Question

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e) After a semester of instrumental analysis study, you found a job in a local environmental analysis firm. The lab is well equipped and has most of the analytical instruments that we discussed this semester (surprise!). The methods available include: • Flame Atomic Absorption • Double-focusing Mass Spectrometer Spectrometry (AAS) • Molecular Fluorescence • Graphite Furnace AAS Spectrophotometer • ICP-AES • UV-VIS spectrophotometer • ICP-Mass Spectrometer HPLC with fluorescence detection • GC-Mass Spectrometer • Anodic Stripping Voltammetry • Electrospray Ionization - Mass Spectrometer a). Your lab has developed a method for quantifying a particular herbicide (small molecule) commonly found in the soil of Suffolk county. This method involves an automated extraction followed by an on-line fluorescence measurement. One of the samples analyzed in this method gave a result that showed an unusually large amount of this herbicide in this soil sample. You suspect that this result is not due to an abnormally large pesticide concentration, but is actually due to a problem with the analytical method. Choose ONE technique (from the above list) that you would select to investigate this anomalous result. Briefly justify your choice. b). The local government requires that the wastewater treatment effluent from a local wastewater treatment plant be monitored for various metals as it is discharged into ground water from which drinking water is obtained. The heavy metals Cr, Pb, Cd, Cu, Zn in the effluent need to be tested each day. From the list of methods/instruments above, choose the best one for this analysis; briefly justify your choice.

Given a Scenario Question: No other information is included.

Answer 1

(a) The nature of the Herbicide is not mentoned. However, automated extraction followed by fluoreecense of the sample is used as an estimation to quantify. To cross check this data, one has to look other quantitative analytical technique. Out of which fluorescense and related techniques cant be chosen due to suspected error in the previous case. Anodic Striipping Voltammetry can be used to detect the amount of herbicide present in the sample. It is a quantitative analytical technique. ONE CONDITION IS THAT THE SAMPLE SHOULD BE AN ELECTROLYTE.

(b) To find the metals, any atomic emmision or absorption spectroscopy will serve the purpose. However, to determine different elements ICP-AES Inductive coupled - atomic emission spectroscopy is widely reccommended for analys in pharma and water samples because of its reliability.