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AOAC 2018

132nd AOAC Annual Meeting & Exposition

132nd AOAC Annual Meeting & Exposition
132nd AOAC Annual Meeting & Exposition

SCIENTIFIC SESSION

Wednesday, August 29
9:20–9:45 a.m.
Optimizing a 190+ Pesticides Multi-Residue Screening Workflow for the Preparation and Analysis of Produce by LC-MS/MS
Landon A. Wiest (presenter), Dan Li, Alexandria M Pavkovich, Joe Konschnik, Sue Steinike, and Justin Steimling
Restek Corporation
For more information, email Landon A. Wiest.
Read abstract

Pesticides are ubiquitously used to help increase crop yields; however, they can pose health risks for the general public and farm workers. Faster multi-residue 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, and other produce samples will be presented.

3:00–4:30 p.m.
Trusting Your Cannabis Testing Results Requires Trusting Your CRMs
Joe Konschnik (presenter), Jason Fisher
Restek Corporation
For more information, email Joe Konschnik.
Read abstract

The need for testing Cannabis plant, extract and infused product samples requires analytical methods developed and followed by Cannabis testing laboratories produce scientifically sound results which ensure the safety and quality of such products. One of the many challenges faced by method developers is acquiring suitable reference materials (RMs) which are used to calibrate analytical platforms and procedures, confirm the identity and quantify the concentration of required analytes. Understanding the difference between a reference material and a certified reference material (CRM) is important in defining the quality of data generated by an analytical procedure. This is especially important in the absence of official consensus standard methods for potency and contaminants. The authors will also discuss ISO 17034 requirements to properly manufacture and package a CRM which include confirming identify and purity of starting materials, traceability, stability and uncertainty. Challenges specific to Cannabis CRMs will also be presented.

RESTEK TECHNICAL POSTERS

Monday, August 27
The LC-UV Analysis of 16 Cannabinoids of Interest in Commercially Available CBD Oils
Joe Konschnik (presenter), Justin Steimling, Ashlee Reese, Ty Kahler, Colton Myers, Susan Steinike
Restek Corporation
For more information, email Joe Konschnik.
Download a PDF of the full presentation.
Read abstract

More than 100 cannabinoids have been isolated from cannabis in addition to the five most commonly tested: THC, THCA, CBD, CBDA, and CBN. While analytical approaches have been published that show the separation of these major cannabinoids, many do not take into account the possibility of interferences from, or coelutions with, other cannabinoids that may be present and that may bias results. This is most problematic in concentrates where minor cannabinoids can be enriched to detectable levels that were not observed in the flower. Additionally, some terpenes have been shown to absorb UV light at 228 nm, the wavelength cannabinoids are typically detected, which can result in an additional source of interference. In this study, the LC-UV separation of 16 cannabinoids of interest was performed while monitoring for the potential impact from minor cannabinoids and terpenes on reported potency values. The method is applied to commercially available CBD oils and vape solutions that have recently become suspect due to inaccurate label claims. A fast analysis of cannabinoids by UHPLC using a sub-2 µm LC column is also shown.

Tuesday, August 28
Using Modified QuEChERS for the Extraction of Pesticide Residues in Botanical Ingredients Using GC-MS/MS
Joe Konschnik1, Riki Kitano2, Julie Kowalski1, Sharon Lupo1, Dan Li1, Tairo Ogura2, Nicole Lock2, Robert Clifford2
1. Restek Corporation, 2. Shimadzu Scientific Instruments, Inc.
For more information, email Joe Konschnik.
Download a PDF of the full presentation.
Read abstract

Botanical ingredients have been used for centuries in Asia and their increased use in the US is a multibillion-dollar industry. Many of these supplements have been concentrated and dried from original plant matter that was treated with pesticides. Validated methods are needed to determine pesticide residue levels in these finished products. The preparation uses a Quick Easy Cheap Effective Rugged Safe (QuEChERS) extraction procedure in addition to solid phase extraction (SPE). 10 milliliters of water and 10 milliliters of acetonitrile are added to one gram of the dried, finely powdered supplement, along with 4 grams of anhydrous magnesium sulfate and 1 gram of sodium chloride. The different phase layers are expressed using a centrifuge and 1.25 milliliters is removed and extracted through a solid phase extraction (SPE) column containing both graphitized carbon black and a bottom layer of primary-secondary amine with anhydrous sodium sulfate to remove any residual water. Gas chromatography is well suited for the analysis of these samples with the ability to resolve multicomponents that include coextracted interferences. The samples chosen—ginseng, green tea, chamomile—represent a complex matrix that requires coupled mass spectrometry in the determination of trace-level pesticides. This work reviews the extraction and analysis of 165 pesticides to include multimatched calibration standards, calibration curves, and mean pesticide recoveries for each matrix.

Optimizing a 190+ Pesticides Multi-Residue Screening Workflow for the Preparation and Analysis of Produce by LC-MS/MS
Landon A. Wiest (presenter), Dan Li, Alexandria M Pavkovich, Joe Konschnik, Sue Steinike, and Justin Steimling
Restek Corporation
For more information, email Landon A. Wiest.
Download a PDF of the full presentation.
Read abstract

Pesticides are ubiquitously used to help increase crop yields; however, they can pose health risks for the general public and farm workers. Faster multi-residue 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, and other produce samples will be presented.

Wednesday, August 29
Analysis of Bisphenols and Perfluorinated Compounds by LC-MS/MS Using Raptor 1.8 µm Columns
Landon A. Wiest (presenter), Shun-Hsin Liang, Justin Steimling, Joe Konschnik, Sue Steinike, and Ty Kahler
Restek Corporation
For more information, email Landon A. Wiest.
Download a PDF of the full presentation.
Read abstract

There are myriad contaminants that have impact on our food and environment. In this poster, we present separations performed by the Restek Raptor 1.8 µm column family on two classes of contaminants: bisphenols and perfluorinated alkyl acids (PFAs). Bisphenol A (BPA), widely used in the production of polycarbonate plastic and epoxy resins, is an endocrine disruptor that leads to harmful health effects. As public awareness increases, many products are advertised as “BPA-free,” but still use BPA analogues that have similar harmful properties. An analytical method using a Raptor Biphenyl 1.8 µm column has been developed that resolves BPA and its most prevalent analogues for monitoring human exposure to bisphenols. Similarly, PFAs are widely used across a broad range of products, such as firefighting foams, coating additives, textiles, and cleaning products. PFAs are resistant to degradation and have become persistent environmental pollutants in soil, air, groundwater, municipal refuse, and landfill leachates. The potential adverse effect on animal and human health has been reported for long-chain PFAs, in particular, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). To phase out the application of long-chain PFAs, a wide range of short-chain PFAs are used as replacements, leading to rising levels of their disposition in environmental and human matrices. A Raptor C18 1.8 µm column is well suited to baseline separating many of the most common PFA residues.

A Perfect Pairing: HILIC and Superficially Porous Particles in Food Analyses
Landon A. Wiest (presenter), Dan Li, Joe Konschnik, Sue Steinike, and Ty Kahler
Restek Corporation
For more information, email Landon A. Wiest.
Download a PDF of the full presentation.
Read abstract

In residue analyses, separations with good selectivity accompanied by highly sensitive detection are desired. This can be difficult to achieve with polar compounds analyzed by reversed-phase liquid chromatography (RPLC). Hydrophilic Interaction Liquid Chromatography (HILIC) encompasses a wide range of stationary phases that provide suitable retention and selectivity for many classes of polar molecules. When approaching RPLC, there are limited retention mechanisms to consider. Aliphatic hydrocarbon stationary phases (e.g., C18) provide van der Waals interactions between the phase and the analytes, while phenyl-type stationary phases (e.g., Biphenyl) provide primarily π-π interactions. HILIC phases encompass a wider variety of chemical interactions that are used with a high-organic (typically buffered) mobile phase consisting primarily of acetonitrile and water. The intermolecular interactions between analytes and stationary phase can include, but are not limited to, hydrogen bonding, strong/weak cation or anion exchange, zwitterionic phases, and many proprietary phases that contain “polar-embedded” groups. The objective of this poster is to deconvolute the phase chemistry of several HILIC stationary phases and set some basic ground rules for method development. We will also offer solutions for some common issues that are encountered with the use of HILIC, as well as show some examples of how to improve your HILIC separations.

Analysis of trans-Fatty Acids in Food Products Using Various GC Columns
Jana Rousova (presenter), Chris English, Joe Konschnik
Restek Corporation
For more information, email Jana Rousova.
Download a PDF of the full presentation.
Read abstract

Partially hydrogenated oils, which are the main source of artificial trans-fatty acids (TFAs), have been phased out in Europe and the United States due to concerns of their negative effect on human health. Unfortunately, artificial TFAs remain present in the food industry of the rest of the world. Moreover, certain food products have been exempted from the ban, such as frosting. In order to analyze the presence of TFA in U.S. food products, we evaluated several fat-containing products: margarine, shortening, butter-flavored popcorn, and chocolate frosting. The fatty acids were trans-esterified using sodium methoxide and analyzed on multiple Restek columns, namely Rtx-2330, Rt-2560, and FAMEWAX using GC-FID and GC-MS. With the exception of frosting, none of the studied products contained TFAs. However, there was a tradeoff. The elimination of partially hydrogenated oils lead to significant increase of saturated acid content in margarine and shortening as compared to previously reported values by USDA. In terms of column selection, the Rt-2560 was the best choice for the separation of C18:1 isomers extracted from chocolate frosting.

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