This post details set up and testing of the replacement Cytek Guava Muse instrument.

Overview

Our last instrument was defective and did not pass system checks. Cytek sent a new instrument that I set up and tested today.

Set up

I followed steps in the Guava manual to set up the instrument. Here are the steps I followed:

• Inserted and secured the flow cell
• Attached the flow cell tubing
• Filled the cleaning bottle with Instrument Cleaning Fluid (ICF) ~ 20 mL
• Filled the waste bottle with bleach (10 mL)
• Connected waste and cleaning bottle tubing
• Powered on the system
• Logged into the instrument as Admin with password 1234
• Set date and time
• Perform complete system clean with ICF fluid and DI water

System check

I then performed system checks on the instrument. For each kit, I brought the components to room temperature before mixing. Each replicate was made with 20 µL beads and 380 µL dilution fluid. I followed this procedure for preparing the check kit:

• Bring components to room temperature
• Mix the beads with a P1000 pipette for about 30 seconds (gentle mixing)
• Add 20 µL of beads to a new Guava Muse 1.5 mL tube
• Add 280 µL of dilution fluid to the tube
• Mix with the P1000 pipette for about 15 seconds
• Select the system check kit option on the Muse
• Add the check kit information
• Load sample, mix right before loading
• The check kit reads the same sample three times. Between each reading, mix with pipette for about 15 sec

Check kit attempt #1

• Lot GA4200063812324 (previously opened)
• Expires 8/9/2027
• Code ASSVW99F
• Expected 51000 particles/mL

Failed on all three reps (all values were high). I then made a new replicate. The second attempt also failed (all values were high).

I then made samples from a new test kit.

Check kit attempt #2

• Lot GA420006387125 (new)
• Expires 4/3/2028
• Code ATSVW99G
• Expected 52000 particles/mL

Failed the first, second, and third attempts. The first attempt had one replicate reading that was OK, the others were all too low.

I made one last attempt with another kit after another cleaning.

System clean

I then ran another complete clean on the instrument. After the cleaning, I tried another check kit.

Check kit attempt #3

• Lot GA4200063882123 (new)
• Expries 8/9/2027
• Code ASSVW99F
• Expected 51000 particles/mL

This round passed! Values were 49800-48100 particles/mL. The CV was 1.93%.

I think the pass may have been due to the second cleaning. Next time I’ll try doing two cleanings before reading values or running samples.