Quantitative Determination of Spermidine in 50 German Cheese Samples on a Core–Shell Column by High-Performance Liquid Chromatography with a Photodiode Array Detector Using a Fully Validated Method

In the current study, the spermidine (<b>8</b>) contents of 51 German and 9 international cheese samples (from France, Ireland, Italy, The Netherlands, and Switzerland) were analyzed by a modified and fully validated method using high-performance liquid chromatography with photodiode array detection. After precolumn derivatization of biogenic amines with dansyl chloride (<b>11</b>), the compounds were separated on a Kinetex C18 column and detected at λ = 254 nm. This method for compound<b> 8</b> analysis in cheese was validated for the first time according to U.S. Food and Drug Administration (FDA) guidelines for bioanalytical method validation with regard to selectivity, precision, accuracy, recovery, linearity, lower limit of detection (LOD), lower limit of quantitation (LOQ), standard solution stability, short- and long-term stability, freeze–thaw stability, and benchtop stability. The detector response was linear from 0.002 to 8 mg/L <b>8</b> (<i>R</i><sup>2</sup> > 0.999). Low LOD and LOQ values of 1 and 2 μg/L, respectively, reflected the high sensitivity of the method. The intra- and interday recoveries of the <b>8</b>-spiked cheese samples ranged between 87.7 and 102.6%. This validated method was selective, accurate, and precise and was successfully applied for the quantitative analysis of compound<b> 8</b> in 60 cheese samples. Furthermore, the simultaneous detection of eight additional biogenic amines is possible but not validated.