Way back in 1986, an article was published by Bruce, M. et.al. entitled “A serious source of error in antiglobulin testing.” Transfusion, 1986; 26:177-181. In their study, the authors evaluated 26 saline solutions from multiple manufacturers, obtained from 10 blood banks. They discovered a pH range of 4.8 – 8.4 in these 26 saline solutions.

In the abstract, the authors stated that: 
“The investigation of a failure of proficiency showed that certain saline solutions are inappropriate for use in blood group serology tests. In particular, it was found that solutions of unexpectedly low pH…. could severely compromise the sensitivity of the antiglobulin test when used as wash solutions. The observed loss of sensitivity ranged from a reduction in titration score to a complete failure in the detection of clinically significant blood group antibodies.” Some examples of Anti-D, Anti-S, Anti-s, 
Anti-Fya, Anti-Jka, Anti-Mia and Anti-Vw failed to react or reacted weakly, when AHG testing was performed using saline with pH of less than 6.5. Again, from the abstract, they concluded that “improved standardization and sensitivity (in serological tests) could be achieved by using phosphate-buffered saline pH 7.0-7.2... It is recommended that unbuffered saline solutions of pH less than 6.0 should not be used for serological testing.”

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