Why do some batches of tablets prepared using the same ingredients and following the same process show different dissolution profiles?
This question remained largely unanswered until about five years ago, because the chemical composition measured with traditional laboratory equipment, such as HPLC (high-performance liquid chromatography), often could not explain the dissolution failure.
However, with the emergence of near infrared (NIR) chemical imaging systems in troubleshooting laboratories, the situation has changed, because this new technology provides access to the structure, or the arrangement of chemical entities, within solid dosage form products.

Refer this reference cite for further detail,

JANIE DUBOIS AND E. NEIL LEWIS"Advanced Troubleshooting Of Dissolution Failure", The Pharmaceutical Solutions Update, www.pharmaceuticalonline.com, Page 38-45