Infrared Transmission Research Articles

Synthesis of cesium, sodium and nitrogen derived titanates using the Pechini sol-gel method

Cesium and sodium titanates with the respective stoichiometries of CsxTi2-x/4□x/4O4 (x ≈ 0.7) and Na2Ti6O13 was synthesized by making use of the Pechini sol-gel method. Direct intercalation of hydrazine hydrate in cesium and sodium titanates proved unsuccessful with the direct intercalation of ammonium into cesium titanate achieved. The protonated form of cesium titanate was successfully intercalated with hydrazine hydrate. Findings of the structural properties of the various titanates obtained from X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, Fourier-Transform Infra-Red spectroscopy, Raman spectroscopy and transmission electron microscopy are presented.

Prediction of infertile chicken eggs before hatching by the Naïve-Bayes method combined with visible near infrared transmission spectroscopy

The traditional candling methods are very hard to discriminate the infertile chicken eggs from the fertile ones before hatching on the poultry farm. The purpose of this study was to detect infertile chicken eggs before hatching by use of the nondestructive technique of visible near infrared transmission spectroscopy. The Naïve-Bayes method was adopted to link spectral data and qualitative observation values of chicken eggs to build a model. Five preprocessing methods were applied to spectral data to improve the robustness of the models. The internal test method of leave one cross validation and an external test method were employed to test the predictive ability of the established models. Naïve-Bayes with a second derivative by the Savitzky-Golay preprocessing method was selected as the optimal prediction model by comparing with four evaluation parameters of other models. The overall accuracy of the model using the second derivative—Savitzky-Golay preprocessing method was 91.67%, while the sensitivity and the specificity were 95% and 100%, respectively. The prediction ability of the optimal model was assessed by use of unknown new egg samples. The average overall prediction accuracy of the prediction set containing 111 eggs was 89.12%, while the sensitivity and specificity were 88.14 and 90.38%, respectively. Results showed that the prediction model had good predictability and stability. Therefore, visible near infrared transmission spectroscopy would be an appropriate technology to detect infertile chicken eggs before hatching.HighlightsThe infertile chicken eggs from the fertile ones before hatching were discriminatedVisible near infrared spectroscopy first detected infertile chicken eggs before hatching.Naive bayes classifier with five different pre-processing methods were compared.The unknown eggs were predicted by the optimal Naive bayes prediction model.

Studies on UV/Visible Absorption and IR Transmission Characteristics of Cu2+ Ion in a Soda-Magnesia-Lime-Silica Glass for Solar Application

ABSTRACT The aim of this investigation is to study the UV/Visible absorption and infra-red transmission characteristics due to Cu+/Cu2+ redox in silica glass. The glass composition 18Na2O-2MgO-8CaO-72SiO2 (mol%) containing different concentrations of CuO were prepared by melting route. The optical absorption spectra of the glasses were recorded on an UV/Visible/NIR spectrophotometer in the wavelength range of 200-1100 nm. The linear absorption coefficient was found to be around 7.60 cm–1 per wt% of CuO in the glass samples. The Cu2+ band was attributed to spin allowed transition from 2Eg →2T2g level in the glass and the applicability of Urbach’s rule was tested for Cu+ ion. It was found that optical band gap for Cu+ was 4.03 eV and its band width was 0.43 eV in the glass. The oscillator strength of the Cu+ ion band (ƒabs) in the glass was reported. The absorption and transmission characteristics of glass containing Cu+ and Cu2+ ions showed a decrease in absorption coefficient of Cu2+ beyond red spectral region. This dictates that glass containing copper ions can be used for IR transmitting purpose and can convert the solar energy into electrical energy for photovoltaic applications.

Effect of Nickel-spinal-Ferrites on EMI shielding properties of polystyrene/polyaniline blend

Magnetic and electrically conductive polymeric nanocomposites were fabricated using polystyrene (PS) as matrix, Nickel Ferrites (NiFe) as magnetic nanofiller and polyaniline (PANI) as electrically conductive nanofiller. Electromagnetic interference (EMI) shielding and infrared (IR) blocking are the main application of these nanocomposites. PANI and NiFe were successfully prepared by chemical and co-precipitation methods respectively. The successful fabrication of nanofillers was confirmed by the X-ray diffraction technique. DC conductivity and dielectric properties were first analyzed and a huge increase in both dielectric constant and DC conductivity was observed. Dielectric Constant seemed to be increased from 2.2 for PS to 5.5 for PS/PANI/NiFe composite. For the measurement of EMI shielding effectiveness (SE), Vector Network Analyzer was used in 0.1–20 GHz frequency range. IR spectroscopy was used to measure IR transmission in near-infrared (NIR) region of 700–2500 nm wavelength range. PS film is transparent for both NIR waves and microwaves, by observing almost 90% transmission in the NIR range and about − 3 dB SE in the microwave region. IR transmission reduces to less than 0.5% for PS/PANI/NiFe composite in the whole NIR range. Also, in the microwave region, − 3 dB shielding enhanced to less than − 35 dB in a broad range of frequency from 0.1 to 20 GHz.

Effect of porosity and hexagonality on the infrared transmission of spark plasma sintered ZnS ceramics

Tailoring phase transition and microstructural evolution during sintering is crucial for the fabrication of ZnS ceramics transparent to infrared (IR) radiation. Herein, we have described the phase transition, microstructure, and related IR transmission of spark-plasma-sintered ZnS ceramics in terms of sintering temperature and pressure. The pore characteristics of spark-plasma-sintered ZnS ceramics were evaluated using Mie scattering theory. Changes in hexagonality and residual pore characteristics of the microstructure affected IR transmission of the sintered specimens. High temperature and pressure condition of SPS were found to increase excessive hexagonal phase (>20%), mainly contributing to a transmittance decay in the range 2–4 μm.

Infrared transparent millimeter wave antenna based on sapphire substrate

AbstractWe describe a novel millimeter wave antenna based on sapphire substrate. An infrared transparent millimeter wave antenna and the characterization of its radiation pattern, gain, main frequency, and dielectric infrared transmission were reported. The proposed antenna was constructed from several infrared transparent dielectric materials with thin gold film array elements using a photolithographic process. Several single‐layer infrared‐transparent substrates were stacked. As a infrared transparent window, the antennas have applications in multimode communications, navigation, and detection, particularly for millimeter wave and infrared wavelength in a common aperture system.

Salt-inclusion chalcogenides: an emerging class of IR nonlinear optical materials

Non-centrosymmetric metal chalcogenides such as AgGaS2 and AgGaSe2 are two of the commercial nonlinear optical (NLO) crystals widely used in the infrared (IR) region. Nevertheless, the inherent incompatibility between the wide energy gap (Eg) and large second-harmonic generation (SHG) efficiency (dij) hinders their high-power laser applications. Recently, the development of salt-inclusion chalcogenides with non-centrosymmetric structures has attracted more and more attention and interest owing to their intensive potential applications originating from their wide Eg, strong dij, ultrahigh laser-induced damage thresholds (LIDTs) and large IR transmission range. In this frontier paper, we review the recent progress of salt-inclusion chalcogenides (including 28 related compounds) as favourable candidates for IR-NLO materials, which can be divided into 3 types according to their chemical compositions and structural characteristics: (i) the [RaXb][GanQ2n] type and its derivatives, (ii) [NaBa4Cl][Ge3S10] and its derivatives, and (iii) the [A3X][MB12(MQ4)3] type. The relationships between the non-centrosymmetric structures and NLO properties of these 3 types of compounds are summarized and briefly remarked. In addition, the present challenges of creating new IR-NLO salt-inclusion chalcogenides and future perspectives in this field are discussed.

Transformation of aqueous protein attenuated total reflectance infra-red absorbance spectroscopy to transmission.

Infrared (IR) spectroscopy is increasingly being used to probe the secondary structure of proteins, especially for high-concentration samples and biopharmaceuticals in complex formulation vehicles. However, the small path lengths required for aqueous protein transmission experiments, due to high water absorbance in the amide I region of the spectrum, means that the path length is not accurately known, so only the shape of the band is ever considered. This throws away a dimension of information. Attenuated total reflectance (ATR) IR spectroscopy is much easier to implement than transmission IR spectroscopy and, for a given instrument and sample, gives reproducible spectra. However, the ATR-absorbance spectrum varies with sample concentration and instrument configuration, and its wavenumber dependence differs significantly from that observed in transmission spectroscopy. In this paper, we determine, for the first time, how to transform water and aqueous protein ATR spectra into the corresponding transmission spectra with appropriate spectral shapes and intensities. The approach is illustrated by application to water, concanavalin A, haemoglobin and lysozyme. The transformation is only as good as the available water refractive index data. A hybrid of literature data provides the best results. The transformation also allows the angle of incidence of an ATR crystal to be determined. This opens the way to using both spectral shape and spectra intensity for protein structure fitting.

Enriched silver plasmon resonance activity on the sonochemical synthesis of ZnO flowers with α-Fe2O3 as an efficient catalyst for photo-Fenton reaction and photo-oxidation of ethanol

We report the preparation of flower-shaped ZnO bunches with the α-Fe2O3 photocatalyst using the sonochemical method followed by the photodeposition of Ag nanoparticles. The Ag-ZnO/α-Fe2O3 photocatalyst was utilized for the removal of the environmental pollutant Methylene Blue (MB) dye. From our results, it was found that the Ag-ZnO/α-Fe2O3 photocatalyst exhibited higher photocatalytic activity when compared to ZnO/α-Fe2O3 with the addition of H2O2. Moreover, the higher plasmon resonance activity of the Ag with a photocatalyst degraded the MB dye within 30 min in the presence of H2O2. The different pH and the molar ratio of H2O2 were influenced by the degradation performance. In addition, the ZnO@α-Fe2O3 and Ag-ZnO/α-Fe2O3 photocatalysts were used for the generation of the OH radicals and the formation of formaldehyde and CO2 as analyzed by diffuse reflectance infra-red transmission (DRIFT) spectroscopy.

Improvement of glyphosate adsorption using new composites based on Ghassoul and chitosan: Kinetics and equilibrium study

Clay materials combined with other compounds are intensely used in several fields. The present study focuses on the synthesis of organoclays and nanocomposites based on the intercalation of surfactant and biopolymer into swelling Moroccan clay. The produced materials were used in the removal of glyphosate from the aqueous medium. The organoclay was obtained by the intercalation of cetyltrimethylammonium bromide (CTAB) in the interlamellar space of stevensite, and the nanocomposite was fabricated by the direct interaction between the stevensite and chitosan. These materials were characterized by mean X-Ray Diffraction, Fourier Transform Infra-Red Spectroscopy (FTIR), Thermal Analysis and Transmission Electron Microscopy (TEM). The results showed that the stevensite is the dominant clay mineral of Ghassoul and confirmed that the nanocomposite has an intercalated clay structure. The batch mode was accomplished to quantify the glyphosate removal capacity from aqueous solution by these materials. The enhancement of hydrophobic properties has promoted the retention of the herbicide. The pseudo-second-order kinetic model of adsorption was the most suitable to describe the process of adsorption and the Freundlich isotherm equation fitted satisfactory the adsorption isotherm data. The capacity of adsorption was more outstanding for the nanocomposite chitosan/Ghassoul and reached a significant value of 159.10 mg.g-1. The nanocomposites based on chitosan/Ghassoul could be considered as promising materials for treatments of pesticide-contaminated water.

A study on the spectral, microstructural, and magnetic properties of Eu-Nd double-substituted Ba0.5Sr0.5Fe12O19 hexaferrites synthesized by an ultrasonic-assisted approach.

In this study, an examination on the spectral, microstructural, and magnetic characteristics of Eu-Nd double-substituted Ba0.5Sr0.5Fe12O19 hexaferrites (Ba0.5Sr0.5NdxEuxFe12-2xO19 (x = 0.00-0.05) HFs) fabricated by an ultrasonic-assisted approach has been presented. An UZ SONOPULS HD 2070 ultrasonic homogenizer with frequency of 20 kHz and power of 70 W was used. The chemical bonding, structure and the morphology of the products were evaluated by Fourier-Transform Infrared (FT-IR) Spectroscopy, XRD (X-ray diffraction), scanning and transmission electron microscopy and techniques. The textural properties of the prepared nanomaterials were examined by using the Brunauer-Emmett-Teller (BET) method. The magnetic properties were studied using a vibrating sample magnetometer (VSM) at room temperature (RT) and low temperature 10 K. The magnitudes of various magnetic parameters including Ms (saturation magnetization), Mr (remanence) and Hc (coercivity) were estimated and evaluated. The M-H loops revealed the hard ferrimagnetic nature for all products at both temperatures. The Ms and Mr values showed a decreasing tendency with increasing degree of Eu3+ and Nd3+ substitutions whereas Hc values displayed an increasing trend. At RT, Ms, Mr and Hc values lie in the ranges of 63.0-68.8 emu·g-1, 24.6-39.2 emu·g-1 and 2252.4-2782.1 Oe, respectively. At 10 K, the values of Ms, Mr and Hc lie between 87.5-97.1 emu·g-1, 33.5-40.1 emu·g-1 and 2060.6-2417.2 Oe, respectively. The observed magnetic properties make the prepared products promising candidates to be applied in the recording media.

VIS-NIR spectral and particles distribution of Au, Ag, Cu, Al and Ni nanoparticles synthesized in distilled water using laser ablation

In this research, gold (Au), silver (Ag), copper (Cu), aluminium (Al) and nickel (Ni) nanoparticles have been prepared by laser ablation in distilled water using Q-switched Nd: YAG. Comparative analysis between 1064 nm and 532 nm laser wavelength in term of absorption spectra and particle size distribution is performed. The synthesized nanoparticles were characterized by visible (VIS) and near infrared (NIR) spectrometer and transmission electron microscopy (TEM). The effect of laser pulse energy and laser wavelength on the size distribution and absorbance spectrum of metal nanoparticles was studied. The absorption peak intensities of the nanoparticles increase at higher laser pulse energy. It is discovered that for all metals, 532 nm laser produced nanoparticles with higher absorption peak intensities than 1064 nm. The work also shows that there is no noticeable difference in the size of the nanoparticles produced at 532 and 1064 nm for the Ni and Cu metals. However, a considerable size difference can be seen for Au, Ag, and Al at the two laser wavelengths. Smaller Ag nanoparticles were produced by 1064 nm laser while smaller Au and Al nanoparticles were produced by 532 nm laser.

Designing Textile Architectures for High Energy-Efficiency Human Body Sweat- and Cooling-Management

Thermal management of textiles requires local microclimate control over heat and wet dissipation to create a comfortable thermal-wet environment at the interface of the human body and clothing. Herein, we design a fabric capable of both sweat- and cooling-management using a knitted fabric featuring a bilayer structure consisting of hydrophobic polyethylene terephthalate and hydrophilic cellulose fibers to simultaneously achieve high infrared (IR) transmittance and good thermal-wet comfort. The IR transmission of this cooling textile increased by ~ twofold in the dry state and ~ eightfold in the wet state compared to conventional cotton fabric. When the porosity changes from 10 to 47% with the comparison of conventional cotton fabric and our cooling textile, the heat flux is increased from 74.4 to 152.3 W/cm2. The cooling effect of the cooling fabric is 105% greater than that of commercial cotton fabric, which displays a better thermal management capacity for personal cooling. This bilayer design controls fast moisture transfer from inside out and provides thermal management, demonstrating high impact not only for garments, but also for other systems requiring heat regulation, such as buildings, which could mitigate energy demand and ultimately contribute to the relief of global energy and climate issues.

Descending Infrared Transmission Spectra of CdZnTe Substrates Due to Surface Roughness

The (111)B-oriented Cd0.96Zn0.04Te substrates with rough surfaces have been found to have infrared (IR) transmission spectra which decrease rapidly in intensity as the photon energy increases. The rough surfaces were produced by Everson etching or rough polishing. The descending spectra could be qualitatively described by an equation found in the literature. Flat low intensity IR transmission spectra were found to be due to a combination of free carrier absorption and rough surfaces. The B-side of the substrate is the growth side. By etching the A-side of the substrate only we found that the black layer formed by the Everson etch on this side introduces two features in the IR transmission spectra: a dip at approx. 625 cm−1 and a special kind of ascending IR transmission spectrum: The ascending spectrum increases from approx. 65% at 500 cm−1 up to 72.5% at the highest wavenumbers around 4000 cm−1. There is a correlation between the dip and the ascending spectrum: six out of the seven spectra with largest dip have the highest transmission at 4000 cm−1 suggesting a common origin.

Ultrafast x-ray absorption near edge spectroscopy of Fe3O4 using a laboratory based femtosecond x-ray source.

Ultrafast time-resolved x-ray absorption near edge spectroscopy (XANES) experiment was performed on a magnetite (Fe3O4) film using a femtosecond laser plasma x-ray source delivering Bremsstrahlung radiation. Ultrafast temporal evolution of the XANES of Fe3O4 following an excitation by an infra-red (IR) laser pulse was observed in a pump-probe scheme. The Fe K x-ray absorption edge shifts towards low energy upon IR excitation as much as 12 eV, which is mainly attributed to the charge transfer between the Fe ions. The shift in the absorption edge occurred within about 150 fs, typical time of non-thermal electronic redistribution. The charge transfer also causes an ultrafast increase in the IR transmission in the similar time scale.

Application of deep brief network in transmission spectroscopy detection of pesticide residues in lettuce leaves

AbstractTo realize the quick, nondestructive detection of pesticide residues in lettuce leaves, a new method based on deep brief network (DBN) combined with near‐infrared transmission spectroscopy, was studied in this article. Two kinds of pesticide residues (fenvalerate and triazoline) and distilled water were sprayed on the surface of lettuce leaves, respectively. In addition, near infrared transmission spectroscopy was used for collecting spectral data of 240 lettuce samples. Furthermore, Savitzky–Golay combined with multiplicative scatter correction was used to denoise the raw spectral data. Then, after preprocessing spectral data, DBN was used to extract features and identify kinds of pesticide residues in lettuce leaves. Moreover，successive projection algorithm (SPA) was used to select characteristic wavelengths. After all, support vector machine (SVM), PLS‐DA, and k‐nearest neighbor were carried out to establish classification models based on full spectral data, data extracted by DBN and data extracted by SPA. Consequently, DBN–SVM performed best and the accuracy of training set and test set reached 98.89 and 95.00%, respectively. Hence, the method of near infrared transmission spectroscopy combined with DBN–SVM is practical for the qualitative analysis of pesticide residues in lettuce leaves.Practical applicationsUsing near infrared spectroscopy could detect the kinds of pesticide residues in lettuce leaves quickly and effectively. A new method involving deep brief network (DBN) was proposed to extract the features of spectral data. Results in this study showed that the DBN is feasible and effective for building classification models of different pesticide residues.

Diagnostic performance of direct and indirect methods for assessing failure of transfer of passive immunity in dairy calves using latent class analysis

Accurate diagnosis of failure of transfer of passive immunity (FTPI) in newborn calves is an essential component of dairy farm management plan. Several methods (direct and indirect) are available for diagnosis of FTPI in dairy calves. However, the indirect methods offer an advantage over the direct methods in not requiring an experienced veterinarian, rapid, cost efficient and can be performed under field-setting. The objective of this study was to estimate the diagnostic performance of radial immunodiffusion (RID) assay, transmission infrared (TIR) spectroscopy and digital Brix refractometer for diagnosis of FTPI in dairy calves using latent class models at four cut-off values of digital Brix refractometer. Holstein calves (n = 691) from 40 commercial dairy farms in the four Atlantic Canada provinces were blood-sampled and tested for detection of FTPI. Results showed that the number of calves with FTPI was 253 (36.6%) by RID, 194 (28.1%) by TIR and 204 (29.5%) by Brix refractometer at cut-off value of 8.2%. Estimates of SeRID was higher than SeTIR and SeBrix, at all Brix refractometer cut-offs, but with increase of Brix refractometer cut-off from 8.2 to 8.5%, SeRID and SeTIR were decreased from 96.0% (95% PCI: 88.0–99.0) and 79.0% (95% PCI: 70.0–85.0), to 92.0% (95% PCI: 77.0–99.0) and 74.0% (95% PCI: 61.0–82.0), respectively. SpRID and SpTIR were always higher than SpBrix at all tested cut-offs and were above 92.0%, and 96.0%, respectively. With increasing the cut-off of Brix refractometer from 8.2 to 8.5%, SeBrix estimate has remarkably increased from 79.0% (95% PCI: 70.0–96.0) to 95.0% (95% PCI: 87.0–100.0), respectively. Whilst, SpBrix was decreased from 95.0% (95% PCI: 91.0–98.0) at cut-off 8.2% to 84.0% (95% PCI: 78.0–94.0) at cut-off 8.5%. In conclusion, RID has a higher Se than TIR and Brix, if the latter is used with cut-offs of 8.2% or 8.3%. However, the higher the cut-off, the more comparable sensitivities of RID and digital Brix refractometer. The median estimate of SpTIR was always higher than SpRID and SpBrix at all tested cut-offs. However, the 95% confidence interval estimates of the three tests were overlapping across the tested cut-offs of digital Brix refractometer reflecting the inability to prefer a test over the other based on the Sp estimate.

One pot synthesis of stable water soluble thiol capped CdTe nanoparticles: Effect of precursor ratio, refluxing time and capping group on the optical property

Highly crystalline, monodispersed and stable water soluble thiol capped cadmium telluride nanoparticles (CdTe NPs) were synthesized via an environmental friendly, simple one-pot method in the absence of an inert atmosphere at constant pH. The effect of varying the precursor ratio and capping agent while keeping all other parameters constant, on the optical and structural properties of the as-synthesized nanocrystals was investigated. The optical and structural properties of the as-synthesized CdTe NPs was explored by using UV–visible (UV–Vis) absorption and photoluminescence (PL) spectroscopy, Fourier transform infra-red spectroscopy (FTIR) and transmission electron microscopy (TEM). Optical analysis shows that all the as-synthesized CdTe NPs possesses good optical properties with 1:0.8 ratio showing the highest absorbance and emission wavelength at different reaction time. The thiol capped water soluble CdTe NPs were optically stable at ambient conditions for several months.

Optical Properties of a Sulfur-Rich Organically Modified Chalcogenide Polymer Synthesized via Inverse Vulcanization and Containing an Organometallic Comonomer.

Inverse vulcanization is the method by which molten sulfur can be combined with comonomers to form stable polymers termed "organically modified chalcogenide" or "ORMOCHALC" polymers. One advantage to ORMOCHALC polymers is that they can possess important optical properties, such as high refractive index and strong infrared (IR) transmission, while being easier to fabricate than glass materials with similar optical properties. In the present work, a new ORMOCHALC is fabricated by using tetravinyltin as a comomoner with sulfur. This is the first example of an organometallic molecule being used as a comonomer to develop ORMOCHALCs. The result is an ORMOCHALC polymer that has the highest refractive index reported for a "sulfur and comonomer" polymer and that demonstrates unprecedented transmission in the IR region.

Using serum and plasma samples to assess failure of transfer of passive immunity in dairy calves

The objectives of this study were (1) to determine the differences in IgG and total protein (TP) content of serum and plasma samples collected from the same calves; (2) to evaluate the correlation between calf serum and plasma IgG levels, Brix scores, and TP concentrations; (3) to determine whether different cut-off values should be used for plasma and serum to assess failure of transfer of passive immunity (FTPI) in dairy calves; and (4) to evaluate the level of agreement between results obtained from using serum and plasma samples of the same calves to assess FTPI using optimal cut-off values. Blood samples (n = 217) were collected from Holstein calves at 3 to 10 d of age on 30 commercial dairy farms in Nova Scotia and Newfoundland, Canada. Paired serum and plasma samples were analyzed for IgG concentration by the reference radial immunodiffusion assay, transmission infrared (TIR) spectroscopy, digital and optical Brix refractometers, and optical TP refractometer. The IgG concentrations measured by RID and TIR spectroscopy in serum were similar to those in plasma. However, the Brix and TP refractometer readings were significantly higher in plasma than in serum. The prevalence of FTPI in serum and plasma samples based on a RID-IgG concentration <10 g/L was 43.3 and 46.5%, respectively. The RID-IgG concentration was correlated with TIR-IgG (r = 0.92 and 0.89), digital Brix (r = 0.80 and 0.80), optical Brix (r = 0.77 and 0.77), and optical TP (r = 0.75 and 0.77) refractometers in serum and plasma, respectively. The correlations between paired serum and plasma IgG content were 0.85 by TIR spectroscopy, 0.80 by digital Brix, 0.77 by optical Brix, and 0.79 by optical TP refractometer. The optimal cut-off values for TIR spectroscopy, digital Brix, optical Brix, and TP refractometers to assess FTPI using serum were 13.1 g/L, 8.7% Brix, 8.4% Brix and 5.1 g/dL, respectively; and the optimal cut-off values with plasma were 13.4 g/L, 9.4% Brix, 9.3% Brix and 5.8 g/dL, respectively. When using these optimal cut-off values, the level of agreement (88.1%) between results derived from testing serum and plasma by TIR spectroscopy was substantial, with a kappa (κ) value of 0.76. The results derived from testing serum and plasma by digital Brix refractometer showed substantial agreement (83.4%), with a κ value of 0.65, which is higher than the agreement and κ value (74.7% and 0.51) reported for the optical Brix refractometer. Substantial agreement (81.6%) between serum and plasma TP was also obtained when using the optical TP refractometer, with a κ value of 0.63. In conclusion, serum or plasma samples can be used interchangeably for measuring IgG concentrations and assessing FTPI in dairy calves. However, different cut-offs must be used to assess FTPI depending on the sample matrix. Furthermore, results obtained from serum samples showed higher agreement with the reference RID assay than those obtained from plasma samples.