Dried Urine Spot Sample Collection for Rapid and Sensitive Monitoring of Exposure to Terror Agents; Toxins and Chemical Warfare Agents by LC-MS/MS Analysis

Lilach Yishai Aviram, IIBR, Ness Ziona, Israel (lilachy@iibr.gov.il)

Dried urine spot (DUS) sampling is based on collection of a small amount of urine (20-60 µL) dried on a filter paper and then easily extracted. It offers advantages such as ease of shipping and handling due to a very modest storage volume. These advantages are important in cases of terror attack mass casualty scenarios, in particular those which occur remotely to a lab, and in cases where only a small amount of urine is available, such as post-mortem analysis. Furthermore, numerous studies found that many drugs are more stable in DUS samples than under refrigeration.

In this research, a new approach was developed for high-throughput rapid screening of terror agents in urine microsamples, monitoring ricinine, L-abrine and phosphonic acids. Ricinine and L-abrine may serve as biomarkers of the highly toxic Ricin and Abrine toxins. Phosphonic acids are the direct metabolites of organophosphorus chemical warfare agents (OP-CWAs). Accordingly, their detection serves for evaluating exposure to OP-CWAs in terror or war scenarios.  

The new method is based on a rapid sample preparation (extraction in a methanol/water mixture), followed by LC–MS/MS targeted analysis. The detection limit of ricinine and L-abrine was 100,300 pg/mL respectively, and for phosphonic acids, 1 ng/mL. Good recoveries were obtained with linear response (R²=0.99). This method is highly stable even with DUS samples stored up to 5 months at room temperature before analysis. The method was successfully implemented in two cases: (A) an in vivo experiment where the time-course of isopropyl methylphosphonic acid (sarin hydrolysis product) was determined in mice urine up to 60 hours after mice exposure to 1 LD50 Sarin (i.v.). (B) A real forensic case where a limited volume of human urine was collected 72h after self-injection of a castor bean extract (containing ricine).