How to clean ACQUITY UPLC system for extractables and leachables applications to avoid or remove high chromatographic background and contamination - WKB101758

OBJECTIVE or GOAL

Clean ACQUITY UPLC system for extractables and leachables applications to avoid or remove high chromatographic background and contamination.

(Post-installation cleaning of the ACQUITY is very important for E&L applications because target analytes are often observed as background ions for new systems. An acid/basic/IPA wash is recommended to remove existing contamination and avoid/reduce background interference. This article is a modified version of WKB16167, adapted for E&L applications.)

ENVIRONMENT

• ACQUITY UPLC

PROCEDURE

1. To establish the current background, run 2-3 blank (100% methanol) injections with gradient and solvents used for routine application. 
2. Ensure that the highest quality solvents are used and prepare 500 mL of the following solvents:
   • Acid Wash: 25:25:25:25 IPA/methanol/acetonitrile/water + 5% formic acid
   • Basic Wash: 10% ammonia
   • Neat IPA
   • 80:10 water/methanol (as seal wash)
3. Remove the column before running the ACQUITY wash procedure and replace it with a connecting union. The outlet tubing of the active preheater or the union replacing the column should run to waste. 
4. If a sample loop is used, ensure that the loop is installed on the sample manager.
5. Disconnect the LC from the MS. There should be no flow going to the mass spectrometer!
6. Ensure that all PEEK lines that are normally in the LC-MS flow path remain in the flow path of the cleaning. 
7. Place the seal wash in 90:10 water/methanol and all other lines in Acid Wash. 
8. Load a vial of the Acid Wash into autosampler position 1:A,1.
9. Flush all ACQUITY lines: A and B lines need to be primed for 5 minutes and 10 cycles. Priming of the syringes, including the sample syringe, should be carried out in the Acid Wash. The seal wash should be primed in 90:10 water/methanol for 5 minutes.
10. Run 10 injections of the Acid Wash using "LC METHOD 1" and then 10 injections of the Acid Wash using "LC METHOD 2". Create and load a dummy MS Method if needed. Injection volume is 10 µL.

10. Water flush to clean acid from the system; no injection is needed. Place all ACQUITY lines except seal wash in the Basic Wash. A and B lines need to be primed for 5 minutes and 10 cycles. Priming the syringes, including the sample syringe, should be carried out in the Basic Wash.

11. Load a vial of the Basic Wash into autosampler position 1:A,2.

12. Run 10 injections of the Basic Wash using LC METHOD 1 and then 10 injections of the Basic Wash using LC METHOD 2.

13. Water flush to clean base from the system; no injection is needed. Place all ACQUITY lines except seal wash in the IPA. A and B lines need to be primed for 5 minutes and 10 cycles. Priming of the syringes, including the sample syringe, should be carried out in the IPA.

14. Load a vial of the IPA into autosampler position 1:A,3.

15. Run 10 injections of the IPA using LC METHOD 1 and then 10 injections of the IPA using LC METHOD 2.

16. Place ACQUITY solvent lines in the appropriate solvents but leave any unused lines in IPA.  

17. Run a blank methanol injection with the gradient and solvents used for the routine application and compare this with blank injection prior to cleaning. 

Examples of methanol blank before and after cleaning is shown here. (Note that these examples are for guidance, not system specifications.)

Before cleaning - methanol blank

After cleaning - methanol blank

ADDITIONAL INFORMATION