Measuring the solubilities of 4-hydroxyphenylpyruvic acid, 11-mercapto-undecanoic acid and 4-nitrophenylacetic acid


Method

2 mL microcentrifuge tubes were labelled with their planned contents. 1.5 mL eppendorf style microcentrifuge tubes were labelled with their planned contents and the masses recorded. To three of the 2mL tubes was added 750 µL ethanol and to the remaining three, 750 µL methanol.
Narrow spatula scoopfuls of each solid was added to its correspondingly labelled tube and the tubes vortexed until saturated solutions were prepared. Full details can be found in the log.
As will be seen from the log, 11-mercapto-undecanoic acid could not be used as on directly forming a saturated solution, the entire sample became solid.
The remaining four saturated solutions of 4-hydroxyphenylpyruvic acid in ethanol and methanol and 4-nitrophenylacetic acid were centrifuged for 1 minute at 13, 200 rpm/16,100 g in an Eppendorf 5415D centrifuge. 500 µL supernatant from each solution was added to it's corresponding tube and the samples dried under vacuum on the speedvac for 3 hours 25 minutes. The samples were weighed and returned to the speedvac for a further hour. The samples were weighed after this time and found to be dry.
Full results can be found in the JennyHale-9 spreadsheet.

Discussion

[Have you tried to find if these measurements have been reported in the literature for the sake of comparison? JCB]

Log

05.12.08 GMT
10.22 - Recorded masses of empty 1.5 mL Eppendorfs.
10.29 - Added 750 µL ethanol to three 2 mL microcentrifuge tubes, and 750 µL methanol to remaining three tubes.
10.30 - Added 4 narrow spatula scoopfuls of 4-hydroxyphenylpyruvic acid to ethanol ("HE"). Vortexed for 10 seconds and found solute to be fully dissolved.
10.31 - Added 4 scoops to HE. Vortexed for 15 seconds and found solute had fully dissolved.
10.33 - Added 4 scoops to HE. Vortexed for 1 minute in 10 second intervals to leave a dark orange saturated solution.
10.36 - Added 4 narrow spatula scoopfuls of 4-hydroxyphenylpyruvic acid to methanol ("HM"). Vortexed for 10 seconds and found solute to be fully dissolved.
10.38 - Added 4 scoops to HM. Vortexed for 10 seconds and found solute to be fully dissolved.
10.39 - Added 4 scoops to HM. Vortexed for 10 seconds and found solute to be fully dissolved.
10.40 - Added 2 extra large scoops to HM. Vortexed for 1 minute in 10 second intervals to leave a dark orange saturated solution.
10.44 - Added 4 narrow spatula scoopfuls of 11-mercapto-undecanoic acid to ethanol ("ME"). Vortexed for 40 seconds in 10 second intervals and found solute to be fully dissolved.
10.46 - Added 4 scoops to ME. Vortexed for 20 seconds in 10 second intervals and solute found to be fully dissolved.
10.47 - Added 4 scoops to ME. Vortexed for 30 seconds in 10 second intervals and solute found to be fully dissolved.
10.49 - Added 4 scoops to ME. Vortexed for 30 seconds in 10 second intervals and solute found to be fully dissolved.
10.50 - Added 4 scoops to ME. Vortexed for 30 seconds in 10 second intervals and solute found to be fully dissolved.
10.51 - Added 4 scoops to ME. Vortexed for 1 minute in 10 second intervals and solute found to be fully dissolved.
10.53 - Added 4 scoops to ME. Vortexed for 1 minute in 10 second intervals and solute found to be fully dissolved.
10.55 - Added 4 scoops to ME. Vortexed for 1 minute in 10 second intervals and solute found to be not fully dissolved.
10.59 - Added 8 narrow spatula scoopfuls of 11-mercapto-undecanoic acid to methanol ("MM"). Vortexed for 20 seconds in 10 second intervals and found solute to be fully dissolved.
11.00 - Added 8 scoops to MM. Vortexed for 1 minute in 10 second intervals and solute found to be not fully dissolved.
11.03 - Added 4 extra large narrow spatula scoopfuls of 4-nitrophenylacetic acid to ethanol ("NE"). Vortexed for 1 minute in 10 second intervals to leave a yellow saturated solution.
11.06 - Added 4 extra large narrow spatula scoopfuls of 4-nitrophenylacetic acid to methanol ("NM"). Vortexed for 1 minute in 10 second intervals and solute found to be fully dissolved.
11.08 - Added 2 extra large scoopfuls to NM. Vortexed for 1 minute to leave a yellow saturated solution.
11.11 - Vortexed HE for 1 minute and solution still saturated.
11.13 - Vortexed HM for 1 minute and solution still saturated.
11.15 - Added 4 scoops to ME. Vortexed for 2 minutes in 10 second intervals. Solute fully dissolved.
11.18 - Added 8 scoops to ME. Vortexed for 1 minute in 10 second intervals. Solute fully dissolved.
11.22 - Added 4 scoops to MM. Vortexed for 1 minute in 10 second intervals. Solute fully dissolved.
11.24 - Added 4 scoops to MM. Vortexed for 30 seconds in 10 second intervals. Solute fully dissolved.
11.27 - Added 4 scoops to MM. Vortexed for 30 seconds in 10 second intervals. Solute fully dissolved.
11.30 - Transferred ME and MM to larger vessels as 2 mL tubes full.
11.35 - Added 4 scoops to ME. Vortexed for 1 minute in 10 second intervals. Solute fully dissolved.
11.37 - Added 4 scoops to MM. Vortexed for 1 minute in 10 second intervals. Solute fully dissolved.
11.39 - Added 4 scoops to ME. Vortexed for 1 minute in 10 second intervals. Solute fully dissolved.
11.41 - Added 4 scoops to MM. Vortexed for 1 minute in 10 second intervals. Solute fully dissolved.
11.43 - Vortexed ME for 40 seconds in 10 second intervals.
11.45 - Added 4 scoops to ME. Vortexed for 1 minute in 10 second intervals to leave an apparently saturated solution.
11.47 - Vortexed MM for 30 seconds in 10 second intervals.
11.48 - Added 4 scoops to MM. Vortexed for 1 minute in 10 second intervals to leave an apparently saturated solution.
11.50 - Vortexed ME for 1 minute in 10 second intervals and solution still saturated.
11.52 - Vortexed MM for 1 minute in 10 second intervals. Decided solution now was a very fine suspension.
11.55 - Centrifuged the solutions HE, HM, NE and NM.
11.58 - Took 500 µL of supernatant from HE, HM, NE and NM and added to corresponding eppendorf. Puzzled over how to centrifuge. remaining samples as new vessels didn't fit in any centrifuge.
12.00 - Discovered that both ME and MM had suddenly set into a cream coloured waxy solid, so abandoned them.
12.05 - Put samples on speedvac.
15.25 - Removed samples from speedvac and recorded tube masses.
15.30 - Returned to speedvac.
16.30 - Removed from speedvac and masses recorded.