Assessing the Extent of Degradation in the UV Radiation and Heat-Catalyzed Oxidised Whole Milk Powder : The UV Photoacoustic and Diffuse Reflectance Spectroscopies Versus the Peroxide Value

The extent of quality loss caused by enzymatic and nonenzymatic browning reactions in milk powders is usually assessed by the chemical methods, among which the determination of peroxide value (PV) is a widely used approach. In this paper, peroxide values obtained from deliberately oxidized (UV irradiation combined with the thermal stress) whole milk powders are compared to the results of photoacoustic spectroscopy (PAS) and diffuse reflectance spectrometry (DRS) in the ultraviolet and visible region. The same samples were also investigated by various methods in the near-infrared (NIR) region. The experimental data suggest a good degree of correlation between the PV and the PAS and DRS data collected at 335 nm

Integration and fusion of standard automated perimetry and optical coherence tomography data for improved automated glaucoma diagnostics

<p>Abstract</p> <p>Background</p> <p>The performance of glaucoma diagnostic systems could be conceivably improved by the integration of functional and structural test measurements that provide relevant and complementary information for reaching a diagnosis. The purpose of this study was to investigate the performance of data fusion methods and techniques for simple combination of Standard Automated Perimetry (SAP) and Optical Coherence Tomography (OCT) data for the diagnosis of glaucoma using Artificial Neural Networks (ANNs).</p> <p>Methods</p> <p>Humphrey 24-2 SITA standard SAP and StratusOCT tests were prospectively collected from a randomly selected population of 125 healthy persons and 135 patients with glaucomatous optic nerve heads and used as input for the ANNs. We tested commercially available standard parameters as well as novel ones (fused OCT and SAP data) that exploit the spatial relationship between visual field areas and sectors of the OCT peripapillary scan circle. We evaluated the performance of these SAP and OCT derived parameters both separately and in combination.</p> <p>Results</p> <p>The diagnostic accuracy from a combination of fused SAP and OCT data (95.39%) was higher than that of the best conventional parameters of either instrument, i.e. SAP Glaucoma Hemifield Test (p < 0.001) and OCT Retinal Nerve Fiber Layer Thickness ≥ 1 quadrant (p = 0.031). Fused OCT and combined fused OCT and SAP data provided similar Area under the Receiver Operating Characteristic Curve (AROC) values of 0.978 that were significantly larger (p = 0.047) compared to ANNs using SAP parameters alone (AROC = 0.945). On the other hand, ANNs based on the OCT parameters (AROC = 0.970) did not perform significantly worse than the ANNs based on the fused or combined forms of input data. The use of fused input increased the number of tests that were correctly classified by both SAP and OCT based ANNs.</p> <p>Conclusions</p> <p>Compared to the use of SAP parameters, input from the combination of fused OCT and SAP parameters, and from fused OCT data, significantly increased the performance of ANNs. Integrating parameters by including a priori relevant information through data fusion may improve ANN classification accuracy compared to currently available methods.</p

Determination of sunset yellow in multi-vitamin tablets by photoacoustic spectroscopy and a comparison with alternative methods

Photoacoustic (PA) spectroscopy in the visible wavelength region was shown to be suitable for a direct (no preparatory steps involved) quantification of sunset yellow (E110) colour in effervescent multi-vitamin tablets. Measurements on powdered tablets containing E110 were performed at 480?nm at which wavelength this synthetic colour shows appreciable absorbance. The PA data obtained were compared to the results acquired by diffuse reflectance spectroscopy and conventional spectrophotometry. Intrinsic simplicity, ease of sampling and rapid response were the most important advantages of the PA technique. In terms of sensitivity the performance of the three methods were comparabl

Water content of acacia honey dertermined by two established methods and by optothermal window

The major objective of the research study described here was to explore the potential of the optothermal window (OW) technique as a new approach towards a simple, rapid determination of water content in honey. Water, major component of foods, influences their physical and chemical properties. Single mode RLT-1480-40G laser diode and the standard addition method were used to calibrate the response of the OW detector at analytical wavelength of 1478 nm and to determine water content of Acacia honey. The performance of the OW method was compared to that of well established gravimetry and refractometry; the values obtained by the three different methods are practically the sam

Water content of acacia honey dertermined by two established methods and by optothermal window

The major objective of the research study described here was to explore the potential of the optothermal window (OW) technique as a new approach towards a simple, rapid determination of water content in honey. Water, major component of foods, influences their physical and chemical properties. Single mode RLT-1480-40G laser diode and the standard addition method were used to calibrate the response of the OW detector at analytical wavelength of 1478 nm and to determine water content of Acacia honey. The performance of the OW method was compared to that of well established gravimetry and refractometry; the values obtained by the three different methods are practically the sam

Direct quantification of carotenoids in low fat babyfoods via laser photoacoustics and colorimetric index a

Carotenoids are important antioxidants found in various foods including those for nutrition of infants. In this investigation, the total carotenoid content (TCC) of nine different commercially available baby foods was quantified using colorimetric index a * obtained via reflectance colorimetry (RC) and by laser photoacoustic spectroscopy (LPAS) at 473 nm. The latter requires a minimum of sample preparation and only a one time calibration step which enables practically direct quantification of TCC. Results were verified versus UV–Vis spectrophotometry (SP) as the reference technique. It was shown that RC and LPAS (at 473 nm) provide satisfactory results for a *, R 2 = 0.9925 and R 2 = 0.9972, respectively. Other color indices do not show a correlation with TCC. When determining the TCC in baby foods containing tomatoes, it is necessary to select a different analytical wavelength to compensate for the effect of lycopene’s presence in the test samples

Determination of lactose in raw milks by means of the combined He-Ne laser optothermal window

The concept of OW (with 632.8 nm He–Ne laser), combined with colorimetry based on a reaction of anthrone-sulphuric acid, was proposed as a new tool for determination of lactose in raw milk. Data obtained from various milk samples by OW colorimetry were compared to those acquired from the MilkoScan analyser; the correlation between the two methods is high

Determination of free fatty acids in cooking oil: traditional spectrophotometry and optothermal window assay

The concept of optothermal window (OW) (with 632.8 nm He-Ne laser used as a radiation source), combined with copper soap based colorimetry, was proposed as a new analytical tool to determine total free fatty acid (FFA) content in thermally treated cooking oil. The results obtained were compared to those acquired by conventional spectroscopy; the correlation between the two methods is high for FFA concentrations exceeding 2 µmol/m

Non-destructive Measurement of Total Carotenoid Content in Processed Tomato Products : Infrared Lock-In Thermography, Near-Infrared Spectroscopy/Chemometrics, and Condensed Phase Laser-Based Photoacoustics—Pilot Study

Carotenes found in a diversity of fruits and vegetables are among important natural antioxidants. In a study described in this paper, the total carotenoid content (TCC) in seven different products derived from thermally processed tomatoes was determined using laser photoacoustic spectroscopy (LPAS), infrared lock-in thermography (IRLIT), and near-infrared spectroscopy (NIRS) combined with chemometrics. Results were verified versus data obtained by traditional VIS spectrophotometry (SP) that served as a reference technique. Unlike SP, the IRLIT, NIRS, and LPAS require a minimum of sample preparation which enables practically direct quantification of the TCC

Determination of trace elements in lithium niobate crystals by solid sampling and solution-based spectrometry methods

Solid sampling (SS) graphite furnace atomic absorption spectrometry (GFAAS) and solution-based (SB) methods of GFAAS, flame atomic absorption spectrometry (FAAS), inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) were elaborated and/or optimized for the determination of Cr, Fe and Mn trace elements used as dopants in lithium niobate optical crystals. The calibration of the SS-GFAAS analysis was possible with the application of the three-point-estimation standard addition method, while the SB methods were mostly calibrated against matrix-matched and/or acidic standards. Spectral and non-spectral interferences were studied in SB-GFAAS after digestion of the samples. The SS-GFAAS method required the use of less sensitive spectral lines of the analytes and a higher internal furnace gas (Ar) flow rate to decrease the sensitivity for crystal samples of higher (doped) analyte content. The chemical forms of the matrix produced at various stages of the graphite furnace heating cycle, dispensed either as a solid sample or a solution (after digestion), were studied by means of the X-ray near-edge absorption structure (XANES). These results revealed that the solid matrix vaporized/deposited in the graphite furnace is mostly present in the metallic form, while the dry residue from the solution form mostly vaporized/deposited as the oxide of niobium