Falsely Low Urine Δ9-Tetrahydrocannabinol COOH Levels from Metal Lid Specimen Containers with a Low-Density Polyethylene Lining.

Abstract

To the Editor: Our laboratory offers a multianalyte LC-MS/MS urine drug testing panel to assist with compliance monitoring for patients enrolled in chronic pain management programs (1). Recently, we investigated switching from a plastic-only urine collection container (Globe Scientific; item number: 6220) to a metal lid type (Covidien; item number: 2200SA). Both of the containers, not including the lids, were composed of polypropylene. Low-density polyethylene (LDPE)1 lined the inside of the metal lid to ensure a secure fit when closed. The plastic-only container did not have a liner. The quantitative influence of the specimen container was originally investigated by splitting spiked urine specimens and inverting the metal lid container …