Timing is everything! Under-mixing can lead to uneven distribution of ingredients throughout the batch, resulting in a final product that is over or under fortified. Over-mixing wastes energy, time and reduces throughput and can result in stratification or un-mixing.
Although target mix times are usually well-known for specific formulations, many factors influence the optimum time needed for an individual batch including wear of equipment, lot-to-lot variation of raw materials, or environmental conditions.
Bruker has developed a faster solution for measuring blend homogeneity–enabling feedback in less than a minute. Samples are measured (with no sample prep) either directly in-line, or at-line using a sample thief to fill sample cups.
The precision and performance of Bruker FT-NIR analyzers results in improved detection limits, and when combined with the Bruker Conformity Index (CI) software, makes it simple for users to implement.
Current analytical procedures rely on measuring assay value of a tracer material in grab samples using HPLC or other lab-based methods. When the coefficient of variation is less than 5 %, the batch is typically considered homogenous. The drawback is that lab analysis takes expertise and time, and may require several iterations before reaching the target CV.
Unlike methods that predict numerical values and require a large investment in calibration development, the CI method is based on scanning the target samples to set the limits of acceptance based on the standard deviation at each wavelength over the NIR spectral range. To determine the level of detection, test samples are prepared with over or under addition of target materials to confirm to what level differences in product can be detected by the FT-NIR analyzer.
When a sample is scanned and a data point is outside the limit, the sample is flagged as non-conforming. CI software makes it simple to set targets. Work-to-date indicates that 8 cm-1 resolution shows significant improvement over 16 cm-1 resolution, allowing users to more tightly control blend homogeneity. The CI software also offers graphical views of which areas of the spectrum are non-conforming, assisting users in troubleshooting problematic batches.