Final answer:
The purple top tube should be collected first for dermal samples as it contains EDTA, which prevents clotting and preserves the integrity of the sample.
Step-by-step explanation:
The color tube top that should be collected first for dermal samples is the purple top tube. This tube contains the anticoagulant EDTA, which prevents clotting and preserves the integrity of the sample. It is commonly used for collecting blood samples for cell counting and DNA testing. The purple top tube is suitable for dermal samples because it ensures that the sample does not clot and provides a standardized method for sample collection.