A sample collection kit includes a sample collector, a polycarbonate container, and a preservative solution. The sample collector includes an absorbent pad with a collecting element that receives a sample of oral fluid. The absorbent pad also includes an interior portion that extends into a handle. The handle includes an upper casing and a lower casing. The collecting element can be treated with a surfactant to optimize recovery of analytes from the oral sample and/or their absorbance onto the absorbent pad. A polycarbonate container receives the absorbent pad or the sample collector and stores it for testing of analytes. A dextran sulfate preservative solution is included in the polycarbonate container that inhibits enzymatic activity on a collected sample.
