Fixatives

For DNA samples, ice cold 70% ethanol added quickly to 100 uL cell suspension with rapid vortexing.

For antigen-DNA combinations, standard fixative is ice cold 70% ethanol added quickly with low speed vortexing after antibody staining and prior to DNA stains.

Please note that some antigens will not tolerate ethanol. Test the effect with FACS first before continuing. You may need to use a low paraformalydhyde concentration of 0.5% instead of ethanol. The CVs of your DNA peaks will be wider.

For neutralization of human samples or unknown biohazards, use 1% paraformaldehyde (always prepared fresh in PBS, pH 7.4) for 10 minutes.

For long-term storage (e.g. one to two weeks) of fluorochrome-stained surface antigens, use 0.5% paraformaldehyde.

Please note that the longer you store cells in paraformaldehyde, the more cellular autofluorescence you will observe.