2.4 Quality assurance and quality control
Quality assurance and quality control is an efficient method to get a more accurate result during the sampling and testing of groundwater. One of the most important activities associated with sampling site selection satisfies the objective of the present research. Once well selected, sampling documentation and collection was carried out. All the samples were collected in the 1 litre polyethylene bottle washed with a 10% HNO3 solution. An ionic balance error (IBE) equation is used to get an accuracy of analytical results between the concentration of major cation and anion in milliequivalent per litre (meq/L) for all collected samples (Eqn.2). The value of IBE should not exceed the acceptable limit of ± 10%.
\(IBE=\frac{\sum{Cations-\ \sum\text{Anions}}}{\sum{Cations+\ \sum\text{Anions}}}\times 100\)