Harris County lab shows quick peptide screening with inlet and paper‑spray ionization

Kyle Burks of the Harris County Institute of Forensic Sciences demonstrated a set of rapid mass‑spectrometry approaches that forensic labs can use to presumptively identify high‑mass peptides, including intact human growth hormone and smaller research peptides, without switching to a full electrospray source.

Burks, speaking during the final morning session, said his lab has moved away from traditional color and crystalline presumptive tests and now relies on automated screening combined with GC‑MS confirmation. "We do all presumptive tests for our case work by GCF ID, mainly because it's an automated approach and it's much more selective than say a color test," he said, adding that the lab uses GC‑MS (and sometimes IR) for confirmatory work.

Why it matters: intact peptides and proteins such as human growth hormone (HGH, roughly 22,124 Da) often do not ionize or register on instruments configured for volatile small molecules. That can leave detectives and prosecutors without usable chemical information. Burks showed inlet ionization and paper‑spray sampling paired with a time‑of‑flight mass analyzer can produce rapid, ESI‑like spectra and allow teams to generate a presumptive identification within seconds.

Methods and results: the team introduced small volumes directly to the mass spectrometer inlet and used 3‑nitrobenzonitrile (3‑NBN) as a matrix to boost ionization efficiency. In tests with insulin and other samples, adding 3‑NBN increased signal intensity substantially (the presenter reported roughly a 40‑fold theoretical increase while sample concentration was reduced). For an HGH standard the group observed an intact mass near 22,124.5 Da; paper‑spray sampling produced a comparable observed mass (22,123.8 Da). Burks also described a rapid trypsin digestion workflow, C18 cleanup and deconvolution with the software package the talk cited as "Megtran," followed by Mascot database searching; a bovine serum albumin digest returned 96% significance and ~36% sequence coverage in their quick workflow.

Peptide identification and limitations: in one sample the team presumptively identified two smaller peptides — melanotan II and GHRP‑6 — that are commonly sold as research peptides online. Burks cautioned that presumptive results still require comparison with authenticated standards for confirmation in casework and noted the lab relies on GC‑MS and other confirmatory approaches for formal reporting.

Practical issues: Burks described procurement hurdles when ordering some peptide standards (masked invoice descriptions and vendor restrictions) and explained the lab used third‑party procurement (through distributors such as Fisher/Anduin) to acquire authenticated materials for validation. He also discussed instrument‑maintenance tradeoffs, saying the lab avoids frequent ESI source swaps because contamination and throughput concerns in high‑volume forensic drug labs make ambient‑inlet approaches more practical for routine presumptive screening.

Funding and next steps: Burks acknowledged National Institute of Justice funding for the research and collaborators who aided prototype development and validation. He emphasized that while inlet ionization and paper‑spray can speed presumptive identifications, formal confirmation in casework still requires comparison with known standards and established confirmatory workflows.

The session ended with no audience questions and a break for lunch; the afternoon session was scheduled to start at 1:35 p.m.