elemental analysis, certified reference material (CRM) multi element standard solution IV (CertiPUR® 1.11355.0100 Lot. No. HC081563, Merck) were used and the operating condition are given in **Table 3**.
