Exp115

Researcher
David Bulger

Objective
Verification of the SAMS using varying concentrations of benzoic acid in DMF.

Procedure
Benzoic acid was chosen as the solute since it is readily available (inexpensive) and dissolves easily in a variety of solvents. Evaporation has the potential for increasing the concentration measured. Therefore, a solvent with a low vapor pressure should be chosen. For this experiment, DMF was chosen as the solvent. The purity of the solvent will first be confirmed using NMR. The following concentrations will be tested: 0.01 __M__, 0.10 __M__, 0.50 __M__, 1.00 M. 2.00 __M__, and 3.00 __M__. Using 1-mL and 2-mL volumetric flasks, solutions of known concentration will be made up. Then the solution concentrations will be measured using the semi-automated solubility measurement (SAMS) using proton NMR. In ONSC Exp103, Khalid Mirza found the relaxation delay to play an important role in making the signals relatively equivalent across the spectrum. To verify these results, the accuracy of the SAMS method will also be measured with a variable relaxation delay. **[note that Khalid used a 50s delay, which is more than 10 times longer than you are using here JCB]**
 * 1) Confirm Purity of Solvent using NMR
 * 2) Calibrate Pipets
 * 3) Make 1-mL of 0.01 __M__ solution in 2-mL volumetric flask and mix thoroughly
 * 4) Run NMR with relaxation delay of 4.00 sec with 1000-uL of solution
 * 5) Run NMR with relaxation delay of 1.00 sec
 * 6) Run NMR with relaxation delay of 0.50 sec
 * 7) Run NMR with relaxation delay of 0.25 sec
 * 8) Run NMR with relaxation delay of 0.10 sec
 * 9) Run NMR with relaxation delay of 0.05 sec
 * 10) Clean volumetric flask and NMR tube with DMSO
 * 11) Repeat steps 3-10 with 0.10 __M__, 0.50 __M__, 1.00 M. 2.00 __M__, and 3.00 __M__ solutions

Results
[|Exp115_0] [|Exp115_1] [|Exp115_2] [|Exp115_3] [|Exp115_4] [|Exp115_5] [|Spectrum 432 - DMSO1] [|Spectrum 433 - DMSO2] [|Spectrum 434 - DMSO3] [|Spectrum 435 - DMF1] [|Spectrum 436 - DMF2] [|Spectrum 437 - DMSO4] [|exp115_440] [|exp115_445] [|exp115_448] [|exp115_451] [|exp115_454] [|exp115_457] [|exp115_460] [|exp115_463] [|exp115_466] [|exp115_469] [|exp115_472] [|exp115_475] [|exp115_478] [|exp115_481] [|exp115_484] [|exp115_487] [|exp115_490] [|exp115_493] [|exp115_496] [|exp115_499] [|exp115_502] [|exp115_505] [|exp115_508] [|exp115_511] [|exp115_514] [|exp115_517] [|exp115_520] [|exp115_523] [|exp115_526] [|exp115_529] [|exp115_532] [|exp115_535] [|exp115_538] [|exp115_541] [|exp115_544] [|exp115_547] [|Raw Data for Spectrum 432 - DMSO1] [|Raw Data for Spectrum 433 - DMSO2] [|Raw Data for Spectrum 434 - DMSO3] [|Raw Data for Spectrum 435 - DMF1] [|Raw Data for Spectrum 436 - DMF2] [|Raw Data for Spectrum 437 - DMSO4] [|Raw Data for exp115_440] [|Raw Data for exp115_445] [|Raw Data for exp115_448] [|Raw Data for exp115_451] [|Raw Data for exp115_454] [|Raw Data for exp115_457] [|Raw Data for exp115_460] [|Raw Data for exp115_463] [|Raw Data for exp115_466] [|Raw Data for exp115_469] [|Raw Data for exp115_472] [|Raw Data for exp115_475] [|Raw Data for exp115_478] [|Raw Data for exp115_481] [|Raw Data for exp115_484] [|Raw Data for exp115_487] [|Raw Data for exp115_490] [|Raw Data for exp115_493] [|Raw Data for exp115_496] [|Raw Data for exp115_499] [|Raw Data for exp115_502] [|Raw Data for exp115_505] [|Raw Data for exp115_508] [|Raw Data for exp115_511] [|Raw Data for exp115_514] [|Raw Data for exp115_517] [|Raw Data for exp115_520] [|Raw Data for exp115_523] [|Raw Data for exp115_526] [|Raw Data for exp115_529] [|Raw Data for exp115_532] [|Raw Data for exp115_535] [|Raw Data for exp115_538] [|Raw Data for exp115_541] [|Raw Data for exp115_544] [|Raw Data for exp115_547] [|IdentificationSpectrum.pdf] [|ONSC115-1]**[you have to provide ranges and the links to the spectra to get the calculation results JCB]** media type="googlespreadsheet" key="tw4NieIkrHbTLfLES337rGg" height="400" width="800"
 * Pictures**
 * NMR Spectra**
 * Spreadsheets**

Discussion
The SAMS spreadsheet doesn't seem to be calculating the integrations correctly as it keeps measuring zero for peaks that clearly exist.
 * [One point to keep in mind is that to just look at the effect of relaxation time a molecule with a rapidly relaxing methyl group - like 2-phenylbutanoic acid - gives you a way of internally comparing integrations without the additional error of sample preparation JCB]** Good point.
 * [Despite all my caveats I am still very interested in what you have found from your experiment :) JCB]**
 * [Can you put your spectra in the SAMS spreadsheet so we can compare? JCB]**

Table 115.1: Percentage Error Comparisons
 * Spectrum || Relaxation Delay (sec) || Known Concentration (M) || Measured Concentration (M) || Percent Error (%) ||
 * 440-475 || NA || 0.01-0.1 || Undetectable Signal || NA ||
 * [|exp115_481] || 1 || 0.5 || 0.5080 || 1.60 ||
 * [|exp115_484] || 0.5 || 0.5 || 0.4938 || 1.24 ||
 * [|exp115_487] || 0.25 || 0.5 || 0.5123 || 2.46 ||
 * [|exp115_490] || 0.1 || 0.5 || 0.5123 || 2.46 ||
 * [|exp115_493] || 0.05 || 0.5 || 0.5134 || 2.68 ||
 * [|exp115_496] || 4 || 1 || 0.9797 || 2.03 ||
 * [|exp115_499] || 1 || 1 || 1.0090 || 0.90 ||
 * [|exp115_502] || 0.5 || 1 || 0.9689 || 3.11 ||
 * [|exp115_505] || 0.25 || 1 || 0.9413 || 5.87 ||
 * [|exp115_508] || 0.1 || 1 || 1.0090 || 0.90 ||
 * [|exp115_511] || 0.05 || 1 || 0.9758 || 2.42 ||
 * [|exp115_514] || 4 || 2 || 1.9772 || 1.14 ||
 * [|exp115_517] || 1 || 2 || 2.0010 || 0.05 ||
 * [|exp115_520] || 0.5 || 2 || 1.9903 || 0.49 ||
 * [|exp115_523] || 0.25 || 2 || 1.9408 || 2.96 ||
 * [|exp115_526] || 0.1 || 2 || 1.9934 || 0.33 ||
 * [|exp115_529] || 0.05 || 2 || 1.9268 || 3.66 ||
 * [|exp115_532] || 4 || 3 || 3.0136 || 0.45 ||
 * [|exp115_535] || 1 || 3 || 3.0020 || 0.07 ||
 * [|exp115_538] || 0.5 || 3 || 2.9850 || 0.50 ||
 * [|exp115_541] || 0.25 || 3 || 2.9727 || 0.91 ||
 * [|exp115_544] || 0.1 || 3 || 3.0413 || 1.38 ||
 * [|exp115_547] || 0.05 || 3 || 3.0037 || 0.12 ||

[|ONSCEXP115Graphs.docx]

The percentage error for several solutions of known concentrations of benzoic acid in DMF were analyzed in relation to concentration and relaxation delay (Table 1, [|ONSCEXP115Graphs.docx]). A linear line was fitted to the plot of Percentage Error vs Concentration to yield the line y = 0.3464x + 0.732 with R² = 0.824. A linear line was also fitted to the plot of Percentage Error vs Relaxation Delay to yield the line y = -0.2093x + 1.8275 with R² = 0.1357.

The overall percent error was 1.64%, which attests to the accuracy of the SAMS method.

Conclusion
There seemed to be positive correlation between percent error and concentration and no strong correlation between percentage error and relaxation delay. The SAMS method was further supported by the overal percent error of 1.64%.

Log

 * 29.06.09** - Confirm Purity of Solvent

16.10 Gradient Shim and Lock on DMSO sample - failed **[You need deuterated solvent to lock - generally we take about 0.1 ml of the sat solution and dilute it with 0.7 ml of CDCl3 JCB]** 16.12 Autolock - failed 16.13 Manual Shim 16.14 Gradient Shim and Lock (Z1:1506, Z2:-3058, Z3:-4015, Z4:15671) 16.18 Single Pulse NMR run (Autogain: 1) with relaxation delay of 4 sec: [|Spectrum 432 - DMSO1] 16.26 Cleaned NMR tube 16.44 DMSO (from bottle 5040) Single Pulse (Autogain: 1) with relaxation delay of 4 sec: [|Spectrum 433 - DMSO2] 16.57 Cleaned NMR tube 17:02 DMSO (from other bottle) Single Pulse (Autogain: 1) with relaxation delay of 4 sec: [|Spectrum 434 - DMSO3] 17:06 Clean NMR tube 17.22 Gradient Shim and Lock on DMF sample - not enabled for solvent 17.24 DMF Single Pulse (Autogain: 2) with relaxation delay of 4 sec: [|Spectrum 435 - DMF1] Note: All spectra so far have unusual tails probably due to troublesome gradient shims from the DMSO 17.25 Gradient Shim on CDCl3 (Z1:-1235, Z2:-1037, Z3:-143, Z4:847) 17.36 DMF Single Pulse (Autogain: 1) with relaxation delay of 4 sec: [|Spectrum 436 - DMF2] Note: CDCl3 Shimming seems to have solved the problem 17.50 Cleaned NMR tube 17.54 DMSO (from bottle 5040) Single Pulse (Autogain: 1) with relaxation delay of 4 sec: [|Spectrum 437 - DMSO4]

10.50 Calibrate pipets Average % Error: 1.6% Note: In light of the absence of an internal standard, the volume of concentrated solution does not matter in the overall analysis. Added 0.002 4 g of benzoic acid to 2-mL volumetric flask 15.01 Added DMF up to 2-mL mark and mixed by hand since no vortexor or sonicator available (benzoic acid readily dissolves - so it should not be a problem at these concentrations) ([|Exp115_0]) 15.06 Trickerated and transfered to 1 dram vial ([|Exp115_1]) 15.08 Cleaned NMR tube 15.15 Transferred 1-mL of 0.01 __M__ solution to NMR tube 15.20 Gradient Shimmed and Locked using CDCl3 (Z1:-1222, Z2:-1005, Z3:-192, Z4:874) 15.25 Single Pulse on 0.01 __M__ sample (autogain: 1) with a relaxation delay of 4 sec: [|exp115_440] 15.35 Single Pulse on 0.01 __M__ sample (autogain: 1) with a relaxation delay of 1 sec: [|exp115_445] 15.39 Single Pulse on 0.01 __M__ sample (autogain: 1) with a relaxation delay of 0.5 sec: [|exp115_448] 15.42 Single Pulse on 0.01 __M__ sample (autogain: 1) with a relaxation delay of 0.25 sec: [|exp115_451] 15.45 Single Pulse on 0.01 __M__ sample (autogain: 1) with a relaxation delay of 0.1 sec: [|exp115_454] 15.47 Single Pulse on 0.01 __M__ sample (autogain: 1) with a relaxation delay of 0.05 sec: [|exp115_457] 15.50 Cleaned NMR tube and volumetric flask with DMF Added 0.024 4 g benzoic acid 16.00 Added DMF up to 2-mL mark and mixed ([|Exp115_2]) 16.04 Trickerated and transfered to 1 dram vial ([|Exp115_3]) 16.08 Transferred 1-mL of 0.1 __M__ solution to NMR tube 16.13 Single Pulse on 0.1 __M__ sample (autogain: 1) with a relaxation delay of 4 sec: [|exp115_460] 16.17 Single Pulse on 0.1 __M__ sample (autogain: 1) with a relaxation delay of 1 sec: [|exp115_463] 16.20 Single Pulse on 0.1 __M__ sample (autogain: 1) with a relaxation delay of 0.5 sec: [|exp115_466] 16.22 Single Pulse on 0.1 __M__ sample (autogain: 1) with a relaxation delay of 0.25 sec: [|exp115_469] 16.25 Single Pulse on 0.1 __M__ sample (autogain: 1) with a relaxation delay of 0.1 sec: [|exp115_472] 16.32 Single Pulse on 0.1 __M__ sample (autogain: 1) with a relaxation delay of 0.05 sec: [|exp115_475] 16.36 Cleaned NMR tube and volumetric flask with DMF Added 0.122 1 g benzoic acid 16.52 Added DMF up to 2-mL mark and mixed ([|Exp115_4]) 16.58 Transferred 0.5 __M__ solution to 1 dram vial 17.00 Trickerated and transferred 1-mL to NMR tube 17.03 Single Pulse on 0.5 __M__ sample (autogain: 1) with a relaxation delay of 4 sec: [|exp115_478] 17.07 Single Pulse on 0.5 __M__ sample (autogain: 1) with a relaxation delay of 1 sec: [|exp115_481] 17.11 Single Pulse on 0.5 __M__ sample (autogain: 1) with a relaxation delay of 0.5 sec: [|exp115_484] 17.13 Single Pulse on 0.5 __M__ sample (autogain: 1) with a relaxation delay of 0.25 sec: [|exp115_487] 17.16 Single Pulse on 0.5 __M__ sample (autogain: 1) with a relaxation delay of 0.1 sec: [|exp115_490] 17.18 Single Pulse on 0.5 __M__ sample (autogain: 1) with a relaxation delay of 0.05 sec: [|exp115_493] 17.21 Cleaned NMR tube and volumetric flask with DMF Added 0.244 2 g benzoic acid 17.35 Added DMF up to 2-mL mark and mixed ([|Exp115_5]) 17.37 Transferred 1 __M__ solution to 1 dram vial 17.41 Trickerated and transferred 1-mL to NMR tube 17.44 Single Pulse on 1 __M__ sample (autogain: 1) with a relaxation delay of 4 sec: [|exp115_496] 17.47 Single Pulse on 1 __M__ sample (autogain: 1) with a relaxation delay of 1 sec: [|exp115_499] 17.51 Single Pulse on 1 __M__ sample (autogain: 1) with a relaxation delay of 0.5 sec: [|exp115_502] 17.54 Single Pulse on 1 __M__ sample (autogain: 2) with a relaxation delay of 0.25 sec: [|exp115_505] 17.57 Single Pulse on 1 __M__ sample (autogain: 1) with a relaxation delay of 0.1 sec: [|exp115_508] 17.59 Single Pulse on 1 __M__ sample (autogain: 1) with a relaxation delay of 0.05 sec: [|exp115_511] 18.03 Cleaned NMR tube and volumetric flask with DMF 10.46 Gradient Shim and Lock on CDCl3 (Z1:-1196, Z2:-1029, Z3:-54, Z4:731) 10.52 Added 0.488 5 g benzoic acid to volumetric flask 11.06 Added DMF up to 2-mL mark and mixed 11.10 Cleaned NMR tube with DMF 11.15 Trickerated and transferred 2 __M__ solution to 1 dram vial 11.17 Transferred 1-mL to NMR tube 11.20 Single Pulse on 2 __M__ sample (autogain: 2) with a relaxation delay of 4 sec: [|exp115_514] 11.24 Single Pulse on 2 __M__ sample (autogain: 2) with a relaxation delay of 1 sec: [|exp115_517] 11.27 Single Pulse on 2 __M__ sample (autogain: 2) with a relaxation delay of 0.5 sec: [|exp115_520] 11.29 Single Pulse on 2 __M__ sample (autogain: 1) with a relaxation delay of 0.25 sec: [|exp115_523] 11.31 Single Pulse on 2 __M__ sample (autogain: 2) with a relaxation delay of 0.1 sec: [|exp115_526] 11.34 Single Pulse on 2 __M__ sample (autogain: 1) with a relaxation delay of 0.05 sec: [|exp115_529] 14.03 Cleaned NMR tube and volumetric flask with DMF 14.17 Added 0.732 7 g benzoic acid to volumetric flask 15.30 Added DMF up to 2-mL mark and mixed 15.37 Trickerated and transferred 3 __M__ solution to 1 dram vial 15.42 Transferred 1-mL to NMR tube 15.45 Single Pulse on 3 __M__ sample (autogain: 2) with a relaxation delay of 4 sec: [|exp115_532] 15.48 Single Pulse on 3 __M__ sample (autogain: 2) with a relaxation delay of 1 sec: [|exp115_535] 15.51 Single Pulse on 3 __M__ sample (autogain: 2) with a relaxation delay of 0.5 sec: [|exp115_538] 15.53 Single Pulse on 3 __M__ sample (autogain: 2) with a relaxation delay of 0.25 sec: [|exp115_541] 15.55 Single Pulse on 3 __M__ sample (autogain: 2) with a relaxation delay of 0.1 sec: [|exp115_544] 15.58 Single Pulse on 3 __M__ sample (autogain: 2) with a relaxation delay of 0.05 sec: [|exp115_547] 16.00 Cleaned NMR tube and volumetric flask with DMF
 * 30.06.09**
 * Pipet - Solvent || Volume (uL) || Predicted Mass (g) || Observed Mass (g) || % Error ||
 * 100 - 1 000 uL DMF || 1 000 || 0.944 0 || 0.958 9 || 1.6 ||
 * 100 - 1 000 uL DMF || 1 000 || 0.944 0 || 0.956 7 || 1.3 ||
 * 100 - 1 000 uL DMF || 1 000 || 0.944 0 || 0.958 9 || 1.6 ||
 * 100 - 1 000 uL DMF || 1 000 || 0.944 0 || 0.960 7 || 1.8 ||
 * 01.07.09**