Quantification of Sunscreen Benzophenone-4 in Hair Shampoos by Hydrophilic Interactions Thin-Layer Chromatography/Densitometry or Derivative UV Spectrophotometry

Figure 3

Selected UV spectra of shampoo solutions and BZ4 standards in pH 6 phosphate buffer-water 1 : 20 (v/v). 1: shampoo matrix (2.5 mg mL⁻¹, 0% BZ4); 2: shampoo matrix (20 mg mL⁻¹, 0% BZ4); 3: shampoo (2.5 mg mL⁻¹, 1.0% BZ4); 4: BZ4 standard (0.04 mg mL⁻¹); 5: shampoo (2.5 mg mL⁻¹, 2.0% BZ4).