# liquid chromatography column - Scott R.P.W.

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sec"

410 LPRINT "Viscosity of Mobile Phase ".M' Poises"

420 LPRINT

421 LPRINT "LIMITING CONDITIONS"

422 LPRINT

423 LPRINT "Particle Diameter Range, 5-100 micron

424 LPRINT "Column length is less than 150cm

425 LPRINT "Column Aspect Ratio L/R must be greater than unity"

426 LPRINT "The Analysis Time must lie between 1 minute and 1 hour"

427 LPRINT

430 LPRINT "COLUMN SPECIFICATIONS"

440 LPRINT

450 LPRINT “Optimum Column Radius

451 LPRINT USING R9,

5S4

452 LPRINT "cm"

460 LPRINT "Optimum Column Length

461 LPRINT USING ¦***.**; L9,

462 LPRINT "cm"

470 LPRINT “Optimum Particle Diameter

471 LPRINT USING ¦***.*’; 10000 *D9,

472 LPRINT “urn"

480 LPRINT

490 LPRINT "ANALYTICAL SPECIFICATIONS"

500 LPRINT

510 LPRINT "Minimum Analysis Time

511 LPRINT USING “***"¦, T9/60,

512 LPRINT "min

520 LPRINT "Column Efficiency

521 LPRINT USING "******"; N

530 LPRINT "Optimum Flow-Rate

531 LPRINT USING ¦*«**"; Q,

532 LPRINT "ml/min"

540 LPRINT "Maximum Sample Volume

541 LPRINT USING “**•**", V9,

542 LPRINT "ml"

550 LPRINT "Solvent Consumption per Analysis

551 LPRINT USING "******"; y,

552 LPRINT "ml"

560 LPRINT 'Column Wall Thickness

561 LPRINT USING '***••"¦ TH,

562 LPRINT "cm"

552 LPRINT "Column Weight

553 LPRINT USING “****.*"; W,

554 LPRINT "g"

570 CLOSE * 1 580 END

Discussion

On running the program,the Performance Criteria are first printed out and then the separation ratio of the critical pair is asked for on the monitor screen. After typing in the appropriate value, the capacity ratio of the first peak of the critical pair followed by the capacity ratio last eluted peak peak are then requested. The request procedure continues until all the necessary information has been entered after which the program runs. Some care must be taken when entering the minimum pressure, maximum pressure and pressure increment. If the range is made too large and the increment too

255

small the program make take a very long time to run. Assuming that the pump has a maximum available output pressure of 6000 p.s.i. then the minimum pressure might be set at 1000 p.s.i., the maximum pressure at 6000 p.s.i. and the increment 100 p.s.i. The program would then identify the column and performance data that are necessary to attain the minimum separation time. When an approximate value for the operating pressure is obtained, the program can then be run again with a more narrow pressure pressure range and an appropriately smaller pressure increment. The packing factors (X) and (y) can, for preparative columns, be taken as 0.65 and 0.8 respectively as, in general, preparative columns can not be packed as efficiently as analytical columns. The diffusivity of the solute in the mobile phase may be calculated from the Arnold Equation (5), or estimated from the diffusivity data provided in the Appendix. The viscosity of the mobile phase can be best obtained from a suitable reference book on solvents (6).

The program assumes a number of limiting conditions,

1/ The practical range of particle diameters Is between 5 and 100 micron, program lines 100 and 110.

2/ The practical range of column length is between 5 and 150 cms, program lines 120 and 130.

3/ The column length must not be shorter than it's radius (the aspect ratio) must not be less than unity, program line 140.

4/ The separation time must be greater than one minute and less than one hour program lines 150 and 160.

These conditions can be changed, if so required, by modifying the appropriate program lines, but care should be taken not to place impractical limits on the separation. During the operation of the program, the current separation ratio, current pressure and current minimum analysis time will continually appear on the monitor screen. When Ine minimum analysis time has been found it will not change on the screen but the program will continue to the maximum pressure has been reached. The optimum conditions will then be printed out. An example of the computer print out is given as follows:-

“?v

COMPUTER REPORT

PREPARATIVE COLUMN DESIGN FOR LC

PERFORMANCE CRITERIA

1/ A defined resolution must be obtained

2/ The analysis must be completed in the minimum time

3/ The analysis must be completed with the minimum solvent

INSTRUMENT CONSTRAINTS

Inlet Pressure Maximum Column Load Multipath Packing Factor Longitudinal Diffusion Packing Factor Column Mobile Phase Fraction

ELECTIVE VARIABLES

Separation Ratio of the Critical Pair Capacity Ratio of the First Peak of the Pair Capacity Ratio of the Last Eluted Peak Diffusivity of Solute in Mobile Phase Viscosity of Mobile Phase

LIMITING CONDITIONS

Particle Diameter Range 5-100 micron Column length is less than 150cm Column Aspect Ratio L/R must be greater than unity The Analysis Time must lie between 1 minute and 1 hour

COLUMN SPECIFICATIONS

Optimum Column Radius 9.20 cm

Optimum Column Length 9 30 cm

Optimum Particle Diameter 9.00 um

1 09

2.5

5

0 000035 sq cm per sec 0.023 Poises

690 p.s.i

5g

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