Table 4. FT stability of 5 calibration sera for 7 anti-PnPS (acceptable range: within ± 20%).

PnPS	FT cycle*
	Serum 748				Serum 752
	1†	2	3	4	1†	2	3	4
4	100.00	94.67	106.67	107.42	100.00	91.52	108.30	105.79
6B	100.00	97.88	100.31	105.56	100.00	98.19	100.29	104.48
9V	100.00	102.72	99.56	104.10	100.00	92.01	103.56	107.22
14	100.00	93.94	96.08	105.19	100.00	92.39	102.40	104.52
18C	100.00	94.86	100.90	98.58	100.00	89.58	103.13	106.08
19F	100.00	99.82	101.15	104.60	100.00	91.05	105.21	108.03
23F	100.00	97.33	99.50	106.22	100.00	93.79	106.82	100.72

FT = freeze thaw, PnPS = pneumococcal polysaccharide.

^*Freeze thaw cycle: sera were subjected to 4 freeze thaw cycles. ^†Relative to FT 1 (%) = (based upon mean value) FT 2/FT 1 × 100.