MACS Buffer

Dillon Corvino

PBS + FCS + EDTA buffer for magnetic-activated cell sorting (MACS) and general washes.
Published

September 18, 2026

Protocol ID: BUF-MACS-BUF Version: v1.0 Author: Dillon Corvino Date: September 18, 2026

Purpose

This buffer is used for washing, resuspending, and handling cells during magnetic-activated cell sorting (MACS) and general processing. It includes EDTA to prevent cell clumping and nonspecific aggregation during magnetic separation.

Linked protocols

  • MUS-LIV-DIG
  • MUS-LNG-DIG
  • MUS-TMR-DIG
  • MUS-SPL-NK-PROLIF

Working buffer composition

Typical preparation for 500 mL:

Component Stock concentration Volume for 500 mL Final concentration Notes
PBS 1x — 488 mL — Base buffer
FCS — 10 mL 2% (v/v) Heat-inactivated if required
EDTA 0.5 M 2 mL 2 mM Sterile stock
Important

Do not use MACS Buffer for liver perfusion or for any step upstream of collagenase digestion. EDTA chelates the Ca2+/Zn2+ cofactors collagenases require, inhibiting digestion. Use FACS Buffer (BUF-FACS-BUF) or PBS for those steps.

Preparation

A. Preparation of stock (if applicable)

Not applicable — prepared directly as the working buffer.

B. Preparation of working buffer

  1. Start with sterile PBS 1x in an appropriate bottle.
  2. Add FCS to achieve 2% (v/v).
  3. Add EDTA to a final concentration of 2 mM.
  4. Mix gently by inversion.
  5. If sterility is required, filter through a 0.22 um filter into a sterile storage bottle.
  6. Label clearly with buffer name, date of preparation, initials, and sterile/non-sterile status.

Storage and stability

  • Store at 4 °C.
  • Recommended use within 4–6 weeks, subject to internal QC and sterility checks.
  • Invert gently before use to resuspend any settled components.
  • Avoid repeated temperature cycling; prepare smaller working aliquots if accessed frequently.

Reagent details

Component Supplier Cat# Notes
PBS 1x [TBD] [TBD] Sterile, Ca2+/Mg2+-free recommended
FCS [TBD] [TBD] Heat-inactivated if required
EDTA 0.5 M [TBD] [TBD] Sterile stock; pH ~8.0

Safety (brief)

  • Handle biological samples in MACS buffer according to institutional biosafety rules.
  • FCS is of animal origin and should be treated as a potential biohazard.
  • EDTA is of low toxicity at working concentrations but should be handled with standard laboratory PPE.

Version history

Version Date Author Change summary
v1.0 2026-09-18 Dillon Corvino Split out of BUF-FACS-MACS (formerly buf_facs_macs_buffer.qmd) so each buffer_id maps to exactly one recipe.