1. You have taken a surface water sample and a duplicate sample at SW3 (surface water location 3). The sample result determined a chloride reading of 153 mg/L, while the duplicate sample determined a chloride reading of 143 mg/L. Calculate the relative percent difference (RPD) between the actual and duplicate samples. Show your calculations (2 marks)

Ans. As we all know,

RELATIVE PERCENT DIFFERENCE =

(Sample result - duplicate result) / (sample result + duplicate result)

_________________________________________________________ x 100

2

So, sample result = 153mg/L and duplicate result = 143mg/L