Poor inter-instrument reproducibility, unstable areas, high baseline, poor peak shape, or unexpected peaks - WKB234708

SYMPTOMS

• Unstable peak areas for analyte or IS
• Running the plate on an identical system shows typical results
• High baseline
• Poor peak shape
• Potential analyte in blanks
• SM and BSM pass leak tests
• Potentially higher than expected system pressure

ENVIRONMENT

• ACQUITY UPLC
• ACQUITY UPLC H-Class
• ACQUITY UPLC H-Class Bio
• ACQUITY UPLC H-Class Quaternary Solvent Manager (QSM)
• ACQUITY UPLC I-Class
• ACQUITY UPLC H-Class PLUS
• ACQUITY UPLC H-Class PLUS Bio
• ACQUITY UPLC I-Class PLUS
• ACQUITY UPLC BSM
• ACQUITY UPLC Sample Manager 
• ACQUITY UPLC Sample Manager - Flow Through Needle PLUS (SM-FTN PLUS)

CAUSE

Contamination or blockage in the LC

FIX or WORKAROUND

1. Perform a system flush using Magic Mix (equal parts ACN/MeOH/IPA/H2O with 0.1% formic acid).
2. After the system flush, put on new mobile phases and columns.

ADDITIONAL INFORMATION

System Flush Protocol:

*Note: Be sure to place a union or a junk column on during the flush to make sure the column is not contaminated. Also, if possible, avoid touching the solvent sinkers when changing out the solvents.

1. Place all mobile phase solvent lines, seal wash, weak needle wash, strong needle wash, and seal wash lines into a clean bottle containing 50% water/50% acetonitrile. NOTE: If there is an incompatibility between the mobile phase or solvents with the isopropanol, flush first with the appropriate intermediate solutions to ensure compatibility.
2. Prime all mobile phase solvent lines for 5 min each.
3. Prime the seal wash.
4. Prime the Sample Manager (SM).
   For a Fixed-Loop(FL) SM: Prime wash and sample syringes for 5 cycles.
   For a Flow-Through Needle (FTN), prime wash for 60 seconds and prime sample syringe for 20 cycles.
5. Place mobile phase solvent lines, weak needle wash, strong needle wash, and seal wash lines into a clean bottle containing Magic Mix (25% water/25% methanol/25% isopropyl alcohol/25% acetonitrile/ 0.1% formic acid).
6. Repeat steps 2-4.
7. Set the fluidics valve on the mass spectrometer to the waste position and the column manager to bypass mode.
8. Perform 15 injections from a vial or well containing Magic Mix.
   SM: Run Time = 0.5 min / Flow Rate = 0.2 mL/min.
   CM: Bypass
   MS Method: Flow to Waste (Method Events), 0.5-Min Run Time
        For a Fixed-Loop system: perform Full-Loop injections with 5x overfill.
        For an FTN, perform 10-uL injections (or the maximum for your needle size).
9. Set the flow of the system at 0.2 mL/min using 50% A1 and 50% B1, or whatever two solvent lines you’d like to use, and allow to pump overnight.
10. Repeat step 8 using 50/% A2 and 50% B2.
11. Allow A2/B2 to flow for a minimum of 4 hours.
12. Place lines in normal mobile phases and washes (using new bottles if possible) and replace the column.
13. Repeat steps 2-4.