The ability to monitor and detect chemical warfare agents and their degradation compounds continues to be of utmost importance. Remote on-site field analysis of these compounds is also extremely important as it relates to treaty verification for the Chemical Weapons Convention, as well as the minimization and elimination of human exposure. A portable instrument has been developed and miniaturized that allows for the detection of these compounds in the field with better quantitative results and higher reproducibility than traditional field test kits. All sample and reagent manipulations are conducted in a completely automated fashion. Quantitative results may be determined colorimetrically using the molybdenum blue reaction for the final degradation product of phosphonic acid based chemical warfare agents with a detection limit of 0.05 ppm. The instrument is based on the flow analysis technique of sequential injection analysis (SIA). The benefits of this approach are that the method provides rapid response, high reproducibility of results, high sensitivity and minimal waste production.
In many circumstances, the ability to perform on-site, point-of-collection analysis can play a pivotal role in the goals or requirements of the inquiry. Toward this end, the use of commercial or customized kits, which require the analyst to manually perform the metering and mixing of reagents with the sample and the subsequent visual, spectrophotometric or other interpretation of the results, has become widespread. Often, these methods can suffer from poor reproducibility and sensitivity in addition to being tedious and time consuming. Flow analysis methods, such as traditional flow injection analysis (FIA) and the more recent sequential injection analysis (SIA), have found widespread use in the automation of sample and reagent handling and subsequent analysis for many important analytes. These methods can be completely automated and offer excellent reproducibility, minimized analysis time, and in certain configurations, very high sensitivity. We have developed a miniaturized, fully portable SIA-based instrument for on-site screening for chemical weapons degradation products during challenge inspections under the Chemical Weapons Convention, as well as for the sensitive analysis of other important environmental analytes. In this paper, we will discuss our portable SIA design, the analytical approaches utilized, and results obtained for the analysis of representative chemical weapons degradation compounds.