Ketoconazol‐Triiodide Ion Pair Complex as a Suitable Carrier in an Iodide Selective Membrane Electrode

A novel membrane sensor for selective monitoring of iodide, consisting of a triiodide‐ketoconazole ion pair complex dispersed in a PVC matrix, plasticized with a mixture of 2‐nitrophenyl octyl ether and dioctylphtalate with unique selectivity toward iodide ions, is described. The influence of membrane composition, pH of test solution and foreign ions on the electrode performance were investigated. The optimized membrane demonstrates a near‐Nernstian response for iodide ions over a wide linear range from 1.0 × 10^?2 to 1.0 × 10^?5 M, at 25 ± 1 °C. The electrode could be used over a wide pH range 3–10 and has the advantages of high selectivity, fast response time and good lifetime (over 4 months). It was successfully used as indicator electrode in potentiometric titrations and direct potentiometric assay of iodide ions.     

Flow injection determination of anisidine value in palm oil samples using a triiodide potentiometric detector

A flow injection analysis (FIA) procedure for the determination of anisidine value (AV) in palm olein using a triiodide detector is described. Undiluted oil sample and chloramine-T reagent were added to a reaction chamber, and reaction was accelerated by applying a short vortex action (typically for 30 s). After allowing the emulsified oil phase to be separated from the aqueous phase (bottom layer), an aliquot of the aqueous phase (containing unreacted chloramine-T) was aspirated into a carrier stream that contained I⁻ where the chloramine-T oxidized the I⁻ to form I₃⁻ which was finally detected by a flow-through triiodide potentiometric detector. Variables that affect the FIA signals such as size of the reaction chamber, oil and reagent flow rates, chloramine-T concentration, vortex time, time for phase separation, carrier stream pH and injected volume were studied. The optimized FIA procedure is linear over 1.0-23.0 AV. The method exhibits good repeatabililty (R.S.D. of ±3.16% (n = 4) for the determination of 5.0 AV) and a sampling rate of 40 samples per hour was achieved. Good correlation (r² = 0.996 (n = 4)) between the proposed method and the manual American Oil Chemists’ Society procedure was found when applied to the determination of twenty different types of palm olein samples.     

分光光度法测定I3-的稳定常数

用分光光度法测定了反应I2+I-=I3-的平衡常数.在350nm处,I3-的摩尔吸光系数为2.3×104L*mol-1*cm-1,而I2和I-在这一波长没有吸收,据此提出了用分光光度法测定I3-稳定常数的方法.研究了适当的实验条件,测定结果为lgK=2.96.     

Untersuchungen an Polyhalogeniden. XXII [1]. Dimethyldiphenylammoniumpolyiodide (Me2Ph2N)In mit n = 3, 13/3, 6, 8: Darstellung und strukturelle Charakterisierung eines Triiodids (Me2Ph2N)I3, Tridecaiodids (Me2Ph2N)3I13, Dodecaiodids (Me2Ph2N)2I12 und Hexadecaiodids (Me2Ph2N)2I16

Studies of Polyhalides. 22. On Dimethyldiphenylammoniumpolyiodides (Me₂Ph₂N)I_n with n = 3, 13/3, 6, and 8: Preparation and Crystal Structures of a Triiodide (Me₂Ph₂N)I₃, Tridecaiodide (Me₂Ph₂N)₃I₁₃, Dodecaiodide (Me₂Ph₂N)₂I₁₂, and Hexadecaiodide (Me₂Ph₂N)₂I₁₆ The new compounds [(CH₃)₂(C₆H₅)₂N]I₃, [(CH₃)₂(C₆H₅)₂N]₃I₁₃, [(CH₃)₂(C₆H₅)₂N]₂I₁₂ and [(CH₃)₂(C₆H₅)₂N]₂I₁₆ have been prepared by the reaction of dimethyldiphenylammonium iodide [(CH₃)₂(C₆H₅)₂N]I with iodine I₂ in ethanol. Their crystal structures have been determined by single crystal X-ray diffraction methods. The structure of the triiodide may be described as a layerlike packing of pairs of nearly linear symmetric anions and tetraedral cations. The tridecaiodide forms zig-zag chains of iodide ions and iodine molecules with the iodide ion also weakly coordinated by two pentaiodide groups. The dodecaiodide is built from two pentaiodide-groups, which are bridged by an iodine molecule and connected with secondary bonds forming double chains. The hexadecaiodide ion forms layers built up from two heptaiodide groups and one iodine molecule. Thus the dimethyldiphenylammonium cation stabilizes a unique series of polyiodides of extraordinary composition and structure.     

Flow injection determination of peroxide value in edible oils using triiodide detector

A flow injection analysis (FIA) method for the determination of peroxide value (PV) in edible oils is described. Oil sample (undiluted) and KI reagent were aspirated into a homemade reaction chamber where the redox reaction between iodide in the aqueous phase and hydroperoxides in the oil was effected by applying a short (typically 30 s) vortex action. After allowing for the emulsified oil phase to be separated from the aqueous phase (bottom layer), an aliquot of the aqueous phase containing triiodide was next aspirated to the surface of a triiodide-selective membrane for detection. The optimized FIA procedure is linear over 0.35-28.0 PV (mequiv. O₂/kg) with a detection limit of 0.32 PV. Exhibiting good reproducibility (R.S.D. of 2.7% (n = 8) for the determination of 1.1 PV) and sampling rate of 80 samples h⁻¹, the proposed method, unlike previous FIA procedures, completely eliminated the use of organic solvents (except the use of 2-propanol for cleaning of reaction chamber). Excellent correlation (R² = 0.9949) between the proposed method and the manual official AOCS method was found when applied to the determination of PV in diverse type of edible oils (n = 20).     

Highly Selective and Sensitive Triiodide PVC‐Membrane Electrode Based on a New Charge‐Transfer Complex of Bis(2,4‐Dimethoxybenzaldehyde)butane‐2,3‐Dihydrazone with Iodine

In this work, a highly selective membrane triiodide sensor based on a new charge‐transfer complex of bis(2,4‐dimethoxybenzaldehyde)butane‐2,3‐dihydrazone with iodine (Iodide Charge Transfer complex: ICT) as membrane carrier is introduced. The influences of five different solvent mediators on sensitivity and selectivity of the proposed sensor were considered. The best performance was obtained with the membrane composition containing 30% poly (vinyl chloride), 63% DBP, 5% ICT and 2% HTAB. The electrode shows a Nernstian behavior over a very wide triiodide ion concentration range (1.0 × 10^?7‐1.0 × 10^?2 M), and a detection limit value of 8.0 × 10^?8 M. The effect of pH on the potentiometric response of the sensor was also studied, and it was found that the response of the electrode is independent of the pH of the solution in the pH range of 4.0–10. The proposed sensor has a very fast response time (< 12 s), and good selectivities relative to a wide variety of common inorganic and organic anions, including iodide, acetate, bromide, chloride, fluoride, nitrite, nitrate, sulfite, sulfate, cyanide and thiocyanate. In fact the selectivity behavior of the proposed triiodide ion‐selective electrode shows great improvements compared to the previously reported electrodes for triiodide ion. The proposed membrane sensor can be used for at least 6 months without any divergence in the potentials. The electrode was successfully applied as an indicator electrode in the titration of triiodide with thiosulfate ion.     

Triiodide Ion‐Selective Electrode Based on Charge‐Transfer Complex of 4,7,13,16,21,24‐Hexaoxa‐1,10‐diazabicyclo‐[8.8.8]hexacosane

Two new highly selective triiodide electrodes have been prepared using charge‐transfer complex of iodine with cryptand 222 as an electroactive ionophore and nitrophenyl octyl ether as a plasticizing agent. The electrodes showed Nernstian response to triiodide ions over a concentration range from 1.0 × 10^?;2 — 7.9 × 10^?;7 M and from 1.0 × 10^?;2 — 1 × 10^?;6 M with detection limits of 6.3 × 10^?;7 and 7.9 × 10^?;7 M for cryptand and its charge‐transfer complex with iodine, respectively. The response times (t_95%) of the sensors were 10 and 5 s. The membrane could be used for more than 1 month without any divergence in potentials. The proposed sensors exhibited very high selectivity for triiodide ion over other anions, and could be used in a wide pH range ?2–10. These electrodes were successfully applied as an indicator electrode in potentiometric titration of copper in ore samples.     

Investigation of sonochemical activities at a frequency of 334 kHz: The effect of geometric parameters of sonoreactor

In this study, the effect of the dimensions of the bottom plate and liquid height was investigated for high-frequency sonoreactors under a vertically irradiated system. The dimensions of the bottom plate did not significantly influence sonochemical activity considering power density. However, as the bottom plate was increased in size, the hydroxyl radical generation rate decreased because of a decrease in power density. It is therefore recommended that sonoreactors with bottom-plate dimensions close to those of the ultrasonic transducer module be used. Liquid height had a significant effect on sonochemical activity, but the trend of the activity considering power density changed as the initial pollutant concentration changed. In the case of low initial concentration of As(III) (1 mg/L), the maximum cavitation yield for As(III) oxidation was observed at liquid heights of 150 mm.     

A new potentiometric sensor for the determination of α-amylase activity

A platinum redox sensor for the direct potentiometric determination of α-amylase concentration has been described. The sensor measured the amount of triiodide released from a starch-triiodide complex, which was correlated with the α-amylase activity after biocatalytic starch degradation. The composition and stability of the potassium triiodide solution was optimized. The starch-triiodide complex was characterized potentiometrically at variable starch and triiodide concentrations. The response mechanism of the platinum redox sensor towards α-amylase was proposed and the appropriate theoretical model was elaborated. The results obtained using the redox sensor exhibited satisfactory accuracy and precision and good agreement with a standard spectrophotometric method and high-sensitive fully automated descret analyser method. The sensor was tested on pure α-amylase (EC 3.2.1.1, Fluka, Switzerland), industrial granulated α-amylase Duramyl 120 T and an industrial cogranulate of protease and α-amylase Everlase/Duramyl 8.0 T/60 T. The detection limit was found to be 1.944 mU for α-amylase in the range of 0-0.54 U (0-15 μg), 0.030 mKNU for Duramyl 120 T in the range of 0-9.6 mKNU (0-80 μg) and 0.032 mKNU for Everlase/Duramyl 8.0 T/60 T in the range of 0-9.24 mKNU (0-140 μg).     

Über Ethylmethyldiphenylammoniumpolyiodide (EtMePh2N)Ix mit x = 3, 5: Darstellung und strukturelle Charakterisierung eines Triiodids (EtMePh2N)I3 und eines Pentaiodids (EtMePh2N)I5

Studies on Polyhalides. 41. On Ethylmethyldiphenylammoniumpolyiodides (EtMePh₂N)I_x with x = 3, 5: Preparation and Crystal Structures of a Triiodide (EtMePh₂N)I₃ and a Pentaiodide (EtMePh₂N)I₅ So far unknown compounds (EtMePh₂N)I_x with x = 3 and 5 have been prepared and structurally characterized. The triiodide (EtMePh₂N)I₃ crystallizes monoclinically in C2/c with a = 3406.1(3) pm, b = 893.1(1) pm, c = 1222.7(1) pm, β = 99.24(1)° and Z = 8. The crystal structure contains cationic and two kinds of anionic layers alternating along [1 0 0]. One anionic layer is composed of triiodide ions forming the typical and widespread observed herring‐bone pattern. The other one contains zigzag chains (I^– · I₂) along [0 0 1] as a so far not observed structural motif. The pentaiodide (EtMePh₂N)I₅ crystallizes triclinically in P 1 with a = 1020.7(1) pm, b = 1023.1(1) pm, c = 1269.5(1) pm, α = 81.88(1)°, β = 72.66(1)°, γ = 60.65(1)° and Z = 2. The crystal structure is divided into along [0 1 1] alternating puckered cationic and anionic layers. The anions have the common shape of a V, but are here of the rare isolated type. From a topological view two pentaiodide ions are connected to chairlike decagonal rings which are concatenated along [0 1 1].