Mix Uniformity CV: Coefficient of Variation Calculator
What Is Mix Uniformity?
Mix uniformity reflects how evenly a mixer (for feed, premix, pharmaceutical granules or powders) blends its components, and is expressed by the coefficient of variation (CV) of a tracer component (such as chloride ion or the active ingredient) measured at multiple sampling points: CV = standard deviation / mean x 100%. The lower the CV, the more uniform the mix. Uniformity directly affects within-batch quality consistency and is a key indicator for mixing-process validation; poor mixing is a common source of quality incidents in feed and pharmaceutical production.
How to Sample and Measure
Following standards such as GB/T 5918, take at least 10 samples at different positions or time intervals (discharge port, bin locations and so on) after mixing, and measure the tracer content (chloride ion for feed, or the main ingredient for premixes). Calculate the mean, standard deviation and CV. Sampling positions must cover the whole mixer or discharge cycle rather than a single spot, sampling should be done under normal operating parameters (not when stopped or in dead zones), and sampling times should span the full batch to guarantee representativeness.
What Are the Acceptance Criteria?
In the feed industry, GB/T 5918 requires a CV <= 10% for compound and concentrated feed (some requirements tighten this to <= 7%), while premix feed demands more, typically CV <= 5%. For solid pharmaceutical dosage forms, mix uniformity follows process-validation requirements (for example, the USP <905> approach or CV < 5%). The tool judges automatically according to the industry standard you select; before judging, confirm that the sampling and tracer detection methods meet the standard so that methodological bias does not affect the conclusion.
How to Use It (Step by Step)
Enter the measured content at each sampling point, and the tool calculates the mean, SD and CV, compares them with the standard, and highlights abnormal points. If the CV exceeds the limit, investigate mixing time (too short, or over-mixing that causes segregation), ingredient addition order, equipment parameters (speed, blades) and tracer uniformity. Re-validate the CV after process changes to confirm the improvement, and archive the investigation and validation records to close the loop.