How to prepare and install mobile phases on an LC/MS system to minimize contamination - WKB96258

OBJECTIVE or GOAL

To minimize contamination when preparing and installing mobile phases on an LC/MS system. It is important to minimize contact with anything that will touch solvents as this is a potential point of contamination. Realize that anything you touch needs to be cleaned prior to use, either by rinsing in a secondary container for external components, or by flushing the system for internal components.

ENVIRONMENT

• ACQUITY UPLC
• ACQUITY UPLC H-Class
• ACQUITY UPLC I-Class
• ACQUITY UPLC M-Class
• Xevo TQD
• Xevo TQ-S cronos
• Xevo TQ-S micro
• Xevo TQ-S
• Xevo TQ-XS
• SQ Detector 2
• ACQUITY QDa
• BioAccord System
• ACQUITY RDa Detector
• SYNAPT G2-S
• SYNAPT G2-Si
• SYNAPT XS
• Vion IMS QTof
• Xevo G2-S
• Xevo G2-XS
• SELECT SERIES Cyclic IMS

PROCEDURE

1. Use only clean, clear borosilicate glass solvent bottles.
   1. Do not put glassware through a dishwasher.
   2. Rinse bottles three times with the final solvent and discard to waste before filling.
   3. Waters does not recommend using the brown/amber solvent bottles that many solvents ship in as the glass is not rated to handle additives.
   4. Waters does not recommend using solvent premixed with additives in a brown/amber bottle as the glass is not rated to handle additives.
   5. Never fill or top off existing solvent bottles as this allows contaminants to concentrate over time.
2. Use only LC/MS-grade solvents and additives.
   1. LC/MS-grade solvents have higher purity standards than HPLC-grade solvents and generally have fewer/lower background ions.
   2. If using on-demand water systems(MilliQ) with 18.2MegaOhm resistance, ensure that the water system is regularly maintained per vendor recommendations.
   3. Waters recommends using the entire 1 L-bottle rather than decanting from 4 L-bottles as remaining solvent in a large container is more susceptible to contamination as it sits in storage.
   4. Only use LC/MS-grade additives such as formic acid and ammonia.
   5. Use single-use ampules of additives rather than continually dipping into a larger shared container.
3. Use clean and dry nitrile gloves to prepare and fit solvents.
   1. If a glove becomes wet at any point, replace it as this can contribute to contamination. (Important note: Most gloves, even "powder-free" gloves, still have powder or anti-stick agents on the outside to prevent sticking.)
   2. Rather than attempting to keep gloves dry, wash prior to use.
      1. Run gloves under LC/MS-grade H2O and scrub them as if washing your hands.
      2. Shake and allow them to air dry. Do not use a towel.
4. Use minimal measurement steps to prepare mobile phase and washes.
   1. For 0.1% formic acid solvents:    
      1. Pour 1 L solvent directly into clean bottle without using any intermediate glassware.
      2. Crack open formic acid ampule and pour entire 1 mL into 1-L solvent bottle.
      3. Do not cap the bottle.
      4. Swirl solvent or vortex to mix.
      5. If using a bottle cap, do not invert bottle to mix as cap may not be clean.
   2. For other solvents with additives:
      1. Pour solvent directly into clean bottle without using any intermediate glassware.
      2. Use clean pipette and pipette tip to measure appropriate volume of additives and add directly to solvent bottle.
      3. Avoid contact between the pipette tip and the bottle or solvent.
      4. Do not cap the bottle.
      5. Swirl solvent or vortex to mix.
      6. If using a bottle cap, do not invert bottle to mix as cap may not be clean.
   3. For washes and other solvent mixtures with no additives (for example, 90:10 H2O:ACN):
      1. Exact measurements are generally not critical for these washes.
      2. Do no use additional graduated cylinders or beakers for intermediate measurements.
      3. Use solvent bottle calibrations to pour appropriate solvent volumes.
      4. Do not cap the bottle.
      5. Swirl solvent or vortex to mix.
      6. If using a bottle cap, do not invert bottle to mix as cap may not be clean.
5. Prepare to insert solvent lines/filters into solvent bottles.
   1. Do not immediately insert solvent lines into solvent bottles.
   2. Prepare a 50:50 H2O:ACN wash solution of LC/MS grade solvents, or decant some freshly made mobile phase in a clean glass container.
   3. Holding solvent lines from above the cap, submerge solvent filters and tubing into the wash solution and swirl for 10 s.
   4. Without touching wet areas of the solvent lines/filters, remove from wash solution, shake, and allow to drip dry for 10 s. Do not dry with a towel or Kimwipe.
   5. Insert solvent line and filter into final mobile phase bottle.
   6. Secure covering to top of solvent bottle.
      1. A solvent cap/plug or aluminum foil is acceptable provided it does not come in contact with the solvent.
      2. Do not use parafilm to cover solvents as this is very likely to introduce contaminants.
   7. Repeat for each solvent line.
   8. Discard wash solution used to rinse solvent filters.
6. Prime all mobile phase/wash lines.
7. Flush LC to waste with high organic mobile phase composition (15% aqueous:85% organic).
8. Run multiple blank injections prior to sample acquisition.

ADDITIONAL INFORMATION