Analytical techniques for the analysis of consumer fireworks

Firework injuries remain high in years after legalisation: its impact on children

PURPOSE

We evaluated the impact of Senate Bill 489 passed in May 2017, allowing the sale and use of fireworks in Iowa 1 June to 8 July and 10 December to 3 January, on hospital presentations for firework injuries in the state. To identify the public health implications of this law, we conducted a detailed subanalysis of hospital presentations to the two level I trauma centres.

METHODS

Hospital presentations for firework injuries from 1 June 2014 to 31 July 2019 were identified using the Iowa Hospital Admission database and registries and medical records of Iowa's two level 1 trauma centres. Trauma centres' data were reviewed to obtain demographics, injury information and hospital course. Prefirework and postfirework legalisation state data were compared using negative binomial regression analysis. Trauma centre data detailing injuries were compared using χ2 and Mann-Whitney U tests as appropriate.

RESULTS

Emergency department (ED) visits and hospital admissions for firework injuries increased in Iowa post-legalisation (B-estimate=0.598±0.073, p<0.001 and B-estimate=0.612±0.322, p=0.058, respectively). ED visits increased postlegalisation in July (73.6% vs 64.5%; p=0.008), reflecting an increase in paediatric admissions (81.8% vs 62.5%; p=0.006). Trauma centres' data showed similar trends. The most common injury site across both study periods was the hands (48.5%), followed by the eyes (34.3%) and face (28.3%). Amputations increased from 0 prelegalisation to 16.2% postlegalisation.

CONCLUSION

Firework legalisation led to an increase in the number of admissions and more severe injuries.

Detection and toxicity modeling of anthraquinone dyes and chlorinated side products from a colored smoke pyrotechnic reaction

"Green" pyrotechnics seek to remove known environmental pollutants and health hazards from their formulations. This chemical engineering approach often focuses on maintaining performance effects upon replacement of objectionable ingredients, yet neglects the chemical products formed by the exothermic reaction. In this work, milligram quantities of a lab-scale pyrotechnic red smoke composition were functioned within a thermal probe for product identification by pyrolysis-gas chromatography-mass spectrometry. Thermally decomposed ingredients and new side product derivatives were identified at lower relative abundances to the intact organic dye (as the engineered sublimation product). Side products included chlorination of the organic dye donated by the chlorate oxidizer. Machine learning quantitative structure-activity relationship models computed impacts to health and environmental hazards. High to very high toxicities were predicted for inhalation, mutagenicity, developmental, and endocrine disruption for common military pyrotechnic dyes and their analogous chlorinated side products. These results underscore the need to revise objectives of "green" pyrotechnic engineering.

An asymmetric pulsed current-assisted electrochemical method for Sr(Ⅱ) extraction using supramolecular composites

The development of effective, economical, and sustainable seawater extraction strontium techniques is of great significance to the environment and industrial needs. In this paper, an asymmetric pulsed current-assisted electrochemical (AP-CE) method was used to extract Sr(Ⅱ) from seawater using a carbon electrode modified by dibenzo-18-crown-6-ether and cellulose acetate. An asymmetric pulsed current was used to prevent unwanted cations from blocking adsorption sites to prevent water splitting. It also prevented the cellulose acetate membrane from sealing the crown ether. Compared with traditional physicochemical adsorption of Sr(Ⅱ), the AP-CE method achieved a higher removal efficiency and adsorption capacity. When the concentrations of Sr(Ⅱ) were 10, 20, 50, and 100 mg L^-1, the removal efficiencies of Sr(Ⅱ) were 99.3%, 97.6%, 97.3%, and 96.1%, and the adsorption capacities of Sr(Ⅱ) were 14.9, 29.3, 73.0, and 144.2 mg g^-1, respectively. This method exhibited excellent selectivity for Sr(Ⅱ) adsorption from simulated seawater, suggesting that the asymmetric pulse electrochemical method is promising for extracting strontium ions from seawater.

Investigations into the source attribution of party sparklers using trace elemental analysis and chemometrics

In Australia, party sparklers are commonly used to initiate or prepare inorganic based homemade explosives (HMEs) as they are the most easily accessible and inexpensive pyrotechnic available on the market. As sparkler residue would be encountered in cases involving these types of devices, the characterisation and source determination of the residue would be beneficial within a forensic investigation. The aim of this study is to demonstrate the potential of using trace elemental profiling coupled with chemometric and other statistical techniques to link a variety of different sparklers to their origin. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the concentration of 50 elements in 48 pre-blast sparkler samples from eight sparkler brands/classes available in Australia. Extracting ground-up sparkler residue in 10% nitric acid for 24 hours was found to give the most reliable quantification. The collected data were analysed using Principal Component Analysis (PCA) to visualise the distribution of the sample data and explore whether the sparkler samples could be classified into their respective brands. ANOVA based feature selection was used to remove elements that did not largely contribute to the separation between classes. This resulted in the development of a 7-elemental profile, consisting of V, Co, Ni, Sr, Sn, Sb, W, which could be used to correctly classify the samples into eight distinct groups. Linear Discriminant Analysis (LDA) was subsequently used to construct a discriminant model using four out of six samples from each class. The model successfully classified 100% of the samples to their correct sparkler brand. The model also correctly matched 100% of the remaining samples to the correct class. This demonstrates the potential of using trace elemental analysis and chemometrics to correctly identify and discriminate between party sparklers.

The characterization of fine particulate matter downwind of Houston: Using integrated factor analysis to identify anthropogenic and natural sources

The interpretation of large air pollution datasets involves a great deal of complexity. To gain a better understanding of the complicated relationships and patterns within datasets, we perform factor analysis. Between December 2015 and December 2017, fine particulate matter (PM_2.5) samples were collected at a suburban site northeast of the Houston metropolitan area, TX. A total of 233 filter samples were analyzed for chemical composition. The average of all PM_2.5 samples consisted of 38.1% inorganic ions, 28.9% elements, 29.1% organic carbon, and 3.7% elemental carbon and other organic materials. Principal component analysis and positive matrix factorization were utilized to identify eight factors: regional aerosols, biomass burning, gasoline combustion, industry, crustal material, incineration, marine dust, and fireworks. The first three contributed more than 70% of the total PM_2.5 mass. The receptor models also captured the impact of fireworks and classified it as a source of PM_2.5 over Houston. To identify the origins of air masses transporting PM_2.5 to the site, we applied the NOAA hybrid single-particle Lagrangian integrated trajectory model and performed a cluster analysis of back trajectories and determined six cluster source regions: the Gulf of Mexico, the Southeast, two midwestern clusters, the Pacific Northwest, and the Southwest. The results of our analysis show that during the summer months, marine and crustal sources were often associated with an onshore flow from the Gulf of Mexico and that four clusters covering 38% of the West Liberty area were strongly influenced by trajectories originating from biomass burning. The results of this study represented a variety of sources that affect the PM_2.5 over the Houston metropolitan area. The quantified contributions of these sources could provide policymakers with useful information for developing more efficient control systems and making more effective decisions to cope with the harmful effects of ambient air pollution.

Chemical Classification of Explosives

This work comprehensively reviews some fundamental concepts about explosives and their two commonly used classifications based on either their velocity of detonation or their application. These classifications are highly useful in the military/legal field, but completely useless for the chemical determination of explosives. Because of this reason, a classification of explosives based on their chemical composition is comprehensively revised, discussed and updated. This classification seeks to merge those dispersed chemical classifications of explosives found in literature into a unique general classification, which might be useful for every researcher dealing with the analytical chemical identification of explosives. In the knowledge of the chemical composition of explosives, the most adequate analytical techniques to determine them are finally discussed.

Modeling and simulation of the infection zone from a cough

The pandemic of 2020 has led to a huge interest of modeling and simulation of infectious diseases. One of the central questions is the potential infection zone produced by a cough. In this paper, mathematical models are developed to simulate the progressive time-evolution of the distribution of locations of particles produced by a cough. Analytical and numerical studies are undertaken. The models ascertain the range, distribution and settling time of the particles under the influence of gravity and drag from the surrounding air. Beyond qualitative trends that illustrate that large particles travel far and settle quickly, while small particles do not travel far and settle slowly, the models provide quantitative results for distances travelled and settling times, which are needed for constructing social distancing policies and workplace protocols.

Effects of fireworks on particulate matter concentration in a narrow valley: the case of the Medellín metropolitan area

The extensive use of fireworks generates large amounts of pollutants, deteriorating air quality and potentially causing adverse health impacts. In Medellín and its metropolitan area, although fireworks are banned during December, their use is widespread during the Christmas season, particularly during the midnight of November 30 (La Alborada) and New Year's Eve (NYE). It is therefore essential to assess the effects of these celebrations on air quality in the region. Air-quality data from the official monitoring network and a low-cost particulate matter (PM) citizen science project, backscattering intensity (BI) retrievals from a ceilometer network, potential temperature from a microwave radiometer, and information from a radar wind profiler provide an excellent platform to study the spatio-temporal distribution of contaminants resulting from the La Alborada and NYE celebrations. Substantial increases in PM2.5 and PM10 mass concentrations due to La Alborada and NYE, ranging in some cases from 50 to 100 μgm^-3, are observed in the Aburrá Valley and particularly in the densely populated communes of Medellín, with most concentration changes corresponding to ultrafine and fine particles. The PM increments resulting from fireworks show almost no increase in the net amount of black carbon in the atmosphere. Ceilometer BI profiles show a substantial change immediately after the La Alborada and NYE midnights, confined to the atmospheric boundary layer (ABL). Strong thermal inversions lead to fairly homogeneous increments in BI within the ABL, lasting until the onset of the convective boundary layer. In contrast, weak thermal inversions lead to rapid dispersion of aerosols, allowing them to episodically escape above the ABL.

Identification of inorganic oxidizing salts in homemade explosives using Fourier transform infrared spectroscopy

Recently, inorganic low explosives, such as pyrotechnic composition, black powder, and ammonium nitrate, are commonly used in improvised explosive devices (IEDs) by the rioter or terrorists since these energetic materials can be obtained easily and legally from civilian markets. Identification of inorganic oxidizing salts in these homemade explosives, including nitrates, chlorates, and perchlorates, is a necessary procedure for forensic investigators to provide criminal evidences. In this article, Fourier transform infrared (FTIR) spectroscopy was used to discriminate NO₃^-, CO₃^2-, ClO₃^-, ClO₄^-, SO₄^2-, and NH₄⁺, whose characteristic absorption bands were explained by vibration modes of the covalent bonds. Then the spectral absorption features of nitrate salts with monovalent or divalent cations were discussed. Furthermore, it was studied whether nitrates or perchlorates can be unequivocally distinguished with the presence of carbonate and sulfate impurities through FTIR technique. Finally, the feasibility of this method was verified through an analytical case of homemade explosives.

Forensic Analysis and Differentiation of Black Powder and Black Powder Substitute Chemical Signatures by Infrared Thermal Desorption-DART-MS

The trace detection and forensic analysis of black powders and black powder substitutes, directly from wipe-based sample collections, was demonstrated using infrared thermal desorption (IRTD) coupled with direct analysis in real time mass spectrometry (DART-MS). Discrete 15 s heating ramps were generated, creating a thermal desorption profile that desorbed more volatile species (e.g., organic and semivolatile inorganic compounds) at lower temperatures (250-400 °C) and nonvolatile inorganic oxidizers at high temperatures (450-550 °C). Common inorganic components of black powders (e.g., sulfur and potassium nitrate) as well as the alternative and additional organic and inorganic components of common black powder substitutes (e.g., dicyandiamide, ascorbic acid, sodium benzoate, guanidine nitrate, and potassium perchlorate) were detected from polytetrafluoroethylene-coated fiberglass collection wipes with no additional sample preparation. IRTD-DART-MS enabled the direct detection of intact inorganic salt species as nitrate adducts (e.g., [KClO4+NO3]-) and larger clusters. The larger ion distributions generated by these complex mixtures were differentiated using principal component analysis (PCA) of the mass spectra generated at two points during the thermal desorption profile (low and high temperatures), as well as at high in-source collision-induced dissociation. The PCA framework generated by the analysis of the two black powders and five black powder substitutes was used to classify samples collected from a commercial firecracker containing both flash powder and black powder. The coupling of IRTD-DART-MS and multivariate statistics demonstrated the powerful utility for detection and discrimination of trace fuel-oxidizer mixtures.

Non-Destructive Trace Detection of Explosives Using Pushbroom Scanning Hyperspectral Imaging System

The aim of this study was to investigate the potential of the non-destructive hyperspectral imaging system (HSI) and accuracy of the model developed using Support Vector Machine (SVM) for determining trace detection of explosives. Raman spectroscopy has been used in similar studies, but no study has been published which is based on measurement of reflectance from hyperspectral sensor for trace detection of explosives. HSI used in this study has an advantage over existing techniques due to its combination of imaging system and spectroscopy, along with being contactless and non-destructive in nature. Hyperspectral images of the chemical were collected using the BaySpec hyperspectral sensor which operated in the spectral range of 400–1000 nm (144 bands). Image processing was applied on the acquired hyperspectral image to select the region of interest (ROI) and to extract the spectral reflectance of the chemicals which were stored as spectral library. Principal Component Analysis (PCA) and first derivative was applied to reduce the high dimensionality of the image and to determine the optimal wavelengths between 400 and 1000 nm. In total, 22 out of 144 wavelengths were selected by analysing the loadings of principal components (PC). SVM was used to develop the classification model. SVM model established on the whole spectrum from 400 to 1000 nm achieved an accuracy of 81.11%, whereas an accuracy of 77.17% with less computational load was achieved when SVM model was established on the optimal wavelengths selected. The results of the study demonstrate that the hyperspectral imaging system along with SVM is a promising tool for trace detection of explosives.

Inland Sea Spray Aerosol Transport and Incomplete Chloride Depletion: Varying Degrees of Reactive Processing Observed during SOAS

Multiphase reactions involving sea spray aerosol (SSA) impact trace gas budgets in coastal regions by acting as a reservoir for oxidized nitrogen and sulfur species, as well as being a source of halogen gases (HCl, ClNO₂, etc.). Whereas most studies of multiphase reactions on SSA have focused on marine environments, far less is known about SSA transported inland. Herein, single-particle measurements of SSA are reported at a site >320 km from the Gulf of Mexico, with transport times of 7-68 h. Samples were collected during the Southern Oxidant and Aerosol Study (SOAS) in June-July 2013 near Centreville, Alabama. SSA was observed in 93% of 42 time periods analyzed. During two marine air mass periods, SSA represented significant number fractions of particles in the accumulation (0.2-1.0 μm, 11%) and coarse (1.0-10.0 μm, 35%) modes. Chloride content of SSA particles ranged from full to partial depletion, with 24% of SSA particles containing chloride (mole fraction of Cl/Na ≥ 0.1, 90% chloride depletion). Both the frequent observation of SSA at an inland site and the range of chloride depletion observed suggest that SSA may represent an underappreciated inland sink for NO_x/SO₂ oxidation products and a source of halogen gases.

Concurrent determination of anions and cations in consumer fireworks with a portable dual-capillary electrophoresis system

A new automated portable dual-channel capillary electrophoresis instrument was built and applied to the concurrent determination of cations and anions. The system uses a single buffer and hydrodynamic injection of the sample is performed autonomously. A novel engraved flow-cell interface is used at the injection ends of the capillaries allowing the autonomous operation of the system. The engraved flow-cell replaces traditionally used split injectors in purpose made capillary electrophoresis systems and makes the system design easier. A new software package with graphical user interface was employed to control the system, making its operation simple and increasing its versatility. The electrophoretic method was optimized to allow the baseline separation of 12 cations and anions commonly found in fireworks. The system was proven to be useful for the analysis of consumer fireworks, saving time and expenses compared to separate analyses for anions and cations. This is the first time that cationic and anionic compositions of fireworks are investigated together. The analysis of samples revealed several inaccuracies between the declared compositions for the fireworks and the obtained results, which could be attributed to cross-contamination during their manufacture or to a transfer between other components of the pyrotechnic item. The presence of certain unexpected peaks, however, had no apparent reason and might represent an irregularity in the manufacture of some devices.