Significant practice in various blending methods is the measurement of properties and analysis of stock qualities as well as product qualities. Samples are extracted for analysis and to verify the blend quality. Any adjustments may be made using the results obtained from the analysis. Sampling systems may be automatic or manual. This topic will discuss points of sampling; online measurement in a fuel blending system; matrices of blend specs versus required stock; final blend qualities for gasoline, diesel, and fuel oils; challenges in analysis and/or online measurement of required qualities; tank-to-tank blending; rundown blending; gasoline quality analysis matrix; diesel quality analysis matrix; fuel oil quality analysis matrix, quality measurement/analysis challenges; etc.