What color tube is 12th in the order of draw for blood collection?

The correct color tube that is 12th in the order of draw for blood collection is gray. This tube is used primarily for the collection of blood samples that require glucose testing, as it contains sodium fluoride and potassium oxalate, which help preserve the glucose levels in the sample.

Following the proper order of draw is essential to prevent contamination of the samples, particularly when different additives in the tubes can interact and affect the test results. The gray tube is positioned later in the sequence, indicating that previous samples have been taken from tubes containing different additives. Using the gray tube at this stage minimizes the risk of additives from earlier tubes affecting the outcome of tests that rely on accurate glucose measurement.

In the context of the other options, the green tube is typically used for tests that require heparin, pink is used for blood bank studies, and orange is utilized for serum determinations with a gel separator. Each of these tubes has a specific place in the order of draw to ensure that the blood samples are collected without cross-contamination.