Download (direct link):
• Chromatographic Techniques (TLC, column, ion-exchange and gas chromatography).
• Microscale Chromatography (TLC, column chromatography, gas chromatography and preparation of a Grignard reagent).
• Electrochemical Techniques (using galvanic cells, using conductometric cells, determining standard electrode potentials, determining solubility products, thermodynamic characteristics of cells, conductometric titrations and using an automatic titrator).
• Polarimetry, Refractometry and Radiochemistry (using a polarimeter, determining the refractive indices of liquids, measuring the rates of radioactive processes and measuring gas-phase emission spectra).
• Inorganic Analysis (gravimetric analysis).
• Volumetric Techniques (using a balance, using a pipette, using a burette and making up solutions).
• Volumetric Analyses Methods (doing a titration, some common end-points and potentiometric titrations).
Basic Laboratory Skills (LGC), The Royal Society of Chemistry, Cambridge, UK, 1998.
Further Laboratory Skills (LGC), The Royal Society of Chemistry, Cambridge, UK 1998.
12.2.6 Useful websites^
• American Chemical Society: http://www.acs.org
• The Royal Society of Chemistry: http://www.rsc.org
• Society of Chemical Industry: http://sci.mond.org
^ As of June 2002. The products or material displayed are not endorsed by the author or the publisher.
Recording of Information and Selected Resources
• International Union of Pure and Applied Chemistry (IUPAC): http://iupac.chemsoc.org
• Laboratory of the Government Chemist (LGC): http://www.lgc.co.uk
• United States Environmental Protection Agency (USEPA): http://www.epa.gov
• National Institute of Standards and Technology (NIST) Laboratory: http://www.cstl.nist.gov
• National Institute of Standards and Technology (NIST) WebBook: http://webbook.nist.gov
• University of Sheffield: http://www.chemdex.org
• Specialized Information Services - chemical information page on drugs, pesticides, environmental pollutants and other potential toxins: http://chem.sis.nlm.nih.gov
• WebElements Periodic Table: http://www.webelements.com
Accurate recording of experimental details prior to, during and after the practical work is an essential feature of all practical science. This chapter has attempted to capture the essential information that needs to be recorded at the same time as the practical work is being undertaken. While perhaps not totally comprehensive, it does offer the ability to be adapted to fit individual needs. In addition, a selected resource list is included to assist the reader.
Methods for Environmental Trace Analysis. John R. Dean
Copyright © 2003 John Wiley & Sons, Ltd.
ISBNs: 0-470-84421-3 (HB); 0-470-84422-1 (PB)
Responses to Self-Assessment Questions
The following table shows the values that you should have obtained.
Quantity m fim nm
6 x 10-7 m 0.000 000 6 m 0.6 fim 600 nm
Quantity moll-1 mmol l-1 fimol l-1
2.5 x 10-3 moll-1 0.0025 moll-1 2.5 mmoll-1 2500 fimol l-1
Quantity figml-1 mgl-1 ng fil-1
8.75 ppm 8.75 figml-1 8.75 mgl-1 8.75 ng fil-1
You should have obtained the straight-line plot shown in Figure SAQ 1.2 below. This figure also shows the relevant mathematical relationship and R2(R) value for such data (see text for further details).
From Figure 1.1, it can be seen that the equation for the straight-line graph is as follows:
y = 0.0076x + 0.0004
Methods for Environmental Trace Analysis
y= 0.187x + 0.0033 R2 = 0.9979
0 2 4 6 8 10
Figure SAQ 1.2 Analysis of lindane in waste water, using the direct calibration approach.
Thus, by rearranging this equation and inputting the y-value (0.026), it can be solved:
7 - 0.0004 = .v
The concentration of lead from the graph is therefore 3.37 ppm (or 3.37 ^gml-1).
By using the dilution factor, you can now calculate the concentration of Pb in the original soil sample in the following way:
470 ml 3.37 fig -1
x — = 1584 fig g 1
This result can also be expressed in terms of other units, e.g. 1584 mg kg-1 or 0.16 wt%.
From Figure SAQ 1.2 it can been seen that the equation for the straight line graph is as follows:
y = 0.187x + 0.0033
Therefore, by rearranging this equation and inputting the y-value (0.26) it can be solved:
' - 0.0033 = -v
The concentration of lindane from the graph is therefore 1.37 ppm (or 1.37 ^gml-1).
By using the dilution factor, you can now calculate the concentration of lindane in the waste water sample in the following way:
0.05 ml 1.37 fig ,
x — = 0.069 figmr1
Responses to Self-Assessment Questions 231
This result can also be expressed in terms of other units, e.g. 69 ngml-1 or 69 ^gl-1.
(a) The results would be described as accurate and precise.
(b) The results would be described as accurate but imprecise.
(c) The results would be described as inaccurate but precise.