Spectroscopic Analysis Methods Research Articles

Neurotrophic neolignans of Pinus koraiensis twigs

Four undescribed neolignan analogs, together with eight known compounds, were isolated from the twigs of Pinus koraiensis (Korean pine). The chemical structure of the isolated compounds was determined through extensive spectroscopic analysis and chemical method. Their relative and absolute configurations were assigned through a well-established empirical rule and electronic circular dichroism (ECD) analysis, respectively. Four compounds (3 and 9–11) at 20 μM concentration showed significant neurotrophic effect by inducing nerve growth factor (NGF) secretion in C6 cells with the stimulation levels a range of 140.82 ± 4.62% to 160.04 ± 11.04%. Additionally, the result indicated that the glycosylation of neolignan led to an improvement in neurotrophic activity compared to their aglycone form. A compound (7) inhibited nitric oxide production with an IC50 value of 31.74 μM in LPS-activated BV2 cells.

Pincer-type complexes with B(3)-H selective bond activation of m-carborane

Herein, we describe the synthesis of a series pincer-type half-sandwich complexes containing selective B(3)-H activation of m-carborane. Four pincer-type complexes containing Cp*M (M = Ir/Rh) and (η6-pcym)Ru metal-corner, ionic Cp*M[m-C2B10H9(CS2CH3)2](CF3SO3) (M = Ir (2), Rh (3)), (η6-pcym)Ru[m-C2B10H9(CS2CH3)2](CF3SO3) (4) and neutral solvolysis product Cp*Ir[m-C2B10H9(CS2CH3)(COS)] (Complex 5), have been prepared. The addition reaction of MeO− toward 2 3 and 4 causes the formation of moderately stable neutral unsymmetrical pincer-type complexes Cp*M{m-C2B10H9(CS2CH3)[CS(SCH3)(OCH3)]} (M = Ir (6), Rh (7)) and (η6-pcym)Ru{m-C2B10H9(CS2CH3)[CS(SCH3)(OCH3)]} (8). The substitution reaction of 2 3 and 4 have also been also explored, unsymmetrical chelate complexes Cp*M(tBuNC)[m-C2B10H9(CS2CH3)2](BPh4) (M = Ir (9), Rh (10)) can be obtained by using tBuNC and NaBPh4. All of these complexes have been characterized, including X-Ray single crystal diffraction, NMR spectroscopy, IR spectroscopy and elemental analysis methods.

Chemical constituents from the flowers of Inula japonica and their anti-inflammatory activity

Ethnopharmacological relevanceThe flowers of Inula japonica (Inulae Flos) can be used to treat cough and asthma and remove phlegm in traditional Chinese medicine (TCM). Aim of the studyOur research aimed to obtain active components with the inhibition of inflammation and MUC5AC production to alleviate asthma symptoms from I. japonica. Materials and methodsThese compounds were separated from the MeOH extract of Inulae Flos by column chromatography over silica gel, AB-8 macroporous resin column, MPLC, and semipreparative HPLC. Their structures were elucidated by detailed spectroscopic data analysis, ECD calculations, and chemical methods. NO production was determined to evaluate anti-inflammatory activity in RAW 264.7 cells. The expression of MUC5AC, IL-1β, and IL-4 were measured in NCI–H292 cells by qRT-PCR. The anti-asthma activity assessments in vivo were performed through H & E and PAS staining, pulmonary function analysis, and cytokines determination by qRT-PCR or ELISA. The expression levels of PI3K, p-PI3K, AKT, p-AKT, MEK, p-MKE, ERK, p-MEK, and IL-1β were analyzed through western blotting. ResultsOne undescribed 1,10-seco-eudesmanolide derivative (1), two previously unreported 1,10-seco-eudesmanolide glycosides (2 and 3), and thirty-two known compounds (4–35) were obtained from Inulae Flos. Compound 11 had the most inhibitory effect against LPS-induced NO production in RAW 264.7 murine macrophages. Meanwhile, compound 11 also attenuated the increase in MUC5AC, IL-1β, and IL-4 mRNA expression in NCI–H292 cells. The results of the animal experiment confirmed that compound 11 significantly ameliorated OVA-induced asthma in a murine model of allergic asthma demonstrated by elevated pulmonary function, reduced inflammatory cell infiltration and mucus production. In addition, compound 11 significantly inhibited the levels of OVA-specific IgE in serum, of IL-4 and IL-6 in BALF, and of MUC5AC, IL-1β , IL-4, IL-5, IL-6 and IL-13 in lung tissue. Finally, compound 11 suppressed PI3K/AKT/MEK/ERK signaling pathway in lung tissue of mice. ConclusionThis study indicated that compound 11 might be a potential therapeutic candidate ameliorating airway inflammation and mucus hypersecretion via PI3K/AKT/MEK/ERK signaling pathway in allergic asthma.

Optimization of the Zebrafish Larvae Pentylenetetrazol-Induced Seizure Model for the Study of Caffeine and Topiramate Interactions.

Epilepsy is a common neurological disorder characterized by seizures that cause neurobiological and behavioral impairment. Caffeine (CAF), which is the most widely consumed stimulant in the world, is reported to influence epileptic seizures and antiepileptic drugs, especially topiramate (TPM). The aim of the study was to optimize the zebrafish larvae pentylenetetrazol-induced seizure model for the study of CAF and TPM interactions, which include the determination of dose space, and the delivery of an analytical method for monitoring CAF, TPM, and CAF metabolite paraxanthine (PAR) in Zebrafish larvae. Methods: The zebrafish larvae, 4 days post-fertilization, were incubated for 18 h with CAF, TPM, or CAF + TPM, with subsequent locomotor activity assessment. Seizures were evoked by adding PTZ solution to obtain a final concentration of 20 mM. Subsequently, the liquid chromatography-mass spectrometry (LC-MS/MS) analytical method was used to simultaneously assess the levels of both CAF and TPM in the larvae. CAF (50 mg/L) and TPM (75 μM) given separately decreased the average larvae locomotor activity compared to the PTZ group but, however, were not able to lower it to the control level. Co-administration of 25 mg/L CAF and 50 μM TPM suppressed the activity to the same level. Adding 25 μM TPM to 50 mg/L CAF decrease the measured CAF level in the larvae. Until proven otherwise, CAF consumption should be regarded as a potential determinant in the modulation of TPM's efficacy in the management of epileptic seizures. The optimized model will contribute to the standardization of studying CAF and TPM interactions and building the understanding of the molecular bases of the interaction.

Comprehensive insights into the binding of crystal violet and pepsin: Spectroscopic analysis, molecular model and biochemical method

As a well-known triphenylmethane dye, crystal violet (CV) has received extensive concerns owing to its harmful influence on human health. Pepsin is a digestive enzyme in the stomach that plays a crucial part in several physiological and pathological process. This research aimed to use spectroscopic experiments, computer simulation and enzyme activity assays to investigate the influence of CV on the functions and structure of pepsin from the perspective of binding. Fluorescence and UV–vis spectra confirmed the complex formation between CV and pepsin. Ka was in the order of 104 M−1, implying a moderate affinity between CV and pepsin. Multi non-covalent interactions played a crucial part in this binding process. The conformational alterations of pepsin caused by CV were reflected in β-sheet content reducing, and the presence of CV caused an activation of pepsin. The outcomes of molecular docking indicated that the interaction of Tyr75/Tyr189 with CV is the major cause for the fluorescence quenching phenomenon of pepsin. For molecular dynamics (MD) simulation, the CV-pepsin and free pepsin systems reached equilibrium in 40 ns. In addition, the compactness of pepsin changed after interacting with CV, which was in line with the results of solvent experiment. From the above results, CV has effects on the properties of pepsin, which may provide novel insights into the toxicological study of CV.

Pyridapeptides F‒I, Cyclohexapeptides from Marine Sponge-derived Streptomyces sp. OUCMDZ-4539

Four new cyclohexapeptides, pyridapeptides F–I (1–4), were isolated from the fermentation broth of marine sponge-derived Streptomyces sp. OUCMDZ-4539. The pyridapeptides F–H (1–3) are composed of β-hydroxyleucine, alanine, O-methylthreonine, hexahydropyridazine-3-carboxylic acid, 5-hydroxytetrahydropyridazine-3-carboxylic acid, and (2S,3R,4E,6E)-2-amino-3-hydroxy-4,6-dienoic acid residues. Pyridapeptide I (4) contains (2S,3R,4E,6E)-2-amino-3-hydroxy-8-methylnona-4,6-dienoic acid residue and a very rare glycose residue, aculose. Their structures were determined based on spectroscopic analysis and chemical methods. Pyridapeptides G–I (2–4) have the 2,3,6-trideoxyhexose units glycosylated at the γ-OH-TPDA residue, displayed significant antiproliferative activity against four (PC9, MKN45, HepG2, K562) or two (PC9, MKN45) human cancer cell lines.

Detection of fentanyl, synthetic opioids, and ketamine in hair specimens from purposive samples of American and Italian populations.

With the current crisis related to the diffusion of fentanyl and other novel opioids in several countries and populations, new and effective approaches are needed to better elucidate the phenomenon. In this context, hair testing offers a unique perspective in the investigation of drug consumption, producing useful information in terms of exposure to psychoactive substances. In this research, we applied targeted ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analytical methods to detect novel synthetic and prescription opioids and other common controlled psychoactive drugs in the keratin matrix. A total of 120 hair samples were analyzed from the United States (US) and Italy, segmented when longer than 6 cm, and then analyzed. In the 60 samples (83 segments in total) analyzed from a purposive sample of data collected in the US, fentanyl was detected in 14 cases (16.9%), with no detection of nitazens or brorphine. We also detected fentanyl metabolites, despropionyl-p-fluorofentanyl, and prescription opioids. In the 60 samples collected in Italy (91 segments in total), ketamine was the most prevalent compound detected (in 41 cases; 45.1%), with ketamine demonstrating a strong correlation with detection of amphetamines and MDMA, likely due to co-use of these substances in recreational contexts. Several common drugs were also detected but no exposure to fentanyl or its analogs were detected. Results of this retrospective exploration of drug use add to increasing evidence that hair testing can serve as a useful adjunct to epidemiology studies that seek to determine biologically confirmed use and exposure in high-risk populations.

Laser-induced nitrogen oxide fluorescence from nitro compounds by 222 nm laser

This paper presents the study results of the single-frequency interaction of KrCl laser broadband radiation with nitro compound vapors in the atmosphere. The optical method of a substance spectroscopic analysis including photofragmentation of a complex R–NO2 molecule followed by laser-induced fluorescence of vibrationally excited fragments of NO X2Π, v''>0 (PF-LIF) was studied in the experiments. It has been shown that R–NO2 molecules exposed to λ = 222 nm FWHM 0.3 nm KrCl laser broadband radiation undergo photofragmentation followed by resonant excitation of several electronic-vibrational levels of NO X2Π, v'' (2,4). At the same time, the concentration of fragmented NO X2Π, v'' (2,4) increases due to the secondary PF-LIF NO2 process during the nanosecond laser pulse.

Efficient and cost-effective determination of Cr(VI) ions using immobilized 4,5-dihydroxynaphthalene-2,7-disulfonic acid disodium salt dihydrate: a novel analytical reagent with high selectivity and sensitivity

ABSTRACT The determination of Cr(VI) ions in real-world samples is of utmost importance due to the critical role it plays in assessing and monitoring the levels of Cr(VI) contamination in water. The present study introduces a time-saving, cost-effective, selective, highly efficient and eco-friendly analytical reagent to detect Cr(VI) ions. This study presents fabrication of immobilised 4,5-dihydroxynaphthalene-2,7-disulfonic acid disodium salt dihydrate (DHNDSADNa) on a polyethylene-polyamine polyacrylonitrile (PPA) matrix for the determination of Cr(VI) ions using X-ray fluorescence, spectroscopic analysis and potentiodynamic titration methods. The findings revealed that the immobilised DHNDSADNa on the PPA matrix is a highly selective, accurate, easily regenerable, and rapid analytical reagent for the determination of Cr(VI) ions. The DHNDSADNa-anchored PPA framework demonstrated distinctive spectroscopic signals at 460 nm and 590 nm for the reagent and its complex with Cr(VI) ions, respectively. The detection limit for Cr(VI) ions was found to be 2 μg/mL, which is lower than that of DHNDSADNa in solution. Furthermore, the reagent exhibited high selectivity and efficiency for Cr(VI) ions even in the presence of other ions such as Co(II), Ni(II), Al(III), Fe(II), Ti(IV), Zr(IV), Ta(V), Mn(II), and W(VI). Last but not least, the immobilised DHNDSADNa on the PPA matrix exhibits superior analytical characteristics compared to previously utilised methods, making it a promising tool for various applications in medicine, pharmacology, biology, chemistry, and engineering.

Therapeutic drug monitoring of mycophenolic acid (MPA) using volumetric absorptive microsampling (VAMS) in pediatric renal transplant recipients: ultra-high-performance liquid chromatography-tandem mass spectrometry analytical method development, cross-validation, and clinical application

BackgroundMycophenolic acid (MPA) is widely used in posttransplant pharmacotherapy for pediatric patients after renal transplantation. Volumetric absorptive microsampling (VAMS) is a recent approach for sample collection, particularly during therapeutic drug monitoring (TDM). The recommended matrix for MPA determination is plasma (PL), and conversion between capillary-blood VAMS samples and PL concentrations is required for the appropriate interpretation of the results.MethodsThis study aimed to validate and develop a UHPLC-MS/MS method for MPA quantification in whole blood (WB), PL, and VAMS samples, with cross and clinical validation based on regression calculations. Methods were validated in the 0.10–15 µg/mL range for trough MPA concentration measurement according to the European Medicines Agency (EMA) guidelines. Fifty pediatric patients treated with MPA after renal transplantation were included in this study. PL and WB samples were obtained via venipuncture, whereas VAMS samples were collected after the fingerstick. The conversion from VAMSMPA to PLMPA concentration was performed using formulas based on hematocrit values and a regression model.ResultsLC–MS/MS methods were successfully developed and validated according to EMA guidelines. The cross-correlation between the methods was evaluated using Passing-Bablok regression, Bland–Altman bias plots, and predictive performance calculations. Clinical validation of the developed method was successfully performed, and the formula based on regression was successfully validated for VAMSMPA to PLMPA concentration and confirmed on an independent group of samples.ConclusionsThis study is the first development of a triple matrix-based LC–MS/MS method for MPA determination in the pediatric population after renal transplantation. For the first time, the developed methods were cross-validated with routinely used HPLC–DAD protocol.Graphical

Synthesis, Antifungal Activities, Molecular Docking and Molecular Dynamic Studies of Novel Quinoxaline-Triazole Compounds.

Uncontrolled use of antifungal drugs affects the development of resistance to existing drugs. Azole antifungals constitute a large part of antifungal therapy. Therefore, there is a need for new azole antifungals. Within the scope of this study, 17 new triazole derivative compounds were synthesized. Structure determinations were clarified by spectroscopic analysis methods (1H-NMR, 13C-NMR, HRMS). In addition, structure matching was completed using two-dimensional NMR techniques, HSQC, HMBC and NOESY. The antifungal effects of the compounds were evaluated on Candida strains by means of in vitro method. Compound 5d showed activity against Candida glabrata with a MIC90 = 2 μg/mL. Compound 5d showed activity against Candida krusei with a MIC90 = 2 μg/mL. This activity value, which is higher than fluconazole, is promising. In addition, the biofilm inhibition percentages of the compounds were calculated. Molecular docking and molecular dynamics simulations performed with compound 5d are in harmony with activity studies.

Pharmacokinetic evaluation of Sinisan containing vinegar-processed products in depressive rats, a comprehensive perspective of ‘individual herb, herb-pair, and herbal formula’

Ethnopharmacological relevanceAs a classical formula for the treatment of depression, the clinical application of vinegar-processed products of Bupleuri Radix (Bupleurum chinense DC., BR) and Paeoniae Radix Alba (Paeonia lactiflora Pall., PRA) contained in Sinisan (SNS) is still controversial. Aim of the studyThree levels of ‘individual herb, herb-pair, and herbal formula’ were employed to investigate whether and how the processing of main drugs affected the active constituents of pharmacokinetics in SNS, as well as their impacts on the hepatic CYP450 enzyme. Materials and methodsRats were subjected to construct a chronic unpredictable mild stimulation (CUMS) model. A rapid and sensitive ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) analytical method was developed and validated for simultaneously quantitative evaluation of thirteen potential active compounds of SNS in depressive rat plasma, and successfully applied to a holistic comparison of pharmacokinetics. The differences in pharmacokinetic parameters based on three different forms of drug composition from BR and PRA before and after vinegar-processing were compared. Meanwhile, qRT-PCR and Western Blot were utilized to explore the metabolic activity of three isoforms of CYP450 enzyme scattered in the livers of depressive rats. ResultsThe characteristic pharmacokinetics profiles of thirteen representative constituents in CUMS rats were influenced by vinegar-processing of BR and PRA and/or the compatibility. In detail, there were significant differences in the Cmax, AUC0-24, AUC0-∞, t1/2, and MRT0-24 of most constituents among the three different forms of drug composition from BR and PRA before and after vinegar-processing, with the most obvious changes in six constituents from the adjuvant and mediating guide drugs. And also, the pharmacokinetic parameters of seven constituents from BR and PRA in SNS containing vinegar-processed products obviously changed after compatibility. Additionally, the mRNA and protein levels of CYP1A2, CYP2E1, and CYP3A1 were observed to increase significantly with the processing of BR and PRA and the combination/formulation. ConclusionsIn conclusion, SNS containing vinegar-processed products was more conducive to the absorption of most activated constituents compared to the original formula in vivo. The vinegar-processing of BR and PRA and the compatibility co-contribute to the pharmacokinetic variability of active compounds of SNS in CUMS rats, and the extent of contribution varies among drugs, which might be related to the regulation of the hepatic drug metabolizing enzymes. The finding of the investigation could help to better understand how active compounds metabolized in vivo, which might be helpful for guiding the clinical application of SNS containing vinegar-processed products.

Microstructural evolution of TiC nano powders under fast neutron irradiation: A multi-technique analysis

In this work, titanium carbide nano powders were irradiated at normal conditions of 293.15 K and 1 atm with fluencies of 4.0 × 1012 n/cm2, 8.0 × 1012 n/cm2, 1.3 × 1013 n/cm2, 4.0 × 1014 n/cm2, and 1015 n/cm2 (neutron energy 1 MeV). The microstructure of the titanium carbide nano powders after irradiation was examined using X-ray diffraction, Raman spectroscopy, and FTIR spectroscopic analysis methods. The X-ray diffraction analysis revealed that no significant phase transition or amorphization occurred in the TiC nano powders exposed to fast neutrons. More sensitive results obtained from the FTIR analysis showed that the water molecules absorbed on the material surface were disintegrated under the influence of fast neutrons. Exceptional structural stability to neutron irradiation of titanium carbide without amorphization was also observed by morphological analysis via transmission electron microscopy (TEM) and selected area electron diffraction (SEAD).

Pharmacokinetics, Bioequivalence, and Safety of Esomeprazole Magnesium Enteric-Coated Capsules in Healthy Chinese Subjects.

This bioequivalence study is critically important for drug production. Recently, a local pharmaceutical company produced esomeprazole magnesium enteric-coated capsules, a major drug to help to eradicate Helicobacter pylori, but the bioequivalence is not well known. The present study aimed to evaluate the bioequivalence of the 2 esomeprazole magnesium enteric-coated capsules and their pharmacokinetics and safety in 3 biological equivalence trials: fasting, feeding, and mixing. The fasting and mixing trials used single-centered randomized, open-label, single-dose, 2-treatment, 2-period, and 2-sequence crossover design, while the fed trials used single-centered, randomized, open-label, single-dose, 2-treatment, 3-period, 3-sequence partial crossover design. For the fasting and mixing trials, each of the 32 subjects was fasted overnight prior to taking the test preparations or reference preparations. In the fed trial, 54 subjects were given a high-fat meal 1 hour before the drugs were administered. Blood specimens from all subjects were collected against the light within 14hours, with the plasma drug concentration being detected by the validated ultra-performance liquid chromatography-tandem mass spectrometry analysis method. Geometric mean ratio of maximum concentration, the area under the concentration-time curve from time zero to the last measurable concentration, and area under the concentration-time curve from time zero to infinity with 90% confidence interval were calculated. The data from fasting, mixing, and fed trials met the bioequivalence criteria. No serious adverse reactions were found, suggesting that the test and reference preparations of esomeprazole magnesium enteric capsules have similar safety profile.

Chemometrics-assisted spectroscopic methods for rapid analysis of combined anti-malarial tablets.

Combination of piperaquine (PQ) (320mg) and dihydroartemisinin (DHA) (40 mg) is an anti-malarial formulation, which is recommended by World Health Organization (WHO). Simultaneous analysis of PQ and DHA can be problematic due to the lack of chromophores or fluorophores in DHA molecule. Whereas PQ possesses strong UV absorption and it presents in 8 times of DHA contents in the formulation. In this study, two spectroscopic methods, Fourier transform infrared (FTIR) and Raman spectroscopy, were developed for the determination of both drugs in combined tablets. The FTIR and Raman spectra were recorded in the attenuate total reflectance (ATR) and scattering modes, respectively. The original and pretreated spectra from FTIR and handheld-Raman were subjected to Unscrambler® program to construct partial least squares regression (PLSR) model comparing with references values obtained from high performance liquid chromatography (HPLC)-UV method. The optimal PLSR models of PQ and DHA from FTIR spectroscopy were obtained from orthogonal signal correction (OSC) pretreatment at the wavenumbers 400-1,800 cm-1 and 1,400-4,000 cm-1, respectively. For Raman spectroscopy of PQ and DHA, the optimal PLSR models were obtained from standard normal variate (SNV) pretreatment at the wavenumbers 1,200-2,300 cm-1 and OSC pretreatment at the wavenumber 400-2,300 cm-1, respectively. Determination of PQ and DHA in tablets from the optimum model was compared with HPLC-UV method. Results were not significantly different at 95% confidence limit (p-value >0.05). The chemometrics-assisted spectroscopic methods were fast (1-3 min), economical and less labor intensive. Moreover, the handheld Raman spectrometer is portable and can be utilized for onsite analysis to facilitate the detection of counterfeit or substandard drugs at ports of entry.

Deciphering the Color Origin of Pink Conch Pearl Using Nondestructive Spectroscopies and DFT Calculations

Conch pearl is a calcareous concretion produced by the Queen conch mollusk and is of extremely high economic value. Its attractive pink color has remained a mystery for hundreds of years. This difficulty limits the development of cultivation and preservation technology of conch pearl. Due to its super-high value, it is generally impossible to use destructive chemical analysis methods. Here, various nondestructive spectroscopic analysis methods and theoretical calculations were used to reveal the color origin of pink conch pearl. The experimental Raman and UV-Vis spectroscopies were used to characterize the color and pigments. We further discuss the pigments in conch pearl by comparing the Raman spectral characteristics and pigments of the red coral. Based on the characteristics of the experimental spectra, we speculate that the carotenoids color the conch pearl. The theoretical Raman and UV-Vis spectra of all-trans polyene and carotenoids were simulated using DFT calculations. According to the results, we proposed that the pigments in pink conch pearl are polyenes containing 11 shortened C–C bonds with multiplicities > 1.5, which may be demethylated carotenoids.

Gc-ms Analysis and In-vitro Antioxidant Activities of Cissus Quandrangularis Stem Extracts

Plants with therapeutic constituents are gaining prominence in the fields of food and pharmacological industries. Nowadays, researches are focussed mainly on drugs from natural sources with minimal side effects. The aim of the present study was to investigate the phytochemical constituents and antioxidant activity of Cissus quadrangularis stem in Methanol extract. The phytochemical constituents were identified by Gas Chromatography-Mass Spectrometry (GC-MS) analytical method and in-vitro antioxidant activity of methanol extract was investigated by DPPH (2, 2- Diphenyl-1-picrylhydrazyl) Radical Scavenging Activity. The total antioxidant activity revealed that fresh stem has more antioxidant activity compared to dried powdered stem. The Phytochemical analysis carried out by GC-MS technique indicated that thirty two compounds were present in Cissus quadrangularis stem extract. Thus the results anticipated the therapeutic potency of the plant and its basis for further phytochemical and nutraceutical investigation.

New mixed ligand complexes of lanthanide metal cations containing acesulfame/nicotinamide. Synthesis and structural characterizations

The mixed ligand complexes containing acesulfame and nicotinamide ligands of rare earth metal cations Eu3+, Tb3+, Ho3+, Er3+ and Yb3+ were synthesized and their structural characterizations were examined. The complexes' thermal decomposition steps and structural properties were investigated by chemical analysis, infrared spectroscopy, mass analysis, and solid-state UV-vis spectroscopy and thermal analysis methods. According to the results obtained, it is suggested that the metal cations have six coordination sphere. It is recommended that the geometry of the complexes is distorted octahedral with two nicotinamide ligands that make neutral coordination over the nitrogen atom of the pyridine group, two aqua ligands and two monoanionic monodentate acesulfame ligands that coordinated via the acidic imine nitrogen. The coordination compounds perform charge balances with an anionic acesulfame situated the coordination sphere. Except for the Er3+ metal cation complex, it has been determined that all other structures have one hydrate water. From the thermal analysis curves, it was obtained that oxide derivatives of each metal cation were formed in the reaction pots as the last degradation products of Ho3+, Er3+ and Yb3+ complexes. It has been suggested that sulfate salts of related metal cations remain as thermal decomposition products in Eu3+ and Tb3+ metal cation-centered structures.

Assessment of Near-Infrared and Raman Spectroscopy as Analytical Tools to Predict Viscosity of Ice Cream Mixes.

Ice cream is a complex product containing four different phases that affect its microstructure. Viscosity is a critical ice cream quality parameter that is typically measured using off-line methodologies, such as rheometry. In-line viscosity measurements allow continuous and instant analysis compared to off-line methodologies, yet they still constitute a challenge. This work focused on the preliminary study of the potential application of near-infrared (NIR) and Raman spectroscopy as analytical tools to assess the viscosity of ice cream mixes. Historically, partial least squares regression (PLSR) is a standard algorithm used for analysis of spectral data and in the development of predictive models. This methodology was implemented over a range of viscosity values, obtained by varying the ice cream fat content and homogenization conditions. Individual PLSR models showed some predictive ability and better performance compared to the integrated model obtained by data fusion. Lower prediction errors and higher coefficients of determination were obtained for NIR, making this technique more suitable based on model performance. However, other considerations should be accounted during the selection of the best method, such as implementation limitations. This study offers a preliminary comparison of the spectroscopic methods for quantitative analysis of viscosity of aged ice cream mixes and a starting point for an in-situ application study.

Spectral separation degree method for Vis-NIR spectroscopic discriminant analysis of milk powder adulteration

Adulteration detection of adding ordinary milk powder to high-end dedicated milk powder is challenging due to the high similarity. Using visible and near-infrared (Vis-NIR) spectroscopy combined with k-nearest neighbor (kNN), the discriminant analysis models of pure brand milk powder and its adulterated milk powder (including unary and binary adulteration) were established. Standard normal variate transformation and Norris derivative filter (D = 2, S = 11, G = 5) were jointly used for spectral preprocessing. The separation degree and separation degree spectrum between two spectral populations were proposed and used to describe the differences between the two spectral populations, based on which, a novel wavelength selection method, named separation degree priority combination-kNN (SDPC-kNN), was proposed for wavelength optimization. SDPC-wavelength step-by-step phase-out-kNN (SDPC-WSP-kNN) models were established to further eliminate interference wavelengths and improve the model effect. The nineteen wavelengths in long-NIR region (1100–2498 nm) with a separation degree greater than 0 were used to establish single-wavelength kNN models, the total recognition-accuracy rates in prediction (RARP) all reached 100%, and the total recognition-accuracy rate in validation (RARV) of the optimal model (1174 nm) reached 97.4%. In the visible (400–780 nm) and short-NIR (780–1100 nm) regions with the separation degree all less than 0, the SDPC-WSP-kNN models were established. The two optimal models (N = 7, 22) were determined, the RARP values reached 100% and 97.4% respectively, and the RARV values reached 96.1% and 94.3% respectively. The results indicated that Vis-NIR spectroscopy combined with few-wavelength kNN has feasibility of high-precision milk powder adulteration discriminant. The few-wavelength schemes provided a valuable reference for designing dedicated miniaturized spectrometer of different spectral regions. The separation degree spectrum and SDPC can be used to improve the performance of spectral discriminant analysis. The SDPC method based on the separation degree priority proposed is a novel and effective wavelength selection method. It only needs to calculate the distance between two types of spectral sets at each wavelength with low computational complexity and good performance. In addition to combining with kNN, SDPC can also be combined with other classifier algorithms (e.g. PLS-DA, PCA-LDA) to expand the application scope of the method.