Green synthesis of CQDs for determination of iron and isoniazid in pharmaceutical formulations

Abstract

Camphor leaves were used as the precursor for the hydrothermal synthesis of carbon quantum dots. The preparation method is simple and rapid, and the raw material is environmentally friendly and easy to obtain. Without additional modification, the carbon quantum dots were used as fluorescent probes for the sensitive and selective detection of Fe³⁺ and isoniazid at different excitation wavelengths. For Fe³⁺, at the excitation wavelength of 320 nm, the ratio of fluorescence intensity of CQD solution after adding Fe³⁺ to CQD solution without Fe³⁺ addition, F/F₀, and Fe³⁺ concentration showed a good linear relationship in the range of 2.72 × 10⁻⁵ to 1.00 × 10⁻⁴ mol L⁻¹ (R² = 0.9912), and the limit of detection was 8.16 μmol L⁻¹. For isoniazid, at the excitation wavelength of 270 nm, the ratio of fluorescence intensity of CQDs solution with isoniazid to CQDs solution without isoniazid, F/F₀, and isoniazid concentration showed good linear relationships in the range of 3.81 × 10⁻⁶ to 1.00 × 10⁻⁵ mol L⁻¹ (R² = 0.9941) and 1.00 × 10⁻⁵ to 2.10 × 10⁻⁴ mol L⁻¹ (R² = 0.9910) respectively, and the limit of detection was 1.14 μmol L⁻¹. A fluorescence method for the determination of Fe and isoniazid content was proposed. The method has been used to detect iron in iron supplement tablets and isoniazid in isoniazid tablets with satisfactory results.