Hand-held Spectrometer Research Articles

Prediction of meat quality traits in the abattoir using portable and hand-held near-infrared spectrometers

The use of near-infrared spectrometers (NIRS) for predicting meat quality traits directly in the abattoir was tested with three trials. For the calibration trial, spectra were acquired from the cross-cut surface of the Longissimus thoracis muscle on 1166 carcasses of Piemontese young bulls with a portable visible-near-infrared spectrometer (Vis-NIRS) and with a small hand-held instrument (Micro-NIRS). A sample of the same muscle was analyzed to provide the reference. Validation statistics of the two instruments were similar. Predictabilities of meat color and purge loss were good, whereas for the other traits they were less promising. The repeatability trial showed that post-slaughter factors, not predictable by NIR spectra collected in the abattoir, affect reference meat quality values. A trial under operative conditions showed that both spectrometers were able to capture the major sources of variation in most of the meat quality traits. Overall, NIRS could be used to predict the animals' “native” characteristics exploitable for genetic improvement of meat quality traits.

Food powders classification using handheld Near-Infrared Spectroscopy and Support Vector Machine

The aim of this study is to build a classifier model based on spectra data collected using handheld spectrometer that can classify between different types of food powders (flour and starch). A total of 70 samples were prepared from three different types of flour (whole wheat, organic wheat, and rice flour) and two different types of starch (corn and tapioca starch). Handpalm size handheld spectrometer is used to record the spectrum of each sample, the spectrometer has wavelength range of 900nm to 1700nm. The spectra data is pre-processed using gaussian smoothing to filter the data from noise and unrelated information. Multivariable data analysis method as principle component analysis (PCA) is used to eliminate irrelevant data and reduce the number of variables to three principle components for easier analysis and visualization. Support vector machine (SVM) is used to build a classification model. The training/calibration of the model was done by using 80% of the dataset while the remaining 20% was for testing the model. The results show that with proper pre-processing and PCA, classification of 100% accuracy can be achieved. This study indicates the potential future application of this approach for rapid detection in food powders fraud and adulteration.

A Surface-Enhanced Raman Spectral Library of Important Drugs Associated With Point-of-Care and Field Applications.

During the past decade, the ability of surface-enhanced Raman spectroscopy (SERS) to measure extremely low concentrations, such as mg/L and below, and the availability of hand-held Raman spectrometers, has led to a significant growth in the number and variety of applications of SERS to real-world problems. Most of these applications involve the measurement of drugs, such as quantifying medication in patients, identifying illicit drugs in impaired drivers, and more recently, identifying drugs used as weapons. Similar to Raman spectroscopy, most of the point-of-care and field applications involve the identification of the drug to determine the course of action. However, unlike Raman spectroscopy, spectral libraries are not readily available to perform the necessary identification. In a large part, this is due to the uniqueness of the commercially available SERS substrates, each of which can produce different spectra for the same drug. In an effort to overcome this limitation, we have measured numerous drugs using the most common, and readily available SERS material and hand-held Raman analyzers, specifically gold colloids and analyzers using 785 nm laser excitation. Here we present the spectra of some 39 drugs of current interest, such as buprenorphine, delta-9 tetrahydrocannabinol, and fentanyl, which we hope will aid in the development of current and future SERS drug analysis applications.

1217. Predicting the Efficacy of an Antimicrobial Surface Coating Utilizing X-Ray Fluorescence Spectroscopy (XRF)

BackgroundContaminated surfaces are a critical risk factor for transmitting infectious disease. Current disinfection products provide short-term antimicrobial action; however, these surfaces can be re-contaminated within hours after cleaning. To address this limitation, long-lasting antimicrobial polymer coatings have been developed as an adjunct to traditional disinfecting and cleaning protocols. Due to the micro-scale thickness and transparency of the coating, confirmation of its presence on surfaces is difficult with conventional methods; therefore, this study explores a novel approach to measuring durable polymer coatings on stainless steel coupons to validate their presence and relative antimicrobial activity.MethodsIn this study, we utilized a hand-held X-ray fluorescence spectroscopy (XRF) analyzer to quantitatively evaluate the amount of antimicrobial polymer coating deposited on stainless steel test surfaces. Stainless steel surfaces with amounts of coating ranging from 0.12 to 3.60 mg/in.2 were analyzed for their XRF profile using a hand-held spectrometer. Additionally, the relationship between the XRF spectra and antimicrobial activity was evaluated using a modified version of an existing sanitization protocol for hard surfaces using Staphylococcus epidermidis as the test organism.ResultsComparison of the amount of antimicrobial polymer coating (in mg) and the XRF values (photon count) revealed a calibration curve with a high degree of linearity (R2 = 0.993) especially for surfaces that had lower mass (Figure 1). In addition, the relationship between XRF values and antimicrobial efficacy also were found to be well-correlated with a logarithmic trend (R2 = 0.9308) (Figure 2).ConclusionThe observed trends between coating mass, XRF value and antimicrobial efficacy suggests that these analytical techniques are viable options for determining the presence of invisible antimicrobial polymer coatings. Additionally, laboratory-based calibration curves based on XRF values can be used to predict the level of antimicrobial activity of surfaces that have been treated with polymer coatings. These findings suggest that the use of a hand-held XRF spectrometer can be a rapid and cost-effective method for assessing the presence and efficacy of polymer coatings. Disclosures All authors: No reported disclosures.

Detection and differentiation between potato (Solanum tuberosum) diseases using calibration models trained with non-imaging spectrometry data

The proportion of light at wavelengths across the electromagnetic spectrum that is either absorbed, transmitted or reflected from a plant leaf is dependent on leaf structure, physiology and biochemistry. Since these elements are influenced by pests, pathogens and their associated induced diseases, the detection, differentiation and diagnosis of plant diseases is theoretically possible by non-destructive analysis of the light reflected from plant leaves. In this study the utility of analysis of light over the visible and near-infrared (400–1000 nm) portion of the spectrum to detect and distinguish between several economically important potato diseases, using either Partial Least Squares and BackPropagation Neural Network spectral calibration models was explored. Models could detect and distinguish between diseases with obvious foliar symptoms (blackleg and late blight), even pre-symptomatically, correctly classifying spectra from greenhouse experiments with an accuracy of 84.6%. When these diseases were analysed separately, models could distinguish between spectra from healthy and pre-symptomatic leaves, plus three classes of late blight lesion advancement with 92% accuracy. For blackleg, models distinguished between spectra from healthy, pre-symptomatic foliage and plants expressing blackleg symptoms with a 74.6% classification accuracy. However, models trained on spectra from whole-plant readings from field trials did not have this level of accuracy, with an r2 between target and model values of 0.66 for late blight, 0.31 for blackleg symptoms and 0.41 for healthy foliage. Regardless of greenhouse or field environment, models failed to detect or distinguish between diseases with subtle foliar impacts (black dot, powdery scab and Rhizoctonia diseases). While deployment of hand-held spectrometers for disease detection on a broad-acre scale is impractical, these findings could underpin methods to analyse hyperspectral imaging data with sub-plant resolution for incorporation into precision agriculture and Integrated Pest Management programmes for potato blackleg and late blight management.

A chemometric modeling-free near infrared barcode strategy for smart authentication and geographical origin discrimination of Chinese ginseng.

With the growing interest in alternative medicine, handy identification and differentiation of herbal medicines are becoming increasingly important. Here we report a chemometric modeling-free near infrared (NIR) barcode strategy for the smart identification and geographical origin discrimination of Chinese ginseng. The novel strategy demands the transformation of Chinese ginseng (standard and sample) NIR spectra into a barcode representation through assigning zero intensity to every NIR peak except the peaks having intensities greater than average peak intensity. Meanwhile, for Chinese ginseng standard NIR barcode, barcoding condition such as padding size was carefully optimized. It has been demonstrated that the padding size for each bar in the barcode is 8 cm-1. By comparing the percentage of nonzero overlap between Chinese ginseng standard barcode and sample barcodes, eight batches of samples (including Chinese ginseng, American ginseng and counterfeit) were successfully identified with 100% accuracy, respectively. Interestingly, the discrimination of the origin of ginsengs from three provinces (Jilin, Liaoning and Heilongjiang) of Northeastern China was achieved utilizing NIR barcode method. Two characteristic bars at 7750 and 8250 cm-1 were inspected in the ginseng sample from Jilin province, two specific bars at 6780 and 7015 cm-1 were displayed in the ginseng sample from Liaoning province and three distinct bars at 6560, 6910 and 7995 cm-1 were monitored in the ginseng sample from Heilongjiang province. The results indicate that the proposed method will be greatly expanded and applied as an inspecting platform for the on-site analysis and valid identification of Chinese ginseng in herbal markets by a handheld spectrometer or barcode scanner.

Bioinspired Brochosomes as Broadband and Omnidirectional Surface-Enhanced Raman Scattering Substrates

Surface-enhanced Raman scattering (SERS) substrates capable of working under laser excitation in a broad wavelength range are highly desirable in diverse application fields. Here, we demonstrate that the bioinspired Ag brochosomes, hollow microscale particles with submicroscale pits, have broadband and omnidirectional SERS performance. The SERS performance of the Ag brochosomes under near-infrared laser excitation makes them promising for applications in biosensing fields, such as the sensitive detection of Staphylococcus aureus bacteria and bovine hemoglobin protein. Additionally, the SERS intensity was insensitive to the incident angle of the laser beam, resulting from the spherical structure of the Ag brochosomes. The omnidirectional SERS performance makes the Ag brochosomes have application potential for in-the-field analysis using a hand-held Raman spectrometer for which it is difficult to accurately control the laser beam normal to the SERS substrates. Overall, the broadband and omnidirectional brochosome SERS substrates will find applications in diverse fields, particularly in biomedicine and in-the-field analysis.

Sedimentary environment and facies of the Huagang Formation in the northern central Xihu Depression, East China Sea Basin, China

The sedimentary facies of the Huagang Formation, the major petroleum exploration horizon in the Xihu Depression in the East China Sea Basin, have not been well constrained, owing to limited drilling and core recovery. Interpretations are vague and vary from beach bar, braided river and braided-river delta front sediments. In this paper, the paleosedimentary environments of the Huagang Formation are discussed based on detailed organic and inorganic geochemical analysis and proxies used to interpret the sedimentary facies. Kerogen, dominated by sapropelinite, is mainly of Type I and Type II, and n-Paraffins are dominated by short-chain and medium-chain, with no obvious odd-over-even advantages. The distribution of isoprenoid alkanes and steroids indicates that the organic matter in mudstones is mainly of lacustrine and mixed origins. Elemental ratios of Th/U (4–6), V/Cr (1–4), Ni/Co (3–11) and V/(V + Ni) (0.5–0.75) indicate that in the area studied, the Huagang Formation was deposited under anoxic to reduced conditions with some oxygen-enriched horizons. Both inorganic and organic geochemical signatures show that the Huagang Formation was mainly deposited in an aquatic environment but with some minor periods of subaerial exposure. The sequence of the Huagang Formation is characterised by interbedded grey-white thick sandstones and grey-black thin mudstones. Normally graded cycles are widely developed, with rare mudstone in the upper part and scoured surfaces at the base. The cumulative grainsize distribution curve is mainly a two-stage type. The sedimentary facies indicative markers are dominated by braided-river channel deposits and combined with the paleosedimentary environments it is inferred that the sedimentary system in the study area was typical of a braided-river delta front. The cores available were intensively analysed using a hand-held X-ray fluorescence spectrometer to probe the variations in the paleoclimate and show that the braided-river channels were controlled by paleoclimate. During arid climatic settings, the sediments within individual channels were thin, and grainsizes varied significantly; at the base of each channel, basal conglomerates were common. In contrast, under humid climatic settings, thin multi-stage channels were superimposed, and the bottom often developed erosion surface.KEY POINTSThe paleosedimentary environments are discussed based on detailed organic and inorganic geochemical analysis.The Huagang Formation was deposited in a freshwater lacustrine basin under warm and humid climatic settings.The Huagang Formation is characterised by braided-river delta front facies.The development of braided-river channels was controlled by paleoclimate.

Single nanowire makes tiniest spectrometer

Meet the world’s smallest optical spectrometer. Crafted from a single nanowire less than 100 µm long, the device can measure the intensity of colored light across the visible spectrum and may eventually lead to miniature spectrometers that could be installed in a cell phone (Science 2019, DOI: 10.1126/science.aax8814). “Our spectrometer is about 1,000 times smaller than any previous spectrometer that people have demonstrated,” says Tawfique Hasan at the University of Cambridge who is part of the team that built the device. Scientists routinely use optical spectrometers to study the composition of materials, including the atmospheres of exoplanets and human tissue samples. Advances in electronics and optics have already delivered handheld spectrometers. But building spectrometers that are even smaller—less than a few millimeters wide—is a huge challenge, Hasan says, not least because of the difficulty of miniaturizing optical components like interference gratings that split white light into its component c...

Single-nanowire spectrometers.

Spectrometers with ever-smaller footprints are sought after for a wide range of applications in which minimized size and weight are paramount, including emerging in situ characterization techniques. We report on an ultracompact microspectrometer design based on a single compositionally engineered nanowire. This platform is independent of the complex optical components or cavities that tend to constrain further miniaturization of current systems. We show that incident spectra can be computationally reconstructed from the different spectral response functions and measured photocurrents along the length of the nanowire. Our devices are capable of accurate, visible-range monochromatic and broadband light reconstruction, as well as spectral imaging from centimeter-scale focal planes down to lensless, single-cell-scale in situ mapping.

Evaluation of diesel exhaust fluid (DEF) using near-infrared spectroscopy and multivariate calibration

Diesel engines are responsible for high NOx emission rates in the atmosphere. The urea-selective catalytic reduction (SCR) system is one of the most promising techniques for NOx emission control. The SCR system uses a urea solution known as Diesel Exhaust Fluid (DEF) that contains 32.5% (v/v) of urea dissolved in deionized water. The quality control of the urea concentration in DEF, which directly affects the efficiency of the SCR system, follows the ISO 22241-2 protocol. A simple, practical and efficient methodology to evaluate DEF requirements that uses near-infrared (NIR) spectroscopy and multivariate calibration is presented in our work. For this, DEF commercial samples and mixtures containing urea and deionized water were analyzed in a Fourier Transform Near Infrared Spectrometer (FT-NIR) and in a MicroNIR handheld spectrometer. The urea concentration in the commercial samples and mixtures was quantified by refractive index, according to ISO 22241-2. Partial Least Squares (PLS) models were developed to predict urea content. Variables selection techniques, such as Interval Partial Least Squares (iPLS) and Jack-knife, were tested. The handheld NIR instrument performed well and provided PLS models with RMSEP values statistically equivalent to the PLS models developed in the benchtop instrument. All the RMSEP values obtained were lower than the reproducibility of the ISO protocol. A feasible calibration transfer approach between the benchtop and the handheld instrument was demonstrated. The described methodology, aimed at in-field use for surveillance and DEF quality control purposes, represents a potential alternative to determine the urea concentration in DEF.

Feasibility of Quantitative Analysis of Magnesium and Calcium in Edible Salts Using a Simple Laser-Induced Breakdown Spectroscopy Device.

Feasibility of a simple laser-induced breakdown spectroscopy (LIBS) device has been investigated for the analysis of Mg and Ca in edible salts. The LIBS spectrometer was assembled with a compact low-power diode-pumped solid-state laser (DPSSL) and a non-gated low-resolution handheld spectrometer. A simple sampling process was employed for on-site application. A piece of filter paper was dipped in the aqueous solution of a sample salt and dried for analysis using LIBS. Maintaining the sample surface height at the optimum position was critical to generate plasmas persistently due to the low pulse energy of the DPSSL. The varying height of the filter paper surface was monitored and compensated, while the sample stage was translated to collect spectra from different positions. The variation of line intensities of Mg and Ca could be attributed to the inhomogeneous distribution of dry residues. To correct this, the peak that consists of the Na(I) and C(II) lines at 568 nm was employed as a reference signal for intensity normalization of the analyte Mg(II) and Ca(II) lines. For edible salt products, the normalized Mg(II) and Ca(II) line intensities could be well correlated with the concentrations of Mg and Ca determined using inductively coupled plasma optical emission spectroscopy. Our results indicate that a simple LIBS device in combination with the simple sampling method is promising as an on-site salt quality assessment methodology.

Prediction of the total acid number (TAN) of colombian crude oils via ATR–FTIR spectroscopy and chemometric methods

Reactions as the attack by naphthenic and hydrogen sulfide have caused corrosion problems in the petroleum industry due to they affect the crude oil heating furnaces and distillation towers at temperatures between 220 and 400 °C. The total acid number (TAN) measurement has been used as a test to quantify the acid compounds in crude oils and has shown to be a reliable indicator of their corrosion degree. However, the standard method for the TAN measurement, ASTM D-644, involves long times, environment unfriendly wastes and high costs for each analysis. A more appropriate method for the TAN determination is implemented in this paper, by correlating Fourier transform infrared spectroscopy (FTIR) spectral data of the samples with the standard method measurements using multivariate regression models. In particular, the intensities and frequencies of their mid-infrared attenuated total reflectance (MIR-ATR) spectra (4000 - 400 cm−1) are used as independent variables of several principal component regression (PCR) and partial least squares regression (PLSR) models. The latter are employed to correlate the spectra with their respective TAN values so as to obtain a suitable prediction model. Twenty-six (26) samples of Colombian crude oils are used for the study with a TAN ranging from 0.1 to 6.8 mg KOH/g crude oil (ASTM D-664). The models are evaluated according to the coefficient of determination (R2), the root mean square error of calibration (RMSEC) and of prediction (RMSEP). The best model is obtained via PLSR using as few as four components (i.e. factors), which attains a calibration R2 of 0.981 and an RMSEC of 0.317 mg KOH/g crude oil, while for prediction it attains an R2 of 0.996 and an RMSEP of 0.160 mg KOH/g crude oil. It is observed that the functional groups COOH, CH3 and CH2 contribute the most to the prediction models. The designed methodology is faster and environmentally friendly since it does not require sample pretreatment and the use of toxic reagents, and of low-cost compared with the standard procedure since FTIR measurements can be easily taken anywhere using a hand-held or portable spectrometer and a laptop.

Relevance of a near infrared spectral index for assessing tillage and fertilization effects on soil water retention

Agricultural practices are expected to have significant effects on soil physical properties, such as soil structure and soil water retention (SWR) properties are among the relevant properties that can be used to assess these effects. Ex-situ measurements are costly and time-consuming. Visible (vis) and near infrared (NIR) spectroscopy has been widely used as a rapid, cost-effective and nondestructive technique to predict many soil properties, including soil water content (SWC). In this study, we explored the ability of vis-NIR to assess the effects of soil tillage and fertilization on SWR. The study was performed on silty soil samples with 10.4 g kg−1 of organic carbon content and a pH of 5-6.5. Undisturbed soil blocks were collected from an experimental station located in Brittany, France. In 2012, the field was designed as two separate experiments, each with a different tillage system (conventional tillage (CT) and shallow tillage (ST)). For each experiment, two fertilizer types were considered (mineral and organic). Six undisturbed soil blocks were sampled at each of two depths (0–15 cm and 15–25 cm) and from each agricultural practice. Soil was sampled on two dates: before starting the treatment (2012) and after 5 years of agricultural practices (2017). From each soil block, four aggregates 3–4 cm wide and 5–6 cm long were collected. The whole aggregates were set at a number of matric potentials, from saturation to the permanent wilting point (pF = 4.2). At a given pressure head, soil samples were scanned in triplicate to acquire reflectance spectra from 400 to 2500 nm using a handheld spectrometer (ASD Fieldspec®). We focused on the absorption band near 1920 nm and used a new NIR spectral index based on the band’s full width at half maximum, called SWSI. Our results showed a linear relation between SWSI and SWC (R² > 0.99). Moreover, the slope and intercept of this linear relation were significantly correlated with water holding capacity (WHC) and soil quality. Using these parameters, we found that SWR and soil physical quality under CT were significantly greater under cattle manure (CTC) than under mineral fertilizer (CTM) or at T0. This significant effect was more pronounced at 15–25 cm. In ST treatments, SWR properties and soil quality were significantly lower than at T0. More importantly, our results show that the slope and intercept of the linear relation offer a way to summarize and assess the effects of agricultural practices on SWR properties and soil structural quality.

Investigations into the use of handheld near-infrared spectrometer and novel semi-automated data analysis for the determination of protein content in different cultivars of Panicum miliaceumL.

A set of 42 millet (panicum miliaceum L.) samples was investigated for its protein content using standard Kjeldahl analysis and near-infrared spectroscopy. The performance of three handheld spectrometers was compared to a benchtop instrument. The used spectrometers operate in different regions of the NIR, which gives interesting insights into the applicability of each region. Additionally, semi-automated, consumer-oriented multivariate data analysis was compared to sophisticated data evaluation.The performance of the near-infrared instruments was compared using important statistical parameters of the established cross- and test set validated partial least squares regression (PLS-R) models. Milled and intact samples were analysed, in order to further evaluate the importance of homogeneity.The results showed that the benchtop spectrometer is capable of accurately analysing protein content of millet grains, with root mean square error (RMSEP) values for milled and intact grains of approximately 0.5%. Two PLS-R models of handheld instruments also yielded good results for milled grains with RMSEP values of about 0.6%. The semi-automated multivariate data analysis showed some drawbacks compared to standard data processing software. For intact grains, however, similar results could be achieved.

Investigating the total antioxidant capacity of gluten-free grains with miniaturized near-infrared spectrometer

The use of ever smaller near-infrared instruments is becoming more and more prevalent, since they are cheaper, more versatile and often advertised as high-performance spectrometer. The last claim is rarely verified by independent researchers, which is why the presented work evaluates the performance of three hand-held spectrometers in comparison to a benchtop instrument. Seventy-seven samples comprising buckwheat, millet and oat were investigated for their total antioxidant capacity using Folin–Ciocalteu and near-infrared spectroscopy. Partial least squares regression models were established using cross- and test set validation. Results showed that all instruments were able to predict total antioxidant capacity to some extent. The coefficients of determinations ranged from 0.823 to 0.951 for cross-validated and from 0.849 to 0.952 for test set validated models. Errors for cross-validated models ranged from 1.11 to 2.08 mgGAE/g and for test set validated models from 1.02 to 1.86 mgGAE/g.

A Handheld Miniature Ultraviolet LED Fluorescence Detection Spectrometer

This paper presents a handheld micro-fluorescence spectrometer with an integrated ultraviolet light-emitting diode. A small transmission grating was used as a dispersive element to disperse light. The spectrum was detected by a CCD array. The instrument can be connected to a PC or a smartphone through a USB cable for data processing and spectrum display. The spectrometer is 30 × 30 × 100 mm3 only. The spectrometer with a wavelength range from 380 to 750 nm had a spectral resolution of 3 nm. The fluorescence spectra from edible oil, chlorophyll, and paper were measured by the spectrometer we designed. This spectrometer has the advantages of compact structure, small size, light weight, fast detection speed, convenient use, and low cost.

Handheld near-infrared spectrometer for on-line monitoring of biodiesel production in a continuous process

In this work, the use of a handheld near-infrared spectrometer (MicroNIR) for on-line monitoring of biodiesel production in a continuous process is described. The process consists of a laboratory scale reactive distillation column where transesterification reactions between cottonseed oil and ethanol take place. This column can operate with different ethanol to oil molar ratios. In the present study, a severe condition using an excess of ethanol at the point monitored with NIRS was applied. This condition caused problems in modelling the content of the alkyl ester, particularly because of the broad and intense band related to the ethanol in the spectral region covered by MicroNIR. Therefore, for process monitoring and control, both an estimate of the alkyl ester as well as of ethanol contents were carried out. To deal with this, PLS calibration models were developed to estimate concentrations of ethanol and alkyl ester at the bottom of the column. In addition, in order to estimate the yield of the alkyl ester, a PLS model to assess glycerol content was also developed. In spite of the problematic conditions under which the column operated, mainly related to the excess of ethanol, the models presented satisfactory results for ethanol (RMSEP = 1.66 wt%), alkyl ester (RMSEP = 2.15 wt%) and glycerol (RMSEP = 1.08 wt%) quantifications and have demonstrated the feasibility of the handheld instrument to monitor biodiesel production in a continuous process.

Field and laboratory validation of remote rover operations Science Team findings: The CanMars Mars Sample Return analogue mission

The CanMars Mars Sample Return Analogue Deployment (MSRAD) was a closely simulated, end-to-end Mars Sample Return (MSR) mission scenario, with instrumentation, goals, and constraints modeled on the upcoming NASA Mars 2020 rover mission; this paper reports on the post-mission validation of the exercise. The exercise utilized the CSA Mars Exploration Science Rover (MESR) rover, deployed to Utah, USA, at a Mars-analogue field site. The principal features of the field site located near Green River, Utah are Late Jurassic inverted, fluvial paleochannels, analogous to features on Mars in sites being considered for the ESA ExoMars rover mission and present within the chosen landing site for the Mars 2020 rover mission. The in-simulation (“in-sim”) mission operations team worked remotely from The University of Western Ontario, Canada. A suite of MESR-integrated and hand-held spectrometers was selected to mimic those of the Mars 2020 payload, and a Utah-based, on-site team was tasked with field operations to carry out the data collection and sampling as commanded by the in-sim team. As a validation of the in-sim mission science findings, the field team performed an independent geological assessment. This paper documents the field team's on-site geological assessment and subsequent laboratory and analytical results, then offers a comparison of mission (in-sim) and post-mission (laboratory) science results. The laboratory-based findings were largely consistent with the in-sim rover-derived data and geological interpretations, though some notable exceptions highlight the inherent difficulties in remote science. In some cases, available data was insufficient for lithologic identification given the absence of other important contextual information (e.g., textural information). This study suggests that the in-sim instruments were largely adequate for the Science Team to characterize samples; however, rover-based field work is necessarily hampered by mobility and time constraints with an obvious effect on efficiency but also precision, and to some extent, accuracy of the findings. The data show a dearth of preserved total organic carbon (TOC) – used as a proxy for ancient biosignature preservation potential – in the fluvial-lacustrine system of this field site, suggesting serious consideration with respect to the capabilities and opportunities for addressing the Mars exploration goals. We therefore suggest a thorough characterization of terrestrial sites analogous to those of Mars rover landing sites, and in-depth field studies like CanMars as important, pre-mission strategic exercises.

Improved calibration transfer between near-Infrared (NIR) spectrometers using canonical correlation analysis

The application of mobile near-infrared (NIR) spectrometers in field measurements is growing. Calibration transfer techniques offer simple solutions for enabling models constructed on benchtop instruments for use on mobile spectrometers. Since different types of spectrometers with different components, scanning ranges and resolutions cause great differences in the spectral response, calibration transfer is difficult to apply. In this paper, we focus on calibration transfer among benchtop, portable and handheld spectrometers by a method of calibration transfer based on canonical correlation analysis (CTCCA). Its capability was illustrated by the example of a group of NIR spectra dataset for predicting reducing sugars, total sugar, and nicotine contents in tobacco leaves. The experimental results showed that the transferability of CTCCA was superior to other conventional calibration transfer methods, including piecewise direct standardization, spectral space transformation, calibration transfer based on independent component analysis, and calibration transfer based on the weight matrix. Moreover, the best transfer results were obtained in the three cases by canonical correlation analysis method executing transfer while the spectra were not interpolated, which shows that this approach has the advantage of easy implementation for calibration transfer. Therefore, CTCCA without interpolation calculation offers a new and simple solution for transferring the spectra acquired by mobile spectrometers to the optimized spectral models built on benchtop devices to improve the accuracy of the results. Additionally, the results show that the benchtop spectrometer is more suitable as the master instrument for calibration transfer with more accurate prediction than using a portable device as the master.