Element Wavelength(nm) Slit width(nm) Working range(mg L -1 ) Ca 422.7 0.5 1-10

Question

Element Wavelength(nm) Slit width(nm) Working range(mg L-1 ) Ca 422.7 0.5 1-10 Mg 202.6 1 1-20 K 769.9 1 1-6 Na 586.9 0.2 0.1-2.0 1. The typical results for the analysis of the metals of interest in the two samples are given below: Typical concentration mg L-1 Sample Na Mg Tap Water Diet Pepsi 2.5 Using these results determine any dilution that will be necessary to place these concentrations within the working range of standards suggested in the These working ranges are given on your answer sheet procedure. Calculate this as a dilution factor. For example, if the concentration is ten times too concentrated, the dilution factor required will be ten-fold. We will use an autodiluter to get the concentrations within the working range before analysis.

Explanation / Answer

Solution:

Tap water:

Typical concentration is 50 mg/L

We want range of dilution factor:

If we see lower limit of concentration 0.1 mg/L then typical concentration is 500(50/0.1) times more concentrated so dilution factor is = 500

  If we see upper limit of concentration 20 mg/L then typical concentration (50mg/L) is 2.5(50/20) times more concentrated so dilution factor is = 500

So we can conclude that dilution factor can be in the range of 2.5-500 to place these concentrations in standard range.

Typical concentration is 5 mg/L

There is no dilution required in this case because concentration is already in working range.

Dilution factor = 1

Typical concentration is 30 mg/L

We want range of dilution factor:

If we see lower limit of concentration 1 mg/L then typical concentration is 30(30/1) times more concentrated so dilution factor is = 30

  If we see upper limit of concentration 10 mg/L then typical concentration (30mg/L) is 3(30/10) times more concentrated so dilution factor is = 3

So we can conclude that dilution factor can be in the range of 3-30 to place these concentrations in standard range.

Typical concentration is 5 mg/L

There is no dilution required in this case because concentration is already in working range.

Dilution factor = 1

Diet pepsi:

Typical concentration is 60 mg/L

We want range of dilution factor:

If we see lower limit of concentration 0.1 mg/L then typical concentration is 600(60/0.1) times more concentrated so dilution factor is = 600

  If we see upper limit of concentration 20 mg/L then typical concentration (60mg/L) is 3(60/20) times more concentrated so dilution factor is = 3

So we can conclude that dilution factor can be in the range of 3-600 to place these concentrations in standard range.

Typical concentration is 22 mg/L

We want range of dilution factor:

If we see lower limit of concentration 1 mg/L then typical concentration is 22(22/1) times more concentrated so dilution factor is = 22

  If we see upper limit of concentration 6 mg/L then typical concentration (22mg/L) is 3.6(22/6) times more concentrated so dilution factor is = 3.67 = 4 (approx.)

So we can conclude that dilution factor can be in the range of 4-22 to place these concentrations in standard range.

Typical concentration is 3 mg/L

There is no dilution required in this case because concentration is already in working range.

Dilution factor = 1

Typical concentration is 2.5 mg/L

There is no dilution required in this case because concentration is already in working range.

Dilution factor = 1

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