Validation and application of a liquid chromatography-tandem mass spectrometric method for the simultaneous determination of testosterone and dihydrotestosterone in rat prostatic tissue using a 96-well format.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to extract and quantify the androgen concentration in the rat prostate. This method introduced a novel 96-well plate format for the extraction and derivatization of testosterone (T) and dihydrotestosterone (DHT) from rat prostatic tissue that greatly simplified the sample preparation procedure. Due to the difficulty to obtain reproducible specimens with non-detectable level of androgen, a matrix-free standard solution was used for method validation. Both T and DHT calibration curves were linear over the calibration range (12.5-2500 pg) with correlation coefficient values greater than 0.9900. The intra-day and inter-day accuracy, reported as %bias, and precision, reported as %CV, of T and DHT were within +/-10%. The lower limit of detection (LLOD) and lower limits of quantification (LLOQ) for both T and DHT were determined to be 5 and 12.5 pg. The validation results demonstrated the selectivity, sensitivity, accuracy, precision, linearity and ruggedness of the method, as well as the suitability of the method for simultaneous detection of T and DHT in rat prostatic tissues. The validated method was successfully applied to determine the physiological T and DHT level in rat prostatic tissues. Similarly to the serum concentration profile pattern, T and DHT intraprostatic levels peaked 2 h after lights-on and decreased after lights-off with DHT level approximately 4-fold greater than T.