Check the correct option (s) considering the diagram above represented of a TLC ((Thin-layer chromatography) with four spots (A, B, C and D). Substances 1, 2, 3 and 4 are presented for purposes of illustration and for the development of the issue in hypothetical situations.
( ) Flavonoids are substances widely used for quality control purposes in research laboratories. Among the chromatographic techniques used, thin layer chromatography (TLC) is the most versatile. However, the TLC (in Silica) illustrated could not match the showed structures.
( ) A pharmacist received four samples identified on the labels as 1, 2, 3 and 4 and, in order to establish the RF of each of them, he performed a TLC analysis using the solvent: toluene: ethyl acetate: methanol system (7: 3: 1) and assigned the following order for the stains (A: Substance1; B: Substance 4; C: Substance 2; D: Substance 3).
( ) Substance 4 has two absorbance maximums, at 270-295 nm (benzoyl portion - Band II) and at 350-385 nm (cinnamoyl portion - Band I)
( ) An analyst did not have a TLC plate and chose to distinguish the samples by spectrophotometry, as he observed that substances 1, 2, 3 and 4 had different spectra of ultraviolet and color.
( ) One analyst noted that he did not apply the samples in the order and coded the spots on the TLC as A, B, C and D. Considering the chemistry of these structures he concluded the following: A: Substance 4; B: Substance 1; C: Substance 2; D: Substance 3)
( ) Substance 3 has an ultra-violet spectrum quite characteristic of flavonoids, with two absorbance maximums, at about 254 nm (benzoyl portion - Band I) and 365 nm (cinnamoyl portion - Band II)
( ) The four substances (1, 2, 3 and 4) showed in the analysis carried out by spectrophotometry by the analyst ultraviolet spectra with absorption at about 240-295 nm (benzoyl portion).
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