Food and Beverage
by Anthony J. Midey, Clinton A. Krueger, Mark A. Osgood, Jianglin Wu, and Ching Wu
High-Performance Ion Mobility Spectrometry: A Tool for Rapid Food Safety Screening
F
ood safety detection requirements demand rapid analytical methods in both the laboratory and field. High- performance ion mobility spectrometry (HPIMS) provides the speed and portability of previous IMS benchtop instruments, but with resolving power comparable to liquid chromatography (LC). Direct electrospray ionization (ESI) from a sample syringe adds the advantages of ESI to detect priority targets such as drug residues, dyes, and plasticizers, even in food matrices, for potential on-site screening with higher throughput.
Introduction Consumers rely on screening protocols to en-
sure the safety of the food supply reaching the market. Identifying chemical contaminants present becomes the detection challenge, whether the adulteration occurs accidentally during the growing and/or production pro- cess, or intentionally for enhancing profit.1,2 Ideally, screening methods should be sensi- tive, selective, and portable, allowing the technique to be used where contamination could be introduced.
For these reasons, ion mobility spectrometry applications for analysis in the burgeoning
foodomics field are expanding.3 IMS is a wide-
ly adopted gas–phase sample separation and detection technique ubiquitous to security screening in aviation and law enforcement to find trace amounts of explosives and drugs of abuse in the field. IMS also has a long history of chemical weapons agent (CWA) monitor- ing by the military.4,5
These instruments are
compact and utilize primarily room air as the separating medium with total analysis times in seconds. However, the systems also suffer from low resolution.
Currently, many food screening protocols utilize gas or liquid chromatography (GC or LC) to detect the target constituents, methods which are not as easily adapted to on-site or field use. Subsequently, many previous IMS applications have focused on detecting emitted volatiles as- sociated with food and beverage contamination via atmospheric pressure chemical ionization methods (APCI) for sample introduction.3,6 However, electrospray ionization sources are being implemented more.7–10
To address unmet
needs in food safety aimed at faster, potentially more portable screening methods, the current work utilizes the GA2100 ESI-HPIMS (Excellims Corp., Acton, MA) to demonstrate rapid de- tection of several high-priority contaminants
including phthalates, consumer-grade dyes, and veterinary drug residues. This work ex- pands upon earlier studies using ESI-HPIMS for analyzing nutritional supplements7 of-concept food safety studies.11
and proof-
High-performance ion mobility spectrometry with
electrospray ionization High-performance ion mobility spectrometry has two key components: 1) a source for intro- ducing and ionizing samples, and 2) the HPIMS analyzer for separating them. Combining an ESI source with HPIMS provides a powerful combi- nation where substances that can be dissolved in solvent or are already liquids can be readily analyzed. ESI is well-known as a “softer” ioniza- tion source preserving the native structure of the analyte and minimizing fragmentation before entering the instrument.7,11–13
For the current work, the GA2100 standalone benchtop ESI-HPIMS shown in Figure 1 (right) has been used with the Directspray ESI source (Excellims). Directspray ionizes the sample by ESI directly from the 100-µL gas-tight syringe needle containing the sample. This syringe can simply be rinsed 2–3 times prior to analyzing
Figure 1 – High-performance ion mobility spectrometry (HPIMS) instrument (left); GA2100 ESI-HPIMS with Directspray ESI source (right). AMERICAN LABORATORY • 10 • JUNE/JULY 2013
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46