Organic Chemistry Lab - How to choose the best instrument for the situation and

Question

Organic Chemistry Lab - How to choose the best instrument for the situation and list a reason why?

NMR - can identify the number and position of atoms on an organic compound (especially hydrogens and carbons), important for identifying chemical structure. Each instrument run takes approximately 5 minutes and requires 5-10 mg analyte. GCMS - separates components of a volatile mixture by their boiling point and polarity, then identifies them by their mass. Each instrument run can take from 5-25 minutes and requires much less than 1 mg, more like a nanogram of analyte. Can search results against libraries of spectra to quickly find the identity of the analyte. LCMS-same as GCMS, separates components in instead of gas phase IR - can identify covalent bonds on a molecule by their characteristic absorbance of infrared energy. Each instrument run can take 1-3 minutes and requires 1-10 mg of analyte. The instrument is portable and allows identification by searching against a library of spectra to quickly find the identity of the analyte. Real world situation: (choose the best instrument for the situation and list a reason why) An ink sample, collected at a crime scene, contains a unique set of organic dyes and chemicals that could identify the brand and type of pen used. Paint chips found at the scene of a hit run need to be identified immediately to aid in apprehending the vehicle. A patient's blood sample may contain tumor markers that signal a high probability of cancer. A drug lead was synthesized in a pharmaceutical lab and the researcher is trying to discover if his reaction led to the correct product. Cattle farmers suspect that a nearby water source is contaminated with pesticide run-off from an adjacent farm and is causing health issues in their cattle. A chemical waste/safety officer forgot to label two liquid bottles and needs to quickly determine their identity.

Explanation / Answer

1. NMR

Reason: NMR spectroscopy and dyeing performance on silk, wool and cotton fibres. The percentage dye bath exhaustion on different fibres has been found to be reasonably good and acceptable.

2. IR

Reason:

Infrared (IR) Spectrscopy is most valuable and instrument. used to analyse Dried Paints.

3. LCMS

Reason: Higher specificity and sensitivity than current methodologies Less specimen required More accurate, reproducible results.

4. NMR

Reason: the potential of harnessing the ability of nuclear magnetic resonance (NMR) spectroscopy to monitor intermolecular interactions as a tool for drug discovery.

5. LCMS

Reason: Higher specificity and sensitivity than current methodologies Less specimen required More accurate, reproducible results.

6. IR

Reason : Good in identification quickly in 1-3 minutes.

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