When an XRF laboratory subcontracts work, this work shall be placed with a competent subcontractor (the subcontractor must complies with ISO/IEC 17025:2005 for the work in question).
The laboratory shall advise the customer of the arrangement in writing and, when appropriate, gain the approval of the customer, preferably in writing.
The laboratory is responsible to the customer for the subcontractor’s work, except in the case where the customer or a regulatory authority specifies which subcontractor is to be used.
The laboratory shall maintain a register of all subcontractors that it uses for tests and/or calibrations.