Quantitative determination of 5-aminolaevulinic acid and its esters in cell lysates by HPLC-fluorescence

The development of a reliable sensitive method for the HPLC determination of 5-aminolaevulinic acid (ALA) and ALA esters in cell lysates is described. The method relies on the quantification of a fluorescent derivative of ALA following its derivatisation with acetylacetone and formaldehyde. Following this procedure it is possible to quantify ALA in cell lysates with no need for pre-purification of the sample. The method has been validated in two ranges of concentration (0.6–65 μM, 0.1–10 μg/mL, and 30–600 μM, 5–100 μg/mL), and has also been extended and validated for the determination of ALA released from ALA prodrugs after acidic hydrolysis.