Analysis of Glyphosate Residues in Foods from the Canadian Retail Markets between 2015 and 2017.

Underlying the risk management of pesticides to protect human health and to facilitate trade among nations are sound scientific data on the levels of compliance with standards set by governments and internationally from monitoring of the levels of pesticides in foods. Although glyphosate is among the universally used pesticides in the world, monitoring has been hampered by the analytical difficulties in dealing with this highly polar compound. Starting in 2015, using liquid chromatography/tandem mass spectrometry (LC-MS/MS) that permits accurate and reproducible determination of glyphosate, the prevalence, concentrations, and compliance rates were determined. In this work, the glyphosate residues contents of 7955 samples of fresh fruits and vegetables, milled grain products, pulse products, and finished foods collected from April 2015 to March 2017 in the Canadian retail market are reported. A total of 3366 samples (42.3%) contained detectable glyphosate residues. The compliance rate with Canadian regulations was 99.4%. There were 46 noncompliant samples. Health Canada determined that there was no long-term health risk to Canadian consumers from exposure to the levels of glyphosate found in the samples of a variety of foods surveyed. The high level of compliance (99.4% of samples with the Canadian regulatory limits) and the lack of a health risk for noncompliant samples indicate that, with respect to glyphosates, the food available for sale in Canada is safe.

Validation of the Biofish-300 SUL Enzymatic Biosensor for the Detection of Sulfite in Crustacean.

Background: Sulfites are some of the oldest and most widespread preservatives in our food supply. They are food additives that have antioxidant properties, but they are also recorded as allergens by the main international regulatory bodies on food safety because of their adverse health effect. Hence, sulfites maximum concentration in foodstuff is regulated and they must be ensured by the agro-food processing industries. The most widely used technique for the quantification of sulfites is the Modified Monier-Williams (AOAC Official Method 990.28). Objective: In this method, SO2 is released from sulfites and some bound compounds when the sample is mixed with an acid (normally hydrochloric acid, but sometimes phosphoric acid) and heated. The SO2 is distilled using a stream of nitrogen gas, which carries the gaseous SO2 into an absorbing solution of hydrogen peroxide (H2O2) where it is oxidised to sulphuric acid. The amount of SO2 distilled into the H2O2 is determined by titration with 0.1M sodium hydroxide. Apart from being time consuming (at least 2 h) and the usage of toxic solvents, the method presents some other disadvantages that make it inappropriate as a routine-control technique for the agro-food industry. Hence, the industry demands simple, fast and accurate methods for sulfite level monitoring. Methods: BIOLAN is a SME that develops and commercializes biosensors for quantitative analysis of food quality and safety parameters, based on its proprietary enzyme-based electrochemical biosensor technology platform. This technology enables high accurate and robust analysis with a compact device that help the users to control the quality in an easy and safety manner. Biofish-300 SUL method is a highly specific enzimatic biosensor for the rapid quantification of sulfite, measured as SO2 content, in crustaceans. It consists on the extraction of sulfite in an aqueous based solution, by the aid of an Ultra-turrax or similar, and its subsequent quantification by the biosensor after previous calibration (3 min). Results: Sulfite in raw shrimp head-on, raw shrimp head-off, and boiled shrimp was analyzed, and performance was examined using naturally contaminated and spiked samples by comparisons with AOAC Official Methods of AnalysisSM (OMA) 990.28. Linearity, selectivity, matrix, consistency, and robustness were evaluated. All results were within acceptable ranges except robustness, which reflected deviation in the sample volume and ultraturrax time compared with the standard assay procedures described in the Biofish 300 SUL Instruction Manual. Accuracy, assessed as a comparison of the Biofish results with the OMA results, ranged from 82 to 115% in all samples except for fortified raw shrimp head-on, in which the low level yielded an accuracy of 138%. The method bias was in general negative in both incurred and fortified high levels, and slightly positive in incurred low levels. Repeatability was very good as shown by the low RSDr values, demonstrating acceptable repeatability precision with results <10% in most of the evaluated values. Regression analyses showed a good correlation between the Biofish and OMA methods with R² = 0.99 in all cases. Conclusions: As a whole, accuracy, recovery and bias within range results indicate that the kit provides accurate and precise sulfite quantification for all the evaluated matrices, confirming that sample preparation and assay procedures produce acceptable results. Biofish 300 SUL has proved to be a suitable tool for monitoring sulfite levels in quality control routines due to its high accuracy, precision, rapid response and ease of use. Highlights: With a simple sample preparation, results are obtained in approximately 3 min, making a big difference with other technologies that require specific skills or tedious sample pretreatments and analysis procedures.

Liquid chromatography post-column oxidation (PCOX) method for the determination of paralytic shellfish toxins in mussels, clams, oysters, and scallops: collaborative study.

Sixteen laboratories participated in a collaborative study to evaluate method performance parameters of a liquid chromatographic method of analysis for paralytic shellfish toxins (PST) in blue mussels (Mytilus edulis), soft shell clams (Mya arenaria), sea scallops (Placopectin magellanicus), and American oysters (Crassostrea virginicus). The specific analogs tested included saxitoxin, neosaxitoxin, gonyautoxins-1 to -5, decarbamoyl-gonyautoxins-2 and -3, decarbamoyl-saxitoxin, and N-sulfocarbamoyl-gonyautoxin-2 and -3. This instrumental technique has been developed as a replacement for the current AOAC biological method (AOAC Official Method 959.08) and an alternative to the pre-column oxidation LC method (AOAC Official Method 2005.06). The method is based on reversed-phase liquid chromatography with post-column oxidation and fluorescence detection (excitation 330 nm and emission 390 nm). The shellfish samples used in the study were prepared from the edible tissues of clams, mussels, oysters, and scallops to contain concentrations of PST representative of low, medium, and high toxicities and with varying profiles of individual toxins. These concentrations are approximately equivalent to 1/2 maximum level (ML), ML, or 2xML established by regulatory authorities (0.40, 0.80, and 1.60 mg STX diHCl eq/kg, respectively). Recovery for the individual toxins ranged from 104 to 127%, and recovery of total toxin averaged 116%. Horwitz Ratio (HorRat) values for individual toxins in the materials included in the study were generally within the desired range of 0.3 to 2.0. For the estimation of total toxicity in the test materials, the reproducibility relative standard deviation ranged from 4.6 to 20%. A bridging study comparing the results from the study participants using the post-column oxidation (PCOX) method with the results obtained in the study director's laboratory on the same test materials using the accepted reference method, the mouse bioassay (MBA; AOAC Official Method 959.08), showed that the average ratio of results obtained from the two methods was 1.0. A good match of values was also achieved with a new certified reference material. The results from this study demonstrated that the PCOX method is a suitable method of analysis for PST in shellfish tissue and provides both an estimate of total toxicity, equivalent to that determined using the MBAAOAC Official Method 959.08, and a detailed profile of the individual toxin present in the sample.

Pre- versus post-column oxidation liquid chromatography fluorescence detection of paralytic shellfish toxins.

Both pre- and post-column oxidation liquid chromatography methods with fluorescence detection are available for detecting paralytic shellfish toxins. Each method has been evaluated in multiple laboratories and validated as a potential alternative to the mouse bioassay. This communication compares the advantages and limitations of both methods. For a given laboratory, the selection of either method may be based primarily on practicality and less on any deficiencies in scientific merit.

Comparison of AOAC 2005.06 LC official method with other methodologies for the quantitation of paralytic shellfish poisoning toxins in UK shellfish species.

A refined version of the pre-column oxidation liquid chromatography with fluorescence detection (ox-LC-FLD) official method AOAC 2005.06 was developed in the UK and validated for the determination of paralytic shellfish poisoning toxins in UK shellfish. Analysis was undertaken here for the comparison of PSP toxicities determined using the LC method for a range of UK bivalve shellfish species against the official European reference method, the PSP mouse bioassay (MBA, AOAC 959.08). Comparative results indicated a good correlation in results for some species (mussels, cockles and clams) but a poor correlation for two species of oysters (Pacific oysters and native oysters), where the LC results in terms of total saxitoxin equivalents were found to be on average more than double the values determined by MBA. With the potential for either LC over-estimation or MBA under-estimation, additional oyster and mussel samples were analysed using MBA and ox-LC-FLD together with further analytical and functional methodologies: a post-column oxidation LC method (LC-ox-FLD), an electrophysiological assay and hydrophilic interaction liquid chromatography with tandem mass spectrometric detection. Results highlighted a good correlation among non-bioassay results, indicating a likely cause of difference was the under-estimation in the MBA, rather than an over-estimation in the LC results.

Liquid chromatographic post-column oxidation method for analysis of paralytic shellfish toxins in mussels, clams, scallops, and oysters: single-laboratory validation.

A single-laboratory validation study was conducted for the LC post-column oxidation analysis of paralytic shellfish toxins (PST): saxitoxin (STX); neosaxitoxin (NEO); gonyautoxins (GTX) 1-5; decarbamoyl gonyautoxins (dcGTX) 2 and 3; decarbamoyl saxitoxin (dcSTX); and N-sulfocarbamoyl-gonyautoxin-2 and 3 (C1 and C2) in mussels (Mytilus edulis), soft shell clams (Mya arenaria), scallops (Placopectin magellanicus), and oysters (Crassostrea virginicus). The instrumental technique was developed for the analysis of PST in shellfish as an alternative to the precolumn oxidation method, AOAC Official Method 2005.06, and a replacement for the current AOAC biological method 959.08. The method used reversed-phase LC with post-column oxidation and fluorescence detection. Test materials for method recovery were prepared by fortification of blank material with a cocktail of PST. Materials used to determine method repeatability and intermediate precision were prepared by blending blank material with naturally incurred material. The target total toxicity levels evaluated in the study were 0.40, 0.80, and 1.60 mg STX x diHCl equivalents per kilogram [(eq/kg) 1%, 1, and 2 times the regulatory limit]. Linearity, recovery, and within-laboratory precision parameters of the method were evaluated. Correlation coefficients of the calibration curves for all toxins studied were > 0.99. Total toxin recovery ranged from 94 to 106% at the three levels of interest. Repeatability and intermediate precision RSD ranged from 2 to 7% and 2 to 8%, respectively. The method LOD and LOQ (assuming the presence of all toxins) were determined to be equivalent to 0.18 and 0.39 mg STX x diHCl eq/kg. The method is intended for a regulatory framework and will be submitted for an AOAC collaborative study.

Simultaneous determination of 17 sulfonamides and the potentiators ormetoprim and trimethoprim in salmon muscle by liquid chromatography with tandem mass spectrometry detection.

A simple, robust method using liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of 17 sulfonamides [sulfanilamide (SNL), sulfacetamide (SAA), sulfaguanidine (SGD), sulfapyridine (SPY), sulfadiazine (SDZ), sulfathiazole (STZ), sulfamerazine (SMR), sulfamethoxazole (SOZ), sulfamoxole (SXL), sulfisoxazole (SXZ), sulfamethizole (SML), sulfamethazine (SMZ), sulfamethoxypyridazine (SMP), sulfamonomethoxine (SMM), sulfachloropyridazine (SCP), sulfaquinoxaline (SQX), and sulfadimethoxine (SDM)] and 2 potentiators [ormetoprim (OMP) and trimethoprim (TMP)] in fish tissue has been developed. The analytes were extracted from homogenized fish tissue with water-acetonitrile (50 + 50). The extract was clarified by centrifugation and a portion defatted with hexane. The analytes were partitioned into chloroform and evaporated to dryness. The redissolved residue was applied to a C18 reversed-phase column with a water-acetonitrile (0.1% acetic acid) gradient. All of the compounds were completely separated and detected in <10 min at 30 degrees C using LC/MS/MS. Standard curves were linear over the range of 0.02 to 5 ng injected. The limit of detection varied from 0.1 ng/g for SMZ and OMP to 0.9 ng/g for SXL and SOZ. Recoveries varied from 100% for SDM, SOZ, and SQX and 85% for SMR, OMP, and TMP to approximately 30% for SAA. Relative standard deviations for repeat analysis varied from 4% for SMZ and SCP to 23% for SAA.

Determination of malachite green and leucomalachite green in a variety of aquacultured products by liquid chromatography with tandem mass spectrometry detection.

A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for determining the residues of malachite green (MG) and leucomalachite green (LMG) in a number of aquatic species. MG and its metabolite were extracted from homogenized tissues with a perchloric acid-acetonitrile solution; the extract was centrifuged; and an aliquot was taken, concentrated, and passed through a chemically bonded octadecyl C18 solid-phase extraction column. The compounds of interest were eluted with acetonitrile, and the eluate was evaporated to dryness. The residue was dissolved in acetonitrile and diluted with water in preparation for analysis by LC/MS/MS. MG and its metabolite were determined by reversed-phase LC using a Luna C18 column with an ammonium hydroxide-formic acid buffer in acetonitrile gradient and MS/MS detection using multiple reaction monitoring. Calibration curves were linear for all analyses between 5 and 500 pg injected for both analytes, with recoveries ranging from 81% for LMG to 98% for MG in salmon spiked at the 1 ng/g level. Detection limits of 0.1 ng/g for both MG and LMG were easily obtainable using the recommended method. The operational errors, interferences, and recoveries for spiked samples compared favorably with those obtained by established methodology. The recommended method is simple, rapid, and specific for monitoring residues of MG and LMG in a number of aquatic species.