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EPRW 2020

EPRW 2020—AT HOME

Restek at EPRW 2020
Restek at EPRW 2020

VENDOR SESSIONS

LC-MS/MS Analysis of Glyphosate and Other Polar Contaminants in Food with a Novel Ion Exchange/HILIC Column
Hansjoerg Majer, Xiaoning Lu, Dan Li, Connor Flannery
Restek Corporation
For more information, email Hansjoerg Majer.
Read abstract

Glyphosate is a broad-spectrum herbicide widely used throughout the world. The International Agency for Research on Cancer classified glyphosate as a probable human carcinogen. Direct analysis of underivatized glyphosate, however, can be challenging due to its minimum retention on a reversed-phase or HILIC column and severe adsorption onto the stainless flow path.

We have developed a hybrid ion exchange/HILIC column and LC-MS/MS method that enables the detection of glyphosate, aminomethylphosphonic acid (AMPA), and glufosinate, as well as other polar contaminants in various food matrices, in one run. Additionally, the nonspecific binding of glyphosate onto stainless steel is minimized with a simple passivation solution.

Extraction of glyphosate and other polar contaminants from food matrices, such as baby cereal, spinach, strawberry, and tea, was performed with QuPPe methods (Quick Polar Pesticides Methods). The extracted samples were directly loaded onto the hybrid ion exchange/HILIC column (2.1 mm id x 30 mm L) for separation, followed by tandem mass spectrometric analysis with a Shimadzu LC-MS/MS 8045 or 8060 instrument. For a large volume (100-500 µL) sample injection, a guard column (2.1 mm id x 5 mm L) was employed in front of the column to protect the column and minimize peak broadening. The mobile phase was water (A) and acetonitrile (B), each with 0.5% formic acid, respectively. And the flow rate was typically 0.3-0.6 mL/min.

One of the major challenges in the direct HPLC analysis of underivatized glyphosate and its metabolites is their minimum retentions on a reversed-phase (e.g., C18) or HILIC (e.g., silica and diol) column. The hybrid ion exchange (IEX)/HILIC column offers different separation mechanisms, i.e., ion exchange and HILIC interactions with ionic polar analytes. It shows high retention and selectivity for glyphosate, AMPA (glyphosate’s metabolite), and glufosinate as well as other polar analytes. On a relatively short (3 cm) column and under the simple LC-MS conditions, these structurally related polar compounds are well separated with a retention k’ for glyphosate, AMPA, and glufosinate being about 30, 4, and 16, respectively. Also noted is the symmetric peak shapes for all of the 18 ionic polar analytes, which can be difficult to achieve by other methods.

With the column, a LC-MS/MS method has been developed in various food matrices, including baby cereal, spinach, strawberry, tea, and wheat.

Unlocking the Mystery of Pesticides CRM Stability for Food Analysis
Joe Konschnik, Jason Fisher, Landon Wiest, Jana Rousova Hepner, Karen Risha
Restek Corporation
For more information, email Joe Konschnik.
Read abstract

There is a growing global need for pesticide residues testing in a wide variety of food commodities. In response to this need, testing laboratories must develop versatile analytical methods and workflows in order to produce scientifically sound results that ensure the safety of our food. One of the many challenges faced by food chemists is acquiring suitable pesticide certified reference materials (CRMs) to calibrate analytical equipment, monitor method performance, and confirm the identity and concentration of hundreds of pesticide residues in food samples. Questions regarding the stability of pesticide CRMs abound among users, and there’s a need to educate and inform the community. CRM producers invest considerable resources to ensure the stability of their products. The authors will present proper CRM handling and storage practices as guidance to ensure stability based on the results of several multiresidue pesticide stability studies. The results of three pesticide mix stability studies will be shown demonstrating what can be expected after pesticide mix ampuls are opened and stored for use and also when mixed together for routine LC-MS/MS and GC-MS/MS laboratory analysis.

RESTEK TECHNICAL POSTERS

PV-19: The Detection of Fipronil and Fipronil Sulfone in Eggs
Hansjoerg Majer2, Jamie York1, Landon Wiest2, Justin Steimling2, Ty Kahler2, Kevin Schug1
1. The University of Texas at Arlington, 2. Restek Corporation
For more information, email Hansjoerg Majer.
Read abstract

Fipronil is a pesticide in the phenylpyrazole class and is used for a wide array of products, including some home flea and tick preventatives/treatments for household pets. The use of fipronil near animals for human consumption or laying hens is not permitted in Europe as fipronil is fat soluble and could contaminate meat and chicken eggs. However, millions of eggs were destroyed last year due to illegal use of fipronil in Europe near laying hens, which resulted in the contamination of millions of eggs with the insecticide. Fipronil and its metabolite of similar toxicity, fipronil sulfone, inhibit the action of GABA in the central nervous system. Fipronil is more effective at blocking the GABA action in insects than in mammals, but fipronil sulfone is less selective. Once ingested, fipronil can cause hypertension, paralysis, and death in insects and can cause indigestion, sweating, nausea, dizziness, agitation, vomiting, and seizures in humans. Because of the illegal use of fipronil around laying hens, it is crucial to develop a rapid, reliable, and sensitive method for detection of fipronil and its metabolite in eggs. In this study, we optimized methods for extraction of fipronil from eggs using QuEChERS. We also evaluated multiple HPLC stationary phases and developed an optimized method calibrated from 0.1 to 10 ppb.

PV-20: LC-MS/MS Analysis of Glyphosate and Other Polar Contaminants in Food with a Novel Ion Exchange/HILIC Column
Hansjoerg Majer, Xiaoning Lu, Dan Li
Restek Corporation
For more information, email Hansjoerg Majer.
Read abstract

Glyphosate is a broad-spectrum herbicide widely used throughout the world. The International Agency for Research on Cancer classified glyphosate as a probable human carcinogen. Direct analysis of underivatized glyphosate, however, can be challenging due to its minimum retention on a reversed-phase or HILIC column and severe adsorption onto the stainless flow path.

We have developed a hybrid ion exchange/HILIC column and LC-MS/MS method that enables the detection of glyphosate, aminomethylphosphonic acid (AMPA), and glufosinate, as well as other polar contaminants in various food matrices, in one run. Additionally, the nonspecific binding of glyphosate onto stainless steel is minimized with a simple passivation solution.

Extraction of glyphosate and other polar contaminants from food matrices, such as baby cereal, spinach, strawberry, and tea, was performed with QuPPe methods (Quick Polar Pesticides Methods). The extracted samples were directly loaded onto the hybrid ion exchange/HILIC column (2.1 mm id x 30 mm L) for separation, followed by tandem mass spectrometric analysis with a Shimadzu LC-MS/MS 8045 or 8060 instrument. For a large volume (100-500 µL) sample injection, a guard column (2.1 mm id x 5 mm L) was employed in front of the column to protect the column and minimize peak broadening. The mobile phase was water (A) and acetonitrile (B), each with 0.5% formic acid, respectively. And the flow rate was typically 0.3-0.6 mL/min.

One of the major challenges in the direct HPLC analysis of underivatized glyphosate and its metabolites is their minimum retentions on a reversed-phase (e.g., C18) or HILIC (e.g., silica and diol) column. The hybrid ion exchange (IEX)/HILIC column offers different separation mechanisms, i.e., ion exchange and HILIC interactions with ionic polar analytes. It shows high retention and selectivity for glyphosate, AMPA (glyphosate’s metabolite), and glufosinate as well as other polar analytes. On a relatively short (3 cm) column and under the simple LC-MS conditions, these structurally related polar compounds are well separated with a retention k’ for glyphosate, AMPA, and glufosinate being about 30, 4, and 16, respectively. Also noted is the symmetric peak shapes for all of the 18 ionic polar analytes, which can be difficult to achieve by other methods.

With the column, a LC-MS/MS method has been developed in various food matrices, including baby cereal, spinach, strawberry, tea, and wheat.

PV-29: Optimizing a 190+ Pesticides Multiresidue Screening Workflow for the Preparation and Analysis of Produce by LC-MS/MS
Landon Wiest, Dan Li, Alexandria Pavkovich, Joe Konschnik, Sue Steinike, Justin Steimling
Restek Corporation
For more information, email Landon Wiest
Read abstract

Pesticides are ubiquitously used to help increase crop yields; however, they can pose health risks for the general public and pollinators. Faster multiresidue screening workflows, which combine easier sample preparation techniques that yield higher recoveries with lower instrument detection limits in fruits and vegetables, are often sought. Accomplishing these goals increases sample throughput and reduces costs for laboratories and their clients. To demonstrate the feasibility of developing improved methods, organic celery and other representative matrices were spiked with pesticides down to 10 ppb. Samples were extracted using QuEChERS salts (AOAC 2007.01 and original unbuffered) and cleaned up with complementary dSPE containing MgSO4 along with appropriate amounts of C18, PSA, and GCB sorbents for each matrix. Each sample was diluted 10x with water prior to analysis. Separations were performed with a sterically protected superficially porous C18 (Raptor ARC-18) column (100 mm x 2.1 mm, 2.7 µm) analyzed by a UHPLC-MS/MS in selected reaction monitoring mode. Optimized LC-MS/MS conditions, pesticide separations, and recovery (accuracy and precision) results from organic celery, spinach, orange, avocado, brown rice flour, and honey will be presented.

PV-30: Optimizing Sample Preparation for the Analysis of Over 200 Multiresidue Pesticides in Produce by GC-MS/MS
Jana Rousova Hepner, Alexandria Pavkovich, Joseph Konschnik, Chris English
Restek Corporation
For more information, email Jana Rousova Hepner.
Read abstract

Optimization of sample preparation is an important step in mitigating matrix effects in the pesticides multi-residue workflow. Using the QuEChERS approach followed by dispersive solid phase extraction (dSPE) allows for customization of solutions based on matrices. In order to efficiently select the combination that yields the highest analyte response and provides sufficient clean-up, we first tested 40 representative pesticides with different QuEChERS salts and dSPE clean-up materials. The results were evaluated based on; the responses of all tested pesticides, responses of commodity relevant pesticides, and the overall cleanliness of the samples. To demonstrate the feasibility of developing optimized methods, organic celery and other representative matrices were spiked with over 200 pesticides at two levels, 100 ppb and 10 ppb. Non-spiked commodities were also analyzed for the presence of incurred pesticides. Separations were performed using a Rxi-5MS column (30 m x 0.25 mm x 0.25 μm) and analyzed by GC-MS/MS in selected reaction monitoring mode. Optimized sample preparation conditions, pesticide separations, and recovery results from organic celery, spinach, and other produce will be presented.

PV-31: Analytical Solutions for the Determination of Pesticides in Cannabis Products
Nathaly Reyes Garcés, Colton Myers, Ashlee Gerardi, Justin Steimling
Restek Corporation
For more information, email Ashlee Gerardi.
Read abstract

The use of cannabis for medicinal and/or recreational purposes has become legal in several states. Regulations that permit the use of different forms of cannabis demand effective and reliable analytical strategies to ensure the safety of cannabis users. Pesticides content is one of the main parameters tested in cannabis and cannabis-derived products due to the risks that these compounds pose for human health. The list of regulated pesticides varies from state to state: Oregon, for instance, set control levels for 59 pesticides whereas California law requests testing for 66 (58 pesticides also regulated by Oregon plus 8 more). The main challenges associated with pesticides testing rely on the broad range of physicochemical properties of these compounds, the low action levels requested by the law, and the complexity and diversity of matrices to be analyzed. The purpose of this work is to present sample preparation and instrumental strategies for the accurate quantitation of the Oregon and California lists of pesticides in cannabis products. Parameters such as sample cleanup, extract stability, method linearity, accuracy, precision, and matrix effects were all taken into consideration. Our results evidence that solid phase extraction (SPE) can provide a simple yet effective way to remove interferences from sample extracts. In addition, matrix effects vary significantly from matrix to matrix; hence, adequate chromatographic separation, the use of ion ratios, and internal standards are all important to ensure reliable results.

PV-32: Unlocking the Mystery of Pesticides CRM Stability for Food Analysis
Joe Konschnik, Jason Fisher, Landon Wiest, Jana Rousova Hepner, Karen Risha
Restek Corporation
For more information, email Joe Konschnik.
Read abstract

There is a growing global need for pesticide residues testing in a wide variety of food commodities. In response to this need, testing laboratories must develop versatile analytical methods and workflows in order to produce scientifically sound results that ensure the safety of our food. One of the many challenges faced by food chemists is acquiring suitable pesticide certified reference materials (CRMs) to calibrate analytical equipment, monitor method performance, and confirm the identity and concentration of hundreds of pesticide residues in food samples. Questions regarding the stability of pesticide CRMs abound among users, and there’s a need to educate and inform the community. CRM producers invest considerable resources to ensure the stability of their products. The authors will present proper CRM handling and storage practices as guidance to ensure stability based on the results of several multiresidue pesticide stability studies. The results of three pesticide mix stability studies will be shown demonstrating what can be expected after pesticide mix ampuls are opened and stored for use and also when mixed together for routine LC-MS/MS and GC-MS/MS laboratory analysis.

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