Microdetermination of the fluoride ion using an amplification reaction

Summary A new simple, rapid and accurate amplification micro method for fluoride determination is described. It is based on the reaction between the sparingly soluble calcium iodate and the fluoride ion. After adding isopropyl alcohol to the solution, so that its final concentration is 65%, and filtering, an equivalent amount of the iodate is obtained. The latter is titrated iodometrically resulting in a six-fold amplification of the titre. The method is reproducible over a range from 0.4–8 mg fluoride ion. The mean recovery is 99.69%, after applying a correction factor due to potassium iodate solubility.

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Zusammenfassung Ein Multiplikationsverfahren zur Mikrobestimmung von Fluorid wurde beschrieben. Es beruht auf der Umsetzung zwischen dem schlecht löslichen Calciumjodat und Fluorid. Nach Zusatz von i-Propylalkohol, bis die Lösung 65% davon enthält, wird filtriert. Die äquivalente Jodatmenge wird jodometrisch titriert. Zwischen 0,4 und 8 mg Fluorid sind die Ergebnisse reproduzierbar. Bei Anwendung eines Korrekturfaktors wegen der Löslichkeit von Kaliumjodat wurden 99,69% Fluorid wieder gefunden.

     

Application of biphasic reaction procedure using ferric chloride dissolved in an imidazolium salt and benzotrifluoride (FeIm-BTF procedure) to aza-Prins cyclization reaction

Aza-Prins cyclization reaction of N-tosyl-3-butenylamine with aliphatic and aromatic aldehydes was performed using a combination of FeCl₃ and 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF₆) or 1-butyl-3-methylimidazolium tetrachloroferrate (BmimFeCl₄) in benzotrifluoride (BTF). The desired N-tosyl-4-chloro-2-substituted piperidines were obtained from aliphatic aldehydes in comparable yields to those for the previously reported reactions in which FeCl₃ was used in CH₂Cl₂. On the other hand, significant progress for the piperidine synthesis from aromatic aldehydes has been achieved, particularly when BmimFeCl₄ was used with FeCl₃ in BTF.     

The resolution obtained from low energy ion scattering using an ion cyclotron resonance spectrometer

The resolving power of the low energy ion scattering technique with FT-ICR spectrometry is discussed. Resolution improvement due to simultaneous registration of scattered ions with different masses is shown.     

The micro-determination of gold with p-dimethyl-aminobenzylidenerhodanine

Gold can be determined in the range 4–14 μg within 2% by a simple extraction of chlorauric acid in 0.12 N hydrochloric acid with a solution of p-dimethylaminobenzylidenerhodanine in iso-amyl acetate A 1:1 complex is formed with maximum absorption at 515 mμ.     

Hydroxytropylium chloride: the first crystal structure of an unfunctionalized hydroxytropylium ion

The crystal structure of hydroxytropylium chloride, C₇H₆OH⁺·Cl⁻, the hydrochloride salt of tropone, is described, which represents the first crystallographic characterization of an unfunctionalized hydroxytropylium ion. Crystals were obtained serendipitously from a sample of chlorotropylium chloride after partial hydrolysis. This highlights the role of hydroxytropylium ions as an intermediate in the hydrolytic decomposition of halotropylium halides to tropone. The solid‐state structure consists of layers, in which the hydroxytropylium and chloride ions interact via both strong hydrogen bonds formed by the hydroxy protons and weaker hydrogen bonds formed by the tropylium protons to produce a two‐dimensional network.     

Quantitative analysis of chloride in brackish water: an application to the hyperchromic effect of copper(II) ion with chloride ion.

A new modified method was applied to the determination of chloride anion in brackish water by using a common copper(II) sulfate solution and a spectrophotometer. The result of the quantitative analysis demonstrated that chloride concentrations were 1.61% w/v and 1.74% w/v at ebb tide and flood tide, respectively, of the Muya River. On the other hand, chloride concentrations were 1.17% w/v at ebb tide and 1.65% w/v at flood tide of the Yoshino River. The new method proved that chloride concentration corresponded well with results from Mohr and conductive methods. Therefore, the newly developed method can be exploited as common means to measure chloride concentration in aqueous solutions. Moreover, it is also valuable for application to other types of environmental samples.     

The simultaneous determination of chloride, nitrate and sulphate by isotachophoresis using bromide as a leading ion

A new method has been devised to allow the determination of small inorganic anions using isotachophoresis. This method makes use of indium(III) as a counter ion to manipulate the effective mobilities of inorganic anion species by means of complexation reactions. This new procedure successfully allowed the simultaneous determination of nitrate, chloride and sulphate to be realised on a capillary scale instrument and in a chip-based separation device. The electrolyte system developed to allow the separation to be achieved employed a 10mM bromide-based leading electrolyte containing 1.25 mM indium(III) at pH 3.15 and a terminating electrolyte of cyanoacetic acid.     

Multiplexed protein detection using an affinity aptamer amplification assay

Affinity probe capillary electrophoresis (APCE) is potentially one of the most versatile technologies for protein diagnostics, offering an excellent balance between robustness, analysis speed and sensitivity. Combining the immunosensing and separating strength of capillary electrophoresis with the signal enhancement power of nucleic acid amplification, aptamers can further push the analytical limits of APCE to offer ultrasensitive, multiplexed detection of protein biomarkers, even when differences in electrophoretic mobility between the different aptamer-target complexes are limited. It is demonstrated how, through careful selection of experimental parameters, simultaneous detection of picomolar levels of three target proteins can be achieved even with aptamers that were initially selected under very different conditions and further taking into account that the aptamers need to be modified to allow successful PCR amplification. Aptamer-enhanced APCE offers limits of detection that are orders of magnitude lower than those that can be achieved through traditional capillary electrophoresis-based immunosensing. With recent developments in aptamer selection that for the first time realise the promise of aptamers as easily accessible, high affinity recognition molecules, it can therefore be envisioned that aptamer-enhanced APCE on parallel microfluidic platforms can be the basis for a truly high-throughput multiplexed proteomics platform, rivalling genetic screening for the first time.     

Electric properties of the chloride ion

The dipole (), quadrupole (C), and dipole-quadrupole (B) polarizabilities and the dipole hyperpolarizability () of the chloride ion have been calculated by using the many-body perturbation theory approach and a series of large polarized GTO/CGTO basis sets. The complete fourth-order treatment of the electron correlation effects with a basis set comprising the s, p, d, f, and g functions gives: =38.01 a.u., C=211.5 a.u., B=–5.14×10³ a.u., and =128. 5×10³ a.u. as compared to the corresponding SCF values (=31.49 a.u., C=158.9 a.u., B=–2.92×10³ a.u., =57.7×10³ a.u.). The quenching of polarizabilities of the Cl^– ion in solutions and ionic crystals is discussed.     

Stoichiometry and products of ozone reaction with chloride ion in an acidic medium

It is shown by means of direct spectrophotometry in the UV and visible ranges that the only product of the O₃ reaction with Cl⁻(aq) in an acidic medium is molecular chlorine Cl₂; in solutions, it is in equilibrium with the complex ion Cl₃⁻. It is found that the consumption of one ozone molecule corresponds to the formation of one chlorine molecule. The stoichiometric equation for the reaction is obtained.     

Potentiometric determination of cetylpyridinium chloride using a new type of screen-printed ion selective electrodes

A new type of screen-printed ion-selective electrode for the determination of cetylpyridinium chloride (CPC) is presented. These new electrodes involve in situ, modified and unmodified screen-printed ion-selective electrodes for the determination of CPC. The screen-printed electrodes (SPEs) show a stable, near-Nernstian response for 1 × 10⁻² to 1 × 10⁻⁶ M CPC at 25 °C over the pH range 2-8 with cationic slope 60.66 ± 1.10. The lower detection limit is found to be 8 × 10⁻⁷ M and response time of about 3 s and exhibit adequate shelf-life (6 months). The fabricated electrodes can be also successfully used in the potentiometric titration of CPC with sodium tetraphenylborate (NaTPB). The analytical performances of the SPEs are compared with those for carbon paste electrode (CPE) and polyvinyl chloride (PVC) electrodes. The method is applied for pharmaceutical preparations with a percentage recovery of 99.60% and R.S.D. = 0.53. The frequently used CPC of analytical and technical grade as well as different water samples has been successfully titrated and the results obtained agreed with those obtained with commercial electrode and standard two-phase titration method. The sensitivity of the proposed method is comparable with the official method and ability of field measurements.     

Detecting a sodium chloride ion pair in ice using terahertz time-domain spectroscopy.

The hydrogen bond resonance of a sodium chloride (NaCl) ion pair trapped in aqueous ice has been observed by transmission terahertz time-domain spectroscopy. The absorption peak of a sodium chloride ion pair in ice is 1.65 THz at 83 K. By investigating the interaction of the cation and anion with other chemical compounds, we deduce that the absorption peak originates from the hydrogen bond resonance of sodium chloride and water molecules. The charge redistribution that occurs when other ion pairs are added to aqueous salt solution changes the absorption spectrum. Furthermore, the results also indicate that simple molecules such as sodium halides have fingerprints in the terahertz region when the ions are trapped in ice. NaCl ion pairs in seawater and in Ringer's solution were examined.     

Elimination of chloride interference on arsenic speciation in ion chromatography inductively coupled mass spectrometry using an octopole collision/reaction system

Anion-exchange chromatography with inductively coupled plasma mass spectrometry (ICP-MS) is often used for the speciation of arsenic (As). In this work, either He or H₂ was introduced to the octopole collision/reaction cell to eliminate chloride (Cl⁻) interferences during As speciation by ICP-MS. Polyatomic species, ⁴⁰Ar³⁵Cl and ³⁸Ar³⁷Cl, which are formed in high chloride matrices interfere with the ICP-MS detection of ⁷⁵As. These interferences were reduced or eliminated by introducing He or H₂ to the collision/reaction cell, with some loss in sensitivity when compared to the standard mode (no gas). For example, the sensitivity of As(V) was 30.4 and 17.7% of that observed in standard mode when introducing He and H₂, respectively. Chloride interference was completely eliminated using a flow rate of 3.0 mL min^− 1 with H₂ as a reaction gas with detection limits in the range of 0.3-0.6 μg L^− 1. The developed method was applied to determination of arsenic species in waters containing high concentrations of chloride by following a simple procedure and without modification of the ICP-MS instrument.     

The determination of lactate,acetate, chloride and phosphate in an intravenous solution by non-suppressed ion chromatography

Summary The determination of acetate, lactate, chloride and phosphate in an intravenous solution is investigated using non-suppressed ion chromatography with indirect UV absorption detection. When phthalate eluents are used with low capacity anion-exchange columns, the above solute species cannot be resolved unless acetonitrile is added to the eluent. Optimum results are obtained with 0.3 mM phthalate (pH 6.0) containing 30% acetonitrile as eluent. The improved resolution with this eluent is attributed to the existence of a partial reversed-phase retention mechanism operating on the unfunctionalised portions of the styrene-divinylbenzene polymeric ion-exchange material.     

Variable low-mass filtering using an electrodynamic ion funnel

An adjustable low-mass filter has been developed for an electrospray ionization (ESI) source to block ions associated with unwanted background species from entering the mass spectrometer. The low-mass filter is made by using an adjustable potential energy barrier from the conductance-limiting plate of an electrodynamic ion funnel, which prohibits species with higher ion mobilities from exiting the ESI source. We show that this arrangement provides a linear voltage adjustment for low-mass filtering from m/z 0 to 500. Mass filtering above m/z 500 is also performed; however, higher-mass species are attenuated. The mass filter was tested with a liquid chromatography/mass spectrometry (LC/MS) analysis of a bovine serum albumin (BSA) tryptic digest and resulted in the ability to block low-mass, background species, which accounted for 40-70% of the total ion current immediately behind the ESI source during peak elution and detection.     

Lateral spread of an amplification signal using an enzymatic system on a conductive surface

In this letter, we report a novel signal amplification phenomenon that rapidly and dramatically increases both the magnitude and the lateral extent of the original signal. This phenomenon utilizes an enzyme immobilized on a conductive surface to generate amplified signals at locations remote from the original site of enzyme activity. The result is demonstrated on a microfluidic platform using the established precipitating enzyme-substrate system of horseradish peroxidase (HRP) and 3,3',5,5'-tetramethylbenzidine (TMB) on a surface plasmon resonance (SPR) imaging system.     

The micro-determination of carbon and hydrogen in fluorine-containing organic compounds

Summary The sample is burned in a silica combustion tube, using a 4 ml per minute oxygen stream. Oxidation of the combustion products is completed by passing them over a platinum contact heated to 750°C, after the manner ofFriedrich. Silver wool at the same temperature removes sulphur and halogens, including the fluorine from any hydrogen fluoride produced, and granular sodium fluoride at about 270°C is used to absorb silicon tetrafluoride.The water vapour and carbon dioxide are determined in the usual way by absorption in magnesium perchlorate and soda-asbestos respectively. Satisfactory results have been obtained for the analyses of 4 mg samples of compounds containing the elements C, H, O, F, the standard deviation of the results for hydrogen being about ±0,1% H and for carbon being about ±0,2% C.Preliminary work indicates that fluorocarbons may be analysed if water-vapour is introduced into the system, and that the presence of nitrogen in compounds presents no difficulty when an external absorbent for nitrogen oxides is used. Certain refinements are included, which are applicable to the conventional apparatus for micro carbon and hydrogen determination.

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Zusammenfassung Zur Bestimmung von Kohlenstoff und Wasserstoff in fluorhaltigen organischen Verbindungen wird die Substanz in einem Quarzverbrennungsrohr im Sauerstoffstrom von 4 ml/Minute verbrannt. Die vollständige Oxydation der Verbrennungsprodukte erfolgt nachFriedrich durch Überleiten über einen Platinkontakt bei 750°C. Bei derselben Temperatur hält Silberwolle Schwefel und alle Halogene einschließlich Fluor zurück, soweit es als Fluorwasserstoff vorliegt. Zur Absorption von Siliciumtetrafluorid wird gekörntes Natriumfluorid bei etwa 270°C verwendet.Wasserdampf und Kohlendioxyd werden in der üblichen Weise mittels Magnesiumperchlorat bzw. Natronasbest bestimmt. Bei Einwaagen von 4 mg Substanz irgendeiner Verbindung der Elemente C, H, O und F werden befriedigende Ergebnisse erhalten. Die durchschnittlichen Abweichungen von der Theorie betragen für Wasserstoff etwa ±0,1%, bei Kohlenstoff etwa ±0,2%.Vorversuche haben gezeigt, daß fluorhältige Kohlenwasserstoffe bei gleichzeitiger Zufuhr von Wasserdampf in die Apparatur analysiert werden können und daß die Gegenwart von Stickstoff in der Analysensubstanz keine Schwierigkeiten mit sich bringt, wenn ein zusätzliches Absorptionsmittel für Stickstoffoxyde vorgesehen ist. Einige Verbesserungen der herkömmlichen Apparatur für die Mikro-C-H-Bestimmung werden angeführt.

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Résumé L'échantillon est brûlé dans un tube à combustion en silice, utilisant un débit d'oxygène de 4 ml par minute. L'oxydation des produits de combustion se complète en les faisant passer sur un contact de platine chauffé à 750° C d'après le procédé deFriedrich. La laine d'argent à la même température élimine le soufre et les halogènes y compris le fluor de tout fluorure produit et le fluorure de sodium granulaire à 270° environ sert à absorber le tétrafluorure de silicium.La vapeur d'eau et le gaz carbonique sont dosés comme d'habitude par absorption sur le perchlorate de magnésium et l'amiante sodé respectivement. Des résultats satisfaisants ont été obtenus pour les analyses de 4 mg d'échantillons de composés contenant les éléments C, H, O, F; l'erreur moyenne des résultats pour l'hydrogène étant ±0,1% H et pour le carbone, environ ± 0,2% C.Un travail préliminaire indique que les hydrocarbures fluorés peuvent être analysés si l'on introduit de la vapeur d'eau dans le système et que la présence d'azote dans les composés ne présente pas de difficulté quand on utilise un absorbant extérieur pour les oxydes de l'azote. Certaines améliorations applicables à l'appareil classique pour les microdosages de carbone et d'hydrogène sont incluses.

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With 4 Figures.