S.C. Code § 39-31-40
Each pound of bulk rice shall contain after rinsing at least eighty-five per cent of the thiamine, niacin and iron required in Section 39-31-20. Rinsing for the purposes of enforcement shall be as follows: Transfer one hundred grams of the milled rice to a two-liter Erlenmeyer flask containing one liter of water at twenty-five degrees centigrade. Stopper the flask and rotate it for exactly one-half minute so that the kernels are kept in motion. Allow the kernels to settle for one-half minute, then pour off eight hundred and fifty milliliters of the water along with any floating or suspended matter. Enrichment ingredients are then determined on the wet rice and water remaining in the flask and are calculated on the basis of the rice before washing.
S.C. Code § 39-31-40