. Author manuscript; available in PMC: 2008 Jun 1.

Published in final edited form as: Anal Biochem. 2007 Mar 7;365(1):31–39. doi: 10.1016/j.ab.2007.03.002

Table 1.

Verification of [AscH⁻] by the method of standard additions.

	Swine Plasma	Dog Plasma	Orange Juice	U937 Cells
[AscH⁻] /μM	44.8 ± 3.0	93.2 ± 4.8	2700 ± 81	6500 ± 320
[AscH⁻] in well /μM ^a	3.7 ± 0.25	7.7 ± 0.4	11.0 ± 0.33	36.9 ± 1.8
Expected Spike 1 /μM ^b	5.2^c ± 0.25	12.7 ^d ± 0.4	16.0 ^d ± 0.33	56.9 ^e ± 1.8
Observed Spike 1 /μM ^b	5.6 ^c ± 0.35	13.9 ^d ± 0.5	16.4 ^d ± 0.49	57.8 ^e ± 1.5
Expected Spike 2 /μM ^b	6.7 ^f ± 0.25	17.7 ^g ± 0.4	21.0 ^g ± 0.33	76.9 ^h ± 1.8
Observed Spike 2 /μM ^b	7.6 ^f ± 1.1	19.8 ^g ± 0.4	21.4 ^g ± 0.68	81.3 ^h ± 3.1

These numbers are the final concentrations in the non-spiked wells of the plate after all additions and dilutions.

These numbers are the final expected and observed concentrations in the spiked wells of the plate after all additions and dilutions. Using two sample students’ t-tests, the p-values were found to be: for the swine plasma, p = 0.358, df = 37 for the first spike and p = 0.434, df = 20 for the second; for the dog plasma p = 0.080, df = 19 for the first spike and p= 0.001, df = 22 for the second; for the orange juice p = 0.501, df = 52 for the first and p = 0.600, df = 40 for the second; for the cells p = 0.706, df = 15 for the first spike and p = 0.243, df = 12 for the second.

^c–h

Ascorbate was added to increase the final concentration in the well by: (c) 1.5 μM; (d) 5.0 μM; (e) 20 μM; (f) 3.0 μM; (g) 10 μM; and (h) 40 μM.