Tuesday, May 12, 2009

Which electrode for which titration

Which electrode for which titration?

Titrant Specifics Electrode description* Order No. Reference Electrolyte Remarks

Aqueous acid/bases


Ecotrode Plus 6.0262.100 c(KCl) = 3 mol/L 6.2308.020
alkaline samples Unitrode6.0259.100

c(KCl) = 3 mol/L
6.2308.020


titrations performed at high temperatures Unitrode 6.0259.100

Idrolyte
6.2308.040


titrations with small sample volumes Combined LL micro pH glass electrode
OR
Combined flat membrane pH glass electrode

6.0234.100


6.0227.100

c(KCl) = 3 mol/L

6.2308.020

Shaft diameter 6.4 mm, minimal immersion depth; 10 mm

Shaft diameter 12 mm, minimal immersion depth; 1–2 mm

titrations in water with low conductivity

Aquatrode plus 6.0257.000

c(KCl) = 3 mol/L

6.2308.020

Typical application: water analysis - p&m value etc.

Perchloric acid

See AB 80 and Monograph"Non-aqueous titration of acids and bases with potentiometric endpoint indication" Solvotrode - combined LL pH glass electrode, ground-joint diaphragm (PCTFE) 6.0229.100 c(LiCl) = 2 mol/L in ethanol 6.2312.010

easy to clean sleeve diaphragm

IMPORTANT: When not in daily use, store in LiCI sat. in ethanol and soak membrane in distilled water before use. However, when in daily use, store in distilled water, so that only the membrane is immersed, not the diaphragm. Before the measurement lift the diaphragm sleeve slightly and allow a small amount of electrolyte to flow out. Rinse the electrode with distilled water, replenish the reference electrolyte and start the titration (see bottom of chart).

IMPORTANT: Never fill the Solvotrode with LiCIO4 in glacial acetic acid!

TBAOH

See AB 80 and Monograph"Non-aqueous titration of acids and bases with potentiometric endpoint indication" Solvotrode - combined LL pH glass electrode, ground-joint diaphragm (PCTFE)
6.0229.100

c(TEABr) = 0.4 mol/L in ethylen glycol1

6.2320.000

Potassium methylate


Solvotrode - combined LL pH glass electrode, ground-joint diaphragm (PCTFE)

6.0229.100

c(TEABr) = 0.4 mol/L in ethylen glycol1
6.2320.000

Cyclohexyl-amine


Solvotrode - combined LL pH glass electrode, ground-joint diaphragm (PCTFE)
6.0229.100

c(LiCl) = 2 mol/L in ethanol 6.2312.010


Silver nitrate

AB 25

Ag-Titrode, possibly Ag2S coated

6.0430.100



arsenite, cerium sulphate, iron (III), iodine, potassium bromate, sodium nitrite, sodium thiosulphate, oxalic acid, permanganate, titanium

For titrations where the pH value during the titration doesn't change. Pt-Titrode
6.0431.100

Electrode is also available with a plug-in head S (6.0431.500 )
For titrations during which the pH value changes. Combined LL Pt-ring electrode 6.0451.100

c(KCl) = 3 mol/L

6.2308.020



Karl Fisher reagent


Double Pt-wire electrode

6.0338.100



Cr3+ , Fe2+,

Also for COD titrations Micro Au-Titrode 6.0435.110

L = 160 mm, Loger version available: (6.9904.023), L= 250 mm


EDTA

Back-titration of the BaCl2 excess. For sulphate determination see AB 140.

Polymer membrane electrode, Ca2+
6.0508.110

c(KCl) = 3 mol/L

6.2308.020

a separate reference electrode is needed.
Order no: 6.0750.100

EDTA

Complexon® III and IV

Determination of Al, Ba, Ca, Cd, Bi, Co, Fe, Mg, Ni, Pb, Zn. See AB 125

Ion selective electrode Cu2+

6.0502.140

c(KCl) = 3 mol/L

6.2308.020

a separate reference electrode is needed.
Order no: 6.0750.100
Determination of Ca, Mg, See AB 125

Polymer membrane electrode, Ca2+

6.0508.110



Surfactants in aqueous media

Tego® trant A 100,2
see AB 233

Ionic surfactant electrode
6.0507.120

c(KCl) = 3 mol/L

6.2308.020

a separate reference electrode is needed.
Order No: 6.0726.100

sodium lauryl sulphate, see AB 233

«Cationic surfactant» electrode
6.0507.150

c(KCl) = 3 mol/L

6.2308.020

a separate reference electrode is needed.
Order No: 6.0726.100

Sodium tetra phenyl borate, see AB 230, AB 263

NIO surfactant electrode
6.0507.010

Inner chamber of the reference electrode:
c(KCI) = 3 mol/L (6.2308.020)
Outer chamber: c(NaCL) = 1 mol/L

a separate reference electrode is needed.
Order No: 6.0726.107


Non aqueous surfactants

Nonaqueous media, solvents as Chloroform, MIKB, see AB 269

Surfactrode resistant
6.0507.130

c(KCl) = 3 mol/L

6.2308.020

a separate reference electrode is needed.
Order No: 6.0726.107

electrode not suitable for high salt concentrations and pH > 10

Nonaqueous media, solvents as MIKB

Two phase titration, see AB 269

Surfactrode refill
6.0507.140

c(KCl) = 3 mol/L

6.2308.020

a separate reference electrode is needed.
Order No: 6.0726.107

electrode not suitable for Chloroform


AB = Application Bulletin

* All these electodes are equipped with a Metrohm plub-in head G3

1) TEABr 0.4 mol/L tetra ethyl ammonium bromide in ethylene glycol (6.2320.000) is an electrolyte solution for non-aqueous titrations. It is very useful when titrating low acid contents with TBAOH. In such cases the LiCI sat. in ethanol (6.2312.000) would cause an alkali error during the measurement. The Solvotrode is a combined pH glass electrode specially designed for non-aqueous titrations. This electrode is normally filled with LiCI sat. in ethanol. However, when titrating with TBAOH we strongly recommend replacing the CiCI electrolyte with 0.4 mol/L TEABr in ethylene glycol. This electrolyte can of course also be used for all other non-aqueous titrations with various titrants.

2) TEGO trant A 100
6.2317.000 (6 g)
6.2317.010 (60 g)
Available on request 6.2317.020 (500 g)

3 To connect an electrode with plug-in head G to a Titrino or 726/796 Titroprocessor, use one of the following cables: 6.2104.020 (1 m), 6.2104.030 (2 m) or 6.2104.040 (3 m); to connect an electrode an electrode with plug-in head S to the above instruments, use cable 6.2104.510 (1 m). See Metrosensor Electrode Catalog for additional information.

Storage of the Solvotrode when not in daily use: Store the Solvotrode in LiCI sat. in ethanol. Use a normal electrode holder.

More information on Electrodes

> See also: which electrode for which application?
> Metrosensor On-line Catalog
> Metrosensor Electrodes Catalog for download (Info Center -> Products)

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Analytical instruments

Latest articles from 'Analytical instruments'

Sub categories in Analytical instruments

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Quality Management made easy: Order form for free QM / validation documents

Application bulletin no.283:
Validation of Metrohm burets
Application bulletin no. 278:
Validation of the 743 Metrohm Rancimat using Standard Operating Procedures
Application bulletin no. 277:
Validation of Metrohm Ion Chromatographs
Application bulletin no. 276:
Validation of Metrohm VA instruments using Standard Operating Procedures
Application bulletin no. 273:
Validation of Metrohm KF coulometers according to GLP/ISO 9001
Application bulletin no. 272:
Validation of Metrohm Conductometers
Application bulletin no. 271:
Validation of Metrohm pH Meters
Application bulletin no. 255:
Validation of Metrohm KF Titrators and KF Oven according to GLP/ISO 9001
Application bulletin no. 252:
Validation of Metrohm titrators (potentiometric) according to GLP/ISO 9001



ArticleTautan
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Friday, May 8, 2009

Karl Fischer water determination with the KF drying oven

Summary
The KF drying oven makes it possible to determine the water content of samples that either undergo unwanted side reactions with the Karl Fischer reagent or are unsuitable for direct introduction into the titration vessel. With this method the sample is heated up in the oven and the released water is transferred by a stream of dry carrier gas (e.g. nitrogen or air) to the titration vessel, where it is titrated.


[PDF] Application Bulletin



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Validation of Metrohm conductometers

Metrohm, Application Bulleitin N0. 272 / 2e

Summary
Among other things, GLP (Good Laboratory Practice) requires that the accuracy and precision of analytical instruments are checked at regular intervals using Standard Operating Procedures (SOP). The procedures described below are meant as a guideline for setting up a Standard Operating Procedure to check your conductometer and the conductivity measuring cell. The limits specified should be regarded as examples. Depending on the requirements placed on the accuracy of the measuring system these limits may have to be redefined in the Standard Operating Procedure.



[PDF] Application Bulletin





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Validation of Metrohm pH meters using Standard Operating Procedures

Metrohm, Application bulletin No.271/3e

Summary
Among other things, GLP (Good Laboratory Practice) requires that the accuracy and precision of analytical instruments are checked at regular intervals using Standard Operating Procedures (SOPs). The user is advised to validate the pH meter as a whole integrated measuring system, i.e. including the electrode(s) and any stirrer that may be used. The checking of the electronic and mechanical components can and should be carried out by qualified personnel from the manufacturing company as part of regular servicing. All newer Metrohm pH meters are provided with start-up test routines, which check that the instrument is functioning perfectly when it is switched on. If no error message is displayed it can be assumed that the instrument is functioning correctly. Metrohm also supplies its instruments with integrated diagnostic programs, which enable the user to check the functioning of certain components in the event of malfunctions or erratic behavior and to localize the fault. These diagnostic programs can also be included in a validation procedure. The procedure described below is meant as a guideline for setting up a Standard Operating Procedure to check your pH meter (with electrode connected). The limits specified should be regarded as examples. Depending on the requirements placed on the accuracy of the measuring system these limits may have to be redefined in the Standard Operating Procedure.



[PDF] Application Bulletin
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Standard methods in water analysis use of Metrohm instruments

Metrohm, Application Bulletin No. 221/2e

Summary
This bulletin gives a survey of standard methods from the field of water analysis. You will also find the analytical instruments required for the respective determinations and references to the corresponding Metrohm Application Bulletins and Application Notes. The following parameters are dealt with: electrical conductivity, pH value, fluoride, ammonium and Kjeldahl nitrogen, anions and cations by means of ion chromatography, heavy metals and NTA/EDTA by means of voltammetry,
chemical oxygen demand (COD), water hardness, free chlorine as well as a few other water components.

Application Bulletin No 221/2e




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Thursday, March 12, 2009

Effect of Partial Replacement of Forage Neutral Detergent Fiber with By-Product Neutral Detergent Fiber in Close-Up Diets on Periparturient Performanc


TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS
 ACKNOWLEDGEMENTS
 REFERENCES
Abstract
The objective of this study was to determine the effect of partial replacement of forage neutral detergent fiber (NDF) with by-product NDF in close-up diets of dairy cattle on periparturient metabolism and performance. Holstein cows (n = 45) and heifers (n = 19) were fed corn silage-based diets containing 1) 30% oat hay, or 2) 15% oat hay and 15% beet pulp from d –21 relative to expected parturition until parturition. After parturition, all animals received the same lactation diet. Animals were group-fed from d –21 to –10 relative to expected parturition and fed individually from d –10 until 14 d in milk. Animals were required to have at least 5 d of prepartum dry matter intake (DMI) data to remain on the study. Data were analyzed as a randomized design and subjected to ANOVA using the MIXED procedure of SAS. Close-up diet did not affect DMI, total tract nutrient digestibility, energy balance, or serum content of nonesterified fatty acids and ß-hydroxybutyrate during the last 5 d prepartum. Prepartum body weight and body condition score were similar between treatments. There was no carryover effect of close-up diet on DMI, energy balance, milk yield, body weight, body condition score, or serum content of nonesterified fatty acids and ß-hydroxybutyrate during the first 14 d in milk. In summary, partial replacement of forage NDF (oat hay) with by-product NDF (beet pulp) did not affect periparturient metabolism or performance.

Key Words: intake • neutral detergent fiber • nonforage fiber source • transition cow

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Flow-injection chemiluminescent determination of metoclopramide hydrochloride in pharmaceutical formulations and biological fluids using the [Ru(dipy)

Abstract
A flow-injection (FI) methodology using (2,2 -dipyridyl) ruthenium(II) [Ru(dipy)3 2+ ] chemiluminescence (CL) was developed for the rapid and sensitive determination of metoclopramide hydrochloride. The method is based on the CL reaction of metoclopramide with
Ru(dipy)3 2+ and KMnO4 in a sulfuric acid medium. Under the optimum conditions, a calibration graph was obtained over the concentration range 0.005–3.5 g ml−1 with a limit of detection (S/N = 2) of 1 ng ml−1 . The correlation coefficient was 0.99993 (n = 8) with a relative
standard deviation of 0.48% for 10 determinations of 1 g ml−1 of drug. The method was successfully applied to the determination of metoclopramide in pharmaceutical preparations and biological fluids after IP administration of 25 mg kg−1 dose to rats. The elimination
half-life was 2.5 ± 0.4 h.

© 2003 Published by Elsevier B.V.
Keywords: Metoclopramide; Chemiluminescence flow-injection; Potassium permanganate –Tris(2,2 -dipyridyl) ruthenium(II) reaction; Pharmaceutical
analysis; Biological fluids

[PDF] Flow-injection chemiluminescent determination of metoclopramide

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Wednesday, March 11, 2009

5 MATERIALS: APPARATUS, REAGENTS, SAMPLES

5.1 Introduction

Quality analytical work can only be performed if all materials used are suitable for the job, properly organized and well cared for. This means that the tools are adequate and in good condition, and that sample material receives attention with respect to proper handling, storing and disposal.

The tools used for analysis may be subdivided into four categories:

1 Primary measuring equipment (pipettes, diluters, burettes, balances, thermometers, flow meters, etc.)

2. Analytical apparatus or instruments.

3. Miscellaneous equipment and materials (ovens, furnaces, fridges, stills, glassware, etc.)

4. Reagents.

The saying that a chain is as strong as its weakest link applies particularly to these items. An analyst may have gone out of his/her way (as he/she should) to prepare extracts, if the cuvette of the spectrophotometer is dirty, or if the wavelength dial does not indicate the correct wavelength, the measurements are in jeopardy. Both the blank and the control sample (and a possible "blind" sample or spike) most likely will reveal that something is wrong, but the harm is already done: the problem has to be found and resolved, and the batch might have to be repeated. This is a costly affair and has to be minimized (it is an illusion to think that it can be totally prevented) by proper handling and maintenance of the equipment.

Also the quality and condition of a number of other working materials have to be watched closely. The calibration of thermometers, burettes and pipettes, particularly the adjustable types, may exceed the acceptable tolerance (and be put out of use). New glassware may look clean but always needs to be washed. Glassware may give off unwanted elements (boron, silicon, sodium). The same goes for milling and grinding equipment (pestles and mortars, tungsten carbide grinders, brass or steel sieves). For virtually all analyses glassware needs to be rinsed with deionized water after washing. Therefore, if glassware, such as volumetric flasks, is shared by analysts, they should be able to rely on the loyalty and good laboratory practice of their colleagues.

A similar reasoning applies to reagents. One of the most prominent sources of the errors made in a laboratory is the use of wrongly prepared or old reagents. Therefore, reagents have to be prepared very carefully and exactly following the prescriptions, they have to be well labelled and expiry dates have to be observed closely. Filtering a pH buffer solution in which fungi are flourishing may save time and reagent but is penny-wise and pound-foolish.

Of equal importance for the quality of the work is the proper handling of the sample material. Not only the technical aspects such as sample preparation, but particularly the safeguarding of identity and integrity of the samples as well as the final storage or disposal (chain of custody).

As part of the overall quality assurance, in this chapter a number of instructions and suggestions are presented to ensure the analytical reliability of the main tools and proper organization of sample handling.

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An arsenic(III)-oxidizing bacterial population: selection, characterization, and performance in reactors

Aims: To select an autotrophic arsenic(III)-oxidizing population, named CASO1, and to evaluate the performance of the selected bacteria in reactors.
Methods and Results: An As(III)-containing medium without organic substrate was used to select CASO1 from a mining environment. As(III) oxidation was studied under batch and continuous conditions. The main organisms present in CASO1 were identified with molecular biology tools. CASO1 exhibited significant As(III)-oxidizing activity between pH 3 and 8. The optimum temperature was 25°C. As(III) oxidation was still observed in the presence of 1000 mg l-1 As(III). In continuous culture mode, the As(III) oxidation rate reached 160 mg l-1 h-1. The CASO1 consortium contains at least two organisms – strain b3, which is phylogenetically close to Ralstonia picketii, and strain b6, which is related to the genus Thiomonas. The divergence in 16S rDNA sequences between b6 and the closest related organism was 5·9%, suggesting that b6 may be a new species.
Conclusions: High As(III)-oxidizing activity can be obtained without organic nutrient supply, using a bacterial population from a mining environment.
Significance and Impact of the Study: The biological oxidation of arsenite by the CASO1 population is of particular interest for decontamination of arsenic-contaminated waste or groundwater.

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HYDROTALCITE-LIKE MINERALS (M2Al(OH)6(CO3)0.5.XH2O, WHERE M = Mg, Zn, Co, Ni) IN THE ENVIRONMENT: SYNTHESIS, CHARACTERIZATION AND THERMODYNAMIC STABIL

Introduction
Hydrotalcite-like layered double hydroxides (LDH), of the formulation M2Al(OH)6(CO3)0.5.H2O, where M = Mg, Zn, Co, Ni, have been prepared, the products characterized and their solubility products measured at ionic strengths of 0.0065 and 0.0128 M and at 25°C. Steady-state solubility was reached after 100 days. The solubility products have been formulated according to the following reaction: M2Al(OH)60.5CO3 H2O +6H+ " border="0"> 2M2+ Al3+ + 0.5CO32– + H2O where


Average values of Kso for I = 0, estimated using the Davies equation, are 25.43, 20.80, 22.88 and 20.03 for Mg, Zn, Co and Ni, respectively. Model calculations reveal that the thermodynamic stability of the LDHs is greater than that of the corresponding divalent hydroxides for Zn, Co and Ni below a pH of ~10, 9 and 8, respectively, and at least up to pH 12 for Mg.

Key Words: Cobalt • Hydrotalcite • Magnesium • Nickel • Solubility • Zinc




This article has been cited by other articles:


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 Eur J MineralHome page
S. Tumiati, G. Godard, N. Masciocchi, S. Martin, and D. Monticelli
Environmental factors controlling the precipitation of Cu-bearing hydrotalcite-like compounds from mine waters. The case of the "Eve verda" spring (Aosta Valley, Italy)
European Journal of Mineralogy, February 1, 2008; 20(1): 73 - 94.
[Abstract] [Full Text] [PDF]

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 Clays and Clay MineralsHome page
R. k. Allada, E. Peltier, A. Navrotsky, W. H. Casey, C. A. Johnson, H. T. Berbeco, and D. L. Sparks
CALORIMETRIC DETERMINATION OF THE ENTHALPIES OF FORMATION OF HYDROTALCITE-LIKE SOLIDS AND THEIR USE IN THE GEOCHEMICAL MODELING OF METALS IN NATURAL WATERS
Clays and Clay Minerals, August 1, 2006; 54(4): 409 - 417.
[Abstract] [Full Text] [PDF]

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 Clays and Clay MineralsHome page
E. Peltier, R. Allada, A. Navrotsky, and D. L. Sparks
NICKEL SOLUBILITY AND PRECIPITATION IN SOILS: A THERMODYNAMIC STUDY
Clays and Clay Minerals, April 1, 2006; 54(2): 153 - 164.
[Abstract] [Full Text] [PDF]

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C. A. Johnson and K. C. Abbaspour
Hydrological and geochemical factors controlling leachate composition in incinerator ash landfills
Geological Society, London, Special Publications, January 1, 2004; 236(1): 607 - 617.
[Abstract] [PDF]
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Validation of Some Procedures for Quantifying Platinum at sub-g/L Level in Some Real Matrices by Catalytic Adsorptive Stripping Voltammetry

Abstract
The potential toxicological properties of platinum group elements, usually present in real matrices at sub-ng/g level, explain the increasing interest in developing specific and sensitive analytical methods. In this work, a validation study was performed in order to ensure the fitness-for-purposes of procedures developed for quantifying platinum in tap water, beer and lettuce using an extremely sensitive method based on catalytic adsorptive stripping voltammetry. The work involved the estimation of selectivity, detection and quantitation limits, range, accuracy (trueness plus precision), uncertainty of measurement (UOM), robustness and recovery. The results are discussed in the light of the most recent literature findings.

Abstract | References | Full Text: PDF (Size: 173K) | Related Articles | Citation Tracking

Keywords
Catalytic adsorptive stripping voltammetry • Platinum • sub-g/L level • Tap water • Beer • Lettuce

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Physico-Chemical Properties, Composition and Oxidative Stability of Camelina sativa Oil Oxidative Stability of Camelina sativa Oil

Summary
Camelina sativa is a cruciferous oilseed plant. With the aim of describing the general characteristics of the oil obtained from the seeds of plants grown in Slovenia and of comparing it to camelina oil from other countries we determined some physico-chemical properties, fatty acid composition, iodine and saponification value and followed its oxidative stability under different storage conditions. The density at 20 °C was (0.9207 ± 0.0001) g/cm3 and the refractive index reached 1.4756 ± 0.0001 at 25 °C. The analysis of fatty acids showed 10.3 % of saturated and 55.8 % of polyunsaturated acids, with 16.9 % of linoleic(C18:2), 35.2 % of a-linolenic (C18:3w3) and 1.6 % of erucic acid (C22:1). Determination of oxidative stability of this highly unsaturated oil revealed that the formation of primary oxidation products was affected by photooxidation. The peroxide value, PV, of fresh oil was (2.38 ± 0.01) meq O2/kg, while after 1 month in daylight at room temperature PV reached (21.0 ± 0.1) meq O2/kg. When stored in darkness PV was (8.12 ± 0.08) meq O2/kg. In the fresh oil, the p-anisidine value, AV, was 6.2 ± 0.1, after 11 months at room temperature 10.4 ± 0.1, and after the same time at 8 °C in darkness 7.1 ± 0.1. Susceptibility to oxidation of camelina oil was measured by the Rancimat test and expressed as the induction period. In fresh camelina oil the induction period was 4.8 h.
Key words: Camelina sativa oil, fatty acids, omega-3 fatty acids, density, refractive index, ox-
idative stability

[PDF] Physico-Chemical Properties, Composition and Oxidative Stability ...


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Oil and Fatty Acid Diversity in Genetically Variable Clones of Moringa oleifera from India

Abstract:
The physico-chemical properties of oil from Moringa oleifera seeds from India were determined in the present study. The petroleum ether extracted oil ranged from 27.83 - 45.07% on kernel basis and 15.1-28.4% on whole seed basis in 20 different clones. Leaves and pods showed a good source of vitamin C. Oleic acid (C18:1) has been found to be the major fatty acid being 78.91-85.52% as compared to olive oil, which is considered to be richest source of oleic acid. All the clones from India did not show any presence of behenic acid (C 22:0). The oil was also found to contain high levels of β-sitosterol ranged from 42.29-47.94% stigmasterol from 13.66-16.61%, campesterol from 12.53-16.63%. The γ- and δ-tocopherol were found to be in the range of 128.0-146.95, 51.88-63.5 and 55.23-63.84 mg/kg, respectively.
Key words:Moringa oleifera, seed oil, oleic acid, genetic variability

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Biocorrosion Behavior of Titanium Oxide/Butoxide-Coated Stainless Steel


Introduction
Stainless steel coated with multilayers of Ti oxide/butoxide was prepared via a layer-by-layer sol-gel deposition process. The successful buildup of the Ti oxide/butoxide coatings was ascertained by X-ray photoelectron spectroscopy and static water contact angle measurements. The differences in corrosion behavior between the Ti oxide/butoxide-coated and the uncoated coupons in a simulated seawater-based modified Baar's medium inoculated with Desulfovibrio desulfuricans under anaerobic conditions were investigated by electrochemical analyses, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Electrochemical analyses and SEM results revealed that the pristine, the hydroxylated, and the nitric acid-passivated coupons were all vulnerable to biocorrosion due to localized breakdown of the passive film under synergistic attack of Desulfovibrio desulfuricans and biogenic sulfide ions, leading to destructive pitting and crevice corrosion. However, the Ti oxide/butoxide-coated coupons exhibited desirable resistance in the biocorrosion environment and the coating remained relatively stable throughout the exposure period. EDX analysis revealed that the bioactive properties of the Ti oxide/butoxide coating arose from the concomitant deposition of calcium and phosphorous compounds. The increase in resistance of the Ti oxide/butoxide coatings with time was correlated with the increase in nucleation of calcium apatite in electrochemical studies.


Articles

©2008 The Electrochemical Society
History: Submitted 14 November 2007; revised 25 January 2008; published 11 March 2008
Permalink: http://dx.doi.org/10.1149/1.2885073


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Characteristics of anaerobic mixed cultures isolated from alkaline and oligotrophic habitats

Abstract

Anaerobic microorganisms were isolated from rock cores of Valanginian marl from Oberbauenstock (Switzerland) and from samples of sediments of soda lakes in California. Enrichments from the marl were made under fermenting, sulfate-reducing, and methanogenic conditions with concentrations of organic carbon ranging from 8.4 mg/L to 0.84 g/L, 2.1 mg/L to 0.21 g/L, and 2.6 mg/L to 0.26 g/L, respectively, at neutral and alkaline pH. Organisms from sediment samples were isolated under the same conditions with carbon contents of 8.4, 2.1, and 2.6 g/L, respectively, at alkaline pH. Growth and activity of the mixed cultures obtained were investigated at different values of pH and with limiting carbon source. All cultures obtained were obligate alkaliphilic with an optimum for growth at pH 9.0 for sulfate-reducing and methanogenic cultures, and pH 10.0 for the fermenting culture. At these pH values the cultures also grew under carbon-limited conditions (<10>
Keywords: alkaliphily; anaerobic; enrichment; fermenting bacteria; methanogens; oligotrophy; repositories for radioactive waste; sulfate-reducing bacteria

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Sulfur species in process water of the paper industry by simultaneous conductivity and UV detection

Application Bulletin

- [ Terjemahkan laman ini ]IC Application Note No. Summary: Determination of sulfide and thiosulfate in a process water ... Metrohm Suppressor Module (MSM, 50 mmol/L H ...
www.applikonlab.nl/applikon/images/pdf/u31.pdf -
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Thursday, March 5, 2009

Titration application

Featured Products
Cosa Instrument Corporation
Volumetric Karl Fischer Titrator Model KF-21

The Mitsubishi Volumetric Karl Fisher Titrator, Model KF-21, features automatic conditioning of the electrodes when contaminated, thus reducing maintenance for the user. (read more)


Product Categories for titration application

Titration Instruments - (54 companies)

Titration instruments are used to determine the concentration of dissolved substances. Titration is based on a complete chemical reaction between the specific substance, the analyte, and a reagent or titrant of known concentration that is added to the sample

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Determination of the oxidative stability of vegetable oils by rancimat and conductivity and chemiluminescence measurements

Determination of the oxidative stability of vegetable oils by rancimat and conductivity and chemiluminescence measurements

JournalJournal of the American Oil Chemists' Society
PublisherSpringer Berlin / Heidelberg
ISSN0003-021X (Print) 1558-9331 (Online)
IssueVolume 73, Number 8 / August, 1996
CategoryArticle
DOI10.1007/BF02523413
Pages1039-1043
Subject CollectionChemistry and Materials Science
SpringerLink DateThursday, November 09, 2006
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PDF (458.1 KB)

Article

Determination of the oxidative stability of vegetable oils by rancimat and conductivity and chemiluminescence measurements

Bertrand W. Mathäus1 Contact Information

(1) Institut für Chemie und Physik der Fette der Bundesanstalt für Getreide-, Kartoffel- und Fettforschung, Postfach 1705, D-48006 Münster, Germany

Received: 13 June 1995 Accepted: 28 March 1996

Abstract
The oxidative stability of five different oils was determined by Rancimat analysis with conductivity and chemiluminescence measurements for evaluation of the induction periods. Samples of oil, taken at intervals from the Rancimat apparatus, were used for chemiluminescence measurements. The chemiluminescence results were plotted vs. time, and the resulting curves were evaluated with a graphical tangential procedure in the same way as the curves of the Rancimat method (conductivity measurement). Induction periods of the oils assessed by Rancimat and chemiluminescence methods showed a significant linear correlation (r=0.9865). The temperature dependence of the induction periods evaluated by chemiluminescence and by conductivity was investigated with walnut oil. A marked temperature dependence was observed for both.

Key Words Chemiluminescence - conductivity - induction period - oxidative stability - Rancimat - rapeseed oil - safflower oil - sunflower oil - vegetable oils - walnut oil

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Determination of the oxidative stability of vegetable oils by rancimat and conductivity and chemiluminescence measurements

Determination of the oxidative stability of vegetable oils by rancimat and conductivity and chemiluminescence measurements

JournalJournal of the American Oil Chemists' Society
PublisherSpringer Berlin / Heidelberg
ISSN0003-021X (Print) 1558-9331 (Online)
IssueVolume 73, Number 8 / August, 1996
CategoryArticle
DOI10.1007/BF02523413
Pages1039-1043
Subject CollectionChemistry and Materials Science
SpringerLink DateThursday, November 09, 2006
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Determination of the oxidative stability of vegetable oils by rancimat and conductivity and chemiluminescence measurements

Bertrand W. Mathäus1 Contact Information

(1) Institut für Chemie und Physik der Fette der Bundesanstalt für Getreide-, Kartoffel- und Fettforschung, Postfach 1705, D-48006 Münster, Germany

Received: 13 June 1995 Accepted: 28 March 1996

Abstract
The oxidative stability of five different oils was determined by Rancimat analysis with conductivity and chemiluminescence measurements for evaluation of the induction periods. Samples of oil, taken at intervals from the Rancimat apparatus, were used for chemiluminescence measurements. The chemiluminescence results were plotted vs. time, and the resulting curves were evaluated with a graphical tangential procedure in the same way as the curves of the Rancimat method (conductivity measurement). Induction periods of the oils assessed by Rancimat and chemiluminescence methods showed a significant linear correlation (r=0.9865). The temperature dependence of the induction periods evaluated by chemiluminescence and by conductivity was investigated with walnut oil. A marked temperature dependence was observed for both.

Key Words Chemiluminescence - conductivity - induction period - oxidative stability - Rancimat - rapeseed oil - safflower oil - sunflower oil - vegetable oils - walnut oil

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