(a) Composition. Sampling and testing for composition shall be made on batches of product as often as is necessary to control composition. On continuous production runs, enough samples shall be taken throughout the run to adequately assure composition requirements.

(b) Other chemical analysis or physical analysis. Such tests shall be performed as often as is necessary to assure compliance with standards, specifications or contract requirements.

(c) Weight or volume control. Representative samples of the packaged products shall be checked during the filling operation to assure compliance with the stated net weight or volume on the container.

(d) Keeping quality and stability. A minimum of one sample from each batch of product or one representative sample per hour from a continuous production run shall be taken. For continuous runs, samples shall be taken at the start, each hour, and at the end of the run. Samples should also be taken after resumption of processing following an interruption in continuous operation. Each sample shall be incubated at 90 °F to 100 °F for seven days.