MMF724008 - Environmental Pollution Monitoring and Analysis
Determination of water with Suspected Copper Contamination – Part I
Scenario
An industrial unit is being used as a store by an internet bookseller. The basement of the premises is
being flooded by water which is damaging the stock. The bookseller is convinced that the adjoining
industrial unit, which has a metal plating operation including copper plating is responsible. This is
strongly denied by its owner.
Environmental Health Officers (EHOs) have sampled the basement water and brought you a sample
to report on.
If the copper content is more than 100mg/l then the EHOs will be convinced that the plating shop is
almost certain to be the cause and will examine it very closely.
Your task is to measure the copper concentration in mg/l and state whether the EHOs should
investigate or not.
Introduction
Copper can be quantified spectrophotometrically. The absorbance of a copper containing solution is
directly proportional to concentration over a wide range. The procedure complexes the copper with
ammonia to give a very intense blue colour. A calibration curve is drawn of Absorbance (Y-axis)
against Copper Concentration in mg/l (X-axis). The basement water is also complexed with ammonia
and the copper concentration determined from the calibration curve.
Procedure
You are supplied with a 0.010M solution of copper sulphate CuSO4.
(a) Calibration Curve
To a series of 100 cm3 volumetric flasks pipette 0, 5, 10, 15, 20 and 25 cm3 of the copper sulphate
solution into individual volumetric flasks. Note the actual volumes in Table 1.
Calculate the concentration of copper in each flask in mg/l as follows and insert into Table 1:
The concentration of copper is represented by [Cu]mg/l and is given by:-
[Cu]mg/l =
0.010 𝑥 𝑉𝑜𝑙𝑢𝑚𝑒 𝑎𝑑𝑑𝑒𝑑 (𝑐𝑚3) 𝑥 𝐴𝑡𝑜𝑚𝑖𝑐 𝑊𝑡 𝐶𝑢 𝑥 1000
100
Note:- Atomic Wt Cu is 63.55
To each flask add 10 cm3 of ammonia by pipetting or using a measuring cylinder (It does not matter
if you do not add exactly 10cm3.)
Make each flask up to the mark with water. Stopper and invert several times to mix thoroughly.
Set up an UV/Vis spectrophotometer to 600nm.
Obtain absorbance readings for each of your six solutions. Note these in Table 1.
Plot the calibration graph as Absorbance (Y-axis) versus [Cu]mg/l in Excel, use scatter plot and
determine line equation (y = mx + c).
Table 1 Working Results
Volume CuSO4 Added (cm3)*
[Cu]mg/l
(0)
(5)
(10)
(15)
(20)
(25)
*:- note down actual volume added.
Absorbance
(b) Basement Water Sample
Pipette 5 cm3 of the solution marked Basement Water into a 50 cm3 volumetric flask. This is Diluted
Basement Water.
Add 5 cm3 of ammonia using a measuring cylinder.
Make up to the mark with water. Stopper and invert several times to mix thoroughly.
Read the absorbance of this Diluted Basement Water ………………………………
Determine the concentration of copper in this Diluted Basement Water sample from the calibration
graph using the line of best fit equation.
Calculate the concentration of copper in the original Basement Water sample……………………………..