The single phase TLC method described here successfully quantified 75% of the clinical DOX samples within 15% of established HPLC values and 100% within 16% which meets the FDA acceptance criteria for a bioanalytical system using chromatographic methods . The DOL levels were much lower than the DOX levels which resulted in additional variability and error to the DOL quantification with 50% of the samples being within the 15% error goal. Despite the variability, these DOL levels provide valuable insights for tailoring DOX dosing to individual patients. We also demonstrate that the TLC method can be used with a first-of-its-kind hermetically sealed-cartridge design that makes the TLC process safe, by preventing the release of silica dust and mobile phase fumes and sets the stage to develop this technique for use in the bedside clinical setting.