Abstract: An acetaldehyde screening method is developed by feeding solid polymer sample particles having a free acetaldehyde (“AA”) content of 2 ppm or less, melting at least a portion of the sample particles to obtain a polymer sample having a heat history, and thereafter measuring the amount of acetaldehyde present in the polymer sample having the heat history. There is also provided a screening method in which the quantity of free or residual AA in or on a polymer sample is measured to obtain a first value AAf, the sample is melted, and thereafter the amount of AA generated upon remelting the polymer is measured to obtain a second value AAg.