Advances in LC/MS for Food Safety Testing

The scope, relevance, and level of food safety regulation and testing have never been higher than in today’s global marketplace. President Barack Obama’s signing of the U.S. Food and Drug Administration (FDA) Food Safety Modernization Act (PL 111-353) in January signaled a renewed urgency and commitment to expanding the safety net of food testing and protection measures not only in the United States but around the world.

It’s no surprise. Each year, nearly 48 million people in the United States get sick from contaminated food; some 128,000 are hospitalized, and there are 3,000 foodborne illness-related deaths.¹ As more of our food comes from farther afield, the opportunity for contamination, both manmade and naturally occurring, can only increase. In the United States alone, an estimated 15% of the food supply is imported, including 50% of fresh fruits, 20% of fresh vegetables, and 80% of seafood.² The need for timely, accurate testing at every point along the farm-to-table pathway has never been more acute.

As a result, food suppliers, producers, manufacturers, and local, state, federal, and global regulatory agencies are all facing greater pressure than ever before to test more food products for more contaminants and quantify their presence at lower levels with greater accuracy—and in less time. Advances in screening technologies help to ensure that these critical lines of defense can meet the myriad of new testing requirements and, most importantly, protect the global food supply.

Advances in LC/MS

Food safety relies on a web of technologies to facilitate ongoing food supply monitoring. Mass spectrometry has a long and proven track record of enabling food testing labs to identify and quantify foreign substances in food. Recent advances in the integration of chromatographic separation techniques with tandem mass spectrometry bring a very high level of sensitivity and selectivity to food testing, particularly for the specific detection and identification of contaminants in the presence of other chemicals in a complex matrix.

In recent years, the utilization of liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) has grown rapidly and is now widely recognized as an ideal, highly specific, and extremely sensitive technique for testing food products with superior accuracy and higher throughput than other methods such as LC/ultraviolet (LC/UV), LC/fluorescence, or microbiological and enzyme-linked immunosorbent assay methods. The ability to monitor dozens, sometimes hundreds, of contaminants in a single run greatly improves throughput, and new levels of sensitivity allow more simplified sample preparation protocols. New levels of platform sensitivity allow detection of lower levels of contaminants with less sample preparation, and new workflows, such as multiple reaction monitoring (MRM³), provide unique specificity to help measure low level contaminants in complex matrices. These advanced LC/MS/MS platforms provide the capacity to screen for more analytes at lower levels, with greater accuracy, and in less time.

Recently developed workflows provide high sensitivity quantitative information, as well as supporting data to confirm the identification of contaminants found. The workflow uses the high sensitivity MRM functionality to provide sensitive and accurate quantitation while simultaneously acquiring full scan MS/MS spectra that can be matched to spectral libraries to provide high-confidence identification. The full scan MS/MS spectra functionality is also applied to screening for unexpected or unknown contaminants.

Simplified Sample Preparation

The drive toward decreasing time to results places significant demands on food testing laboratories to do more, faster. Preparative steps associated with sample testing are often the most time consuming and can be prone to error or the introduction of unrelated contaminants. As a result, for many technologies, sample preparation has been a rate-limiting step to achieving higher throughput in screening applications.

The sensitivity and specificity of LC/MS/MS can help to minimize extensive cleanup or pre-concentration steps. In some cases, a sample extract can be directly injected, enabling a “dilute and shoot” workflow.³ Also, sample derivatization is rarely required, unlike GC/MS, for which a time-consuming derivatization step is often necessary to improve ionization and/or volatility.