(a) Except where approved in writing by the Department, licensees making tests by the approved testing methods stated in section 511, shall use equipment and follow the methods and procedures outlined in the 18^th edition of the Official Methods of Analysis of the Association of Official Analytical Chemists International (AOAC), which is incorporated by reference. In the absence of prescribed equipment, methods, and procedures in AOAC, or when the Department has documented evidence that a deviation from AOAC procedures and equipment will provide testing results that are at least as accurate and precise as results obtained under AOAC procedures, the Department may give written authorization to use other testing methods and deviations.

(b) For laboratories that test raw milk for payment by infrared (IR) instrumentation, pursuant to section 511(a)(5) of this article, the procedures and pre-calibration checks outlined in section 15.121 of “Standard Methods for the Examination of Dairy Products”, 17^th edition, which is incorporated by reference, must be followed. A letter requesting approval of an individual instrument for IR payment testing must be submitted to the Department, along with results of the pre-calibration checks and results of a minimum of 4 consecutive sets of IR calibration samples. All mean differences and standard deviations shall meet the established tolerances, and individual differences shall meet the tolerances with a 95% confidence interval. All data will be reviewed and approved by the Department prior to the instrument being approved for payment testing.

(c) When the Babcock method is utilized for the testing of milk and cream for fat content, the readings between lines of demarcation shall be extrapolated and reported to the nearest five one hundredths of one percent (0.05%) or less for milk and the nearest twenty-five one hundredths of one percent (0.25%) or less for cream.