RG 2018/09/05

Objective

To measure Malachite green solutions made on 2018/08/31 with fluorescence spectroscopy. Also make two new solutions that are closer to range of UV-Vis data and run those samples.

Lab Protocol

Parameters used for Fluorescence

• start(nm): 565
• end(nm): 700
• excit: 555
• ex. slit (nm): 5.0
• Emslit (nm): 5.0
• scan speed: 200 nm/min

Data

Calculations

1. Theoretical
   1. 0.3 ppm (0.51194 g of 29.3 ppm Malachite green stock, water added till total mass 50 g)
   2. 1 ppm (1.70648 g of 29.3 ppm Malachite green stock, water added till total mass 50 g)
   3. 3 ppm (5.1194 g of of 29.3 ppm Malachite green stock, water added till total mass 50 g)
   4. 6 ppm (1.023 g of 29.3 ppm Malachite green stock, water added till total mass 10 g)
2. Actual
   1. 0.30885 ppm (0.52711 g of 29.3 ppm Malachite green stock, water added till total mass 50.0000 g)
   2. 1.005200 ppm (1.71704 g of 29.3 ppm Malachite green stock, water added till total mass 50.0490 g)
   3. 3.0006 ppm (5.12300 g of 29.3 ppm Malachite green stock, water added till total mass 50.0245 g)
   4. 5.9173 ppm (2.05505 g of 29.3 ppm Malachite green stock, water added till total mass 10.17574 g)

Figure 1: New Malachite green samples were run in UV-vis to try to fit standard curve better.

Figure 2: New standard curve of peak absorbance at 617 nm vs concentration made with new Malachite green samples.

Figure 3: Rhodimine fluorescence standard curve, intensity versus concentration.

Notes

1. Measured UV-Vis, followed by fluorescence.
   1. Our concentrations were too dilute and no signal picked up by fluorescence.
   2. Made two other solutions of higher concentration but it was still not picked up (3 ppm and 6 ppm).
2. 332 ppb solution was a little off in both UV-Vis and fluorescence.
3. Solutions for fluorescence measurement were prepared by Dr. Hartings.