PAT round 137 April 1999. A,total of 1169 laboratories were enrolled in the PAT Program with 1048 laboratories submitting results on Round 137. Of the 1048 laboratories submitting results, 949 used the Internet data entry system. Table I lists the reference values, performance limits, and participants for each sample type in the PAT Program. Table II presents the summary of the PAT proficiency ratings for each analytical area. PAT round 138 July 1999. PAT Round 138 was sent to participating laboratories on July 1, 1999. For this round, the organic solvent was methanol (MOH) and the metals were cadmium, chromium, and lead. Asbestos/fibers were amosite with one man-made fiber sample.