On the semi-quantification of polycyclic aromatic hydrocarbons in contaminated soil by an enzyme-linked immunosorbent assay kit

The Method and Study of Detecting Phenanthrene in Seawater Based on a Carbon Nanotube-Chitosan Oligosaccharide Modified Electrode Immunosensor

Phenanthrene (PHE), as a structurally simple, tricyclic, polycyclic aromatic hydrocarbon (PAHs), is widely present in marine environments and organisms, with serious ecological and health impacts. It is crucial to study fast and simple high-sensitivity detection methods for phenanthrene in seawater for the environment and the human body. In this paper, a immunosensor was prepared by using a multi-wall carbon nanotube (MWCNTs)-chitosan oligosaccharide (COS) nanocomposite membrane loaded with phenanthrene antibody. The principle was based on the antibody-antigen reaction in the immune reaction, using the strong electron transfer ability of multi-walled carbon nanotubes, coupled with chitosan oligosaccharides with an excellent film formation and biocompatibility, to amplify the detection signal. The content of the phenanthrene in seawater was studied via differential pulse voltammetry (DPV) using a potassium ferricyanide system as a redox probe. The antibody concentration, pH value, and probe concentration were optimized. Under the optimal experimental conditions, the response peak current of the phenanthrene was inversely proportional to the concentration of phenanthrene, in the range from 0.5 ng·mL-1 to 80 ng·mL-1, and the detection limit was 0.30 ng·mL-1. The immune sensor was successfully applied to the detection of phenanthrene in marine water, with a recovery rate of 96.1~101.5%, and provided a stable, sensitive, and accurate method for the real-time monitoring of marine environments.

Rapid synthesis of graphite phase carbon nitride/zeolitic imidazolate framework-8 with hierarchical structure and its superior adsorption of polycyclic aromatic hydrocarbons from aqueous solution

Graphite phase carbon nitride (g-C₃N₄) incorporating zeolitic imidazolate framework-8 (ZIF-8) nanocomposite (g-C₃N₄ /ZIF-8) with hierarchical structure was synthesized successfully by simple and rapid in situ growth method at room temperature. The composites were used as an adsorbent of solid-phase extraction (SPE) and the superior adsorptive removal of polycyclic aromatic hydrocarbons (PAHs) for the first time. Under several optimum conditions, the g-C₃N₄ /ZIF-8-SPE-HPLC-FLD method show low detection limits (0.006-3.41 μg L^-1) and limit of quantification (0.02-11.3 μg L^-1), wide linear ranges from 0.02 to 1000 μg L^-1 for all compounds, correlation coefficients (r) of more than 0.9968, and satisfying reproducibility (relative standard deviations, RSDs < 4.0% for intra-day, RSDs < 8.3% for inter-day), the spiked recoveries at two levels of 10.0, 50.0 μg L^-1 were in the range of 77.4%-114% with the RSDs less than 8.66%. In addition, the g-C₃N₄/ZIF-8 nanocomposites demonstrated excellent enrichment ability and extraction efficiency for PAHs compared with commercial adsorbents, which might since there were strong π-π stacking force, hydrophobic interaction, hydrogen bonding, and more adsorption sites compared with other adsorbents. Finally, the g-C₃N₄ /ZIF-8 based SPE method was combined with high-performance liquid chromatography (HPLC) to detect fifteen PAHs in environmental water samples successfully.

Investigating the quantitative structure-activity relationships for antibody recognition of two immunoassays for polycyclic aromatic hydrocarbons by multiple regression methods

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants found in the environment. Immunoassays represent useful analytical methods to complement traditional analytical procedures for PAHs. Cross-reactivity (CR) is a very useful character to evaluate the extent of cross-reaction of a cross-reactant in immunoreactions and immunoassays. The quantitative relationships between the molecular properties and the CR of PAHs were established by stepwise multiple linear regression, principal component regression and partial least square regression, using the data of two commercial enzyme-linked immunosorbent assay (ELISA) kits. The objective is to find the most important molecular properties that affect the CR, and predict the CR by multiple regression methods. The results show that the physicochemical, electronic and topological properties of the PAH molecules have an integrated effect on the CR properties for the two ELISAs, among which molar solubility (S_m) and valence molecular connectivity index (³χ^v) are the most important factors. The obtained regression equations for Ris^C kit are all statistically significant (p < 0.005) and show satisfactory ability for predicting CR values, while equations for RaPID kit are all not significant (p > 0.05) and not suitable for predicting. It is probably because that the Ris^C immunoassay employs a monoclonal antibody, while the RaPID kit is based on polyclonal antibody. Considering the important effect of solubility on the CR values, cross-reaction potential (CRP) is calculated and used as a complement of CR for evaluation of cross-reactions in immunoassays. Only the compounds with both high CR and high CRP can cause intense cross-reactions in immunoassays.

Gel-based immunoassay for non-instrumental detection of pyrene in water samples

A new qualitative immunologically based tube test for non-instrumental detection of pyrene (PYR) in water samples was developed. The method combines the pre-concentration of analyte by immunoextraction and its detection by immunoassay using Sepharose 4B-immobilized IgG-fraction of a polyclonal anti-PYR antiserum (immunoaffinity gel) and 1-pyrenebutyric acid-horseradish peroxidase conjugate (PYR-BA-HRP). The immunoaffinity gel was placed in a standard 1-ml SPE column through which a 10-ml aliquot of water sample spiked with 10% acetonitrile was passed. Following, free antibody binding sites were detected by application of PYR-BA-HRP. Four minutes after addition of the chromogenic substrate the results were visually evaluated by occurring or stayed away blue colour development for negative and positive samples, respectively. Total time for assay was about 15 min for six samples. Under optimized conditions a cut-off level for pyrene of 0.04 ng ml(-1) was found. At this defined concentration, a set of spiked samples (n=175) was analyzed and very low rates of false negatives (1.2%) and false positives (4.6%) determined which fulfils the requirement set by Commission Decision 2002/657/EC for a screening method. No interference by other PAH compounds like naphthalene, fluoranthene, phenanthrene, anthracene, and benzo[a]pyrene at a concentration of 20 ng ml(-1), i.e., 500-fold excess compared to the defined cut-off level was observed. Different water types like surface water, tap water, bottled water, and melted snow were analyzed for PYR contamination by the proposed method and results confirmed by HPLC-FLD.

Improving soil investigations at brownfield sites using a flexible work strategy and screening methods inspired by the US Environmental Protection Agency's triad approach

Investigations of polluted brownfield sites and sample analyses are expensive, and the resulting data are often of poor quality. Efforts are needed, therefore, to improve the methods used in investigations of brownfield sites to both reduce costs and improve the quality of the results. One approach that could be useful for both of these purposes is the triad strategy, developed by the US Environmental Protection Agency, in which managing uncertainty is a central feature. In the investigations reported here, a field study was conducted to identify possible ways in which uncertainties could be managed in practice. One example considered involves optimizing the uncertainty by adjusting the sizes of samples and the efforts expended in analytical work according to the specific aims of the project. In addition, the potential utility of several toxicity assessment methods for screening sites was evaluated. As well as presenting the results of these assessments, in this contribution we discuss ways in which a flexible work strategy and screening methods inspired of the triad philosophy could be incorporated into the Swedish approach to remediate brownfield sites. A tiered approach taking advantage of field and screening methods is proposed to assess brownfield sites focusing on the response and acceptable uncertainty that are required for the task.

Sonication-laser-excited time-resolved Shpol'skii spectrometry: a facile method for the direct screening of fifteen priority pollutants in soil samples

A unique method for screening polycyclic aromatic hydrocarbons (PAH) in soil samples is reported. Milligrams of soil are sonicated into the vial of a cryogenic fiber-optic probe with 250 microL of n-octane. Pollutants partition into the layer of extracting solvent and the cryogenic probe is then used for fluorescence measurements at liquid helium temperature (4.2 K). N-octane provides PAH with the appropriate Shpol'skii matrix to record highly resolved spectra and characteristic fluorescence lifetimes. Unambiguous PAH determination is directly performed from the layer of extracting solvent with no need for previous PAH separation. The total analysis time from the extraction to PAH identification is approximately 35 min per sample. Limits of detection are at the sub-parts per billion levels. PAH recoveries are similar to those obtained via high-performance liquid chromatography analysis. The simplicity of the experimental procedure, the short analysis time, the selectivity, and the excellent analytical figures of merit demonstrate the advantages of this approach for routine analysis of soil samples.