Quick view Nik NIK Test V - Pentazocine (Talwin) MSRP: Was: Now: $3.00 - $26.50 Fr¶hdes Reagent tests for Pentazocine (Talwin), and can be used as a secondary test for Heroin. Positive Result(s): Dark blue is a positive reaction for Pentazocine. Purple is a positive reaction for Heroin. Choose Options Choose Options