A method to develop and validate an analytical method relating to a plurality of ultra-sound probes of different sonicating efficiencies to identify correct and reproducible operating parameters for de-agglomerating particles of a product of interest, comprising the steps of: i. applying a first power setting to a first ultra-sound probe for sonicating a first sample of the product of interest, measuring and recording a first voltage produced by the ultra-sound probe at the first power setting; ii. sonicating the first sample at the first power setting whilst taking particle size measurements at timed intervals to track the progress of the de-agglomeration of the first sample; iii. selecting a second power setting of the first ultra-sound probe which is different from the first power setting, measuring and recording a second voltage produced by the ultra-sound probe at the second power setting, sonicating a second sample of the product of interest at the second power setting whilst taking particle size measurements at timed intervals to track the progress of the de-agglomeration of the second sample; iv. choosing a power level comprised between the first and the second power setting and the sonication time required for optimum de-agglomeration based on results from the de-agglomeration of the first sample and the second sample; v. determining a validated voltage measured on the ultra-sound probe corresponding to the selected power level; vi. establishing the validated voltage and selected time as the settings for sonication of the product of interest; and selecting a new ultra-sound probe, different from the first ultra-sound probe for sonicating the same product of interest, adjusting the power level of the new ultra-sound probe so that its measured voltage matches the validated voltage of the first ultra-sound probe and sonicating the product with the new ultra-sound probe at the validated voltage and during the time established when using the first ultra-sound probe. i. applying a first power setting to a first ultra-sound probe for sonicating a first sample of the product of interest, measuring and recording a first voltage produced by the ultra-sound probe at the first power setting; ii. sonicating the first sample at the first power setting whilst taking particle size measurements at timed intervals to track the progress of the de-agglomeration of the first sample; iii. selecting a second power setting of the first ultra-sound probe which is different from the first power setting, measuring and recording a second voltage produced by the ultra-sound probe at the second power setting, sonicating a second sample of the product of interest at the second power setting whilst taking particle size measurements at timed intervals to track the progress of the de-agglomeration of the second sample; iv. choosing a power level comprised between the first and the second power setting and the sonication time required for optimum de-agglomeration based on results from the de-agglomeration of the first sample and the second sample; v. determining a validated voltage measured on the ultra-sound probe corresponding to the selected power level; vi. establishing the validated voltage and selected time as the settings for sonication of the product of interest; and <EOS>