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This study investigated the atmospheric deposition of microplastics (MPs) in Auckland, New Zealand, from two sampling sites over a 9-week period. The sizes, morphologies, number counts, and mass concentrations of specific polymers were determined for airborne MPs using a combination of a Nile Red-assisted automated fluorescence microscopy technique in series with pyrolysis-gas chromatography-mass spectrometry (Pyr-GC/MS). This enabled a larger number of MPs to be analyzed from each sample compared to traditional spectroscopic techniques. Microplastic number concentrations increased exponentially with decreasing size. The results show the importance of using consistent methodologies and size cutoffs when comparing microplastic data between studies. Eight polymers were quantified in the atmospheric deposition samples, with polyethylene (PE), polycarbonate (PC), and poly(ethylene terephthalate) (PET) being the most commonly observed. The largest MP deposition rates at an urban rooftop correlated with winds originating from the marine environment with speeds between 15 and 20 m s

Methamphetamine is the most commonly seized amphetamine-type stimulant (ATS) worldwide. Chemical residues associated with the use or manufacture of methamphetamine can persist in the air and surfaces in a property for over 5 years and potentially pose risks to the health and safety of the public. When a house is tested for contamination, the test focuses on the presence of surface methamphetamine residue; however, other hazardous chemicals may also be present, including methamphetamine precursors and reaction products. As little has been reported about the ageing of the methamphetamine inside dwellings, there is currently large uncertainty regarding its fate and/or degradation products in such environments. If the indoor reactivity of methamphetamine is similar to that of nicotine-derived third-hand smoke, the production of a carcinogenic nitrosamine is an expected result. Thus, this proof-of-concept study investigated the reaction of methamphetamine with the common gaseous indoor oxidant nitrous acid (HONO) and monitored the fate of the resulting reaction products in simulated laboratory experiments to further understand the potential health risks associated with contaminated properties. Surface methamphetamine residue was observed to decrease with an exponential decay with an upper limit of 2.38 ± 0.5 × 10-3 min-1 upon exposure to HONO gas (5.7 ppmv, 0.25 L min-1 ). N-nitrosomethamphetamine (NMA), a suspected human mutagen and carcinogen, was detected to have a steady-state formation over the sampling time frame, with a surface area concentration of 0.87 μg/100 cm2 , suggesting that the risks to public health for properties contaminated with methamphetamine may be currently underestimated.

Firework displays produce large amounts of particulate matter (PM), contributing to poor air quality in local areas. Since short-term exposure to particulate matter correlates with increased mortality risks, these celebrations may impact both human health and the environment. Little is known about the particulate matter produced from recreational fireworks, as most studies have focused on professional large-scale events. In New Zealand, it is common for consumer fireworks to be ignited within residential areas during the Guy Fawkes celebration around 5 November. To better understand the contribution of individual fireworks on local air quality, ambient PM10 sampling was conducted in the 10 days surrounding Guy Fawkes Day in Auckland, New Zealand. These data were supplemented with measurements of firework emissions from 11 different individual products, including smoke bombs, sparklers, and Roman candles. Filter sampling results indicated that personal fireworks can contribute to ground level ambient air quality during celebrations, increasing ambient PM10 concentrations by 21.6 μg m−3 over a 12-h sampling period. The use of personal fireworks can expose consumers to PM10 concentrations much higher, up to 9.51 mg m−3 from individual sparkler use under worst-case scenario assumptions. The inhalation of sparkler emissions for just 8 min can lead to an exposure to PM10 mass greater than that from daily recommended limits (50 μg m−3 exposure over 24 h). X-ray fluorescence (XRF) analysis indicated that potassium (K) and strontium (Sr) can be used as tracers for local firework use and that arsenic (As) may be an important contaminant during Guy Fawkes celebrations. The PM from personal fireworks contained large amounts of chlorine (Cl), which may be indicative of perchlorate oxidizers. In addition, lead (Pb) was observed in the PM generated from two of the colored sparklers, which were marketed as “safer” alternatives to more explosive firework products.

Many aspects of the behaviour of iron oxide phases are influenced significantly by the interaction with H4SiO4 which is a ubiquitous solute in aquatic systems. This interaction can involve H4SiO4 sorption and interfacial oligomerization and has a dependence on the structures present on the oxide surface. In this work the sorption and oligomerization of H4SiO4 on the surface of magnetite (Fe3O4) was studied as a function of the particle surface oxidation state. Magnetite samples were prepared from FeCl2:FeCl3 or FeSO4:FeCl3 and were characterised by Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Raman and infrared (IR) spectroscopy. Magnetite from FeCl2:FeCl3 was pure magnetite by XRD but Raman spectra indicated ferrihydrite was present on the “as prepared” surface. Raman also indicated that the ferrihydrite layer was decreased following reduction with hydrazine but was increased following treatment with dilute H2O2. In situ Attenuated Total Reflectance Infrared Spectroscopy (ATRIR) showed the propensity of H4SiO4 oligomerization on magnetite was enhanced following hydrazine reduction and was not influenced by H2O2. In all cases the proportion of oligomers to monomers was significantly greater on the surface of magnetite than on ferrihydrite. The inference is that both the as prepared and the H2O2 oxidised magnetite have a ferric oxide layer that has a local environment similar to ferrihydrite, as indicated by the Raman, however on the magnetite surface this phase does not have the high surface curvature of the ferrihydrite prepared directly from Fe(NO3)3 hydrolysis. The high surface curvature inherent with very small sized particles such as ferrihydrite (≈2 nm), has been linked with a low propensity of H4SiO4 oligomerization on these surfaces. The results from this study support the association between surface curvature and propensity for interfacial H4SiO4 oligomerization. Magnetite prepared from FeSO4:FeCl3 had minor amounts of goethite and was found to promote the formation of a higher degree of 3 dimensional H4SiO4 polymerization on this oxide which is attributed to the nature of the (021) goethite faces.

Firework displays produce large amounts of particulate matter (PM), contributing to poor air quality in local areas. Since short-term exposure to particulate matter correlates with increased mortality risks, these celebrations may impact both human health and the environment. Little is known about the particulate matter produced from recreational fireworks, as most studies have focused on professional large-scale events. In New Zealand, it is common for consumer fireworks to be ignited within residential areas during the Guy Fawkes celebration around 5 November. To better understand the contribution of individual fireworks on local air quality, ambient PM

The toxicity of heavy metals commonly impacts the survival of crustacean and bivalve larvae in hatchery culture, and this has led to the widespread use of EDTA to decrease this toxicity. Since EDTA has a very poor biodegradability leading to potential persistent environmental effects, alternative methods to prevent heavy metal toxicity to shellfish larvae are needed. EDDS is a biodegradable potential alternative to EDTA for this application and was tested as a treatment of the seawater used for rearing aquaculture Greenshell™ mussel (Perna canaliculus) larval embryos in this study. Mussel embryos reared with EDTA or EDDS had significantly better survival than without. The concentrations and spatial distributions of heavy metals in D-veliger larvae as determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and X-ray Fluorescence Microscopy (XFM) suggested that chelating agents increased the levels of calcium in larvae while they reduced the concentration of zinc. In addition, where decreased accumulation of the other heavy metals was not observed, chelating agents affected their distribution within the larvae, especially for copper and arsenic. This is the first study to test the use of EDDS for aquaculture hatchery application and shows that EDDS is an effective biodegradable alternative to EDTA that can mitigate the effects of heavy metals for shellfish larval rearing.

Oxidizing decontamination agents such as the Vanguard-Allen CASCAD foam can be used to contain the blast from an improvised explosive device and can also be used to decontaminate conventional chemical weapons via hydrolysis or oxidation reactions. However, chemical analysis of such foams remains a challenge due to complex sample matrices that can contain chlorine bleaches (such as dichloroisocyanurate), co-solvents, and surfactants. To overcome this issue, we have developed a combined liquid-liquid extraction and solid phase extraction (SPE) protocol that isolates toxicologically relevant anionic analytes, such as monofluoroacetate (CH2FCO2−), from such a matrix. The protocol development was monitored by 1H decoupled 19F NMR spectroscopy, which gave a limit of detection of 0.1 mM for CH2FCO2− using a 20 min acquisition time. After separation using a strong anion exchange (SAX) SPE column and an eluent of 10% ammonia in methanol, the analyte was derivatised using 2,4-dichloroaniline and dicyclohexylcarbodiimide (DCC) before GC–MS analysis. This resulted in a limit of detection of 5.9 μM for monofluoroacetate in a CASCAD decontamination foam matrix.

In aquatic systems ferrihydrite forms as highly porous aggregates that resemble swollen gels. Much insight into the surface chemistry of ferrihydrite has been gleaned using a technique in which ferrihydrite is dried on to the surface of a crystal that acts as an Attenuated Total Reflectance (ATR) medium for in situ infrared (IR) studies of ligand sorption. In this paper BET N2 adsorption, acid-base titration, H4SiO4 isotherms and the relationship between H4SiO4 sorption and H4SiO4 interfacial oligomerization are used to systematically probe the influence of this drying step on ferrihydrite's surface chemistry. This means that insights into sorption reactions revealed from in situ ATR-IR are can be increasingly related to real environmental systems. Comparing the measured acid-base titration curves to the theoretical curve provide a specific surface area (SSA) estimation of ≈600 and 290 m2 g−1 for the fresh and film-dried ferrihydrite respectively, compared to the BET N2 adsorption values of 240 and 140 m2 g−1 where the fresh ferrihydrite was freeze dried prior to BET measurement. The H4SiO4 isotherms were identical on the two ferrihydrite samples when normalized to the titration derived surface areas. The extent of interfacial H4SiO4 oligomerization provides insights into surface structures. Within experimental uncertainty, the process of drying ferrihydrite into a film did not alter either the general trend in the relationship between sorption and oligomerization, or the extent of oligomerization as a function of surface coverage normalized to the titration derived surface areas. Therefore, in comparable laboratory studies where sorption densities for dried films are compared with fresh suspensions the SSA values of 290 and 600 m2 g−1 respectively should be a reasonable estimate.

The use of commercial moisturizers in sexual assault cases has been reported across the globe. Currently, there are limited protocols for the analysis of moisturizers as supporting evidence, and it is unknown if moisturizers persist on skin for forensically-relevant timescales. To better understand the potential for moisturizer evidence to be analyzed as part of a medical examination kit connected to sexual assaults, a participant-based persistence trial was conducted using both glycerol-based and petrolatum-based moisturizer products. Selected target analytes were monitored using GC–MS as tracers of moisturizer persistence: petrolatum, glycerol, cetyl alcohol, isopropyl palmitate, ethylparaben, and methylparaben. The petrolatum-based moisturizer persisted on human skin for 13.5 ± 0.7 h while the glycerol-based moisturizer persisted for 19.8 ± 1 h. Petrolatum had the shortest skin surface lifetime (12 h) while cetyl alcohol had the longest (23.5 h), which may be related to its increased chemical interaction with the skin surface. Exercising and bathing activities correlated with a decrease in moisturizer persistence while skin cover was associated with an increase in moisturizer persistence, meaning the moisturizer lifetimes reported here may underestimate those in covered intimate areas. The observed persistence lifetimes give optimism that moisturizers can be sampled and used as forensic evidence in sexual assault investigations. Through this study, a general sampling and extraction protocol was developed, providing a template that can be used for future work.

The emergence of chemically masked illicit drugs represents a challenge to global initiatives that are working to prevent their manufacture and distribution. Targeted analytical techniques currently used by law enforcement to identify unknown materials rely on spectroscopic and spectrophotometric databases that do not currently include some of these compounds, making their identification challenging. This study aimed to update compound spectral libraries to aid in the rapid detection and identification of these masked drugs, as well as to provide insight into their synthetic procedures. Five commonly employed protecting groups, acetyl, p-tosyl, methoxycarbonyl, Fmoc, and t-Boc, were appended to pseudoephedrine, ephedrine, methamphetamine, and MDMA. Characterization was carried out using NMR, GC-MS, FTIR, high-resolution LC-MS/MS, and common screening color tests. Some of the methoxycarbonyl and t-Boc derivatives and all of the Fmoc derivatives showed partial or full thermal degradation or rearrangement during GC-MS analysis, while LC-MS/MS analysis did not always show characteristic fragmentation that would allow unambiguous assignment of the structure. Restricted rotation in some of the derivatives meant that NMR assignments could only be made using NMR spectra acquired at elevated temperature. Therefore, GC-MS and LC-MS/MS analyses serve complementary roles for these derivatives, with NMR providing confirmation of structure for the pure materials if necessary.

BACKGROUND: Dimethyl sulfide (DMS) is a small sulfur‐containing impact odorant, imparting distinctive positive and / or negative characters to food and beverages. In white wine, the presence of DMS at perception threshold is considered to be a fault, contributing strong odors reminiscent of asparagus, cooked cabbage, and creamed corn. The source of DMS in wine has long been associated with S‐methyl‐l‐methionine (SMM), a derivative of the amino acid methionine, which is thought to break down into DMS through chemical degradation, particularly during wine ageing. RESULTS: We developed and validated a new liquid chromatography–tandem mass spectrometry (LC–MS/MS) method with a stable isotope dilution assay (SIDA) to measure SMM in grape juice and wine. The application of this new method for quantitating SMM, followed by the quantitation of DMS using headspace‐solid phase micro‐extraction coupled with gas chromatography–mass spectrometry (HS‐SPME/GC–MS), confirmed that DMS can be produced in wine via the chemical breakdown of SMM to DMS, with greater degradation observed at 28 °C than at 14 °C. Further investigation into the role of grape juice and yeast strain on DMS formation revealed that the DMS produced from three different Sauvignon blanc grape juices, either from the SMM naturally present or SMM spiked at 50 mmol L⁻¹, was modulated depending on each of the four strains of Saccharomyces cerevisiae wine yeast used for fermentation. CONCLUSION: This study confirms the existence of a chemical pathway to the formation of DMS and reveals a yeast‐mediated mechanism towards the formation of DMS from SMM during alcoholic fermentation. © 2019 Society of Chemical Industry

The deposition of methamphetamine within indoor environments due to illegal activities can pose a health risk for occupants. Current cleaning techniques are costly and inefficient, calling for the development of alternative remediation methods. In addition, the fate of methamphetamine in indoor environments is largely unknown, negatively impacting our knowledge on the health risks associated with contaminated dwellings. Under the conditions of this study, 97% of surface deposited methamphetamine on a paper substrate was consumed after 12 min of exposure to ozone, thus demonstrating potential for its use as a remediation agent. The reaction had an effective second-order rate constant with an upper limit of 2.15 ± 1 × 10-18 cm3 /molecule/s, and the main product observed was phenyl-2-propanone (P2P) at 8.3% yield, as determined using GC/MS. Several products observed in this study have also been reported as by-products of methamphetamine synthesis, including P2P-a known methamphetamine precursor, which indicates that their detection at a potential clandestine site is not necessarily evidence of manufacture.

A porous silicon thin film photonic crystal (rugate) sample with both a radial gradient in the rugate reflectance band wavelength and two spatially separated pore-wall surface chemistries (methylated and oxidized) was monitored by hyperspectral and color imaging while it was dosed with vapors of acetone, ethanol, heptane, 2-propanol, and toluene at concentrations ranging from 100 to 3,000 mg m−3. The shift in the wavelength of the rugate reflectance band maximum at each position along a transect across the two surface chemistries, as derived from the hyperspectral imaging, could discriminate between the different solvents and concentrations of solvents, while the change in hue derived from the color camera data along an analogous transect did not provide discrimination. The discrimination between solvents was mainly due to the two different surface chemistries, and the gradient associated with the change in the rugate reflectance band wavelength did not affect the selectivity significantly. There was spatial variability in the spectral and color responses along the transect independent of the overall rugate reflectance band wavelength gradient and pore-wall surface chemistries, and this was attributed to factors such as the presence of striations in the silicon wafer from which the porous silicon was prepared.

Clandestine laboratories pose a serious health risk to first responders, investigators, decontamination companies, and the public who may be inadvertently exposed to methamphetamine and other chemicals used in its manufacture. Therefore there is an urgent need for reliable methods to detect and measure methamphetamine at such sites. The most common method for determining methamphetamine contamination at former clandestine laboratory sites is selected surface wipe sampling, followed by analysis with gas chromatography-mass spectrometry (GC-MS). We are investigating the use of sampling for methamphetamine vapour to complement such wipe sampling. In this study, we report the use of capillary microextraction (CME) devices for sampling airborne methamphetamine, and compare their sampling efficiency with a previously reported dynamic SPME method. The CME devices consisted of PDMS-coated glass filter strips inside a glass tube. The devices were used to dynamically sample methamphetamine vapour in the range of 0.42-4.2μgm-3, generated by a custom-built vapour dosing system, for 1-15min, and methamphetamine was analysed using a GC-MS fitted with a ChromatoProbe thermal desorption unit. The devices showed good reproducibility (RSD

The public health risks associated with methamphetamine contamination in residential homes is of concern in many jurisdictions. Current regulatory remediation guidelines target the removal of methamphetamine as it is the primary residue found at sites of illicit manufacture and/or use of the drug. However, other substances present, including decomposition products of methamphetamine, may also be of health concern. Identification of such decomposition products will allow scientists to gain a deeper understanding of the degradation mechanisms of methamphetamine in order to identify compounds which may pose risks to public health and to determine more efficient decontamination methods. Controlled oxidative reaction of methamphetamine residue by nitrous acid (HONO) gas, a ubiquitous indoor pollutant, caused the potent environmental carcinogen and potential human mutagen N-nitrosomethamphetamine (NMA) to form. In order to develop a method that could detect this compound in field samples from suspected sites of methamphetamine contamination, samples of NMA were deposited onto wiping media and processed following typical extraction and derivatisation protocols used for methamphetamine surface wipe analysis. NMA was observed to undergo chemical derivatisation with the fluorinated derivatising agent, trifluoroacetic anhydride, to form 2,2,2-trifluoro-N′-formyl-N′-(1-phenylpropan-2-yl)acetohydrazide. The structure was confirmed by synthesis of the derivative and characterisation using GC–MS, LC–MS, and NMR. Detection of NMA at sites with methamphetamine contamination would imply that there is a necessity for additional research to be conducted to ensure that public health is sufficiently protected.

Heavy metal pollution is a concern in many coastal locations where it is frequently deleterious to the survival of young shellfish. Consequently, a great number of commercial shellfish hatcheries around the world rely on the addition of ethylenediaminetetraacetic acid (EDTA) to seawater to ensure successful larval production. Despite the importance of this practice to global shellfish production the mode of action of EDTA in larval production remains undetermined. It is assumed EDTA chelates heavy metals in seawater preventing interference in larval development. Larval mussels (Perna canaliculus) raised in seawater with 3 μM EDTA had a 15 fold higher yield than those without EDTA. The concentration and spatial arrangement of heavy metals in larvae as determined by Inductively Coupled Plasma Mass Spectrometry (ICPMS) and X-ray Fluorescence Microscopy (XFM) was consistent with reduced bioavailability of several metals, especially copper and zinc. This is the first study to confirm the effectiveness of EDTA for managing metal pollution commonly encountered in coastal shellfish hatcheries.

Emerging evidence indicates that levels of advanced glycation end-products (AGEs) correlate with age- and diabetes-related organ damage and may play a causative role in such damage. Increased chelation of Cu(II) ions appears to play an important role in this process, however, the precise relationship between formation of AGEs and accumulation of Cu(II) is yet to be determined. The interaction between AGEs and Cu(II) has been investigated using a collagenous peptide that has been site-specifically modified by a key AGE. Potentiometric titration showed that introduction of this AGE increased the capacity of the host-peptide to bind Cu(II). This result was confirmed by mass spectrometric characterisation of the AGE-modified peptide-Cu(II) system.

Enhancement of the sebaceous components of fingermarks is often performed using an aqueous staining solution. We propose an alternative approach using a bodipy-based lipid-selective dye (LD540) in a fluorous solvent. This fluorous approach can result in excellent retention of the spatial distribution of lipids and can be used on substrates unsuited to treatment with aqueous solutions. We demonstrate the new possibilities enabled by using fluorous solvents by staining fingermarks on an NaCl salt plate and on a block of ice.

Capillary microextraction of volatiles (CMV), a high surface area sampling technique, was combined with on-sorbent derivatisation to develop a sensitive alternative to dynamic solid phase microextraction (SPME) sampling for airborne methamphetamine. CMV devices pre-loaded with pentafluorobenzyl chloroformate were used to sample methamphetamine vapour at a concentration of 4.2 μg m−3 for periods of 2–10 min and the retained analytes analysed using gas chromatography-mass spectrometry (GC–MS). The methamphetamine pentafluorobenzyl carbamate derivative formed under ambient conditions. This CMV technique showed over 60 times greater sensitivity compared to dynamic solid phase microextraction (SPME) sampling for airborne methamphetamine, and the CMV devices could be stored for up to 5 days post-sampling, without loss of analyte. The inter-device variability (∼15%) was the same for the CMV devices with or without prior derivatisation, however the intra-device reproducibility was under 7% when derivatised.

A line-scan hyperspectral imager can provide real-time spectral information at many points along a transect of a gradient-modified material. This is demonstrated by monitoring the optical reflectance spectrum of a porous silicon photonic crystal with a hydrophobic/hydrophilic pore-wall surface composition gradient while it is immersed in water to which ethanol is added. The combination of the hyperspectral imager and the pore-wall composition gradient allows a detailed study of the pore filling process. It is observed that even the most hydrophobic pores fill to a small extent when only a small amount of ethanol has been added. This gradient of filling is in contrast to visible observation of the porous silicon samples, which can suggest a step change in pore filling. The pore-filling process can take many minutes when the solution composition allows pores at a given position along the gradient to be about 50% filled. These observations demonstrate the utility of aligning a line-scan hyperspectral imager with a gradient material.

article i nfo The iron oxide phases that precipitate in weathered environments can contain large amounts of adsorbed silicic acid (H4SiO4). This adsorbed silicate can be present as monomeric or oligomeric silicate species and affects many properties of iron oxides such as morphology, phase stability and surface charge. Therefore understanding the chemistry of H4SiO4 at iron oxide interfaces is important to describe the geochemistry of iron oxides and the elements that are associated with iron oxides. In this study we have measured the Si 2s and Si 2p binding energies (BE) in the XPS spectra of silicate adsorbed onto preformed ferrihydrite under conditions where the silicate surface chemistry is well defined. The positions of both the Si 2s and Si 2p peaks are indicative of the degree of polymerization of adsorbed silicate, but the Si 2p peaks overlap with an Fe 3p multiplet splitting peak. For ferrihydrite-adsorbed H4SiO4 the Si 2s peak BE increased from 153.1 to 153.9 eV as the H4SiO4 surface concentrations (ΓSi in mol Si (mol Fe) −1 ) increased from 0.03 to 0.2. The low ΓSi Si 2s BE value is slightly lower than the Si 2s BE of the orthosilicate almandine (153.3 eV), while the high ΓSi value lies midway between almandine and the tectosilicate quartz (154.6 eV). The positions of the Si 2s peaks correlate with the Si-O stretching bands (ν(Si-O)) in the FTIR spectra and are consistent with a model in which monomeric silicate species are present at low ΓSi and one dimensional oligomers are formed at higher ΓSi. The Si 2s BE and ν(Si-O) for synthetic and natural ferrihydrites co-precipitated with silicates are substantially lower than those for silicate adsorbed onto preformed ferrihydrite, clearly indicating a lower degree of silicate polymerization for silicate adsorbed onto the internal surfaces between ferrihydrite domains. The Si 2s and ν(Si-O) for co-precipitated ferrihydrites appear to be indicative of the age of the ferrihydrite and the rate of ferric precipitation.

Evaluation of the risk posed by contaminants present during and after decontamination of clandestine methamphetamine laboratories requires a connection between the levels of contaminants measured and those actually present at the scene. The recoveries of pseudoephedrine and methamphetamine from glass, stainless steel, and a range of impermeable surfaces likely to be found in a clandestine laboratory were examined, using GC-MS of derivatized samples as the analytical method. When surfaces had been cleaned prior to drug deposition, wiping with water-dampened filter paper can recover 60-80% of pseudoephedrine immediately after deposition, and at least 50% of the pseudoephedrine still present on a surface after 2 days when deposited at a surface concentration of 2.5 microg/100 cm(2). Wiping with methanol-dampened filter paper could recover 60-90% of the methamphetamine immediately after deposition, and could recover at least 50-60% of the methamphetamine still present after 2 days when 0.6 microg/100 cm(2) was initially deposited on the surface. Recoveries were lower for surfaces that had not been pre-cleaned. Methamphetamine and pseudoephedrine showed significant volatility in both the free base and hydrochloride forms, with experiments in an enclosed format showing up to half the recovered drug being present on a glass plate held about 4mm above a substrate contaminated with one of the drugs at the above surface concentrations after 2 days. It is therefore important to remove any visible bulk contaminants and remove obvious pseudoephedrine or methamphetamine-contaminated surfaces prior to heating, ventilation or sealing of a clandestine laboratory to avoid redistribution of material around the site. A revised method for pseudoephedrine analysis was developed that could also detect the pseudoephedrine-formaldehyde adduct that can form from trace pseudoephedrine present at clandestine laboratories.

Silicic acid (H4SiO4) can have significant effects on the properties of iron oxide surfaces in both natural and engineered aquatic systems. Understanding the reactions of H4SiO4 on these surfaces is therefore necessary to describe the aquatic chemistry of iron oxides and the elements that associate with them. This investigation uses attenuated total reflectance infrared spectroscopy (ATR-IR) to study silicic acid in aqueous solution and the products formed when silicic acid adsorbs onto the surface of a ferrihydrite film in 0.01 M NaCl at pH 4. A spectrum of 1.66 mM H4SiO4 at pH 4 (0.01 M NaCl) has an asymmetric Si–O stretch at 939 cm−1 and a weak Si–O–H deformation at 1090 cm−1. ATR-IR spectra were measured over time (for up to 7 days) for a ferrihydrite film (≈1 mg) approaching equilibrium with H4SiO4 at concentrations between 0.044 and 0.91 mM. Adsorbed H4SiO4 had a broad spectral feature between 750 and 1200 cm−1 but the shape of the spectra changed as the amount of H4SiO4 adsorbed on the ferrihydrite increased. When the solid phase Si/Fe mole ratio was less than ≈0.01 the ATR-IR spectra had a maximum intensity at 943 cm−1 and the spectral shape suggests that a monomeric silicate species was formed via a bidentate linkage. As the solid phase Si/Fe mole ratio increased to higher values a discrete oligomeric silicate species was formed which had maximum intensity in the ATR-IR spectra at 1001 cm−1. The spectrum of this species suggests that it is larger than a dimer and it was tentatively identified as a cyclic tetramer. A small amount of a polymeric silica phase with a broad spectral feature centered at ≈1110 cm−1 was also observed at high surface coverage. The surface composition was estimated from the relative contribution of each species to the area of the ATR-IR spectra using multivariate curve resolution with alternating least squares. For a ferrihydrite film approaching equilibrium with 0.044, 0.14, 0.40 and 0.91 mM H4SiO4 the area of the spectra accounted for by monomeric species were 92%, 49%, 23% and 6%, respectively. The remainder was oligomer apart from a small amount (

Discrimination of material based on elemental composition was achieved within a compositional data (CoDa) analysis framework in a form appropriate for use in forensic science. The methods were carried out on example data from New Zealand nephrite. We have achieved good separation of the in situ outcrops of nephrite from within a well-defined area. The most significant achievement of working within the CoDa analysis framework is that the implications of the constraints on the data are acknowledged and dealt with, not ignored. The full composition was reduced based on collinearity of elements, principal components analysis (PCA) and scalings from a backwards linear discriminant analysis (LDA). Thus, a descriptive subcomposition was used for the final discrimination, using LDA, and proved to be more successful than using the full composition. The classification based on the LDA model showed a mean error rate of 2.9% when validated using a 10 repeat, three-fold cross-validation. The methods presented lend objectivity to the process of interpretation, rather than relying on subjective pattern matching type approaches.

Adsorption of Cu 2+ , Zn 2+ , Cd 2+ , and Pb 2+ onto goethite is enhanced in the presence of sulfate. This effect, which has also been observed on ferrihydrite, is not predicted by the diffuse layer model (DLM) using adsorption constants derived from single sorbate systems. However, by including ternary surface complexes with the stoichiometry FeOHMSO 4 , where FeOH is a surface adsorption site and M 2+ is a cation, the effect of SO 4 2− on cation adsorption was accurately predicted for the range of cation, goethite and SO 4 2− concentrations studied. While the DLM does not provide direct molecular scale insights into adsorption reactions there are several properties of ternary complexes that are evident from examining trends in their formation constants. There is a linear relationship between ternary complex formation constants and cation adsorption constants, which is consistent with previous spectroscopic evidence indicating ternary complexes involve cation binding to the oxide surface. Comparing the data from this work to previous studies on ferrihydrite suggests that ternary complex formation on ferrihydrite involves complexes with the same or similar structure as those observed on goethite. In addition, it is evident that ternary complex formation constants are larger where there is a stronger metal–ligand interaction. This is also consistent with spectroscopic studies of goethite–M 2+ –SO 4 2− and phthalate systems showing surface species with metal–ligand bonding. Recommended values of ternary complex formation constants for use in SO 4 -rich environments, such as acid mine drainage, are presented.

Exposure of forensic evidence to either hydrogen chloride or chlorine can result in acidification to such an extent that enhancement of fingermarks with ninhydrin or cyanoacrylate is inhibited. Under these circumstances, pretreatment of samples with volatile bases such as triethylamine or ethanolamine prior to using these enhancement techniques can lead to successful visualization of fingermarks. Alternatively, physical enhancement techniques such as powder dusting or small particle reagent can be used on acidified non-porous substrates, although the former technique is subject to increased background under such conditions.

Digital microfluidics involves the manipulation of molecules and materials in discrete packages. This paper reviews our work using amphiphilic magnetic microparticles constructed from porous silicon. An individual porous particle can be used to carry a nanomole or smaller quantities of a reagent, and assemblies of the particles can encapsulate and transport microliter droplets of liquid containing inorganic, organic, or biological molecules. The tracking and identification of each particle can be accomplished with spectral labels that are encoded into the particles during their synthesis. When used to chaperone liquid droplets, the labels can identify the separate droplets prior to mixing and also the combined droplets after mixing. Magnetic iron oxide nanoparticles encapsulated in the porous matrix allow the manipulation of the particles or whole droplet assemblies with a magnetic field, and they also allow heating of the particle's payload by means of an externally applied RF field. Examples of organic, inorganic, and biomolecular addition reactions, catalytic reactions, and thermolysis reactions are described.

The forensic application of the luminol chemiluminescence reaction is reviewed. Luminol has been effectively employed for more than 40 years for the presumptive detection of bloodstains which are hidden from the naked eye at crime scenes and, for this reason, has been considered one of the most important and well-known assays in the field of forensic sciences. This review provides an historical overview of the forensic use of luminol, and the current understanding of the reaction mechanism with particular reference to the catalysis by blood. Operational use of the luminol reaction, including issues with interferences and the effect of the luminol reaction on subsequent serological and DNA testing is also discussed.

Improved detection of forensic evidence by combining narrow band photographic images taken at a range of wavelengths is dependent on the substance of interest having a significantly different spectrum from the underlying substrate. While some natural substances such as blood have distinctive spectral features which are readily distinguished from common colorants, this is not true for visualization agents commonly used in forensic science. We now show that it is possible to select reagents with narrow spectral features that lead to increased visibility using digital cameras and computer image enhancement programs even if their coloration is much less intense to the unaided eye than traditional reagents. The concept is illustrated by visualising latent fingermarks on paper with the zinc complex of Ruhemann's Purple, cyanoacrylate-fumed fingerprints with Eu(tta) 3 (phen), and soil prints with 2,6-bis(benzimidazol-2-yl)-4-[4′-(dimethylamino)phenyl]pyridine [BBIDMAPP]. In each case background correction is performed at one or two wavelengths bracketing the narrow absorption or emission band of these compounds. However, compounds with sharp spectral features would also lead to improved detection using more advanced algorithms such as principal component analysis.

Ferrihydrite adsorption of Co, Pb and Cd is enhanced in the presence of sulfate. This effect, which has been observed previously for Cu and Zn, is not predicted by the diffuse layer model using adsorption constants derived from single sorbate systems. However, by including ternary surface complexes with the stoichiometry ≡FeOHMeSO 4 , where ≡Fe is an Fe on the ferrihydrite surface and Me is Co, Pb, or Cd, the effect of SO 4 on cation adsorption is accurately predicted for the range of cation, ferrihydrite and SO 4 concentrations studied. Surface site heterogeneity for Co, Pb and Cd adsorption in the absence of SO 4 also was considered. While Co adsorption could be described with a 2-site model (with site densities of 5×10 −3 and 2×10 −1 mol mol Fe −1 ) Pb adsorption required a third site with a higher affinity and a site density of 3.5×10 −4 mol molFe −1 . Cadmium adsorption was reasonably well described with a 2-site model but showed some evidence for a third higher affinity site. Recommended values of adsorption constants for use in SO 4 -rich environments, such as acid mine drainage, are presented.

The chemical stability of electrochemically alkylated porous silicon is studied. The hydride-terminated surface of p-type or p++-type porous silicon is stabilized by electrochemical reduction of or...

The FTIR band corresponding to the Si–C stretch in methylated porous silicon shows an anomalous isotope shift for CD3 due to mixing of the stretch and the methyl rocking motion. The shift in the Si–C stretching frequency observed for 13 CH 3 is that expected for the change in reduced mass of the methyl group. The Si–C band is in a region (650– 690 cm −1 ) where it will be obscured by residual Si–H bands unless alkylation proceeds to high coverage such as is observed upon methylation (ca. 80% replacement of Si–H). The Raman spectra of porous silicon and methylated porous silicon are reported, and it is shown that this technique is not significantly better than FTIR for the identification of the Si–C stretching band.

The crystal structure of [FeIII(TF4TMAP)(H2O)2](CF3SO3)5·2CH3CN·2H2O (a = 13.065(2) A, b = 13.375(2) A, c = 13.839(2) A, α = 110.97°, β = 104.97°, γ = 94.22°, V = 2144.2(6) A3, Z = 1) shows that th...

We report a thermally tunable multispectral imaging filter based on reversible condensation of volatile organic fluids within a nanoporous one-dimensional photonic crystal. The photonic crystal (optical rugate filter) comprises oxidized porous silicon, prepared by electrochemical etch of silicon and subsequent air oxidation (porous silica rugate filter, pSiF). The reflectance spectrum of the pSiF is designed and constructed to match two of the red emission bands of the luminescent complex europium(III) tris-dipicolinate, [Eu(dpa)3](3-), which has been used as an indicator for anthrax spores. When the pSiF is fitted with a thermoelectric Peltier cooler/heater and sealed in a container with 2-propanol vapor, microcapillary effects drive the temperature-dependent condensation/evaporation of 2-propanol into/out of the porous nanostructure. Thermal cycling experiments show that the wavelengths of the spectral bands of the pSiF are reversibly tuned by ±35 nm for a temperature change of ±40 °C. Difference images of a UV-illuminated scene containing the [Eu(dpa)3](3-) target, obtained by reflection from pSiF that is continuously thermally cycled through the emission bands of the dye, show that the target can be discriminated from the background or from control targets with overlapping but dissimilar luminescence spectra.

The deprotonated form of the water-soluble porphyrin 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin, H2OBT(4-N-MePy)P4+, has a strong affinity for lithium and f...

The effect of ionic strength on reactions at aqueous interfaces can provide insights into the nature of the chemistry involved. The adsorption of H(4)SiO(4) on iron oxides at low surface silicate concentration (Γ(Si)) forms monomeric silicate complexes with Fe-O-Si linkages, but as Γ(Si) increases silicate oligomers with Si-O-Si linkages become increasingly prevalent. In this paper, the effect of ionic strength (I) on both Γ(Si) and the extent of silicate oligomerization on the ferrihydrite surface is determined at pH 4, 7, and 10, where the surface is, respectively, positive, nearly neutral, and negatively charged. At pH 4, an increase in ionic strength causes Γ(Si) to decrease at a given H(4)SiO(4) solution concentration, while the proportion of oligomers on the surface at a given Γ(Si) increases. At pH 10, the opposite is observed; Γ(Si) increases as I increases, while the proportion of surface oligomers at a given Γ(Si) decreases. Ionic strength has only a small effect on the surface chemistry of H(4)SiO(4) at pH 7, but at low Γ(Si) this effect is in the direction observed at pH 4 while at high Γ(Si) the effect is in the direction observed at pH 10. The pH where the surface has zero charge decreases from ≈8 to 6 as Γ(Si) increases so that the surface potential (Ψ) is positive at pH 4 for all Γ(Si) and at pH 7 with low Γ(Si). Likewise, Ψ0 at pH 10 for all Γ(Si) and at pH 7 with high Γ(Si). The diffuse layer model is used to unravel the complex and subtle interactions between surface potential (Ψ) and chemical parameters that influence interfacial silicate chemistry. This analysis reveals that the decrease in the absolute value of Ψ as I increases causes Γ(Si) to decrease or increase where Ψ is, respectively, positive or negative. Therefore, at a given Γ(Si), the solution H(4)SiO(4) concentration changes with I, and because oligomerization has a higher H(4)SiO(4) stoichiometry coefficient than monomer adsorption, this results in the observed dependence of the extent of silicate oligomerization on I.

One-dimensional photonic crystals (rugate filters) constructed from porous silicon were modified by the chemical hydrosilylation of terminal alkenes (decyl, 10-carboxydecyl, and 10-hydroxydecyl) in the presence of a concentration gradient of diazonium salt initiators. The concentration gradient was generated by vertically orienting the Si wafer containing the porous Si layer in an alkene solution and then introducing the diazonium salt at the bottom edge of the wafer. Slow diffusion of the salt led to a varying density of grafted alkene across the surface of the porous layer. The modified surfaces were end-capped with methyl groups by electrochemical grafting to impart improved stability and greater hydrophobicity. The surface modified with 10-carboxydecyl species was ionized by deprotonation of the carboxy groups to increase the hydrophilicity of this porous silicon surface. The pore-wall modification gradients were characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The more hydrophilic portion of the gradient changes color when water infiltrates the porous nanostructure because of a shift in the stop band of the photonic crystal. The more hydrophobic portion of the gradient excludes water, although mixtures of water and ethanol will infiltrate this region, depending on the concentration of ethanol in the mixture. A simple visual sensor for small quantities of ethanol in water, capable of detecting ethanol concentrations of between 0 and 8% with a resolution of 1% is demonstrated.

Silicic acid (H4SiO4) adsorbs at the ferrihydrite–water interface as monomeric or oligomeric surface silicate complexes. ATR-IR spectra were used to determine the proportions of monomeric and oligomeric surface silicate as a function of pH and Si surface concentrations (ΓSi) for H4SiO4 in ferrihydrite suspensions. At each pH the proportion of adsorbed silicate present as monomers decreased as ΓSi increased while at a given ΓSi the proportion of adsorbed silicate present as monomers was higher at higher pH. ATR-IR spectra for ferrihydrite suspensions in combination with the adsorption isotherm data were used to calibrate the Diffuse Layer Model (DLM) to describe H4SiO4 adsorption as monomers and oligomers on ferrihydrite surface sites (≡FeOH). Using a set of reactions that were consistent with the ATR-IR spectra the DLM could accurately describe the H4SiO4 adsorption isotherms, the distribution of surface monomeric and oligomeric silicates, and the decrease in surface potential with ΓSi. The reactions included the formation of monomeric complexes (≡FeH(3−n) SiO 4 ( - n ) ) and trimeric silicate complexes formed between two surface sites(≡Fe2H(6−n)Si3 O 10 ( - n ) ) . This oligomer stoichiometry is consistent with previous studies suggesting the surface silicate oligomer is formed by a solution H4SiO4 bridging two adjacent adsorbed monomers to form a linear trimer. This study also showed that carbonate can enhance H4SiO4 adsorption between pH 9 and 11. The data were consistent with formation of an outer-sphere complex between a solution H 3 SiO 4 - and a protonated adsorbed carbonate species which is analogous to the mechanism by which carbonate enhances the goethite adsorption of sulfate.

Thin film porous silicon layers have been constructed in which the level of chemical modification to the pore walls is altered in a controlled gradient across the material. The gradient modification within such a nanoporous material represents a significant advance over gradients imposed across a flat surface. Gradients of methyl, pentyl acetate, and decyl groups are formed via electrochemical attachment of organohalides with an asymmetric electrode arrangement. The stability and hydrophobicity of the latter two systems have been improved through postprocess “end-capping” of the porous silicon with methyl groups. Two-dimensional mapping transmission FTIR microspectrophotometry and ATR-FTIR have been employed to characterize these new materials. Cleaving the surface-attached pentyl acetate groups to 5-hydroxypentyl groups leads to materials that can act as efficient visual indicators of the ethanol concentration in water over the range 1−10 vol %.

Oxide surfaces can promote specific lateral interactions between adsorbed species that become concentrated in specific orientations at an interface. In this article, in situ attenuated total reflectance (ATR) IR spectra were collected over time (from 0 to approximately 100 h) as the iron oxide ferrihydrite reacted with H(4)SiO(4) (between 0.007 and 1.65 mM) and at a pH of 4, 7, or 10. Under all conditions, the first product formed was a monomeric surface species with distinct bands at 945 and 880 cm(-1), and a bidentate (2)C complex with SiO(4) sharing corners with two edge-linked Fe octahedra was proposed. Once a certain surface concentration (Gamma(Si)) of monomers was reached, a condensed oligomeric surface species with Si-O-Si linkages was observed on the surface with bands at 1005, 917, and 827 cm(-1) and one or more bands at1050 cm(-1). This species was observed as a minor surface component at Gamma(Si) that was up to 10 times lower than the calculated density of (2)C adsorption sites on ferrihydrite and became the dominant surface species at higher Gamma(Si). This formation of a specific oligomer is rationalized on the basis of a recent model for the ferrihydrite surface, with the arrangement of (2)C adsorption sites on the (021) ferrihydrite face causing adjacent Si monomers to be held in an orientation that is conducive to the formation of a condensed Si species upon insertion of a solution H(4)SiO(4). Therefore, this model predicts that the ferrihydrite surface may act as a template for oligomerization in one dimension forming segments of pyroxene-like structures. The ATR-IR spectra and changes in the surface species' composition with time are consistent with such a model.

A particle-based multiplexed DNA assay based on encoded porous SiO2 photonic crystal disks is demonstrated. A “spectral barcode” is generated by electrochemical etch of a single-crystal silicon wafer using a programmed current-time waveform. A lithographic procedure is used to isolate cylindrical microparticles 25 microns in diameter and 10 microns thick, which are then oxidized, modified with a silane linker, and conjugated to various amino functionalized oligonucleotide probes via cyanuric chloride. It is shown that the particles can be decoded based on their reflectivity spectra, and that a multiple analyte assay can be performed in a single sample with a modified fluorescence microscope. The homogeneity of the reflectivity and fluorescence spectra, both within and across the microparticles is also reported.