Nonhydrolytic sol-gel approach to facile creation of surface-bonded zirconia organic-inorganic hybrid coatings for sample preparation. Ι. Capillary microextraction of catecholamine neurotransmitters

Alhendal, Abdullah; Mengis, Stephanie; Matthews, J. H.; Malik, Abdul

doi:10.1016/j.chroma.2016.09.036

Cited by 9 publications

(6 citation statements)

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“…To compare the microextraction performances of the created sol–gel niobia sorbents, a recently introduced parameter, specific extraction (SE), was employed. SE is defined as follows: .

SE = \frac{The mass of analyte extracted (μ g)}{mass of sol - gel sorbent (normalg)}

…”

Section: Methodsmentioning

confidence: 99%

“…Desorbed amount of the analyte was obtained from the HPLC peak area obtained through desorption of the extracted analyte using the HPLC mobile phase. DE was calculated using the following equation :

Desorption efficiency (%) = \frac{Amount desorbed}{Amount extracted} \times 100

…”

Section: Methodsmentioning

confidence: 99%

“…Desorption efficiency (DE, %) was determined to evaluate the completeness of desorption of the extracted analytes from sol–gel CME sorbent. Each analyte was injected into the HPLC column by using a 40 cm piece of deactivated fused‐silica capillary as the external sampling loop.…”

Section: Methodsmentioning

confidence: 99%

“…To that end, we have designed the Nb 2 O 5 -C 18 (+ve) sorbent capable of providing all three of the above-mentioned interactions: (a) electrostatic interactions of the analyte phosphate groups with the positive charge on the sorbent, (b) Lewis acid-base interaction between analyte phosphate group (Lewis base) with the Lewis acid sites on niobia and (c) van der Waals interactions between various moieties the sorbent and the analyte. The SE [34] values presented in Table 1 show that coating (iii) has clearly provided 50-60% higher compared to coating (i). This enhanced extraction performance of sorbent (iii) compared to sorbent (i) is due to the ability of sorbent (iii) to provide two additional types of molecular level interactions ((a) electrostatic interactions between the positive charge on the sorbent and the phosphate group on the OPCs and (b) molecular level interactions provided by the bonded ligand) that are unavailable in extraction with sorbent (i).…”

Section: Extraction Of Organophosphorus Pesticides and Nucleotides Usmentioning

confidence: 97%

“…To compare the microextraction performances of the created sol-gel niobia sorbents, a recently introduced parameter, specific extraction (SE), was employed. SE is defined as follows: [34].…”

Section: Characterization Of Cme Performances By Specific Extractionmentioning

confidence: 99%

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Sol–gel niobia sorbent with a positively charged octadecyl ligand providing enhanced enrichment of nucleotides and organophosphorus pesticides in capillary microextraction for online HPLC analysis

Kesani

Malik

2018

J of Separation Science

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A niobia-based sol-gel organic-inorganic hybrid sorbent carrying a positively charged C ligand (Nb O -C (+ve)) was synthesized to achieve enhanced enrichment capability in capillary microextraction of organophosphorus compounds (which include organophosphorus pesticides and nucleotides) before their online analysis by high-performance liquid chromatography. The sorbent was designed to simultaneously provide three different types of molecular level interactions: electrostatic, Lewis acid-base, and van der Waals interactions. To understand relative contributions of various molecular level analyte-sorbent interactions in the extraction process, two other sol-gel niobia sorbents were also created: (a) a purely inorganic sol-gel niobia sorbent (Nb O ) and (b) an organic-inorganic hybrid sol-gel niobia sorbent carrying an electrically neutral-bonded octadecyl ligand (Nb O -C ). The extraction efficiency of the created sol-gel niobia sorbent (Nb O -C (+ve)) was compared with that of analogously designed and synthesized titania-based sol-gel sorbent (TiO -C (+ve)), taking into consideration that titania-based sorbents present state-of-the-art extraction media for organophosphorus compounds. In capillary microextraction with high-performance liquid chromatography analysis, Nb O -C (+ve) had shown 40-50% higher specific extraction values (a measure of extraction efficiency) over that of TiO -C (+ve). Compared to TiO -C (+ve), Nb O -C (+ve) also provided superior analyte desorption efficiency (96 vs. 90%) during the online release of the extracted organophosphorus pesticides from the sorbent coating in the capillary microextraction capillary to the chromatographic column using reversed-phase high-performance liquid chromatography mobile phase.

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“…To compare the microextraction performances of the created sol–gel niobia sorbents, a recently introduced parameter, specific extraction (SE), was employed. SE is defined as follows: .