(1) Residual solvent analysis is intended to accurately quantitate and report solvent residue left behind from product processing.

(2) Laboratories must use a method approved by the department to analyze residual solvents.

(3) Methanol and any other solvent listed in chapter 314-55 WAC must not be used in any preparation or analysis procedure for residual solvent testing.

(4) Upon receipt of a sample at a laboratory, the sample treatment must follow the method requirements for preservation and storage.

(5) When an extraction solvent is used in method it must be an organic solvent that is capable of accomplishing the dilution of the sample while still able to meet the quality control requirements of this method and regulatory requirements, and is NOT a required analyte per regulations. The selected solvent must be specifically cited in a lab's standard operating procedure(s).

(6) Subsampling and homogenization protocols must be specified in the approved method(s) to include:

(a) The lab must analyze at least 0.2 grams of sample per residual solvents analysis.

(b) Upon receipt of sample, the portion of the sample that is to be used for residual solvents analysis must be stored to minimize solvent evaporation.

(c) Homogenization of residual solvent samples by the lab is prohibited unless necessary due to sample composition. If homogenization is necessary, steps must be taken to minimize evaporative loss.

(7) Laboratories must limit batch size to 20 samples in a preparation batch not including quality controls.

(8) The ICV must meet a minimum of 80 - 120 percent recovery for each analyte.

(9) CCV, surrogate, LCS and matrix spike samples must meet a minimum of 70 - 130 percent recovery for each analyte.

(10) Sample duplicates and matrix spike duplicates must have a relative percent difference (RPD) value of less than 20 percent.