This paper describes the construction of a polarimeter for the identification of chemical substances. The device was built with low-cost materials, measures the phenomenon of optical activity and has educational applicability. The measurement of optical activity is achieved through the measurement of the resulting polarized radiation in a photodiode connected to a voltmeter after passing through polarizing and analyzing filters.
Keywords:
chemical substance; optical activity; polarimeter
| Components | Price (R$ - Brazilian currency) |
|---|---|
| Polarizing disc 50 mm (polarizer) | 29.0 |
| Polarizing disc 50 mm (analyzer) | 29.0 |
| Digital voltmeter | 21.0 |
| 360-degree protractor | 1.5 |
| Photodiode detector | 13.0 |
| Support box for photodiode detector | 5.0 |
| Light source - laser pointer | 23.0 |
| Light source support and polarimeter base | 15.0 |
| PVC pipe 50 mm | 2.0 |
| Glass tube 10 mL | 25.0 |
| Total* * The total price does not include the labor cost for mounting the polarimeter. |
| Concentration (%) | LI (volts) | ORAa a Observed displacement of polarized light was to the right in all cases. (degree) | SRb b Experiments conducted at temperature of 24ºC and with light source at wavelength of 650 nm. (degree cm2 g-1) |
|---|---|---|---|
| 1 | 3.4 ± 0.1 | 98.0 ± 1.0 | 9800 |
| 10 | 3.0 ± 0.2 | 99.0 ± 2.0 | 990 |
| 15 | 2.6 ± 0.1 | 103.0 ± 1.0 | 680 |
| 20 | 2.1 ± 0.1 | 105.0 ± 2.0 | 525 |
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