Residual 1,2-dibromoethane in mango, capsicum, passionfruit and papaw after fumigation against Queensland fruit fly, Dacus tryoni (Froggatt)

Residual 1,2-dibromoethane (EDB) was measured in mango, capsicum, passionfruit and papaw following treatment with biologically effective levels of EDB. Post-fumigation forcedairing periods, storage conditions and times of storage were varied. The duration of the forced-airing period after fumigation had no significant effect on the rate of dissipation of EDB from mango. Fumigated mango required storage at 21� for at least 3 days before EDB levels fell to the maximum residue level (MRL) of 0.1 mg/kg. Cool storage of mango extended the time required for the EDB level to fall to the MRL to at least 6 days. Fumigated capsicum stored at 21�C required 2 days for EDB levels to fall to the MRL while, with fumigated papaw, this took at least 4 days. Even after storage for 7 days, EDB levels in fumigated passionfruit exceeded the MRL so the fumigation procedure was unsuitable for use with passionfruit. A kinetic model was proposed which explained the behaviour of EDB in the various trials and in other literature reports. All samples were analysed by X-ray fluorescence spectrometry (X-RF) and many results were confirmed more specifically and more sensitively by gas chromatography-mass spectrometry. Comparison ofresults by these two methods, including the results of samples spiked with low levels of EDB, helped remove doubts about the suitability of X-RF for the determination of residual EDB.

Download Full-text

An Interlaboratory Comparative Study on the Quantitative Determination of Glyphosate at Low Levels in Wheat Flour

Journal of AOAC International ◽

10.5740/jaoacint.15-024 ◽

2015 ◽

Vol 98 (6) ◽

pp. 1760-1768 ◽

Cited By ~ 6

Author(s):

Emanuela Simonetti ◽

Gérald Cartaud ◽

Robert M Quinn ◽

Ilaria Marotti ◽

Giovanni Dinelli

Keyword(s):

Quantitative Determination ◽

Performance Assessment ◽

Wheat Flour ◽

Residue Level ◽

Analytical Determination ◽

Maximum Residue Level ◽

Organic Products ◽

Low Levels ◽

Analytical Laboratories

Abstract In recent years, the use of glyphosate has dramatically increased worldwide, and there is growing concern about contamination of organic products caused by its heavy use on neighboring fields. Glyphosate is found as a residue not only in soil, plants, and groundwater but also in humans and animals. Considering the controversy on glyphosate maximum residue level in foodstuff and the difficulties in its analytical determination, the main purpose of the present paper was to investigate the competence and accuracy of 13 accredited European laboratories in determining glyphosate in wheat flour at a level close to their reporting limit of 10 μg/kg. According to the results of this performance assessment, the laboratories were not able to quantify glyphosate at trace levels. Therefore, their specified reporting limits of 10 μg/kg were not supported by their results, and a reporting limit of around 50 μg/kg of glyphosate in flour seems to be more appropriate to guarantee reliable and robust results. The widespread use of glyphosate and its harmfulness to humans make its detection at trace levels a primary goal for analytical laboratories. This is achievable through the improvement of QA and/or the optimization of the method of analysis used for glyphosate detection.

Download Full-text

Deltamethrin residues applied in different formulations in staked cucumber and the actions of insecticides on the pickleworm control

Horticultura Brasileira ◽

10.1590/s0102-05362008000300006 ◽

2008 ◽

Vol 26 (3) ◽

pp. 321-324 ◽

Cited By ~ 2

Author(s):

Gilberto C de Baptista ◽

Luiz Roberto P Trevizan ◽

André A Franco ◽

Renato A da Silva

Keyword(s):

Gas Chromatography ◽

Pesticide Residues ◽

Residue Level ◽

Concentrate Suspension ◽

Evaluation Period ◽

Emulsifiable Concentrate ◽

Maximum Residue Level ◽

Low Levels ◽

Vegetables And Fruits ◽

Sampling Times

Pesticide residues, especially in vegetables and fruits, are a reason for concern with respect to the health of consumers and workers that need to return to areas that have been treated with these agrochemicals. The objectives of this experiment were to (a) study the behavior of deltamethrin residues from different formulations on cucumber fruits; and (b) correlate insecticide contents in the fruits with pickleworm control. Treatments were as follows: (a) control; (b) three 30 mL applications of deltamethrin 25 EC 100 L-1 water (emulsifiable concentrate formulation); (c) three 7.5 mL applications of deltamethrin 100 EC 100 L-1 water (emulsifiable concentrate); and (d) three 3.75 mL applications of deltamethrin 200 CS 100 L-1 water (concentrate suspension). Samples were taken at (-1), zero, 1; 3; 5; 7, and 14 days after the last application. Residues were determined by the gas chromatography technique, using an electron capture detector. In order to evaluate insecticide effectiveness, six infestation surveys were conducted during the same sampling times. Although at low levels, the deltamethrin residues in the fruits were above the maximum residue level (MRL = 0.03 mg kg-1), even one day after the end of the safety interval (2 days), and were higher for the CS formulation. The insecticide was effective to control the pest during the entire evaluation period.

Download Full-text

Total Reflection X-Ray Fluorescence Spectroscopy: Analysis Of Gaas And InGaAs

Advances in X-ray Analysis ◽

10.1154/s037603080001613x ◽

1993 ◽

Vol 37 ◽

pp. 585-593

Author(s):

Leigh Ann Filcs-Sesler ◽

Don Plumton ◽

Yung-Chung Kao ◽

Tae S. Kim

Keyword(s):

Nondestructive Method ◽

Device Fabrication ◽

Total Reflection ◽

Surface Contamination ◽

Device Performance ◽

Spectroscopy Analysis ◽

X Ray ◽

Low Levels ◽

Metallic Impurities

AbstractThis article explores applications of total reflection x-ray fluorescence (TRXRF) to GaAs processes. The applications include determination of surface contamination and InGaAs layer thicknesses. Surface contamination can deteriorate device performance and can occur in starting substrates and in subsequent processing. We demonstrate that TRXRF is a quick, nondestructive method for identifying sulfur contamination on incoming wafers and low levels of metallic impurities from device fabrication. Variable angle TRXRF has been used to determine heterostmeture film thickness, measuring films of InGaAs on GaAs as thin as 4 nm.

Download Full-text

DETERMINATION OF URANIUM IN FLOTATION CONCENTRATES AND IN LEACH LIQUORS BY X-RAY FLUORESCENCE

Canadian Journal of Chemistry ◽

10.1139/v59-005 ◽

1959 ◽

Vol 37 (1) ◽

pp. 20-28 ◽

Cited By ~ 6

Author(s):

G. L. Smithson ◽

R. L. Eager ◽

A. B. VanCleave

Keyword(s):

Direct Measurement ◽

Pilot Plant ◽

Internal Standard ◽

Liquid Extraction ◽

X Ray ◽

Liquid Liquid Extraction ◽

Northern Saskatchewan ◽

Plant Operations ◽

Time Required

X-Ray fluorescence has been applied to the analysis of flotation concentrates obtained from pegmatitic uranium ores occurring in Northern Saskatchewan. Approximate uranium analyses can be obtained by direct measurement on flotation concentrates but more accurate results are obtained by using an internal standard such as strontium or yttrium. The time required for an analysis, as compared to that of conventional chemical or fluorimetric methods, is considerably reduced and flotation pilot plant operations can therefore be more effectively controlled. The method has been extended to include the analysis of sulphate leach liquors obtained from the leaching of pegmatitic ores and their flotation concentrates. Organic phases obtained in liquid – liquid extraction studies can also be rapidly analyzed for uranium by X-ray fluorescence.

Download Full-text

Residue analysis of fosthiazate in cucumber and soil by QuEChERS and GC-MS

Chemical Papers ◽

10.2478/s11696-014-0589-8 ◽

2014 ◽

Vol 68 (10) ◽

Cited By ~ 5

Author(s):

Min Wu ◽

Jiye Hu

Keyword(s):

Solid Phase ◽

Residue Analysis ◽

Field Trials ◽

Residue Level ◽

Gas Chromatography Mass Spectrometry ◽

Dispersive Solid Phase Extraction ◽

First Order ◽

First Order Kinetics ◽

Maximum Residue Level ◽

Relative Standard

AbstractA convenient method was developed for the determination and validation of fosthiazate in cucumber and soil. The procedure is based on liquid partitioning with acetonitrile followed by dispersive solid phase extraction as the clean-up step, after which samples were analysed by gas chromatography-mass spectrometry (GC-MS). The average recoveries ranged from 91.2 % to 99.0 % with relative standard deviations (RSDs) of less than 6.05 %, at three fortification levels (0.02 mg kg−1, 0.1 mg kg−1, 0.5 mg kg−1) in cucumber and soil, and the limits of quantification (LOQs) for fosthiazate were all established at 0.02 mg kg−1. The proposed method was applied successfully to analyses of the dissipation and residue of fosthiazate in field trials. The dissipation rate of fosthiazate was described using pseudo-first-order kinetics with a half-life of 4.33 days and 4.08 days in soil in Beijing and Shandong, respectively. In the terminal residue experiment, fosthiazate residues in cucumber and soil were clearly below the maximum residue level (MRL, 0.2 mg kg−1) set in China.

Download Full-text

Determination of low levels of retained austenite in low-carbon high-manganese steel using X-ray diffraction

Materials Science and Engineering A ◽

10.1016/j.msea.2015.01.019 ◽

2015 ◽

Vol 628 ◽

pp. 110-115 ◽

Cited By ~ 4

Author(s):

Helder Carvalho Ferreira ◽

Francisco Jose Martins Boratto ◽

Vicente Tadeu Lopes Buono

Keyword(s):

Retained Austenite ◽

Manganese Steel ◽

Low Carbon ◽

X Ray Diffraction ◽

High Manganese ◽

High Manganese Steel ◽

X Ray ◽

Low Levels

Download Full-text

Emerging Contaminants in Aqueous Matrices Determined by Gas Chromatography-Mass Spectrometry

Brazilian Journal of Analytical Chemistry ◽

10.30744/brjac.2179-3425.ar-08-2021 ◽

2021 ◽

Vol 8 (10Years) ◽

Author(s):

Emerson Hara ◽

Barbara Soares ◽

Adriano Santos ◽

Bruno Santos ◽

Gilberto Abate ◽

...

Keyword(s):

Gas Chromatography ◽

Liquid Chromatography ◽

Emerging Contaminants ◽

Gas Chromatography Mass Spectrometry ◽

Aqueous Samples ◽

Analytical Protocol ◽

Derivatizing Agent ◽

Low Levels ◽

Silylation Reaction

Reports on the determination of emerging contaminants (EC) in aqueous samples have been increasingly common. Due to the low levels of concentration of the analytes as well as the complexity of this matrix, the analysis is done preferably by liquid chromatography (LC). Owing to the polar character of most of the EC determination by gas chromatography is deprecated. One way to overcome this barrier is through derivatization, which, in some cases, can be a lengthy step, presents risks to the analyst as well as to the environment due to the toxicity of the derivatizing agent, and, thus, ends up favoring the use of LC. An analytical protocol was developed in this work to increase the efficiency of derivatization in a shorter reaction time for the determination of ibuprofen, 4-octylphenol, 4-nonylphenol, triclosan, bisphenol A, diclofenac, estrone, 17-β-estradiol, estriol, coprostanol, and cholesterol. The proposal then was to carry out the silylation reaction of the analytes with the aid of a domestic microwave oven. The results indicated that the use of the device provided an increase in the efficiency of the reaction, due to the homogeneous heating of the solution. Besides, there was a significant decrease in the derivatization time of the analytes from 30 min to 5 min. Additionally, through a design of experiments (DOE), it was possible to perceive the influence of some instrumental parameters of GC-MS, such as temperature, pressure intensity, and pressure pulse time in the injector on the detectability of the investigated analytes. This study allowed a satisfactory separation of the analytes and an average increase in their areas of up to 35%. These aspects made it possible to obtain an analytical method with limits for the detection and quantification of EC between 0.03-11.00 ng mL-1 and 0.10-33.35 ng mL-1, respectively, and uncertainties below 9%. The developed method was applied in the determination of the analytes in coastal seawater and the determined concentrations varied from 0.24 ng L-1 for estriol and 43.60 ng L-1 for cholesterol. Thus, the improvement of the silylation reaction, combined with the strategy of instrumental optimization, proved to be simple, efficient, and fast, as well as being a comparable alternative to liquid chromatography.

Download Full-text