Graphene Functionalized Graphite Electrode with Diphenylacetylene for Sensitive Electrochemical Determination of Adenosine‐5′‐triphosphate

In this paper a molecular wire modified carbon paste electrode (MW‐CPE) was firstly prepared by mixing graphite powder with diphenylacetylene (DPA). Then a graphene (GR) and chitosan (CTS) composite film was further modified on the surface of MW‐CPE to receive the graphene functionalized electrode (CTS‐GR/MW‐CPE), which was used for the sensitive electrochemical detection of adenosine‐5′‐triphosphate (ATP). The CTS‐GR/MW‐CPE exhibited excellent electrochemical performance and the electrochemical behavior of ATP on the CTS‐GR/MW‐CPE was carefully studied by cyclic voltammetry with an irreversible oxidation peak appearing at 1.369 V (vs. SCE). The electrochemical parameters such as charge transfer coefficient (α) and electrode reaction standard rate constant (k_s) were calculated with the results of 0.53 and 5.28×10^?6 s^?1, respectively. By using differential pulse voltammetry (DPV) as detection technique, the oxidation peak current showed good linear relationship with ATP concentration in the range from 1.0 nM to 700.0 µM with a detection limit of 0.342 nM (3σ). The common coexisting substances, such as uric acid, ascorbic acid and guanosine‐5′‐triphosphate (GTP), showed no interferences and the modified electrode was successfully applied to injection sample detection.     

Electrochemical Sensing of NADH and Glutamate Based on Meldola Blue in 1,2‐Diaminobenzene and 3,4‐Ethylenedioxythiophene Polymer Films

The redox mediator Meldola blue (MB) was entrapped into two polymers, poly‐1,2‐diaminobenzene (p‐DAB) and poly‐3,4‐ethylenedioxythiophene (p‐EDOT) by potential cycling and films were applied to NADH oxidation with subsequent glutamate detection using immobilized glutamate dehydrogenase. Both polymer films were tested for electrocatalysis of NADH using amperometry at E_app=0.1 V vs. Ag/AgCl and similar response characteristics were obtained with sensitivity values of 6.1 nA μM^?1, linear range up to 0.5 mM (R²=0.9972) and LOD of 50 μM. Subsequent amperometric determination of glutamate resulted in sensitivity 0.7 nA μM^?1, linearity 0–100 μM and detection limit of 2 μM glutamate.     

Electrochemical Behaviors of Adenosine‐5′‐triphosphate on Molecular Wire Modified Carbon Paste Electrode and Its Sensitive Detection

A new electrochemical method was proposed for the determination of adenosine‐5′‐triphosphate (ATP) based on the electrooxidation at a molecular wire (MW) modified carbon paste electrode (CPE), which was fabricated with diphenylacetylene (DPA) as the binder. A single well‐defined irreversible oxidation peak of ATP appeared on MW‐CPE with adsorption‐controlled process and enhanced electrochemical response in a pH 3.0 Britton‐Robinson buffer solution, which was due to the presence of high conductive DPA in the electrode. The electrochemical parameters of ATP were calculated with the electron transfer coefficient (α) as 0.54, the electron transfer number (n) as 1.9, the apparent heterogeneous electron transfer rate constant (k_s) as 2.67 × 10^?5 s^?1 and the surface coverage (Γ_T) as 4.15 × 10^?10 mol cm^?2. Under the selected conditions the oxidation peak current was proportional to ATP concentration in the range from 1.0 × 10^?7 mol L^?1 to 2.0 × 10^?3 mol L^?1 with the detection limit as 1.28 × 10^?8 mol L^?1 (3σ) by sensitive differential pulse voltammetry. The proposed method showed good selectivity without the interferences of coexisting substances and was successful applied to the ATP injection samples detection.     

Electrochemical Behaviours and Detection of Adenosine‐5¢‐triphosphate on an Ionic Liquid Modified Carbon Paste Electrode

In this paper a new electrochemical method based on the ionic liquid modified carbon paste electrode (IL‐CPE) was proposed for the determination of adenosine‐5′‐triphosphate (ATP) in a pH 4.5 Britton‐Robinson (B‐R) buffer solution. IL‐CPE was prepared by using 1‐butyl‐3‐methylimidazolium trifluoroacetate (BMIMCF₃COO) as the modifier. Cyclic voltammetry was used to investigate the electrochemical behaviors of ATP on the IL‐CPE, and the results indicated that IL‐CPE exhibited strong electrocatalytic ability to promote the oxidation of ATP with a single well‐defined irreversible adsorption‐controlled oxidation peak appeared. The electrochemical reaction parameters of ATP were calculated with the results of the electron transfer coefficient (α) as 0.40, the electron transfer number (n) as 1.17, the apparent heterogeneous electron transfer rate constant (ks) as 3.66 × 10^‐6 s^‐1 and the surface coverage (Γ_τ) as 2.48 × 10^‐9 mol cm^‐2. Under the selected conditions the proposed IL‐CPE showed good performances to the ATP detection in the concentration range from 0.1 to 1000.0 μmol L^‐1 with the detection limit as 3.65 × 10^‐8 mol L^‐1 (3σ) by differential pulse voltammetry. The method showed good selectivity to the ATP detection without the interferences of coexisting substances and was successfully applied to the ATP injection samples detection with satisfactory results.     

Electrochemical Oxidative Detection of Guanosine‐5′‐triphosphate Based on a New Ionic Liquid Modified Carbon Paste Electrode

An ionic liquid (IL) 1‐(3‐chloro‐2‐hydroxy‐propyl)‐3‐methylimidazolium trifluoroacetate was used as the modifier for the preparation of the modified carbon paste electrode (CPE). The IL‐CPE showed excellent electrocatalytic activity towards the oxidation of guanosine‐5′‐triphosphate (5′‐GTP) in a pH 5.0 Britton‐Robinson buffer solution. Due to the presence of high conductive IL on the electrode surface, the electrooxidation of 5′‐GTP was greatly promoted with a single well‐defined irreversible oxidation peak appeared. The electrode reaction was an adsorption‐controlled process and the electrochemical parameters of 5′‐GTP on IL‐CPE were calculated with the electron transfer coefficient (α) as 0.44, the electron transfer number (n) as 1.99, the apparent heterogeneous electron transfer rate constant (k_s) as 2.21 × 10^?9 s^?1 and the surface coverage (Γ_T) as 1.53 × 10^?10 mol cm^?2. Under the selected conditions a linear calibration curve between the oxidation peak currents and 5′‐GTP concentration was obtained in the range from 2.0 to 1000.0 μmol L^?1 with the detection limit as 0.049 μmol L^?1 (3σ) by differential pulse voltammetry. The proposed method showed good selectivity to the 5‘‐GTP detection without the interferences of coexisting substances and the practical application was checked by measurements of the artificial samples.     

Microelectrode Sensing of Adenosine/Adenosine‐5′‐triphosphate with Fast‐Scan Cyclic Voltammetry

Adenosine and adenosine‐5′‐triphosphate (ATP) are important extracellular signaling molecules. Here, we studied adenosine and ATP using fast‐scan cyclic voltammetry at carbon‐fiber microelectrodes. Although ATP and adenosine have similar oxidation potentials, ATP oxidation current was highly dependent on buffer pH and divalent cation concentrations but adenosine current was not. Therefore, they can be distinguished by adding a divalent cation chelator or calibrating electrodes at different pH values. The enzymatic degradation of adenosine by adenosine deaminase was monitored in a mixture of adenosine and ATP in presence of EDTA (ethylenediaminetetraacetate). This sensing method is promising for enzyme kinetics or in vitro studies.     

Novel adsorptive materials by adenosine 5ʹ‐triphosphate imprinted‐polymer over the surface of polystyrene nanospheres for selective separation of adenosine 5ʹ‐triphosphate biomarker from urine

In this study, we have developed a method to assess adenosine 5?‐triphosphate by adsorptive extraction using surface adenosine 5′‐triphosphate‐imprinted polymer over polystyrene nanoparticles (412 ± 16 nm) for selective recognition/separation from urine. Molecularly imprinted polymer was synthesized by emulsion copolymerization reaction using adenosine 5′‐triphosphate as a template, functional monomers (methacrylic acid, N‐isopropyl acrylamide, and dimethylamino ethylmethacrylate) and a crosslinker, methylenebisacrylamide. The binding capacities of imprinted and non‐imprinted polymers were measured using high‐performance liquid chromatography with UV detection with a detection limit of 1.6 ± 0.02 µM of adenosine 5′‐triphosphate in the urine. High binding affinity (Q_MIP, 42.65 µmol/g), and high selectivity and specificity to adenosine 5′‐triphosphate compared to other competitive nucleotides including adenosine 5?‐diphosphate, adenosine 5?‐monophosphate, and analogs such as adenosine, adenine, uridine, uric acid, and creatinine were observed. The imprinting efficiency of imprinted polymer is 2.11 for urine (Q_MIP, 100.3 µmol/g) and 2.51 for synthetic urine (Q_MIP, 48.5 µmol/g). The extraction protocol was successfully applied to the direct extraction of adenosine 5′‐triphosphate from spiked human urine indicating that this synthesized molecularly imprinted polymer allowed adenosine 5′‐triphosphate to be preconcentrated while simultaneously interfering compounds were removed from the matrix. These submicron imprinted polymers over nano polystyrene spheres have a potential in the pharmaceutical industries and clinical analysis applications.     

Voltammetric Determination of 2′‐Deoxyadenosine and Adenine in Urine of Patients with Hepatocellular Carcinoma Using Fullerene‐C60‐modified Glassy Carbon Electrode

A fullerene‐C₆₀‐modified glassy carbon electrode has been examined for the simultaneous determination of 2′‐deoxyadenosine (2′‐dAdo) and adenine in human blood and urine using Osteryoung square‐wave voltammetry (OSWV) at pH 7.2. Compared to bare glassy carbon electrode (GCE), the modified electrode displays a shift of the oxidation potential in the negative direction with significant increase in the peak current for both the analytes. At modified electrode well‐defined anodic peaks at potential of 1248 mV and 994 mV are observed for 2′‐dAdo and adenine respectively. Linear calibration curves were obtained within the concentration range 10 nM to 100 μM for both the compounds in 0.1 M phosphate buffer solution (PBS) with the limit of detection 0.8×10^?8 M and 0.95×10^?8 M for 2′‐dAdo and adenine respectively. The analytical utility of the present method is demonstrated by quantitative detection of 2′‐dAdo and adenine in human urine of normal subjects as well as in patients with hepatocellular carcinoma. Interfering effect of some coexisting metabolites has also been reported.     

Differential Pulse Voltammetric Determination and Application of Square‐Wave Voltammetry of yRNA on a CPB‐Cellulose Modified Electrode

Electrochemical behavior of remarkably low levels of Ribonucleic acid yeast (yRNA) is studied through differential pulse voltammetry (DPV), and kinetic parameters of the electrochemical reaction have also been calculated through square‐wave voltammetry (SWV), based on immobilization of yRNA on the surface of a CPB‐cellulose modified electrode. YRNA/ CPB‐cellulose/ITO conductive glass electrode is demonstrated by Infrared reflect (IR) and electrochemical impedance spectroscopy (EIS). The oxidation peak potential of yRNA shifts negatively with increasing pH. The peak currents decrease gradually in successive scans and no corresponding reduction peaks occur, indicating that oxidation process of yRNA is completely irreversible. Variables influencing DPV response of yRNA, such as pH, pulse amplitude and electrolyte concentration, are explored and optimized. Peak currents are proportional to the concentration of yRNA in the range of 0.1 μg mL^?1–1.0 μg mL^?1, and the linear regression coefficient equals 0.9923. The detection limit for yRNA is 1.0×10^?10 g mL^?1. Interferences of L ‐cysteine, L ‐alanine, Hemoglobin, Uridine 5′‐monophosphate, Guanosine 5′‐monophosphate, Adenosine 5′‐triphosphate and some metal ions (Co³⁺, Cr³⁺, Ni²⁺, Hg²⁺, Zn²⁺, etc) are negligible. The methods adopted here are more sensitive and selective than currently applied techniques and overcome the drawback of absorption spectroscopy arising from a strong interference due to other UV‐absorbing substances.     

Ultra‐fast adenosine 5′‐triphosphate,adenosine 5′‐diphosphate and adenosine 5′‐monophosphate detection by pressure‐assisted capillary electrophoresis UV detection

Herein, we report a new CE method to measure adenine nucleotides adenosine 5′‐triphosphate, adenosine 5′‐diphosphate, and adenosine 5′‐monophosphate in red blood cells. For this purpose, 20 mmol/L sodium acetate buffer at pH 3.80 was used as running electrolyte, and the separation was performed by the simultaneous application of a CE voltage of 25 kV and an overimposed pressure of 0.2 psi from inlet to outlet. A rapid separation of these analytes in less than 1.5 min was obtained with a good reproducibility for intra‐ and inter‐assay (CV<4 and 8%, respectively) and an excellent analytical recovery (from 98.3 to 99%). The applicability of our method was proved by measuring adenine nucleotides in red blood cells.     

Carbon Paste Electrode Incorporating 1‐[4‐(Ferrocenyl Ethynyl) Phenyl]‐1‐Ethanone for Electrocatalytic and Voltammetric Determination of Tryptophan

A carbon paste electrode spiked with 1‐[4‐ferrocenyl ethynyl) phenyl]‐1‐ethanone (4FEPE) was constructed by incorporation of 4FEPE in graphite powder‐paraffin oil matrix. It has been shown by direct current cyclic voltammetry and double step chronoamperometry that this electrode can catalyze the oxidation of tryptophan (Trp) in aqueous buffered solution. It has been found that under optimum condition (pH 7.00), the oxidation of Trp at the surface of such an electrode occurs at a potential about 200 mV less positive than at an unmodified carbon paste electrode. The kinetic parameters such as electron transfer coefficient, α and rate constant for the chemical reaction between Trp and redox sites in 4FEPE modified carbon paste electrode (4FEPEMCPE) were also determined using electrochemical approaches. The electrocatalytic oxidation peak current of Trp showed a linear dependent on the Trp concentrations and linear calibration curves were obtained in the ranges of 6.00×10^?6 M–3.35×10^?3 M and 8.50×10^?7 M–6.34×10^?5 M of Trp concentration with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods, respectively. The detection limits (3σ) were determined as 1.80×10^?6 M and 5.60×10^?7 M by CV and DPV methods. This method was also examined as a selective, simple and precise new method for voltammetric determination of tryptophan in real sample.     

Fabrication of a Sensitive Cholesterol Biosensor Based on Cobalt‐oxide Nanostructures Electrodeposited onto Glassy Carbon Electrode

Electrodeposited cobalt oxide (CoOx) nanomaterials are not only used for immobilization of cholesterol oxidase (ChOx) but also as electron transfer mediator for oxidation of H₂O₂ generated in the enzymatic reaction. Voltammetry and flow injection analysis (FIA) were used for determination of cholesterol. FIA determination of cholesterol with biosensors yielded a calibration curve with the following characteristics: linear range up to 50 μM, sensitivity of 43.5 nA μM^?1 cm^?2 and detection limit of 4.2 μM. The apparent Michaelis‐Menten constant and the response time of the biosensor are 0.49 mM and 15 s, respectively. This biosensor also exhibits good stability, reproducibility and long life time.     

Electrocatalytic Determination of Ascorbic Acid at the Surface of 2,7‐Bis(ferrocenyl ethyl)fluoren‐9‐one Modified Carbon Paste Electrode

A chemically modified carbon paste electrode with 2,7‐bis(ferrocenyl ethyl)fluoren‐9‐one (2,7‐BFEFMCPE) was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The diffusion coefficient (D=1.89×10^?5 cm² s^?1), and the kinetic parameter such as the electron transfer coefficient, α (=0.42) of ascorbic acid oxidation at the surface of 2,7‐BFEFMCPE was determined using electrochemical approaches. It has been found that under an optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 300 mV less positive than that of an unmodified carbon paste electrode. The catalytic oxidation peak currents show a linear dependence on the ascorbic acid concentration and linear analytical curves were obtained in the ranges of 8.0×10^?5 M–2.0×10^?3 M and 3.1×10^?5 M–3.3×10^?3 M of ascorbic acid with correlation coefficients of 0.9980 and 0.9976 in cyclic voltammetry and differential pulse voltammetry, respectively. The detection limits (2δ) were determined to be 2.9×10^?5 M and 9.0×10^?6 M with cyclic voltammetry and differential pulse voltammetry, respectively. This method was also examined for determination of ascorbic acid in pharmaceutical preparations.     

Selective Detection of Ascorbic Acid Using Octacyanomolybdate‐Doped‐Glutaraldehyde‐Cross‐Linked Poly‐L‐Lysine Film Modified Glassy Carbon Electrode

The present work describes oxidation of ascorbic acid (AA) at octacyanomolybdate‐doped‐glutaraldehyde‐cross‐linked poly‐L ‐lysine (PLL‐GA‐Mo(CN) film modified glassy carbon electrode in 0.1 M H₂SO₄. The modified electrode has been successfully prepared by means of electrostatically trapping Mo(CN) mediator in the cationic film of glutaraldehyde‐cross‐linked poly‐L ‐lysine. The dependence of peak current of modified electrode in pure supporting indicates that the charge transfer in the film was a mixed process at low scan rates (5 to 200 mV s^?1), and kinetically restrained at higher scan rates (200 to 1000 mV s^?1). Cyclic voltammetry and rotating disk electrode (RDE) techniques are used to investigate the electrocatalytic oxidation of ascorbic acid and compared with its oxidation at bare and undoped PLL‐GA film coated electrodes. The rate constant of catalytic reaction k obtained from RDE analysis was found to be 9.5×10⁵ cm³ mol^?1 s^?1. The analytical determination of ascorbic acid has been carried out using RDE technique over the physiological interest of ascorbic acid concentrations with a sensitivity of 75 μA mM^?1. Amperometric estimation of AA in stirred solution shows a sensitivity of 15 μA mM^?1 over the linear concentration range between 50 and 1200 μM. Interestingly, PLL‐GA‐Mo(CN) modified electrode facilitated the oxidation of ascorbic acid but not responded to other electroactive biomolecules such as dopamine, uric acid, NADH, glucose. This unique feature of PLL‐GA‐Mo(CN) modified electrode allowed for the development of a highly selective method for the determination of ascorbic acid in the presence of interferents.     

Voltammetric Monitoring and Speciation of Copper Ions in Italian “Grappa” with Platinum Microelectrodes

A linear sweep voltammetric (LSV) investigation and the anodic stripping voltammetric (ASV) detection of copper ions in ethanol‐water mixtures and grappa samples are reported. The measurements are carried out by using platinum microdisk electrodes. Ethanol‐water mixtures with ethanol content in the range 40–100 vol%, commercially available and raw grappa samples having ethanol content in the above range are examined. From LSV measurements of copper (II) ions added to the samples, the formation of intermediate copper (I) soluble species, which are stabilized mainly by the naturally occurring organic compounds present in the real samples, is observed. The analysis of LSV and ASV current responses against added Cu²⁺ ions provides linear trends over the concentration range 5×10^?5?5×10^?3 M and 5×10^?7?5×10^?5 M, respectively. The sensitivity depends on the ethanol content in the mixture and, as expected, it is the higher the lower the viscosity of the medium. In particular, it varies from 1.54 to 3.53 nA mM^?1 and from 0.114 to 0.263 nA μM^?1 for LSV and ASV measurements, respectively, upon changing the ethanol content from 40 to 100 vol%. In the same range of ethanol content, detection limits obtained by ASV vary from 0.27 to 0.15 μM, respectively. Labile or total copper contents in the grappa samples are determined by ASV measurements performed in the untreated matrices or in the samples acidified with 0.1 M HClO₄, respectively. Finally, acidification of the samples with different amounts of HClO₄ allows also some speciation investigations to be performed.     

Sensitive amperometric pyridoxine sensor based on self‐assembled Prussian blue nanoparticle‐modified poly(o‐phenylenediamine)/glassy carbon electrode

Prussian blue nanoparticles (PBNPs) were prepared by a self‐assembly process on a glassy carbon electrode (GCE) modified with poly(o‐phenylenediamine) (PoPD) film. The stepwise fabrication process of PBNP‐modified PoPD/GCE was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The prepared PBNPs showed an average size of 70 nm and a homogeneous distribution on the surface of the modified electrode. The PBNPs/PoPD/GCE showed electrocatalytic activity towards the oxidation of pyridoxine (PN) and was used as an amperometric sensor. The modified electrode exhibited a linear response for PN oxidation over the concentration range 3–38.5 μM with a detection limit of ca 6.10 × 10^?7 M (S/N = 3) and sensitivity of 2.79936 × 10³ mA M^?1 cm^?2 using an amperometric method. The mechanism and kinetics of the catalytic oxidation reaction of PN were investigated using cyclic voltammetry and chronoamperometry. The values of α, k_cat and D were estimated as 0.36, 1.089 × 10² M^?1 s^?1 and 8.9 × 10^?5 cm² s^?1, respectively. This sensor also exhibited good anti‐interference and selectivity. Copyright © 2016 John Wiley & Sons, Ltd.     

Voltammetric Behavior of Sodium 7-Methoxyl-4＇-hydroxylisoflavone-3＇-sulfonate and Its Application

Voltammetric behavior of sodium 7‐methoxyl‐4′‐hydroxylisoflavone‐3′‐sulfonate (SMHS) in the aqueous solution from pH 1 to 5 was studied by linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. Experimental results showed that in 0.2 mol*L^?1 sodium citrate‐hydrochloric acid buffer solution (pH=4.65), SMHS caused only one reduction wave at ?1.34 V (vs. saturated calomel electrode, SCE), which was an h‐reversible adsorptive wave of SMHS protonized involving one electron and one proton. The peak current of SMHS on linear sweep voltammogram was proportional to its concentration in the range of 8.0 × 10 ?8.0·10 mol*L^?1 (r = 0.995). and the detection limit was 5.0·10^?‐⁶mol*L^?1. The method was applied to determination of SMHS, in synthetic samples. In addition, its scavenging effect on superoxide anion radical was studied by the auto‐oxidation of pyrogallol in HCI‐tris buffer solution (pH = 8.2) in order to explain its peculiar biological effects. The experimental results proved that SMHS has antioxidant quality, and it is an efficient free radical scavenger of superoxide anion radical.     

Voltammetric Determination of Uric Acid at a Fullerene‐C60‐Modified Glassy Carbon Electrode

Glassy carbon electrode modified by microcrystals of fullerene‐C₆₀ mediates the voltammetric determination of uric acid (UA) in the presence of ascorbic acid (AA). Interference of AA was overcome owing to the ability of pretreated fullerene‐C₆₀‐modified glassy carbon electrode. Based on its strong catalytic function towards the oxidation of UA and AA, the overlapping voltammetric response of uric acid and ascorbic acid is resolved into two well‐defined voltammetric peaks with lowered oxidation potential and enhanced oxidation currents under conditions of both linear sweep voltammetry (LSV) and Osteryoung square‐wave voltammetry (OSWV). At pH 7.2, a linear calibration graph is obtained for UA in linear sweep voltammetry over the range from 0.5 μM to 700 μM with a correlation coefficient of 0.9904 and a sensitivity of 0.0215 μA μM^?1 . The detection limit (3σ) is 0.2 μM for standard solution. AA in less than four fold excess does not interfere. The sensitivity and detection limit in OSWV were found as 0.0255 μA μM^?1 and 0.12 μM, for standard solution respectively. The presence of physiologically common interferents (i.e. adenine, hypoxanthine and xanthine) negligibly affects the response of UA. The fullerene‐C₆₀‐modified electrode exhibited a stable, selective and sensitive response to uric acid in the presence of interferents.     

Coordination Centres of Purine Nucleotides: Adenosine‐5′‐diphosphate and Adenosine‐5′‐triphosphate in their Reactions with Nickel(II), Cobalt(II) and Tetramines

Interactions between the nucleotides: adenosine‐5′‐diphosphate (ADP) and adenosine‐5′‐triphosphate (ATP) with Ni^II and Co^II ions, as well as with spermine (Spm) and 1,11‐diamine‐4,8‐diazaundecane (3,3,3‐tet) are the subject of this study. Composition and stability constants of mixed complexes thus formed have been determined on the basis of the potentiometric measurements, whereas interaction centres in ligands have been identified by VIS and NMR spectral parameter analysis. Mixed tetraprotonated complexes with Ni^II, i.e. Ni(ADP)H₄(Spm), Ni(ATP)H₄(Spm), Ni(ADP)H₄(3,3,3‐tet) and Ni(ATP)H₄(333‐tet), are identified as ML·······L′ type adducts, in which the main coordination centre is the nucleotide nitrogen N(1) or N(7) donor atom, and the fully protonated polyamine is engaged in noncovalent interactions with nucleotide phosphate group oxygen atoms. Ni(ADP)H₂(Spm), Ni(ATP)H₂(Spm), Ni(ADP)H₂(3,3,3‐tet) and Ni(ATP)H₂(3,3,3‐tet) complexes represent the {N3} coordination type In diprotonated mixed complexes of Ni^II with spermine are weak noncovalent interligand interactions, providing an additional stabilising effect. Formation of ML·······L′ type molecular complexes has been observed in systems with Co^II: Co(ADP)H₄(Spm), Co(ATP)H₄(Spm), Co(ADP)H₄(3,3,3‐tet) and Co(ATP)H₄(3,3,3‐tet), in which the N(7) atom and oxygen atoms of the phosphate group are involved in coordination and the fully protonated polyamine is engaged in noncovalent interactions with the nucleotide N(1).     

Analysis of short‐chain aliphatic amines in food and water samples using a near infrared cyanine 1‐(ε‐succinimydyl‐hexanoate)‐1′‐methyl‐3,3,3′,3′‐tetramethyl‐indocarbocyanine‐5,5′‐disulfonate potassium with CE–LIF detection

Precolumn derivatization of six short‐chain aliphatic amines by a near‐infrared dye, 1‐(ε‐succinimydyl‐hexanoate)‐1′‐methyl‐3,3,3′,3′‐tetramethyl‐indocarbocyanine‐5,5′‐ disulfonate potassium (MeCy5‐OSu), followed by MEKC–CE–LIF detection has been developed as a method for the determination of aliphatic amines in environmental water and food. Optimum derivatization was operated nicely in pH 9.0 borate buffer at 20°C for 30 min. Well separated peaks were observed with a pH 9.5 BGE containing 10 mmol L^?1 phosphoric acid, 20 mmol L^?1 SDS, and 7% methanol buffered with 1.0 mol L^?1 NaOH. The separation procedure was rapidly achieved within 11 min and the matrix interferences could be effectively eliminated. A linear calibration graph was obtained for 5–200 nmol L^?1 analytes with a correlation coefficient in the range 0.9933–0.9995 for amines. This method was successfully utilized to determine aliphatic amines in lake, sewage water, and red wine with recoveries ranging from 96.4 to 105% and the RSDs ranging from 0.9 to 2.9%. Near‐infrared, LIF‐detector‐compatible MeCy5‐OSu was proved suitable for the accurate, sensitive, and rapid separation and determination of aliphatic amines in water and food samples.