Positive Identification Of Pesticide Residues by Chemical Derivatization-Gas Chromatographic Technique*

2018 ◽  
pp. 83-172
Author(s):  
S . Y . Chau Alfred
Keyword(s):  
Pesticide Residues ◽  
Chromatographic Technique ◽  
Chemical Derivatization ◽  
Positive Identification

Rapid Screening Method for the Determination of Organochlorine Pesticide Residues in Wheat by Electron Capture Gas Chromatography

1972 ◽  
Vol 55 (4) ◽  
pp. 794-799
Author(s):  
Iser Levi ◽  
P B Mazur ◽  
T W Nowicki
Keyword(s):  
Rapid Method ◽  
Organochlorine Pesticide ◽  
Electron Capture ◽  
Pesticide Residues ◽  
Screening Method ◽  
Rapid Screening ◽  
Chromatographic Technique ◽  
Organochlorine Pesticide Residues ◽  
Rapid Screening Method

Abstract A rapid screening method, employing a gas chromatographic technique with electron capture detection, has been developed for t h e analysis of organochlorine pesticide residues in hard red spring wheat. Ground wheat is extracted by ball-milling with an ethyl etherhexane (3 + 97) extractant. After filtration, the extract is cleaned up on a partially deactivated Florisil column, using a single eluting system, ethyl ether-hexane (1 + 99). The eluate i s concentrated before gas chromatographic analysis. Sixteen organochlorine pesticide chemicals were recovered in excess of 80% from wheat samples fortified at 0.010 and 0.200 ppm. Organochlorine pesticide residues were recovered by the rapid method from 18 samples with field-incurred residues as efficiently as by t he Bertuzzi et al. method. Organochlorine pesticide residues were also recovered by t h e rapid method from 4 samples with field-incurred residues and from 2 wheat samples, spiked at 0.500 ppm as efficiently as by the total extraction method of Mumma et al. The rapid method offers a savings in time and solvents over.the Bertuzzi et al. method for the determination of organochlorine pesticide residues in wheat.

Note on a Two-Dimensional Thin Layer Chromatographic Technique for Identification of Pesticide Residues in Troublesome Samples

1969 ◽  
Vol 52 (5) ◽  
pp. 1108-1108
Author(s):  
J A Kawatski ◽  
D L Frasch
Keyword(s):  
Thin Layer ◽  
Pesticide Residue ◽  
Pesticide Residues ◽  
Chromatographic Technique ◽  
Two Dimensional

Abstract Pesticide residue samples which have not been cleaned up enough for confirmatory TLC are spotted and developed in two directions on alumina plates. After ascending development with n-heptane, plates are rotated 90° and developed with n-heptane-saturated acetonitrile to separate residue spots from sample interferences.

Chemical Derivatization Analysis of Pesticide Residues. VIII. Analysis of 15 Chlorophenols in Natural Water by In Situ Acetylation

1984 ◽  
Vol 67 (4) ◽  
pp. 789-794
Author(s):  
Hing-Biu Lee ◽  
Li-Da Weng ◽  
Alfred S Y Chau
Keyword(s):  
Gas Chromatography ◽  
Quantitative Analysis ◽  
Acetic Anhydride ◽  
Petroleum Ether ◽  
Natural Water ◽  
Analytical Method ◽  
Pesticide Residues ◽  
Natural Waters ◽  
Chemical Derivatization

Abstract A rapid analytical method is presented for quantitative analysis of 15 chlorophenols in natural waters by in situ acetylation. In the presence of KHC03, phenols in water are acetylated by acetic anhydride directly without pre-extraction. The resultant acetates are extracted by petroleum ether and analyzed by electron capture gas chromatography. The investigation to optimize the conditions for in situ acetylation of these phenols is also described. This method has been validated and shown to be applicable over a range from 100 to 0.01 ppb with a 1 L water sample.

Solving the mechanisms responsible for organelle behavior in vivo by same-cell correlative light and electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 14-15
Author(s):  
Conly L. Rieder
Keyword(s):  
Electron Microscopy ◽  
Quantitative Analysis ◽  
Light Microscopy ◽  
Living Cell ◽  
Light And Electron Microscopy ◽  
Time Behavior ◽  
Dynamic Interactions ◽  
Positive Identification ◽  
Cellular Components

The behavior of many cellular components, and their dynamic interactions, can be characterized in the living cell with considerable spatial and temporal resolution by video-enhanced light microscopy (video-LM). Indeed, under the appropriate conditions video-LM can be used to determine the real-time behavior of organelles ≤ 25-nm in diameter (e.g., individual microtubules—see). However, when pushed to its limit the structures and components observed within the cell by video-LM cannot be resolved nor necessarily even identified, only detected. Positive identification and a quantitative analysis often requires the corresponding electron microcopy (EM).

An Early Muṣḥaf According to the Reading of Ibn cĀmir

2001 ◽  
Vol 3 (1) ◽  
pp. 71-89 ◽  
Author(s):  
Yasin Dutton
Keyword(s):  
Second Century ◽  
Documentary Evidence ◽  
Positive Identification ◽  
Facsimile Edition

The recent publication of the facsimile edition of MS Paris, Bibliothèque Nationale, Arabe 328a has allowed general access to what is probably one of the oldest, and most important, Qur'an fragments in Europe. The text is unvocalised, but the large number of folios (fifty-six) means that there are enough consonantal variants present to enable a positive identification of the reading represented, which turns out to be that of the Syrian Ibn cĀmir (d. 118/736). This, in combination with the early “Ḥijāzī” script, suggests (a) that this muṣḥaf was copied in Syria, and (b) that this was done some time during the first or early second century AH. In other words, what we have here is almost definitely a muṣḥaf according to the Syrian reading, copied in Syria, at the time when the caliphate had its seat in Syria, i.e. during the Umayyad period. Thus the identification of this particular reading helps in ascertaining the date and provenance of this particular manuscript, as it also fleshes out with documentary evidence the information given in the qirāↄāt literature about this reading.

Reports on Recent Activities of European Food Safety Authority

2019 ◽  
Vol 30 (5) ◽  
pp. 217-220
Keyword(s):  
Pesticide Residues ◽  
Food Products ◽  
Sampling Procedure ◽  
Control Programme ◽  
The European Union ◽  
Eu Member States ◽  
Official Control ◽  
National Programmes ◽  
Control Programmes ◽  
Risk Managers

This report provides an overview of the 2017 official control activities on pesticide residues carried out in the European Union (EU) Member States, Iceland and Norway. It summarises the results of both the 2017 EU-coordinated control programme (EUCP) and the national control programmes (NP). While the NPs are mostly risk based (so called enforcement samples) focusing on pesticides or products originating from countries where a number of exceedances have been observed in the past, the EUCP aims to present a statistically representative snapshot of the situation of pesticide residues in food products that are mostly consumed in the EU following a random sampling procedure. The report includes the outcome of a dietary risk assessment based on the results of the overall 2017 control programmes. The comprehensive analysis of the results of all reporting countries provides risk managers with sound-based evidence for designing future monitoring programmes, in particular for taking decisions on which pesticides and food products should be targeted in risk-based national programmes.

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