Question

These questions relate to ion chromatography to investigate water quality issues.

What is the purpose of making a 0 μM solution that contains no NaF? Why would we want to run a 0 μM sample in the Ion Chromatograph instrument and graph it on a calibration curve? Could you have made the most dilute 10.0 μM solution from weighing solid NaF and adding it to the 200.00 mL volumetric flask with water? Calculate the mass of NaF that would be needed and explain.

Answer 1

1. What is the purpose of making a 0 μM solution that contains no NaF?

Answer: it should be the control sample.

2. Why would we want to run a 0 μM sample in the Ion Chromatograph instrument and graph it on a calibration curve?

Answer: The calibration curve is made to check that method is working linearly within the working range. which started from the initial point 0. it is applicable to all calibration curves. if you got a linear relationship you can calculate the unknown amount of analyte which is lie in between the working range of the method.

3. Could you have made the most dilute 10.0 μM solution from weighing solid NaF and adding it to the 200.00 mL volumetric flask with water? Calculate the mass of NaF that would be needed and explain.

Answer: 10.0 μM solution of NaF means

if you prepare 10M solution of NaF means you have to dissolve 42g in 100ml or 42 x 1000 mg in 100ml or 42 x 1000 x 1000 μg in 100 ml = 40000000μg /100ml

so for 10μM solution you have to divide it by 1000000 = 40μg/100ml or 0.4μg/ml or 0.4ppm.

but you cant weigh this quantity.

so simply weigh 8mg and dissolve in 100ml =80μg/ml

then further take 1 ml of above and dissolve in 200 ml.