Recent advances and applications of synthetic diamonds in solid-phase extraction and high-performance liquid chromatography.

Since the advent of diamond-based adsorbents in the late 1960s, the interest in their use for solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) has steadily increased. This is primarily due to their unique properties, such as extreme chemical and thermal stability, high mechanical strength and biocompatibility, and complex mixed-mode retention mechanisms. Currently, the most commonly used synthetic diamonds in SPE and HPLC are detonation nanodiamonds (DND), high-pressure high-temperature (HPHT) diamonds, and chemical vapour deposition (CVD) diamonds. These diamonds have been either used as individual particles (in both modified and unmodified forms), or for surface modification, or entrapped within composites and core-shell particles to develop new diamond-based adsorbents. These diamond-based adsorbents have been used for a variety of applications, including streamlined proteome analysis; extraction of anions, cations, actinides, uranium, lanthanides, alkaline earth metals, transition metals, and post-transition metals; and development of reversed-phase, normal phase, hydrophilic interaction, ion chromatography, and mixed-mode liquid chromatography columns, to name but a few. These varied applications of different types of diamonds are typically governed by their specific properties. This review discusses the various surface and bulk properties of DND, HPHT diamonds, and CVD diamonds that facilitate or limit their use in different SPE and HPLC based applications.

Recent advances in stir-bar sorptive extraction: Coatings, technical improvements, and applications.

Stir-bar sorptive extraction (SBSE) is a popular solvent-less sample preparation method, which is widely applied for the sampling and preconcentration of a wide range of non-polar solutes. A typical stir-bar for SBSE is composed of a polydimethylsiloxane (PDMS) film, coated onto a glass jacket with an incorporated magnet core. Sampling is carried out by direct immersion or by exposing the stir-bar to the headspace of the sample. To-date the majority of reported SBSE devices have used PDMS as the sorbent, with a few alternative commercially SBSE coatings available (such as polyethylene glycol and polyacrylate), which limits the applicability of SBSE to more polar and hydrophilic solutes. The interest in more selective extraction has been the driving force behind the recent development of novel SBSE coatings, particularly those exhibiting selectivity towards more polar solutes. During the last decade, a significant number of novel SBSE coatings were introduced utilising different fabrication approaches, including surface adhesion, molecular imprinting, sol-gel technology, immobilised monoliths, and solvent exchange processes. A range of nano- and micro-carbon-based materials, functional polymers, metal organic frameworks (MOFs), and inorganic nanoparticles have been employed for this purpose. Some of these SBSE coatings have exhibited higher thermal and chemical stability and delivered wider selectivity profiles. This review aims to summarise these significant developments, reported over the past six years, with specific attention to novel materials and selectivity for extending the potential applications of SBSE.

Development of polydimethylsiloxane-microdiamond composite materials for application as sorptive devices.

The development and application of non-porous and porous sorptive rods, comprised of polydimethylsiloxane-microdiamond (PDMS-MD) composites, is reported. The PDMS-MD composites were made porous using inorganic salt (NaCl and NaHCO3) particles as dissolvable templates. Materials with pore size of ~40 µm down to ~5 µm were produced. The advantages of incorporating up to ~60%microdiamond (2-4 µm) into PDMS included: (1) significant increase in the density, which saw the rods sink within the aqueous sample without addition of secondary metal or glass materials, (2) significant improvement in mechanical stability (the porous composite rods could be thermally treated multiple times before application, unlike porous PDMS), (3) increased thermal stability up to 450-500 °C with only 6% weight loss of volatile components, and (4) higher thermal conductivity, estimated to be 108% higher than for PDMS. The PDMS-MD investigated as a sorbent for extraction, followed by liquid desorption and GC-FID analysis. Recovery of the sorbent for test solutes, isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, and phenethyl acetate, was found to range from ~87% to >100, with RSD of 2.10-12.50% in synthetic wine samples. Non-porous composite rods provided similar % recoveries to a commercial sorptive device (PDMS Twister), whereas porous rods showed improved % recovery for most of the test solutes (>10-20%) when applied under similar conditions. The limits of detection (LOD) for the above solutes within the developed method ranged from 0.60 to 27.30 µg L-1). Application of the PDMS-MD-LD-GC-FID method to white wine samples demonstrated how the PDMS-MD composite material can be applied as a robust and an efficient sorptive phase for trace chemical analysis.

Environmental risks associated with booster biocides leaching from spent anti-fouling paint particles in coastal environments.

Boat maintenance facilities in coastal areas contribute a significant amount of antifouling paint particles (APP) to coastal environments. Very few studies have concentrated on the leaching of booster biocides embedded in old paint particles. Therefore, this study attempted to assess the leaching of Dichlofluanid and Irgarol 1051 from APP collected from Mayflower Marina in southwest England. They were analyzed by GC-MS. A leaching experiment revealed that a considerable amount of Dichlofluanid (ca. 24 µg/L) leached from 0.4 g/L of APP after the first hour, followed by a marked decline in the amount measured in the water over time, almost degrading after 24 h in seawater, affording less of an environmental threat to non-target organisms. Conversely, Irgarol 1051 appeared to be persistent and continuously leached from the 0.4 g/L of APP even after 10 days, yielding a concentration of 0.61 µg/L in seawater, potentially posing a significant threat to the aquatic environment through leaching from APP.