• Nicola Robinson

No more LC! Multi-Component Analysis for Dissolution using Distek Opt-Diss 410


When it comes to analysis of dissolution samples, traditionally there are two main routes for sample analysis; UV spectrophotometry or HPLC. With UV Spectrophotometry considered to be the simpler and less time-consuming method for analysing dissolution samples. However, for products containing more than one active pharmaceutical ingredient (API), analysis by UV spectrophotometer is not considered to be an option. This is because both components often absorb over the same spectral region, causing deviations from the Beer-Lambert Law. The linear relationship between absorbance and concentration values are based upon the measured absorbance at a specific wavelength. In these cases, separation techniques such as HPLC become the usual route of analysis. Although HPLC is a tried and tested favourite in the laboratory, most analysts are familiar with the disadvantages and frustrations it can present, particularly when time is of the essence.


The Distek Opt-Diss 410 presents an innovative third option for dissolution analysis. Utilising fibre-optic UV technology which allows for measurements to be taken directly in the vessel, the in-situ probes are moving light instead of liquid which negates the need to remove samples, filter the samples, replace media and prepare for off-line analysis. Automated data collection with UV readings that can be taken as frequently as every 5 seconds allow for a complete dissolution profile to be constructed with no extra effort from the analyst. The dissolution process from start to final report will only take as long as the dissolution run time. In addition to this, the Distek Opt-Diss 410 incorporates multi-component analysis (MCA) into its software allowing for the complete analysis of products with two APIs or for understanding the interaction of excipients, coating and capsules, without the need for LC separation. Perfect for screening of new formulations and method development projects. The analysis of two spectrally overlapping components is accomplished by applying the Classical Least Squares form of Multiple Linear Regression to the complete spectral and temporal profiles obtained using in-situ fibre optic UV analysers. The algorithm uses a calibration matrix of extinction coefficients to calculate component concentrations in an unknown mixture. These are derived from a training set comprised of the spectra of multiple standard solutions. Then, used in tandem with in-situ fibre optics, the accuracy of the technique is demonstrated by recovering the concentration of two APIs in known mixed solutions. Distek have released a comprehensive white paper demonstrating that two APIs can be accurately quantified, even with highly overlapping spectra, without the need for a separation step. The key to this process is using large data sets that can be obtained only be using the in-situ fibre optic UV probes, large spectral regions are collected instead of just individual wavelengths and complete temporal profiles instead of a few points. The Distek Opt-Diss 410 removes the limitations of moving liquid from dissolution vessel to analyser, allows for more complete data collection and near-real time completion of dissolution testing.


Keeping the science in the vessel. No more sampling, no more consumables, no off-line analysis.


#Distek #Dissolution

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