Writing conclusion and answer the questions for lab report
• There shouldn’t be tables or graphs here, that is what the results section is for. However,tables and graphs should be referenced and discussed.• Place the results into context of the goal of the experiment. What do your results mean?Why are your results important? (Significance)• Did you run into any problems? What were they? How can/did you fix them? How does theerror change the outcome of the experiment?• If there were no apparent problems, what could have led to deviations within your results?The chemistry of the experiment should be discussed. (ex. Did you boil the solution for toolong? How could this affect your results? What kind of error w ould you expect?)• Finally, how can this experiment be improved? What techniques can you improve on?• Post-lab questions can be answered in this section A Multi-component UV Analysis of hops
This experiment’s main goal is to teach participants how to use the brewing process to
calculate the hops solution’s alpha/beta acid ratio. This operation will be done by using UV-vis
spectroscopy. In this experiment, the humulones and lupulones from the dry hop samples were
solubilized by using methanol. We must use both the two-component analysis and the thirdcomponent analysis to calculate the percentage of alpha and beta acids in each hop sample by
the end of the experiment.
Our results from the two-component analysis showed that galena had an alpha
concentration of 0.01101466244 g/L and flacon had 0.0905892 g/L. Galena had a beta
concentration of 0.00546385532 g/L, while the falcon sample had 0.00360862 g/L. Alpha acid
content ranged from 8.79301522% in falcon to 10.80080647% in galena. Approximately
3.5026984% of falcon and 5.357771445% of galena contained beta acids.
– Coffee grinder
– 2.5g hops
– 0.5mL of 6M NaOH
– 25mL volumetric flask
– Prepare Methanolic NaOH
1. Add 0.5 mL NaOH to 250 mL volumetric flask.
2. Add Spectro photometric-grade methanol until the line of the flask and cover it.
– Prepare the samples
1. In the coffee grinder put 3 g of hops.
2. Weight 2.5 g of the ground hops into 100 mL beaker.
3. Pipet 50 mL methanol to the beaker that contain hops and cover the beaker and start
stirring it for 30 minutes.
4. Be careful not to stir the mixture for more than 1 hour.
5. Let the mixture settle for 10 minutes
6. Remove an aliquot of about 50 µl with a micropipette, then I want eight vials of 25 ml.
Add the methanol solution of NaOH
– Prepare blank
1. By using a micropipette put 50 µL methanol in a 25mL flask.
2. Fill the flask with methanol NaOH until the line
– Acquisition of data
1. Zero the spectrophotometer by using the blank.
2. Take your spectrum between 520 and 210 nm for all samples.
3. The record though absorbance at 355 nm, 325 nm, and 275 nm.
1. Analysis the observance of solutions that you record.
– Methanolic NaOH was ready for us
– The solution must stay in a dark place
– We used methanol NaOH instead of methanol in the step of preparing the sample
– The mass of falcon hops was 2.5756g
– The mass of Galenea hops was 2.5495g
alpha conc. (g/L)
beta conc. (g/L)
• The calculation for two-component analysis in falcon:
• Finding the concentration of alpha and beta for falcon:
1) A355 = 31.8 C œ + 46.0 C ß
C œ = (A355 – 46.0 C ß) / 31.8
C œ = (0.45407– (46 x 0.00360862) / 31.8 = 0.0905892 g/L
2) A325 = 38.1 C œ + 33.1 C ß
A325 = 38.1 ((A355 – 46.0 C ß) / 31.8) + 33.1 C ß
C ß = (31.8 A325 – 38.1 A355) / – 700.02
C ß = ((31.8 x 0.46459)– (38.1 x 0.45407))/ -700.02 = 0.00360862 g/L
Mass of alpha/beta in falcon:
1) Mass = C œ x 500 x 0.05
= 0.0905892 g/L x 500 x 0.05 = 0.2264729 g
2) Mass = C ß x 500 x 0.05
= 0.00360862 g/L x 500 x 0.05 = 0.0902155 g
1) % = (mass / original mass) x 100%
2) Alpha% = (0.2264729 g/ 2.5756 g) x 100% = 8.79301522 %
The calculation for third component analysis in falcon:
Finding the concentration of alpha and beta for falcon:
1) Cα= -(A355 x 0.05156) + (A325 x 0.07379) -(A275 x 0.01907)
=-(0.45407x 0.05156) + (0.46459x 0.07379) -(0.27616x 0.01907) = 0.0056038757g/L
2) Cβ = +(A355 x 0.05557) -(A325 x 0.04759) + (A275 x 0.00510)
= (0.45407 x 0.05557) – (0.46459 x 0.04759) + (0.27616 x 0.0051)
The remaining calculations are identical to those for two-component
1. From the overall shape of your absorbance curve, decide if your sample contains mostly
humulones (alpha acids) or lupulones (beta acids).
2. Make a data table containing the absorbance values for all solutions at 355 nm, 325 nm,
and 275 nm.
3. Use the data in the table to do a two-component analysis of your spectrum and
determine the grams of humulones and lupulones in your extract and the % alpha and
beta acids in your original hops sample.
4. Use the derived equations for a three-component analysis to find the concentration of
- and - acids in the solutions you analyzed. How do these values compare to your
two- component analysis? Next, use your values from the three-component analysis to
determine the concentration of - and - acids in the actual extract. Finally, determine
the % - and - acids in the original hops sample. How do they compare to your twocomponent analysis?