CONH Groups Research Articles

The Annelation for Enaminoureides of 3,3-Dimethyl-1,2,3,4-tetrahydroisoquinoline Series by Action of Oxalyl Chloride and Ninhydrin

By reaction of Ritter cyclization of cyanoacetylureas with dimethylbenzylcarbinoles the corresponding enaminoureides were obtained, derivatives of 3,3-dimethyl-1,2,3,4-tetrahydroisoquinoline. The polyfunctional character of obtained compounds is confirmed by the structure of products of reaction with some electrophiles: phenyl isocyanate reacts at the γ-C atom of enamine and CONH2 group of urea, under the action of oxalyl chloride annelation of a pyrrole cycle occurs with the formation of a derivative of 2,3-dioxopyrrolo[2,1-a]isoquinoline. Reaction with ninhydrin occurs similary with enaminoamides having hydrogen atoms at the amide nitrogen: a pyrrole ring is fused with the formation of a system of indeno[1,2-b]pyrrole.

Ionization-Induced Reversible Aggregation of Self-Assembled Polycarbonyl Hydrazide Nanoparticles: A Potential Candidate for Turn-On Base Sensor and pH-Switchable Materials

Hierarchical assembly of nanostructures remains one of the desirable targets in nanoscience. Herewith, we report a hydrogen-bond-promoted polymeric nanoparticle (NP) system that reversibly aggregates into different microstructures upon variation of the concentration of the base in the medium. Polycarbonyl hydrazide, a polyaza-Michael adduct, formed uniform spherical NPs in solution owing to the presence of inherent CO---HNCO hydrogen-bond-based physical cross-links in the system. In the presence of the base, the CONH groups ionized to form the corresponding nitranions, and the resulting anion−π interaction between the ionic polymer NPs promoted the secondary aggregation to different shapes and sizes in the microdomain. The shape of the aggregated microparticles gradually changed from spherical to fiber through flakes upon a gradual increase in the base concentration in the medium. The modulus of these superstructures notably decreased compared to that of the original un-ionized NPs, suggesting the involve...

Construction of nine non-covalently-bonded zinc(II) and cadmium(II) supramolecules containing the mixed-ligands of 3,5-dimethylpyrazole and carboxylates: Their synthesis and characterization

The present report pertains to the synthesis and characterization of nine novel mixed-ligand complexes, Zn(Hdmpz)2(L1)2 (1) (Hdmpz = 3,5-dimethylpyrazole, L1 = 2-furoate), Cd(Hdmpz)4(L2)2 (2) (L2 = 1-hydroxy-2-naphthoate), Zn(Hdmpz)2(L3)2 (3) (L3 = 5-bromosalicylate), Cd(Hdmpz)2(L4) (4) (L4 = 4-nitro-phthalate), Zn(Hdmpz)2(L5)2 (5) (L5 = 3-(2-chloro-phenylcarbamoyl)-acrylate), Zn(Hdmpz)2(L6)2 (6) (L6 = 3-m-tolylcarbamoyl-acrylate), Cd(Hdmpz)2(L6)2 (7), Zn(Hdmpz)2(L7)2 (8) (L7 = 3-p-tolylcarbamoyl-acrylate) and [Cd(Hdmpz)2(L7)2]2·2H2O (9). The resulting complexes were formulated from elemental analysis, IR spectra and single crystal X-ray diffraction analysis. The TGA of all the complexes was also evaluated.The X-ray studies revealed that these complexes display mononuclear to binuclear structures with a tetrahedral geometry around each Zn atom and an octahedral geometry around each Cd atom. The Hdmpz ligands in all the compounds are coordinated only in a monodentate fashion through its neutral N atom. The carboxylate ligands in 1, 2, 3, 5, 6 and 8 act only as unidentate coordination ligands, while the carboxylate ligands in 4 and 7 have a chelating bidentate coordination mode. Compound 9 contains both unidentate bridging and chelating bidentate coordinated carboxylate groups.The uncoordinated O atom of the COO− group in 1, 2 and 3 forms an intramolecular hydrogen bond with the N–H group of the Hdmpz, compound, 4 bears an intramolecular N–H⋯O hydrogen bond between the pyrazole ligand and the coordinated O atom. In 5, 6, 7 and 8, there are intramolecular N–H⋯O hydrogen bonds from the N–H unit of the Hdmpz ligand and the O atom of the CONH group. In 9, the N–H⋯O hydrogen bonds from the –H unit of the Hdmpz ligand, the O atom of the CONH group and the coordinated O atom of the COO− group were found. In addition, in the compound 9 there exists an intra-anion N–H⋯O hydrogen bond between the coordinated O atom and the CONH unit, displaying a S11(7) ring.The intricate intra- and intermolecular classical hydrogen bonds, Br–Br, CH3–Br, CH–N, C–H⋯O, CH3⋯O, O⋯π(C), Cl–π, C–H⋯Cπ, C–H⋯π, CH3–π and π–π associations are elucidated from the X-ray crystallographic studies, which turn the discrete complexes into high-dimensional ordered supramolecular structures.

Adsorption of DNA binding proteins to functionalized carbon nanotube surfaces with and without DNA wrapping.

We examined the adsorption of DNA binding proteins on functionalized, single-walled carbon nanotubes (SWNTs). When SWNTs were functionalized with polyethylene glycol (PEG-SWNT), moderate adsorption of protein molecules was observed. In contrast, nanotubes functionalized with CONH2 groups (CONH2-SWNT) exhibited very strong interactions between the CONH2-SWNT and DNA binding proteins. Instead, when these SWNT surfaces were wrapped with DNA molecules (thymine 30-mers), protein binding was a little decreased. Our results revealed that DNA wrapped PEG-SWNT was one of the most promising candidates to realize DNA nanodevices involving protein reactions on DNA-SWNT surfaces. In addition, the DNA binding protein RecA was more adhesive than single-stranded DNA binding proteins to the functionalized SWNT surfaces.

A selective chemosensor for fluoride ion and its interaction with Calf Thymus DNA

The amido-Schiff base 1 (N1, N3-bis (2-nitrobenzylidene)benzene-1,3-dicabohydrazide) containing a CONH group and CHN linkage has been synthesized by the condensation between isophthalic acid dihydrazide and o-nitrobenzaldehyde. This molecule can act as a fluoride ion sensor with high selectivity and sensitivity. Presence of nitro group in the phenyl ring may be responsible for the detection of fluoride ion visually with a dramatic color change from colorless to deep red in aqueous dimethyl sulphoxide solution. This Schiff base can be used as test kit for sensing of fluoride ion in the solid state. Compound 1 can detect fluoride also in commercially available toothpaste. As the compound has adequate solubility in DMSO–water mixture (7:93, v/v) and having some hydrogen bond donor and acceptor centers, we have investigated its nature of binding with Calf Thymus-DNA (CT-DNA) using theoretical molecular modelling and other experimental methods like UV–vis spectroscopy, circular dichroic and thermal melting studies. Thermodynamic parameters have been obtained using the well known Van't Hoff's equation. From both theoretical and experimental findings it has been observed that it can interact effectively with CT-DNA with binding energy −7.55kcal/mol to −7.50kcal/mol.

Synthesis of Novel 5,6-Disubstituted Pyrrolo [2,3-d]Pyrimidine-2,4-Diones Via One-Pot Three-Component Reactions.

A simple and novel method for the synthesis of 5,6-disubstituted pyrrolo[2,3-d]pyrimidine-2,4-diones has been reported using arylglyoxal-based three-component reactions. Under microwave heating conditions, arylglyoxal, 6-amino uracil, or its derivatives reacts with various thiols in acetic acid medium to provide a series of pyrrolo[2,3-d]pyrimidine-2,4-diones (4) having a thioether and an aryl ring in 5 and 6 positions, respectively. On the other hand reaction of arylglyoxal, amino uracil and malononitrile in place of thiols, provided corresponding 5,6-disubstituted pyrrolo[2,3-d]pyrimidine-2,4-diones (5) with selectively converting one of the -CN to -CONH2 group both in conventional (method A) and microwave heating conditions (method B). This methodology is a simple and efficient protocol for the synthesis of diverse 5,6-disubstituted pyrrolo[2,3-d]pyrimidine-2,4-diones from the readily available starting materials in good yields.

COMPUTER SIMULATION OF FUNCTIONALIZED CARBON NANOTUBES AND GRAPHENE

Nanomaterials based on carbon nanotubes (CNT) and graphenes attract a lot of attention of researchers as the materials capable to raise the development of various industries to the new level, and first of all, of the chemical and electronic sectors. In addition to known experimental methods, new nanosystems are widely studied using advanced tools of quantum-chemical approaches. Modern theoretical methods are of great interest due to their ability to interpret known experimental facts and predict properties of non-synthesized compounds yet. This paper reviews results of theoretical studies performed using the density functional theory (DFT) methods to obtain data on the structure and electronic properties of single-walled CNT and graphene, modified with various impurities, with covalent-ionic and non-covalent binding mechanisms. New computational methods are briefly described that are currently employed to treat the dispersion interaction and enhance possibilities of DFT tools in systems where the van der Waals forces play a significant role. Particular attention is paid to the characteristics of carbon nanomaterials containing technologically important hydroxyl, carboxyl and amino groups. It is shown that the specific peculiarity of band structures of discussed in the literature CNT functionalized by OH, COOH, NHn and CONH2 groups is the partially occupied band in the neighborhood of the Fermi level, which directly affects the CNT conductivity. Modification of graphene layers is analyzed that interact with hydrogen, fluorine, bases of nucleic acids and the metal substrate surface. We also provide accuracy estimates for the calculations of interatomic bond lengths, interaction energy and band gap carried out in the literature using a variety of DFT approximations.

Temperature-, pH- and CO₂-Sensitive Poly(N-isopropylacryl amide-co-acrylic acid) Copolymers with High Glass Transition Temperatures.

A series of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAAm-co-PAA) random copolymers were synthesized through free radical copolymerization in MeOH. The incorporation of the acrylic acid units into PNIPAAm tended to enhance the glass transition temperature (Tg), due to strong intermolecular hydrogen bonding between the amide groups of PNIPAAm and the carboxyl groups of PAA, as observed using 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopic analyses. The lower critical solution temperature (LCST) increased upon increasing the pH of the aqueous solution containing PNIPAAm-co-PAA because the COOH groups of the PAA segment dissociated into COO− groups, enhancing the solubility of the copolymer. In addition, high-pressure differential scanning calorimetry revealed that the LCSTs of all the aqueous solutions of the copolymers decreased upon increasing the pressure of CO2, suggesting that CO2 molecules had displaced H2O molecules around the polar CONH and COOH groups in PNIPAAm-co-PAA, thereby promoting the hydrophobicity of the copolymers in the aqueous solution. In addition, the values of Tg of a film sample increased upon treatment with supercritical CO2, implying that intermolecular interactions in the copolymer had been enhanced after such treatment.

Hydrothermal Reduction of Polyethylenimine and Polyethylene Glycol Dual-Functionalized Nanographene Oxide for High-Efficiency Gene Delivery.

In this study, a physiologically stable dual-polymer-functionalized reduced nanographene oxide (nrGO) conjugate (PEG-nrGO-PEI, RGPP) with high efficiency of gene delivery is successfully synthesized through mixing PEGylated nanographene oxide (PEG-nGO, GP) and polyethylenimine (PEI, 25 kDa) solution under 80 °C for 2 h. This hydrothermal reduction of GP during PEIylation promotes the nucleophilic reaction between the amino moieties of PEI and the epoxy groups (or carboxylic groups) in GP and then forms C-NH- groups (or NH-CO groups) to covalently connect PEI and GP, which makes the RGPP nanocomposite more stable in physiological environments and has superior gene transfection efficiency compared with the nonhydrothermally reduced PEG-nGO/PEI conjugate (GPP) obtained by mixing GP and PEI under 20 °C for 2 h. Moreover, 808 nm laser irradiation (2 W/cm2) for 25 min increases ∼1.5-fold of gene transfection efficiency for RGPP but does not increase the gene transfection efficiency of GPP. Finally, RGPP is also able to efficiently deliver functional plasmid GFP-Bax (pGFP-Bax), exhibiting ∼43% of transfection efficiency in HepG2 cells. Collectively, the RGPP developed here is a highly efficient nanocarrier for gene delivery, and this work encourages further explorations of developing functionalized reduced nano-GO for high-efficiency gene therapy.

Physical Properties of Polyacrylamide/Polyvinylalcohol Silica Nanocomposites

In this paper, samples of Polyacrylamide (PAAm) nanosilica nanocomposites were prepared having different concentration of nanosilica (0.125, 0.25, and 0.5). Polyacrylamide (PAAm) and poly (vinyl alcohol) (PVA) were blended with different ratio (3/1, 1/1, 1/3) using solution-cast technique. The prepared films were characterized by Fourier transform infrared (FTIR), X-ray diffractions (XRD) and scanning electron microscopy (SEM). FTIR spectra showed the presence of hydrogen bonding between–CONH2 groups in PAAm and –OH group in PVA and confirm the hydrophilic nature of the blends. X-ray diffractions shows the presence of a strong broad peak centered at 22º (2θ) confirms the amorphous nature of silica which is supposed to be the characteristic of SiO2. The results obtained from different experimental techniques were supported by SEM image analysis. The thermal stability of the nanocomposites enhanced by increasing the silica content in the blend. The DC electrical conductivity was studied for all prepared samples. It was found that the conductivity increase by increasing silica content as well as, increased by increasing the wt% of PVA.

Structural study on methacrylamide-grafted Tussah silk fibroin fibres

Tussah silk fibroin fibres were modified by grafting with methacrylamide (MAA), with weight gains ranging between 2.6% and 71.4%. Raman and IR spectroscopic analyses showed that upon grafting the fibres underwent slight conformational changes towards a more unordered state, due to the covalent and hydrogen bonds interactions occurring between the polymer (polyMAA) and the amorphous domains of silk fibres.To test the stability towards alkaline hydrolysis, the untreated and MAA-grafted silk fibres (weight gain of 71.4%) were immersed in NaOH 5% at 50°C for different times; the IR and Raman spectroscopic techniques were utilized to elucidate the degradation mechanism as well as the rearrangements of the fibres induced by the treatment.Upon hydrolysis, both the untreated and grafted fibres underwent an enrichment in β-sheet conformation, due to the preferential removal of the unordered domains. As a result of the covalent interactions with silk fibroin, the polymer increased its stability towards alkaline hydrolysis, since its complete solubilization was avoided and the transformation of its CONH2 groups into COO⿿ and COOH was delayed. Vibrational spectroscopy proved to be a valid technique to investigate the mechanism and the effects of the hydrolytic attack, which are both fundamental to design new-generation silk-based materials.

Investigation of tissue level distribution of functional groups and associated trace metals in rice seeds (Oryza sativa L.) using FTIR and LA-ICP-MS

Rice, rich with carbohydrates, proteins, and essential elements such as zinc, has the propensity to bio-accumulate toxic elements. The purpose of this study is to investigate the potential metal–ligand binding sites in the husk, bran and endosperm tissues in rice seeds (Oryza sativa L.) collected from contaminated rice fields near the XKS mine in China using ATR-FTIR spectroscopy, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and elemental analysis. Results demonstrate that the polar atom ratio (N+S+O/C) ranged from 0.92–1.16 in both endosperm and husk. The N/C ratio was greater in endosperm (0.02–0.04) than in the husk (0.01). Thus, metals having an affinity to N containing groups would be expected in higher concentrations in the endosperm including embryo. FTIR spectroscopy revealed –OH, >C=O, Si–OH, O–Si–O functional groups in the husk and –OH, >C=O and CONH2 groups in the endosperm. The tissue-level spatial elemental distribution was unraveled by LA-ICP-MS analysis of rice seed cross-sections. Results showed elevated concentrations of Zn in the embryo and high levels of Sb, As, Pb and Cd on the husk/bran tissues. The rice embryo and edible starch and protein containing endosperm tissues are rich with Zn. It appears that binding sites (i.e. silanol, phenolic and nitrogen containing moieties) in inedible husk tend to localize toxic As, Sb, and Pb in rice seeds.

Stability toward alkaline hydrolysis ofB.morisilk fibroin grafted with methacrylamide

Bombyx mori silk fibroin fibers were grafted with methacrylamide (MAA) and characterized by Raman and infrared (IR) vibrational spectroscopy before and after hydrolysis in NaOH 5% to elucidate the possible interactions between the two components and the stability of the fibers toward alkaline hydrolysis. Upon grafting, the fibers underwent conformational rearrangements toward a more unordered state and lost orientation at weight gains higher than 60%. Vibrational spectroscopy disclosed the occurrence of intermolecular interactions (mainly hydrogen bonds) between B. mori silk fibroin and polyMAA in the grafted fibers, and the formation of covalent bonds has been explored. These strong interactions made the grafted fibers as a whole more stable toward alkaline hydrolysis because they prevented the solubilization of the polymer upon hydrolysis and made slower the transformation of its CONH2 groups into COOH and COO− groups. Upon hydrolysis, silk fibroin underwent an enrichment in the β-sheet crystalline domains, because of the preferential removal of the unordered domains, which were more prone to the OH− attack. IR and Raman spectroscopy proved valid techniques to investigate the degradation mechanism and kinetics of grafted silk fibroin fibers and so for designing high-performing silk-based materials. The A731/A1004 Raman intensity ratio was proposed to spectroscopically evaluate the composition of the grafted samples; its value was found to linearly increase with weight gain (R2 = 0.998), envisaging the possibility of using Raman spectroscopy as a routine analytical technique for qualitative and quantitative characterization of grafted industrial samples. Copyright © 2016 John Wiley & Sons, Ltd.

Discovery of selective N-[3-(1-methyl-piperidine-4-carbonyl)-phenyl]-benzamide-based 5-HT₁ F receptor agonists: Evolution from bicyclic to monocyclic cores.

Preclinical experiments and clinical observations suggest the potential effectiveness of selective 5-HT1F receptor agonists in migraine. Identifying compounds with enhanced selectivity is crucial to assess its therapeutic value. Replacement of the indole nucleus in 2 (LY334370) with a monocyclic phenyl ketone moiety generated potent and more selective 5-HT1F receptor agonists. Focused SAR studies around this central phenyl ring demonstrated that the electrostatic and steric interactions of the substituent with both the amide CONH group and the ketone CO group play pivotal roles in affecting the adopted conformation and thus the 5-HT1F receptor selectivity. Computational studies confirmed the observed results and provide a useful tool in the understanding of the conformational requirements for 5-HT1F receptor agonist activity and selectivity. Through this effort, the 2-F-phenyl and N-2-pyridyl series were also identified as potent and selective 5-HT1F receptor agonists.

Spectroscopic Investigation and Characterizations of PAM/PEO Blends Films

Polymer blends have been obtained in the form of dimensionally stable and free standing films and their properties were characterized by different techniques. FTIR analysis and Raman spectroscopic analysis cleared the hydrogen bonding intermolecular interaction between –CONH2 groups in Poly Acrylamide (PAM) and C-O-C and –CH2OH group in Poly Ethylene Oxide (PEO). From Differential Scanning Calorimeter (DSC) the study shows that crystallinity is increasing with PEO wt%. From polymer interaction parameter we also show that the polymer blend is miscible. Thermal stability of films is investigated by Thermo Gravimetric Analysis (TGA) and derivative Thermo Gravimetric Analysis (DrTG). From UV-Vis absorption spectra, absorption band edge, direct/ indirect band gap and optical activation energy have been calculated.

N-alkylacylamides in thin films display infrared spectra of 3₁₀-, α-, and π-helices with visible static and dynamic growth phases.

A peptide model is a physical system containing a CONH group, the simplest being HCONHCH3 , N-methylformamide (NMF). We have discovered that NMF and N-methylacetamide (NMA), which form hydrogen-bonded oligomers in thin films on a planar AgX fiber, display infrared (IR) spectra with peaks like those of polypeptide helices. Structures can be assigned by their amide I maxima near 1672 (3(10)), 1655 (3(10)), 1653 (α), 1655 (π), and 1635 cm(-1) (π), which are the first IR data for the π-helix. Sharp peaks are an outcome of immobilization of polar species on the polar surface of silver halides. We report the first use of expanded thin-film IR spectroscopy, in which plots of every spectrum over the amide I-II range show pauses or slow stages in the increase or decrease of absorption. These are identified as static phases followed by dynamic phases, with the incremental gain or loss of a helix turn. A general theory can be stated for such processes. Density functional calculations show that the NMA α-helix pentamer (crystal structure geometry) is transformed into a π-helix-like form. For the first time, an entire sequence (3(10)-helix, α-helix, π-helix, quasiplanar species) of spectra has been recorded for NMA.

Spectral analysis, structural elucidation and evaluation of chemical reactivity of synthesized ethyl-4-[(2-cyano-acetyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate through experimental studies and quantum chemical calculations

This paper describes the synthesis, spectral analysis, structural elucidation and chemical reactivity of pyrrole hydrazide–hydrazone: ethyl-4-[(2-cyano-acetyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (ECAHDPC). The 1H, 13C NMR isotropic chemical shifts and electronic absorption spectra have been calculated by GIAO and TD-DFT methods, respectively, and corroborate well with experimental data. The NH proton of the hydrazide–hydrazones (CNNHCO) frame appears as singlet at δ=11.69ppm due to delocalization of nitrogen lone pair with carbonyl group and its proton involvement in intramolecular H-bonding. The calculated wavenumbers of dimer are in good agreement with the experimental results and confirm that the stable conformer forms dimer by hydrogen bonding interactions between pyrrolic NH and carbonyl CO group of ester giving red shift and resonance assisted hydrogen bonding. The binding energy of intermolecular interaction is found to be 10.19kcal/mol after basis set superposition error correction. QTAIM calculations confirm the existence of intermolecular conventional hydrogen bond (NH⋯O), intra and intermolecular non-conventional hydrogen bond (CH⋯O) and intramolecular interaction (C⋯N). The NBO analysis has been performed to evaluate charge transfer and delocalization of electron density. The static first hyperpolarizability (β0) of monomer has been found to be 6.59×10–30esu. The maximum value of reactivity descriptors (fk+, sk+, ωk+) at C(9) indicate that this site is more susceptible to nucleophilic attack, favoring for the formation of heterocyclic compounds.

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) by hydrolyzed acrylamide-grafted PET films

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) using hydrolyzed acrylamide (AAm)-grafted polyethylene terephthalate (PET) films was examined to explore the potential reuse of waste PET materials. Selective recovery of Hg(II) from a mixture of soft acids with similar structure, such as Hg(II) and Pb(II), is important to allow the reuse of recovered Hg(II). An adsorbent for selective Hg(II) adsorption was prepared by γ-ray-induced grafting of AAm onto PET films followed by partial hydrolysis through KOH treatment. The adsorption capacity of the AAm-grafted PET films for Hg(II) ions increased from 15 to 70 mg/g after partial hydrolysis because of the reduction of hydrogen bonding between –CONH2 groups and the corresponding improved access of metal ions to the amide groups. The prepared adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The absorbent film showed high selectivity for the adsorption of Hg(II) over Pb(II) throughout the entire initial metal concentration range (100–500 mg/L) and pH range (2.2–5.6) studied. The high selectivity is attributed to the ability of Hg(II) ions to form covalent bonds with the amide groups. The calculated selectivity coefficient for the adsorbent binding Hg(II) over Pb(II) was 19.2 at pH 4.5 with an initial metal concentration of 100 mg/L. Selective Hg(II) adsorption equilibrium data followed the Langmuir model and kinetic data were well fitted by a pseudo-second-order equation. The adsorbed Hg(II) and Pb(II) ions were effectively desorbed from the adsorbent film by acid treatment, and the regenerated film showed no marked loss of adsorption capacity upon reuse for selective Hg(II) adsorption.

Near Infrared Spectroscopy Detection of Copper in Pig Manure and the Spectral Basis of the Analysis

Conventional methods based on wet chemical analysis for investigating heavy metals in animal manure are relatively expensive and time-consuming. This study investigated the use of near infrared (NIR) spectroscopy to detect copper (Cu) in animal manure and then identified the spectral basis of the calibration. A total of 118 pig manure samples were collected from four provinces in China. Spectra were acquired in the range of 10,000 to 4000 cm−1 using a Fourier-transform near infrared spectrometry system. Results showed that the prediction of Cu concentration in pig manure by NIR spectroscopy is feasible ( r2 = 0.84, root mean square error of prediction= 198 mg kg−1, ratio of standard error to standard deviation = 2.4). Cu in pig manure can be detected by NIR spectroscopy because a high percentage of the Cu is complexed with CONH2 or CONHR functional groups of organic ligands such as protein, urea, amino acids and other amide compounds.

Evaluation of the Salt Content of Canned Sardines in Tomato Ketchup by Diffuse Reflection near Infrared Spectroscopy

This research aimed to determine the salt content of canned sardines in tomato sauce using NIR spectroscopy compared with traditional methods employing an auto-titrator, which are more consuming in terms of time and chemicals used. Scanning of NIR radiation was performed using an FT-NIR spectrometer with a wavenumber range of 12,500–4000 cm−1 (800–2500 nm) with the diffuse reflection mode. Model development was achieved using partial least-squares regression from three groups of samples, which were the sample group that included salt-adjusted samples, the sample group that did not include salt-adjusted samples and the sample group that included only salt-adjusted samples plus five non-salt-adjusted samples. The model from the sample group that did not include salt-adjusted samples used the first derivative + straight-line subtraction spectra between 9403.8 cm−1 and 4242.9 cm−1 with nine partial least-squares factors providing the lowest root mean square error of prediction ( RMSEP), with a coefficient of determination of calibration ( R2) of 0.90, root mean square error of estimation of 0.039%, coefficient of determination for prediction ( r2) of 0.85, RMSEP of 0.046%, average error of prediction (bias) of −0.002% and ratio of standard error of validation to the standard deviation of 2.58. The sample group that included salt-adjusted samples had a skewed distribution. The model returned an RMSEP of 0.109% on test samples, but the performance-to-interquartile range index indicated that this was a poor calibration. For the smaller salt-adjusted samples plus five non-salt-adjusted samples, cross-validation indicated the potential to evaluate salt in canned sardines (root mean square error of cross-validation = 0.158%). It was found that the vibration of water had an effect on the prediction accuracy as well as the vibration of starch and protein. In addition, the CONH2 and CO2H groups, which are common amino acid functional groups, also showed an effect. These findings represent novel findings concerning the use of NIR spectroscopy to determine salt that has no signal of its own in the NIR region.