# How do I determine system dwell volume? - WKB50707

Article number: 50707

## OBJECTIVE or GOAL

Determine the system dwell volume to aid in method transfer from one system to another in which the method is using a gradient. (The same measurement technique is used for the original and the target system.)

## ENVIRONMENT

• ACQUITY UPLC
• I-Class
• H-Class
• Method transfer

## PROCEDURE

1. If necessary, add an ultraviolet detector to the system.
2. Replace the column with a capillary restrictor. (Restriction should maintain a minimum back pressure of 2000 psi for an ACQUITY system.)
3. Prepare Solvent A (100% LC/MS-grade water) and Solvent B (100% LC/MS-grade water with 10 mg/L caffeine).
4. Specify a flow rate of 1.00 mL/min.
5. Solvent manager gradient at initial conditions is 100% Solvent A.
6. Solvent manager gradient at 5 minutes is 100% Solvent A.
7. Solvent manager gradient at 25 minutes is 100% Solvent B.
8. Solvent manager gradient at 30 minutes is 100% Solvent B.
9. Specify the channels to collect the absorbance data, including a trace of the solvent composition percent B.
10. Set the ultraviolet detector wavelength to 273 nm.
11. Run the method.
12. On the chromatogram, do as follows: Determine experimental t1/2 – the absolute time at which the absorbance trace reaches 50% of the absorbance corresponding to 100% B.
13. On the chromatogram, do as follows: Determine programmed t1/2 – the absolute time at which the programmed gradient reaches 50%. For the specified gradient, the time is 15 minutes.
14. Calculate the time corresponding to dwell volume as follows: tD = t1/2 experimental - t1/2 programmed
15. Calculate the dwell volume as follows: VD = tD x F, where F = flow rate in mL/minute.