Pesticide Residues in Food-Based Proficiency Test Materials, Spiking Values versus Consensus Assigned Values

Sykes, Mark; Thompson, Michael; Reynolds, S. L.

doi:10.1021/jf4003363

Cited by 10 publications

(7 citation statements)

References 21 publications

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“…As summarized in Table 2, more than 50 % of the data were having an absolute deviation of [20 % and this large deviation agreed by large with another review work on pesticide testing [13]. Furthermore, the majority of results were lower than the reference values, which might probably be due to overestimated recoveries [14] as being evidenced by a comprehensive study on assessing the ratio of nominal (reference) and consensus values over a number of pesticide PT, or arisen from incomplete extraction of residual pesticides in another study [15]. From our past experience, it is particularly difficult to achieve a good recovery of incurred pesticides in tea and other vegetation samples.…”

Section: Re-evaluation Using Reference Valuessupporting

confidence: 68%

Use of assigned reference values: revisiting a small-scale inter-laboratory comparison for residual pesticides in tea

Sin¹,

Wong²

2015

Accred Qual Assur

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This paper compares reference values assigned by isotope dilution mass spectrometry with participants' consensus values in a small-scale proficiency test (PT) on the determination of residues of organochlorine pesticides (a-endosulfan, b-endosulfan and endosulfan sulfate) in a tea sample. The PT was specifically organized to benchmark the technical capability among the local participating laboratories in Hong Kong providing pesticide testing service to their customers and to identify possible areas for further improvement. Participant's performance, based on z-score, was evaluated using consensus values and standard deviation that was estimated from the Horwitz function. Two out of the seven participating laboratories were identified to produce either questionable or unsatisfactory results (in terms of z-scores), showing that the performance of the majority was satisfactory. However, the number of questionable or unsatisfactory results increased to three if the consensus values were replaced by assigned reference values derived from gas spectrometry-isotope dilution mass spectrometry with higher metrological traceability than those used in obtaining the consensus values. Though the said PT program was fit for its intended purposes at that point of time, revisiting the program explicitly demonstrates the significant importance of assigned reference values in achieving reliable assessment in reality. Unless the bias of consensus values is known with metrological traceability, PT scheme providers should be cautious in assessing the competence of participating laboratories using consensus values particularly in small-scale inter-comparison programs. The importance of pre-wetting dry tea samples to improve recovery of pesticide residues is also noted.

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Section: Re-evaluation Using Reference Valuessupporting

confidence: 68%

Use of assigned reference values: revisiting a small-scale inter-laboratory comparison for residual pesticides in tea

Sin¹,

Wong²

2015

Accred Qual Assur

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“…Content of free fatty acid was determined by KOH titration according to the standard method [13,14]. The conversion of fatty acid was defined as the esterified fatty acid amount to the initial used fatty acid amount.…”

Section: Methodsmentioning

confidence: 99%

Solvent-free enzymatic synthesis of 1, 3-Diacylglycerols by direct esterification of glycerol with saturated fatty acids

Zhong

Gui

et al. 2013

Lipids Health Dis

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BackgroundPure 1, 3-diacylglycerols (1, 3-DAG) have been considered to be significant surfactants in food, cosmetics and pharmaceutical industries, as well as the effect on obesity prevention.MethodsIn this study, a vacuum-driven air bubbling operation mode was developed and evaluated for the enzymatic synthesis of 1, 3-DAG of saturated fatty acids, by direct esterification of glycerol with fatty acids in a solvent-free system. The employed vacuum-driven air bubbling operation mode was comparable to vacuum-driven N2 bubbling protocol, in terms of lauric acid conversion and 1, 3-dilaurin content.ResultsSome operation parameters were optimized, and 95.3% of lauric acid conversion and 80.3% of 1, 3-dilaurin content was obtained after 3-h reaction at 50°C, with 5 wt% of Lipozyme RM IM (based on reactants) amount. Of the lipases studied, both Lipozyme RM IM and Novozym 435 exhibited good performance in terms of lauric acid conversion. Lipozyme TL IM, however, showed low activity. Lipozyme RM IM showed good operational stability in this operation protocol, 80.2% of the original catalytic activity remained after 10 consecutive batch applications. Some other 1, 3-DAG were prepared and high content was obtained after purification: 98.5% for 1, 3-dicaprylin, 99.2% for 1, 3-dicaprin, 99.1% for 1, 3-dilaurin, 99.5 for 1, 3-dipalmitin and 99.4% for 1, 3-disterin.ConclusionThe established vacuum-driven air bubbling operation protocol had been demonstrated to be a simple-operating, cost-effective, application practical and efficient methodology for 1, 3-DAG preparation.

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“…Several other factors, besides particle size, may influence the recoveries of pesticides, e.g., degradation of heat sensitive pesticides or polarity reactivity, stability, and the bound state of the pesticide. − In order to avoid degradation of heat sensitive pesticides, development of heat during an efficient milling procedure should be limited or avoided. Most of the NRLs, especially those employing knife mills or hammer mills, noticed heat produced during milling.…”

Section: Resultsmentioning

confidence: 99%

Role of Sample Processing Strategies at the European Union National Reference Laboratories (NRLs) Concerning the Analysis of Pesticide Residues

Hajeb

Herrmann

Poulsen

2017

J. Agric. Food Chem.

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The guidance document SANTE 11945/2015 recommends that cereal samples be milled to a particle size preferably smaller than 1.0 mm and that extensive heating of the samples should be avoided. The aim of the present study was therefore to investigate the differences in milling procedures, obtained particle size distributions, and the resulting pesticide residue recovery when cereal samples were milled at the European Union National Reference Laboratories (NRLs) with their routine milling procedures. A total of 23 NRLs participated in the study. The oat and rye samples milled by each NRL were sent to the European Union Reference Laboratory on Cereals and Feedingstuff (EURL) for the determination of the particle size distribution and pesticide residue recovery. The results showed that the NRLs used several different brands and types of mills. Large variations in the particle size distributions and pesticide extraction efficiencies were observed even between samples milled by the same type of mill.

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Pesticide Residues in Food-Based Proficiency Test Materials, Spiking Values versus Consensus Assigned Values

Cited by 10 publications

References 21 publications

Use of assigned reference values: revisiting a small-scale inter-laboratory comparison for residual pesticides in tea

Use of assigned reference values: revisiting a small-scale inter-laboratory comparison for residual pesticides in tea

Solvent-free enzymatic synthesis of 1, 3-Diacylglycerols by direct esterification of glycerol with saturated fatty acids

Role of Sample Processing Strategies at the European Union National Reference Laboratories (NRLs) Concerning the Analysis of Pesticide Residues

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