Partitioning of Organic Chemicals to Polyacrylate-Coated Solid Phase Microextraction Fibers:  Kinetic Behavior and Quantitative Structure−Property Relationships

Abstract

The solid phase microextraction technique uses polymercoated fused-silica fibers to extract organic chemicals from an aqueous or gaseous phase. In the current paper, the partitioning behavior of organic chemicals from water to polyacrylate coating is described in terms of a twocompartment model and first-order kinetics. Experimental results show that, through agitation, it is possible to achieve a sufficiently small aqueous diffusion layer around the fiber to prevent aqueous diffusion from being the limiting factor in the absorption process. This then implies that the equilibration time is completely determined by the polyacrylate phase. In addition, the kinetic rate constants derived from the experimental results, viz. the uptake rate constant and polyacrylate-water partition coefficient, are modeled by multivariate techniques, using physicochemical and quantum chemical descriptors. These models clearly show that, besides hydrophobicity expressed as the octanol-water partition coefficient, the energy of the lowest unoccupied molecular orbital (and related properties) and the most positive charge on any hydrogen atom in the molecule are important descriptors. This indicates that hydrogen bonding plays a significant role in polyacrylate-water partitioning. The models that are presented can be used to predict absorption profiles of organic chemicals to polyacrylate-coated fibers, thereby giving the opportunity to predict the kinetics (including equilibration times) by computations alone.

Efficiency of direct solid-phase microextraction from water-comparison of different fibre types including a new C8-coating

“…When seeking an explanation one should bear in mind that extraction yields after 1 h do not refer to an established distribution equilibrium. As pointed out by Vaes et al [30] the uptake of a substance by a given SPME fibre coating is influenced by the hydrophobicity and transport properties of the substance. In the case of moderately hydrophobic substances like mono and disubstituted halobenzenes and the HCHs, extraction yields in Table II have a similar trend as the fibre coating-water distribution constants determined in long-term experiments (120 h extraction) [25].…”

Determination of liposome/water partition coefficients of organic acids and bases by solid-phase microextraction

“…16 In this case, the uptake kinetics should not be influenced by the organic material or other matrices present. Indeed, the presence of humic acids did not significantly influence the uptake kinetics of 2,5-dichlorophenol 9 and of 4-quinolone oxolinic acid.…”

Steady-state diffusion regime in solid-phase microextraction kinetics

“…to (i) elucidate the mechanisms involved in the extraction processes [3][4][5][6] (ii) develop applications in the analysis of organic pollutants including phenol and its derivatives [4][5][6][7], polycyclic aromatic hydrocarbons (PAHs) [8] and organophosphorus pesticides, nitrogen-containing pesticides like triazines [8][9][10][11] in aqueous, gaseous, and dispersed media, including soil [12,13], and (iii) characterise the performance of more polar polymers such as polyacrylate, in the analysis of less hydrophobic organics [7]. Negligible depletion (nd) SPME [7,14,15] samples only an insignificant amount of analyte and is essentially nonThe Netherlands. Tel.…”