I don't know where you can get all-plastic syringes, but most people use
glass syringes with Luer lock attachments for mixing Freund's complete
adjuvant. For example, look at Jim Goding's book, Monoclonal Antibodies
Principles and Practice, 2nd ed. 1986 p. 61-62. You can get glass
syringes from Baxter Scientific Products.
Jack Komisar