Evaluation of pesticide adsorption in gas chromatographic injector and column

Pinho, Gevany Paulino de; Silvério, Flaviano Oliveira; Neves, Antônio Augusto; Queiroz, Maria Eliana Lopes Ribeiro de

doi:10.1590/s0100-40422012000400016

Cited by 8 publications

(4 citation statements)

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“…It has been shown that the intensity of this effect is dependent on the physicochemical properties of pesticides such as polarity, molecular weight, thermal stability, temperature of boiling analytes, etc. 29,30 Negative matrix effect is observed due to degradation of the pesticide in injector or analyte adsorption on the active sites (free silanols groups) from liner. This effect causes decreasing of the analyte flux transferred to the column and consequently the decreasing of the detector signal.…”

Section: Matrix Effect and Linearitymentioning

confidence: 99%

“…31 When the sample matrix is injected, there is a competitive process between the analyte and other matrix compounds to be adsorbed on liner active sites, which favors the analyte availability to the column and consequently bring an increase of the signal. [29][30][31] Thus, the comparative responses between the analyte presented in the standard solution and in the sample matrix are characterized by an response overestimation. Probably these discussed aspects justify the positive matrix effect observed for most pesticides studied, except for dichlorvos (Figure 2a).…”

Section: Matrix Effect and Linearitymentioning

confidence: 99%

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Organophosphorus Pesticide in Sapodilla (Manilkara zapota) Fruit

Alcântara

Paz

Rodrigues

et al. 2018

J. Braz. Chem. Soc.

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A method based on QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction and gas chromatography-mass spectrometry (GC-MS) detection was described for the pesticides dichlorvos, disulfoton, ethoprophos, parathion methyl, fenchlorphos, chlorpyrifos, azinphos methyl and prothiofos in sapodilla. For all compounds studies, it was observed a strong matrix effect showing the need to use matrix matched calibration strategy. Method was validated, and good linearity (R > 0.99) was obtained for all pesticides studied with limits of detection (LODs) and quantification (LOQs) ranging from 0.01 to 0.06 mg kg -1 and 0.03 to 0.2 mg kg -1 , respectively. Recovery studies were performed at different levels (0.08, 0.10, 0.14, 0.20, 0.35 and 1.17 mg kg -1 ) and showed good results (between 70 and 120% with relative standard deviation (RSD) < 20%). A statistical test was applied to the coefficients of the analytical curves obtained in the sapodilla matrix. Analyses of commercial samples showed chlorpyrifos were detected in about 70 and 33% for fruit and pulps samples, respectively. It should be noted that chlorpyrifos is not permitted in sapodilla crops by ANVISA and EC guidelines.

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Section: Matrix Effect and Linearitymentioning

confidence: 99%

Section: Matrix Effect and Linearitymentioning

confidence: 99%

Organophosphorus Pesticide in Sapodilla (Manilkara zapota) Fruit

Alcântara

Paz

Rodrigues

et al. 2018

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…On the other hand, even though it is not fully recognized, there is limited evidence that coexisting pesticides in standard solutions have the potential to cause response alterations for certain other pesticides. de Pinho et al compared the adsorption tendency of chlorpyrifos and deltamethrin in GC with an electron capture detector and found that deltamethrin adsorbed much more readily to the active sites than chlorpyrifos [24]. They also found that deltamethrin acted as a sort of analyte protectant for chlorpyrifos and altered its peak response when both pesticides were mixed and injected to GC with an electron capture detector.…”

Section: Introductionmentioning

confidence: 99%

“…de Pinho et al. compared the adsorption tendency of chlorpyrifos and deltamethrin in GC with an electron capture detector and found that deltamethrin adsorbed much more readily to the active sites than chlorpyrifos . They also found that deltamethrin acted as a sort of analyte protectant for chlorpyrifos and altered its peak response when both pesticides were mixed and injected to GC with an electron capture detector.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the matrix-like effect in multiresidue pesticide analysis by gas chromatography with tandem mass spectrometry

et al. 2017

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In multiresidue pesticide analysis using gas chromatography, it has long been recognized that an increase in the number of pesticides present in a standard solution can result in an enhancement of the peak responses of certain pesticides. Despite being widely acknowledged, this phenomenon has been rarely studied and is poorly understood. In this study, the authors have tentatively called this phenomenon the "matrix-like effect" and demonstrated it clearly using gas chromatography with tandem mass spectrometry. Five selected pesticides, namely, omethoate, terbufos, malathion, procymidone, and permethrin, and four internal standard candidates, namely, triphenyl phosphate, naphthalene-d , phenanthrene-d , and fluoranthene-d , were used to evaluate the matrix-like effect following the addition of 58, 108, and 166 other pesticides. With the exception of naphthalene-d , the responses of all evaluated pesticides and internal standard candidates were dramatically enhanced by the addition of up to 166 coexisting pesticides. The relative response factors of the five pesticides to each internal standard candidate were not constant under the conditions studied, meaning that these internal standard candidates did not adequately compensate for the matrix-like effect, at least for the five evaluated pesticides. The results revealed that the presence of various mixtures of pesticides in standard solutions might act as an unintentional analyte protectant, that is, some sort of troublesome "quasi-matrix."

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