Oxidation of Hydroxy- and Dihydroxybenzoic Acids Under the Udenfriend's Conditions. An HPLC Study

Table 4: Data on linearity.

Standards	λ_max (nm)	Calibration range (μg/mL)	Linear equation	R²	LOD (μg/mL)	LOQ (μg/mL)
3,4-DHBA	258	2.5-250	y=63.077x+30.238	0.9999	1.0	2.5
2,5-DHBA	235	2.5-250	y=27.504x+25.623	0.9997	2.0	2.5
2,3-DHBA	247	2.5-250	y=28.555x−41.925	0.9995	2.0	2.5
2,4-DHBA	258	2.5-250	y=55.925x−21.311	0.9998	2.0	2.5
SA	235	2.5-250	y=24.742x−6.336	0.9999	2.0	2.5

R²: correlation coefficient DHBA: dihydroxybenzoic acid; SA: salicylic acid