13c6 nnal

We purchased [pyridine-D₄]NNN and [¹³C₆]NNN from Cambridge Isotope Laboratories (Andover, MA), while [pyridine-D₄]nornicotine, NNN, NNAL, and [¹³C₆]NNAL (Figure 1) were obtained from Toronto Research Chemicals (Ontario, Canada). Recombinant β-glucuronidase (catalog # G8295) was purchased from Sigma-Aldrich (Milwaukee, WI). Phosphate buffered saline was procured from Invitrogen (Grand Island, NY). All other chemicals were from Sigma-Aldrich, Fisher Scientific (Fairlawn, NJ), or Alfa Aesar (WardHill, MA). True Taper^® 96-well plates were procured from Analytical Sales & Services (Pompton Plains, NJ) and silicone cap mats required to cover the 96-well plates were from Phenomenex (Torrance, CA). Five ml Biotage Isolute Supported Liquid Extraction+ (SLE+) diatomaceous earth-based liquid-liquid extraction cartridges were obtained from Biotage (Charlotte, NC) and Oasis MCX 60 mg, 60 μm solid-phase extraction 96-well plates were from Waters (Milford, MA). Strata SI-1 Silica (55 μm, 70 A, 100 mg) 96-well SPE plates were purchased from Phenomenex (Torrance, CA). A Cerex 96-well positive pressure processor (Chromtech, Apple Valley, MN) and an Eppendorf multi-channel pipette were used during sample processing.

Cotinine, [¹³CD₃]Cotinine, NNAL, and [¹³C₆]NNAL (Figure 1), were procured from Toronto Research Chemicals (Ontario, Canada). Recombinant β-glucuronidase (catalog # G8295) was purchased from Sigma-Aldrich (Milwaukee, WI). True Taper® 96-well plates for sample processing and analysis were from Analytical Sales & Services (Pompton Plains, NJ) while silicone cap mats used to cover the 96-well plates were purchased from Phenomenex (Torrance, CA). Four hundred μL Isolute SLE+ diatomaceous earth solid-phase extraction 96-well plates were from Biotage (Charlotte, NC) while Oasis MCX 10 mg, 30 μm solid-phase extraction 96-well plates were from Waters (Milford, MA). A Cerex 96-well positive pressure processor (Chromtech, Apple Valley, MN) was utilized during sample processing. Dulbecco’s PBS was purchased from Invitrogen (Grand Island, NY) and the rest of the chemicals were obtained either from Fisher Scientific (Fairlawn, NJ), Sigma-Aldrich (Milwaukee, WI) or Alfa Aesar (WardHill, MA) and used without further purification unless otherwise noted. An Eppendorf multichannel pipettor was used during sample processing.