Laser Sensing and Chemometric Analysis for Rapid Detection of Oregano Fraud.

World health is increasingly threatened by the growing number of spice-related food hazards. Further development of reliable methods for rapid, non-targeted identification of counterfeit ingredients within the supply chain is needed. ENEA has developed a portable, user-friendly photoacoustic laser system for food fraud detection, based on a quantum cascade laser and multivariate calibration. Following a study on the authenticity of saffron, the instrument was challenged with a more elusive adulterant, olive leaves in oregano. The results show that the reported method of laser sensing and chemometric analysis was able to detect adulterants at mass ratios of at least 20% in less than five minutes.

Rapid Non-Contact Detection of Chemical Warfare Agents by Laser Photoacoustic Spectroscopy.

Nerve agents have recently been used in battlefield operations, espionage wars, and terrorist attacks. These compounds, like some pesticides, cause organophosphate poisoning. The rapid, noncontact detection of a sarin simulant in the liquid phase has been demonstrated at the Diagnostics and Metrology Laboratory of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development using laser photoacoustic spectroscopy, an infrared absorption technology. The first measurements, carried out with an experimental system based on a quantum cascade laser and developed for the assessment of food authenticity in the "fingerprint region", show that a detection limit of one nanolitre is within the reach of the instrument when chemometric analysis is applied.

Characterization and Discrimination of Italian Olive (Olea europaea sativa) Cultivars by Production Area Using Different Analytical Methods Combined with Chemometric Analysis.

Olives and olive products are particularly important for the national agroindustrial sector, for the aspects related to the production territory (authenticity), and for the link with the Mediterranean Diet. Several studies indicate that the elemental profile of olive and olive products depends on the production area in which the olive trees were grown, and the elemental content of the olives can be used as a marker of the production area. In order to confirm this hypothesis, the multi-elemental profile of olive drupes and olive leaves of eleven cultivars arising from two different production areas was evaluated through ICP-MS and ICP-AES techniques. In addition, some leaf samples were analysed by LPAS in order to evaluate the applicability of this new analytical technique for determining the geographic origin. The obtained results, combined with chemometric tools, showed the possibility of discriminating samples according to the production area on the basis of the elemental content, as well as by LPAS.

Photoacoustic Laser System for Food Fraud Detection.

Economically motivated adulterations of food, in general, and spices, in particular, are an emerging threat to world health. Reliable techniques for the rapid screening of counterfeited ingredients in the supply chain need further development. Building on the experience gained with CO2 lasers, the Diagnostic and Metrology Laboratory of ENEA realized a compact and user-friendly photoacoustic laser system for food fraud detection, based on a quantum cascade laser. The sensor has been challenged with saffron adulteration. Multivariate data analysis tools indicated that the photoacoustic laser system was able to detect adulterants at mass ratios of 2% in less than two minutes.

Hyperspectral Fluorescence LIDAR Based on a Liquid Crystal Tunable Filter for Marine Environment Monitoring.

An innovative hyperspectral LIDAR instrument has been developed for applications in marine environment monitoring research activities, remotely detecting the fluorescence spectra produced in the spectral interval between 400 nm and 720 nm. The detection system is composed by a custom made photomultiplier charge integrating and measuring (CIM) unit, which makes automatic background signal subtraction, and a liquid crystal tunable filter (LCTF). The new instrument therefore has hyperspectral resolution and allows automatic background subtraction; it is compact and automated by custom software that permit to adapt the instrument properties depending on the environmental conditions. Laboratory tests to characterize the instrument performance have been carried out, concluding that this sensor can be employed in remote sites for Chl-a detection.

Proximal Detection of Traces of Energetic Materials with an Eye-Safe UV Raman Prototype Developed for Civil Applications.

A new Raman-based apparatus for proximal detection of energetic materials on people, was developed and tested for the first time. All the optical and optoelectronics components of the apparatus, as well as their optical matching, were carefully chosen and designed to respect international eye-safety regulations. In this way, the apparatus is suitable for civil applications on people in public areas such as airports and metro or railway stations. The acquisition software performs the data analysis in real-time to provide a fast response to the operator. Moreover, it allows for deployment of the apparatus either as a stand alone device or as part of a more sophisticated warning system architecture made up of several sensors. Using polyamide as substrate, the apparatus was able to detect surface densities of ammonium nitrate (AN), 2-methyl-1,3,5-trinitrobenzene (TNT), 3-nitrooxy-2,2-bis(nitrooxymethyl)propyl] nitrate (PETN) and urea nitrate (UN) in the range of 100-1000 µg/cm² at a distance of 6.4 m using each time a single laser pulse of 3 mJ/cm². The limit of detection calculated for AN is 289 µg/cm². AN and UN provided the highest percentages of true positives (>82% for surface densities of 100-400 µg/cm² and fingerprints) followed by TNT and PETN (17%-70% for surface densities of 400-1000 µg/cm² and fingerprints).

New ground-based lidar enables volcanic CO2 flux measurements.

There have been substantial advances in the ability to monitor the activity of hazardous volcanoes in recent decades. However, obtaining early warning of eruptions remains challenging, because the patterns and consequences of volcanic unrests are both complex and nonlinear. Measuring volcanic gases has long been a key aspect of volcano monitoring since these mobile fluids should reach the surface long before the magma. There has been considerable progress in methods for remote and in-situ gas sensing, but measuring the flux of volcanic CO2-the most reliable gas precursor to an eruption-has remained a challenge. Here we report on the first direct quantitative measurements of the volcanic CO2 flux using a newly designed differential absorption lidar (DIAL), which were performed at the restless Campi Flegrei volcano. We show that DIAL makes it possible to remotely obtain volcanic CO2 flux time series with a high temporal resolution (tens of minutes) and accuracy (<30%). The ability of this lidar to remotely sense volcanic CO2 represents a major step forward in volcano monitoring, and will contribute improved volcanic CO2 flux inventories. Our results also demonstrate the unusually strong degassing behavior of Campi Flegrei fumaroles in the current ongoing state of unrest.

Submersible Spectrofluorometer for Real-Time Sensing of Water Quality.

In this work, we present a newly developed submersible spectrofluorometer (patent pending) applied to real-time sensing of water quality, suitable for monitoring some important indicators of the ecological status of natural waters such as chlorophyll-a, oil and protein-like material. For the optomechanical realization of the apparatus, a novel conceptual design has been adopted in order to avoid filters and pumps while maintaining a high signal-to-noise ratio. The elimination of filters and pumps has the advantage of greater system simplicity and especially of avoiding the risk of sample degradation. The use of light-emitting diodes as an excitation source instead of Xe lamps or laser diodes helped save on size, weight, power consumption and costs. For sensor calibration we performed measurements on water samples with added chlorophyll prepared in the laboratory. The sensor functionality was tested during field campaigns conducted at Albano Lake in Latium Region of Italy as well as in the Herzliya Harbor, a few kilometers North East of Tel Aviv in Israel. The obtained results are reported in the paper. The sensitivity achieved for chlorophyll-a detection was found to be at least 0.2 µg/L.

Differential absorption lidar for volcanic CO(2) sensing tested in an unstable atmosphere.

Motivated by the need for an extremely durable and portable instrument to quantify volcanic CO(2) we have produced a corresponding differential absorption lidar (DIAL). It was tested on a volcano (Vulcano, Italy), sensing a non-uniform volcanic CO(2) signal under turbulent atmospheric conditions. The measured CO(2) mixing ratio trend agrees qualitatively well but quantitatively poorly with a reference CO(2) measurement. The disagreement is not in line with the precision of the DIAL determined under conditions that largely exclude atmospheric effects. We show evidence that the disagreement is mainly due to atmospheric turbulence. We conclude that excluding noise associated with atmospheric turbulence, as commonly done in precision analysis of DIAL instruments, may largely underestimate the error of measured CO(2) concentrations in turbulent atmospheric conditions. Implications for volcanic CO(2) sensing with DIAL are outlined.

Volcanic CO2 detection with a DFM/OPA-based lidar.

The DFM/OPA-based lidar BILLI was used to investigate the volcanic plume released by the hydrothermal vent of Pisciarelli, in the Campi Flegrei volcano. BILLI remotely measured CO2 concentrations in cross-sections of the near-vent plume using the differential absorption technique. To our knowledge, this is the first example of lidar-based measurement of volcanic CO2. The spatial resolution was 1.5 m and the temporal resolution 20 s.

Measurement of Mount Etna plume by CO2-laser-based lidar.

The CO2 laser-based agile tuner lidar for atmospheric sensing has been used to profile the volcanic plume of Mount Etna during its most recent eruption. Owing to the transmitted wavelength, this system is practically insensitive to air molecules while it detects aerosol loads, and thus the path attenuation of the laser beam is strongly affected by volcanic particulate. Vertical profiles of extinction coefficient were retrieved up to an altitude above ground level of 5000 m. The observed extinction coefficient ranges from 10(-5) to 5x10(-4) m(-1). The lidar was able to accurately track the spatiotemporal evolution of the volcanic plume thanks to a spatial resolution of 15 m and a temporal resolution of 1 min.

Scanning flow cytometer modified to distinguish phytoplankton cells from their effective size, effective refractive index, depolarization, and fluorescence.

A laser flow cytometer based on scanning flow cytometry has been assembled. The unpolarized and linearly polarized light-scattering profiles, as well as the side emitted light in different spectral bands, were measured, allowing the simultaneous and real-time determination of the effective size and the effective refractive index of each spherelike particle. Additionally, each particle could be identified from depolarization and fluorescence measured simultaneously. The tests with aqueous samples of polystyrene spheres, fluorescent or nonfluorescent, and phytoplankton cells demonstrate that the system is able to retrieve size and refractive index with an accuracy of 1% and that the depolarization and fluorescence measurements allow the classification of particles otherwise indistinguishable.