scholarly journals The Potential of Graphene as an Adsorbent for Five Pesticides from Different Classes in Rape Oil Samples Using Dispersive Solid-Phase Extraction

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Katarzyna Madej ◽  
Katarzyna Janiga ◽  
Wojciech Piekoszewski
Keyword(s):  
Detection Limit ◽  
Mobile Phase ◽  
Solid Phase ◽  
Phase Extraction ◽  
Dispersive Solid Phase Extraction ◽  
Highly Sensitive ◽  
Modified Graphene ◽  
Rape Oil ◽  
Gradient Mode ◽  
Concentration Levels

Isolation conditions for five pesticides (metazachlor, tebuconazole, λ-cyhalothrin, chlorpyrifos, and deltamethrin) from rape oil samples were examined using the dispersive solid-phase graphene extraction technique. To determine the optimal extraction conditions, a number of experimental factors (amount of graphene, amount of salt, type and volume of the desorbing solvent, desorption time with and without sonication energy, and temperature during desorption) were studied. The compounds of interest were separated and detected by an HPLC-UV employing a Kinetex XB-C18 column and a mobile phase consisting of acetonitrile and water flowing in a gradient mode. The optimized extraction conditions were: the amount of graphene 15 mg, desorbing solvent (acetonitrile) 5 mL, time desorption 10 min at 40°C, and amount of NaCl 1 g. The detection limit for metazachlor, tebuconazole, λ-cyhalothrin, and chlorpyrifos was 62.5 ng·g−1, and for deltamethrin, it was 500 ng·g−1. The obtained results lead to the conclusion that graphene may be successfully used for the isolation of the five pesticides from rape oil. However, their determination at low concentration levels, as they occur in real oil samples, requires the employment of appropriately highly sensitive analytical methods, as well as a more suitable graphene form (e.g., magnetically modified graphene).

scholarly journals Use of Magnesium Silicate as a New Type of Adsorbent for Dispersive Solid-Phase Extraction Cleanup of the Quick, Cheap, Effective, Rugged, and Safe Method for Pesticides During Analysis of Lager Beer by Gas Chromatography-Tandem Mass Spectrometry

2019 ◽  
Vol 102 (2) ◽  
pp. 619-624 ◽  
Author(s):  
Sandro Navickiene ◽  
Luis Fabrício Santana Santos ◽  
Alexandre dos Reis Silva
Keyword(s):  
Solid Phase Extraction ◽  
Matrix Effects ◽  
Solid Phase ◽  
Magnesium Silicate ◽  
Phase Extraction ◽  
Dispersive Solid Phase Extraction ◽  
Important Approach ◽  
Efficient Alternative ◽  
Lager Beer ◽  
Concentration Levels

Abstract Background: Pesticides are applied for pest control during the production of cereal grains used in beer production. Given the risks for consumers, it is important to analyze the pesticide residues. Objective: Quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based methods are very effective, and improvement inthe cleanup step is an important approach. Methods: Primary secondary amine (PSA) andmagnesium silicate were evaluated for dispersive-solid-phase extraction (d-SPE) cleanup step in extracts provided by the QuEChERS method in combination with GC-tandem MS for the determination of acetamiprid, terburfos, alachlor, ametryn, atrazine, azoxystrobin, carbofuran, carbosulfan, cypermethrin, deltamethrin, difenoconazole, esfenvalerate, flutriafol,thiamethoxam, and parathion-methyl in lager beer. Results: The amount of 50 mg of magnesium silicate was suitable for cleaning up beer extract as an alternative d-SPE material to PSA. Themethod was validated using beer fortified with pesticides at three concentration levels (0.002, 0.01, and 0.1 μg/mL). Average recoveries ranged from 70 to 123%, with RSDs between 0.3 and 10.5 %. Matrix effects were observed by comparing the slope of matrix-matched standard calibration with that of solvent. The method provided good linearity at the concentration levels of 0.001–2.5 μg/mL. Detection limits ranged from 0.0001 to 0.0007 μg/mL and quantification limits ranged from 0.001 to 0.006 μg/mL. The method was applied to nine beer brands. Conclusions: Results showed that magnesium silicate is an efficient alternative cleanup material to reduce analysiscosts while maintaining the method reliability and accuracy. Highlights: Magnesium silicate was effective as adsorbent for d-SPE step inthe analysis of pesticides in beer.

scholarly journals Determination of pesticides residues in quinoa (Chenopodium quinoa Willd) using QuEChERS and LC-MS/MS

2018 ◽  
pp. 421
Author(s):  
Franz Zirena Vilca ◽  
Graziela Cristina Rossi Moura Andrade ◽  
Walter Alejandro. Zamalloa Cuba ◽  
Valdemar Luiz. Tornisielo
Keyword(s):  
Acetic Acid ◽  
Mobile Phase ◽  
Matrix Effects ◽  
Solid Phase ◽  
Chenopodium Quinoa ◽  
Phase Extraction ◽  
Dispersive Solid Phase Extraction ◽  
Quechers Method ◽  
Pesticides Residues

The QuEChERS method was optimized and validated for the determination of 40 pesticides in 37 samples of quinoa from the harvest 2010-2011 in Puno - Peru. The method involves extraction with 1% acetic acid acetonitrile with CH3COONa anhydrous and MgSO4 followed by dispersive solid-phase extraction with PSA and C18. Analyses were performed with LC-MS/MS using C18 column 150 mm x 2.1 x 3.5 µm, water and acetonitrile 0.1% formic acid used as mobile phase. Spiked quinoa blank at 0.01 and 0.1 mg kg-1 was employed to evaluate recovery ranging from the 31.6 and 125.1% with RSD ≤ 23. The method showed linearity r2 ≥ 0.99 and limits of quantification ranged from 0.001 and 0.01 mg kg-1, and was not observed a matrix effects.  No pesticides residues were observed in the analyzed samples.

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