Determining intrinsic viscosity and Huggins constant of an unknown sample

1. A computer implemented method comprising:

receiving, by a computer system, concentration detector signal values over time, c meas (t), from a concentration detector,

wherein the concentration detector signal values correspond to concentration values of a series of aliquots of an unknown sample injected into an instrument chain,

wherein the instrument chain comprises the concentration detector;

receiving, by the computer system, specific viscosity values over time, η sp (t), from a viscometer,

wherein the specific viscosity values correspond to the series of aliquots,

wherein the instrument chain further comprises the viscometer;

executing, by the computer system, a set of logical operations calculating a total mass of each of the aliquots, m i , as a first integral function of the received concentration detector signal values, c meas (t), corresponding to the each of the aliquots;

executing, by the computer system, a set of logical operations calculating a first intermediate viscosity value of the each of the aliquots, Iη i , as a second integral function of the received specific viscosity values, η sp (t), corresponding to the each of the aliquots;

executing, by the computer system, a set of logical operations calculating a second intermediate viscosity value of the each of the aliquots, I2η i , as a third integral function of the received specific viscosity values, η sp (t), corresponding to the each of the aliquots; and

executing, by the computer system, a set of logical operations fitting the total mass of the each of the aliquots, m i , the first intermediate viscosity value of the each of the aliquots, Iη i , and the second intermediate viscosity value of the each of the aliquots, I2η i , to a fitting function comprising the first integral function, a floating intrinsic viscosity of the unknown sample, [η], the second integral function, a floating Huggins constant of the unknown sample, K h , and the third integral function, resulting in a calculated intrinsic viscosity of the unknown sample and a calculated Huggins constant of the unknown sample.

2. The method of claim 1 wherein the concentration detector is one of a differential refractive index detector (dRI), an ultraviolet absorption detector, a visual absorption detector, an infrared absorption detector, a fluorescence detector, and an evaporative light scattering detector (ELSD).

3. The method of claim 1 wherein the viscometer is a differential viscometer.

4. The method of claim 1 wherein the first integral function is

m

i

=

∫

peak

i

⁢

c

meas

⁡

(

t

)

⁢

dt

.

5. The method of claim 1 wherein the second integral function is

I

⁢

⁢

η

i

=

∫

peak

i

⁢

η

sp

⁡

(

t

)

⁢

dt

.

6. The method of claim 1 wherein the third integral function is

I

⁢

⁢

2

⁢

⁢

η

i

=

∫

peak

i

⁢

η

sp

2

⁡

(

t

)

⁢

dt

.

7. The method of claim 1 wherein the fitting comprises a least squares fitting.

8. The method of claim 7 wherein the least squares fitting comprises a non-linear least squares fitting.

9. The method of claim 1 wherein the fitting function is

m

i

=

1

[

η

]

⁢

I

⁢

⁢

η

i

-

K

h

[

η

]

⁢

I

⁢

⁢

2

⁢

η

i

.

10. The method of claim 1 further comprising

executing, by the computer system, a set of logical operations calculating a figure of merit, FOM, characterizing a contribution of K h to fitting, as a ratio function of K h , the second intermediate viscosity value of the each of the aliquots, I2η i , and the first intermediate viscosity value of the each of the aliquots, Iη i .

11. The method of claim 10 wherein the ratio function is

FOM=( K h I 2η i )/ Iη i .

12. The method of claim 1 further comprising

executing, by the computer system, a set of logical operations calculating a ratio of the first intermediate viscosity value of the each of the aliquots, Iη i , to the total mass of the each of the aliquots, m i ; and

displaying, by the computer system, a plot of the calculated ratio of the each of the aliquots versus the total mass, m i , of the each of the aliquots.

13. A system comprising:

a memory; and

a processor in communication with the memory, the processor configured to perform a method comprising

receiving concentration detector signal values over time, c meas (t), from a concentration detector,

wherein the concentration detector signal values correspond to concentration values of a series of aliquots of an unknown sample injected into an instrument chain,

wherein the instrument chain comprises the concentration detector,

receiving specific viscosity values over time, η sp (t), from a viscometer,

wherein the specific viscosity values correspond to the series of aliquots,

wherein the instrument chain further comprises the viscometer,

executing a set of logical operations calculating a total mass of each of the aliquots, m i , as a first integral function of the received concentration detector signal values, c meas (t), corresponding to the each of the aliquots,

executing a set of logical operations calculating a first intermediate viscosity value of the each of the aliquots, Iη i , as a second integral function of the received specific viscosity values, η sp (t), corresponding to the each of the aliquots,

executing a set of logical operations calculating a second intermediate viscosity value of the each of the aliquots, I2η i , as a third integral function of the received specific viscosity values, η sp (t), corresponding to the each of the aliquots, and

executing a set of logical operations fitting the total mass of the each of the aliquots, m i , the first intermediate viscosity value of the each of the aliquots, Iη i , and the second intermediate viscosity value of the each of the aliquots, I2η i , to a fitting function comprising the first integral function, a floating intrinsic viscosity of the unknown sample, [η], the second integral function, a floating Huggins constant of the unknown sample, K h , and the third integral function, resulting in a calculated intrinsic viscosity of the unknown sample and a calculated Huggins constant of the unknown sample.

14. The system of claim 13 wherein the method further comprises

executing a set of logical operations calculating a figure of merit, FOM, characterizing a contribution of K h to fitting, as a ratio function of K h , the second intermediate viscosity value of the each of the aliquots, I2η i , and the first intermediate viscosity value of the each of the aliquots, Iη i .

15. The system of claim 14 wherein the ratio function is

FOM=( K h I 2η i )/ Iη i .

16. The system of claim 13 wherein the method further comprises:

executing a set of logical operations calculating a ratio of the first intermediate viscosity value of the each of the aliquots, Iη i , to the total mass of the each of the aliquots, m i ; and

displaying a plot of the calculated ratio of the each of the aliquots versus the total mass, m i , of the each of the aliquots.

17. A non-transitory computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform a method comprising:

receiving concentration detector signal values over time, c meas (t), from a concentration detector,

wherein the concentration detector signal values correspond to concentration values of a series of aliquots of an unknown sample injected into an instrument chain,

wherein the instrument chain comprises the concentration detector;

receiving specific viscosity values over time, η sp (t), from a viscometer,

wherein the specific viscosity values correspond to the series of aliquots,

wherein the instrument chain further comprises the viscometer;

executing a set of logical operations calculating a total mass of each of the aliquots, m i , as a first integral function of the received concentration detector signal values, c meas (t), corresponding to the each of the aliquots;

executing a set of logical operations calculating a first intermediate viscosity value of the each of the aliquots, Iη i , as a second integral function of the received specific viscosity values, η sp (t), corresponding to the each of the aliquots;

executing a set of logical operations calculating a second intermediate viscosity value of the each of the aliquots, I2η i , as a third integral function of the received specific viscosity values, η sp (t), corresponding to the each of the aliquots; and

executing a set of logical operations fitting the total mass of the each of the aliquots, m i , the first intermediate viscosity value of the each of the aliquots, Iη i , and the second intermediate viscosity value of the each of the aliquots, I2η i , to a fitting function comprising the first integral function, a floating intrinsic viscosity of the unknown sample, [η], the second integral function, a floating Huggins constant of the unknown sample, K h , and the third integral function, resulting in a calculated intrinsic viscosity of the unknown sample and a calculated Huggins constant of the unknown sample.

18. The computer program product of claim 17 wherein the method further comprises

executing a set of logical operations calculating a figure of merit, FOM, characterizing a contribution of K h to fitting, as a ratio function of K h , the second intermediate viscosity value of the each of the aliquots, I2η i , and the first intermediate viscosity value of the each of the aliquots, Iη i .

19. The computer program product of claim 18 wherein the ratio function is

FOM=( K h I 2η i )/ Iη i .

20. The computer program product of claim 17 wherein the method further comprises:

executing a set of logical operations calculating a ratio of the first intermediate viscosity value of the each of the aliquots, Iη i , to the total mass of the each of the aliquots, m i ; and

displaying a plot of the calculated ratio of the each of the aliquots versus the total mass, m i , of the each of the aliquots.