What is the additive in a royal blue top tube with a red stripe?

The correct choice indicates that a royal blue top tube with a red stripe contains no additive. This type of tube is specifically designed for the collection of trace element specimens or toxicology tests, and the lack of an additive means that it does not interfere with the analysis. Tubes without additives are often used to prevent any potential contamination that could skew results, especially important when measuring trace elements or substances in small quantities.

In contrast, other additives such as EDTA, Sodium Fluoride, and Potassium Oxalate are used in specific types of tubes to help preserve samples or prevent clotting, which would not be appropriate for the specific function of a royal blue tube with a red stripe. Understanding the purpose of different tube types and their additives is crucial for accurate sample collection and analysis in phlebotomy.