Stability-Indicating Photochemical Method for the Assay of Thiamine by Spectrophotometry

Table 3

TC : TH ratios for UV irradiated TH solutions (4 mg %) at pH 9.0–11.0.

pH	TH concentration (mg %)	Time (min)	A370 nm	TC concentration (mg %)^a	TC : TH ratio
9.0	4.0	0	0	0	—
		15	0.221	0.334	0.084 : 1
		30	0.425	0.650	0.162 : 1
10.0	4.0	0	0	0	—
		15	0.512	0.782	0.196 : 1
		30	1.06	1.621	0.405 : 1 (optimum value)
11.0	4.0	0	0	0	—
		15	0.411	0.628	0.157 : 1
		30	0.702	1.073	0.268 : 1

^aThe concentration of TC in photooxidized solution of TH has been calculated from the increase in absorbance at 370 nm of the extracted solution at 30 min irradiation using 654 as the value of A (1% 1 cm) [61].