EXAMPLE LAB REPORTS - Hanover College



EXAMPLE LAB REPORTS.

Topic 1: Tools of biology. Experiment 1-3.

Goal: Determine the accuracy of volumetric devices.

Method: Measure (by weight using a Accula3 V200 balance) the volume of water dispensed by a 100 ml cylinder (generic), a 10 ml serological pipette (Greiner labortechnik), and a 1 ml micropipette (Acura model 821, VWR Scientific Products) when the devices are used at maximal and 1/10th maximal volume. Triplicate measurements were done at room temperature.

Results: The relative error of the 100 ml cylinder was 1.95 + 0.54 % (mean and SEM, n=6) and 3.07 + 1.93 % (Student’s t-test P>0.05) when measuring 100 and 10 ml water, respectively (Figure 1). The relative error of the 10 ml serological pipette was 0.97 + 0.26 % and 2.67 + 0.80 % when measuring 10 and 1 ml (P>0.05), respectively. Finally, the error of the 1 ml micropipette was 0.82 + 1.02 % and 4.83 + 1.87 % when measuring 1 and 0.1 ml water (P>0.05).

Conclusions: Each device is more accurate when used close to its maximal nominal volume then when used at 1/10th of that volume. (Note: the comparisons are not significant!)

Discussion: Because the density of water at room temperature is less than 1, the 100, 10, and 1 ml aliquots of water weighed less than 100, 10, and 1 g, respectively.

[pic]

Figure 1. Determine the accuracy of volumetric devices. Measure (by weight using a Accula3 V200 balance) the volume of water dispensed by a 100 ml cylinder, a 10 ml serological pipette, and a 1 ml micropipette when the devices are used at maximal and 1/10th maximal volume. Triplicate measurements were done at room temperature. Each device is more accurate when used close to its maximal nominal volume then when used at 1/10th of that volume.

Topic 1: Tools of Biology. Experiment 1.

Goal: Compare measurement of pH using a pH meter and pH paper.

Methods: Measure the pH of 3 solutions using pH paper (Colorphast pH 0-14, EM Reagents) and a pH meter (Pinnacle 530, Corning) at room temperature.

Results: The pH of sample 1 was 5 + 0.0 (n = 6) when measured with pH paper and was 5.75 + 0.125 (n = 6) when measured with the pH meter (Figure 1). The pH of solution 2 was 7 + 0.0 and 7.01 + 0.031when measured with pH paper and pH meter, respectively. The pH of solution 3 was 8 + 0.0 and 7.88 + 0.066 when measured with pH paper and pH meter.

Conclusion: The pH was measured accurately by both the pH paper and pH meter but measurements using the pH meter were more precise.

[pic]

Figure 1. Compare measurement of pH using a pH meter and pH paper. Measure the pH of 3 solutions using pH paper (Colorphast pH 0-14, EM Reagents) and a pH meter (Pinnacle 530, Corning) at room temperature.

The pH was measured accurately by both the pH paper and pH meter but measurements using the pH meter were more precise.

Topic 1: Tools of the laboratory. Exercise I, Experiment 2.

Goal: Determine the absorbance spectrum of a dye.

Method: Measure the absorbance of a red, blue, and purple solution from 400 nm to 700 nm in 20 nm increments at room temperature using a Spectronix 21 spectrophotometer.

Results: The spectrum of the red dye showed one large peak with maximum at 500 nm (Figure 1). The spectrum of the blue dye had a single broad peak with maximum at 620 nm. The spectrum of the purple dye had two peaks one with maximum at 500 nm and one with maximum at 620 nm.

Conclusion: The red dye had an absorbance maximum at 500 nm and the blue dye had a maximum at 620 nm. The purple dye was a combination of the red and blue dye.

Explanation: The red dye absorbs blue light; the blue dye absorbs red light.

[pic]

Figure 1. Determine the absorbance spectrum of a dye. Measure the absorbance of a red, blue, and purple solution from 400 nm to 700 nm in 20 nm increments at room temperature using a Spectronix 21 spectrophotometer. The red dye had an absorbance maximum at 500 nm and the blue dye had a maximum at 620 nm. The purple dye was a combination of the red and blue dye.

Topic 1: Tools of the laboratory. Exercise I, Experiment 1.

Goal: Determine the concentration of a dye using standard curve.

Method: Construct the standard curve of a yellow dye by measuring at room temperature the optical density at 420 nm (Spectronix 21) of a solution containing 1, 2, 3, and 4 drops. Measure the optical density of an unknown solution at 420 nm.

Results: The optical density of the yellow solution at 420 nm increased linearly with its concentration: the optical density of the solution with 1 drop () was smaller (P ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download