(a) Performance evaluation samples

(1) Provided by Secretary
The Secretary shall ensure that performance evaluation samples are provided to any laboratory that has applied for accreditation under this chapter.

(2) Analysis by laboratory
A laboratory described in paragraph (1) shall analyze such performance evaluation samples and submit the results of such analysis to the Secretary, as provided for in section 138a of this title.

(3) Testing methods
Samples shall be tested by the laboratory according to methods specifically approved for such purpose by alternate methods of demonstrated adequacy or equivalence, as determined in regulations established under this chapter.

(b) Results of testing

(1) Submission of results
The laboratory shall submit the results of the tests conducted under subsection (a) to the Secretary on forms provided by the Secretary, on or before the date determined by the Secretary.

(2) Evaluation of tests
The Secretary shall evaluate the results of such tests achieved by the laboratory and shall determine whether such laboratory is capable of undertaking an accurate analysis of chemical residues in agricultural products.

(c) Review of accreditation
The Secretary shall ensure that performance evaluation samples for analysis are provided to laboratories accredited under this chapter not less than two times a year.