Inquiries

Coulometric Reagents

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There are two types of coulometric reagents: the anolyte (generating solution),which is placed in the anode chamber of the electrolysis cell, and the catholyte (counter electrolyte), which is placed in the cathode chamber. There are also special anolyte for use with ketones, lower carboxylic acids and silicone oils. AQUAMICRON® can be used in coulometric moisture measurement systems sold by various companies, and it has a worldwide reputation for excellent performance.

AQUAMICRON Series

Product name

Use

Specification

Package

AQUAMICRON® AXI

*AXI [For frit or fritless type cell, equivalent to FLS]
*AXI, AX & AX01[For General-use]
Organic solvents, Inorganic chemicals, Oiles, Petroleum products, Various kind of gases, etc.

Moisture
 maximum
 0.15mgH2O/mL


500mL

AQUAMICRON® AX

AQUAMICRON® AX01

100mL

AQUAMICRON® AS

[For Oils]
Naphtha, Gasolone, Diesel oil, Electrical insulation oil, etc.

Moisture
 maximum
0.15mgH2O/mL 

500mL

AQUAMICRON® AKX

[For Ketones]
 Ketones. Silicone oils. Low carboxylic acids, etc.

Moisture
 maximum
 0.15mgH2O/mL

500mL


AQUAMICRON® CXU

[Catholyte]
 Both AX and AS and AKX available to combine with

Moisture
 maximum
 0.6mgH2O/mL

5mL ampule×
10/case

AQUAMICRON® FLS

[For fritless type cell]
 Organic solvents, Inorganic gases, etc.

Moisture
 maximum
 0.15mgH2O/mL

500mL


AQUAMICRON® AXI/CXU or AX/CXU

Use

General samples

Characteristics
  • Minimal environmental contamination
    Does not include carbon tetrachloride or chloroform
  • Wide range of applications
    Suitable for petroleum products
    Can be used with moisture vaporization method
    (When using AQUAMICRON® AX or AXI in a moisture vaporization method, replenish the vaporized portion with methanol.)
  • High quality, high performance
    Excellent reputation for accurate moisture measurement and end-point stability
    Approximately 800mg of moisture can be measured per 100mL of AQUAMICRON® AX or AXI, and approximately 150mg per 5mL of AQUAMICRON® CXU
  • Easy to use
    These products can be used in the existing coulometric moisture measurement system.

AQUAMICRON®AS/CXU

Use

General samples

Characteristics
  • Wide range of applications
    Especially suitable for oils, petroleum products
  • High quality, high performance
    Excellent reputation for accurate moisture measurement and end-point stability.
    Approximately 800mg of moisture can be measured per 100mL of AQUAMICRON® AS, and approximately 150mg per 5mL of AQUAMICRON® CXU.
  • Easy to use
    These products can be used in the existing coulometric moisture measurement system.

AQUAMICRON®AKX/CXU

Use

Ketones, lower carboxylic acids, some aldehydes (aromatics)

Characteristics
  • Minimal environmental contamination
    Does not include chloroform or methyl cellosolve
  • Wide range of applications
    Suitable for ketones, lower carboxylic acids and some aldehydes
  • High quality, high performance
    Accurate moisture measurement, good end-point stability
    Approximately 300mg of moisture can be measured per 100ml of AQUAMICRON® AKX, and approximately 100mg per 5mL of AQUAMICRON® CXU (when used with AQUAMICRON® AKX).
  • Easy to use
    These products can be used in the existing coulometric moisture measurement system.

AQUAMICRON® AXI or FLS

Use

Suitable for alcohols, esters, benzene, toluene, inorganic gases, etc.

Characteristics
  • Easy to use
    AQUAMICRON® AXI or FLS is a single-solution type reagent. It should be used in single-solution electrolytic cells without diaphragm, fritless type cell.
    Can be used with moisture vaporizati on method(When using AQUAMICRON® AXI or FLS in a moisture vaporization method, replenish the vaporized portion with methanol.)
  • Easy maintenance
    Ceramic diaphragm is not used, therefore it is easy to maintain electrolytic cell in good condition.

Volumetric Reagents

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The items required for volumetric titration are a Karl Fischer titrant and methanol or a dehydrated solvent (used to dissolve or disperse the sample). AQUAMICRON offers a wide range of products suitable for measuring the moisture content of various samples at every levels. Users can select a solvent that is suitable for the samples based on the following tables.

SS Series (pyridine-free and chloroform-free type)

AQUAMICRON Use Specification Package
Titrant SS-Z 1mg [For General-use]
Low moisture content Samples
Titer
0.7-1.2
mgH2O/mL
500mL
Titrant SS-Z 3mg [For General-use] Titer
2.5-3.5
mgH2O/mL
500mL
Titrant SS-Z 5mg [For General-use]
High moisture content Samples
Titer
4.5-5.5
mgH2O/mL
500mL
1L
Solvent GEX [For General-use]
Organic solvents, Inorganic chemicals, Agricultural chemicals, Pharmaceuticals, Fertilizers, Detergents, Foodstuffs, etc.
Moisture maximum
0.2mgH2O/mL
500mL
Solvent OLX [For Oils]
Naphtha, Gasolone, Diesel oil, Electrical insulation oil, etc.
Moisture maximum
0.5mgH2O/mL
500mL
Solvent OLII For Oils and Fats]
Naphtha, Gasolone, Diesel oil, Heavy oil, Electrical insulation oil, Oils and Fats(Hardened oil, Margarine, etc.),etc.
Moisture maximum
0.2mgH2O/mL
500mL
Solvent KTX [For Ketones]
Ketones, Silicone oils, Acetic and other lower carboxylic acids, aldehydes(except acetaldehydes),etc.
Moisture maximum
0.5mgH2O/mL
500mL
Solvent SU [For Sugars]
Sugars, Proteins, Gelatine, Additives, Animal feeds, etc.
Moisture maximum
0.2mgH2O/mL
500mL

When using a moisture vaporization method, mix Solvent GEX with propylene glycol(PG) in a 3:1 ratio (e.g. 90mL of GEX + 30mL of PG).
When using Solvent KTX, it will be needed to make proper adjustments to the parameters. Please contact a manufacturer of the instruments.
An addition of 3g of salicylic acid enables the time for dehydration to get shorter at the first measurment in combined use of 50mL of Solvent SU.

SS Series (pyridine type)

AQUAMICRON Use Specification Package
Titrant SS 1mg
[For General-use]
Low moisture content Samples
Titer
0.7-1.2
mgH2O/mL
500mL
Titrant SS 3mg
[For General-use] Titer
2.5-3.5
mgH2O/mL
500mL
Titrant SS 10mg
[For General-use]
High moisture content Samples
Titer
8-12
mgH2O/mL
500mL
1L
Solvent ML [For General-use]
Organic solvents, Inorganic chemicals, Agricultural chemicals, Pharmaceuticals, Fertilizers, Detergents, Foodstuffs, etc.
Moisture maximum
0.2mgH2O/mL
500mL
Solvent MS [For General-use]
Organic solvents, Inorganic chemicals, Agricultural chemicals, Pharmaceuticals, Fertilizers, Detergents, Foodstuffs, etc.
Moisture maximum
0.2mgH2O/mL
500mL
Solvent CM [For Oils]
Naphtha, Gasolone, Diesel oil, Heavy oil, Electrical insulation oil, Oils and Fats(Hardened oil, Margarine, etc.),etc.
Moisture maximum
0.3mgH2O/mL
500mL
Solvent CP [For Ketones]
Ketones, Silicone oils, Acetic and other lower carboxylic acids, aldehydes(except acetaldehydes),Anilines, etc.
Moisture maximum
0.5mgH2O/mL
500mL
Solvent PP [For Aldehydes]
Acetaldehydes, propionaldehydes, Butyraldehydes, etc.
Moisture maximum
0.2mgH2O/mL
500mL
Solvent PE [For Ketones]
Ketones, Silicone oils, Acetic and other lower carboxylic acids, aldehydes(except acetaldehydes),Anilines, etc.
Moisture maximum
mgH2O/mL
500mL
Solvent FM [For Sugars]
Sugars, Proteins, Gelatine, Additives, Animal feeds, etc.
Moisture maximum
0.2mgH2O/mL
500mL
Solvent ME [For Vaporizer]
Gaseous samples, Nitrogen, etc.
Moisture maximum
mgH2O/mL
500mL

When using a moisture vaporization method, mix Solvent MS with propylene glycol(PG) in a 3:1 ratio (e.g. 90mL of MS + 30mL of PG).
An addition of 3g of salicylic acid enables the time for dehydration to get shorter at the first measurment in combined use of 50mL of Solvent FM.

Water Standards

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  • Manufactured at Mitsubishi Chemical Co. which have ISO9001 accreditation.
  • According to ISO, GMP, GLP, and FDA guidelines. Traceable to NIST SRM2890.
  • Consist of a solvent with specific composition, and exactly confirmed water content. Supplied with Certificate of Analysis.
  • Packaged in single-use glass ampoules.
  • Long shelf life.
Product name Use Specification Package
For Coulometric Titration
AQUAMICRON®
Water Standard 0.1
For checking the accuracy of the coulometric moisture meter Titer
0.1±0.01mgH2O/g
5mL
x10/case
AQUAMICRON®
Water Standard 0.2
For checking the accuracy of the coulometric moisture meter Titer
0.2±0.01mgH2O/g
5mL
x10/case
AQUAMICRON®
Water Standard 1
For checking the accuracy of the coulometric moisture meter Titer
1±0.05mgH2O/g
5mL
x10/case
AQUAMICRON®
Check Solution P
The end-point adjustment solution can be used with both AX and AKX. It can also be used for day-to-day management of coulometric moisture mesurement systems. Moisture
3.8-4.2mgH2O/g
100mL
For Volumetric Titration
AQUAMICRON®
Water Standard 10
For determination of Karl Fischer reagent titer Titer
10±0.5mgH2O/g
8mL
x10/case
AQUAMICRON®
Standard Water/Methanol
Used to assess titer of Karl Fischer reatents(3-10mgH2O/mL). Also can be used for reverse titration. Moisture
2.0±0.04mgH2O/g
250mL
For Vaporization Method
AQUAMICRON®
Solid Water Standard
For evaluation a moisture meter with a water vaporizer Moisture
3.83±0.1%
10g

Karl Fischer Method

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As shown in Formula (1) below, the Karl Fischer method uses Karl Fischer reagent, which reacts quantitatively and selectively with water, to measure moisture content. Karl Fischer reagent consists of iodine, sulfur dioxide, a base and a solvent, such as alcohol.

I2 + SO2 + 3Base + ROH + H2O ⇒ 2Base・HI + Base + HSO4R ・・・・・・・ (1)


As described below, this method can be used in both volumetric and coulometric titration systems.

Coulometric Titration
With coulometric titration, the sample is added to an electrolytic solution, the main constituents of which are iodide ions, sulfur dioxide, a base, and a solvent (such as alcohol). Electrolytic oxidation causes the production of iodine, as shown inFormula (2), resulting in an immediate Karl Fischer reaction. 

2I"  -  2e ⇒ I2 ・・・・・ (2)


According to Faraday's laws, the iodine is produced in proportion to the quantity of electricity. This means that the water content can be determined immediately from the coulombs required for electrolytic oxidation.

 1mg of water = 10.71 Coulombs


As shown in Figure 1, two types of coulometric reagents are required: an anolyte, which is placed in the anode chamber of the electrolysis cell, and a catholyte, which is placed in the cathode chamber. Coulometric reagents do not need assessment. Another advantage is that they can be used repeatedly.
Electrolysis cell of Coulometric Moisture Meter
Figure1:Electrolysis cell of Coulometric Moisture Meter

Volumetric Titration
A dehydrating solvent suitable for the sample is placed in a flask. Titrant is used to remove all moisture from the solvent. The sample is then added.
Titration is carried out using a titrant, the titer (mgH2O/mL) of which has previously been determined. The moisture content of the sample is determined from the titration volume (mL).
The end point is detected using the constant-current polarization voltage method. Figure 2 shows the components of typical commercially available automatic volumetric titration system.


Volumetric Moiture Meter
Figure2:Volumetric Moiture Meter
 


Scope of Applications for Karl Fischer Method

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The Karl Fischer method can be used with a wide range of substances. However, the method depends on a kind of iodometry based on t he reaction between the Karl Fischer reagent and water. The results will therefore show a
positive error if the sample includes substances that react with iodine, and a negative error if the sample includes substances that produce iodine by oxidizing iodide compounds. The following tables list substances that can be titrated directly with Karl Fischer reagents, substances t hat cannot b e titrated directly but can be titrated by means of adjustments based on appropriate chemical reactions or processes, and substances t hat react with Karl Fischer reagents and are therefore unsuitable for direct titration. Even if a substance cannot be titrated directly,its moisture content can be measured by indirect means, such as the water vaporization method.

Compounds that can be titrated directly

Organic compounds

Inorganic compounds

Hydrocarbons(saturated, unsaturated compounds)
Alcohols, Polyhydric alcohols, Phenols, Ethers
Inert ketones(diisopropyl ketone, et al)
Inert aldehydes(formaldehyde, chloral, et al)
Organic acids, Hydroxylic acids, amino acids
Acid anhydrides
Esters, Lactones, Inorganic acid esters
Amines(<pKa9), Amino alcohols
Proteins, Amides, Anilides
Nitriles, Cyanhydrins, Cyanic acid derivatives
Nitro compounds, Oximes, Hydroxamic acids
Thiocyanate, Thioethers, Thioesters
Halogenated hydrocarbons, Halogenated acyls
Sugars, Organic salts and their hydrates

Inorganic salts and their hydrates
Inorganic acids
Chelate compounds
Fertilizers
Calcium carbonate
Polytungsten salts



Compounds that react with Karl Fischer reagents and cannot be titrated directly

Organic compounds

Inorganic compounds

Ascorbic acid, Diacyl peroxides
Peracids,Quinone

Sodium sulfide, Sodium peroxide
Chromates, Dichromates
Ferric oxide, Nickel oxide, Arsenic trioxide
Arsenates, Arsenites, Borates, Boron oxide
Hydrogencarbonates, Carbonates
Metal hydroxides, Metal oxides
Sulfites, Pyrosulfites
Sodium nitrite, Thiosulfates
Cupric salts, Stannous salts

Compounds that can be titrated directly after special processing or under certain conditions

The examination will be necessary for the following compounds though it was said that these could be titrated
directly by the following treatments in former references.

Compounds

Treatment

Ammonia
Ferric salts
Hydrazine derivatives
Hydroxylamine salts
Thiol(mercaptan)
Sulfuric acid
Thioacid
Thiourea

Add acetic acid.
Add 8-hydroxyquinoline.
Add acetic acid.
Add sulfur dioxide: pyridine solution (1:1).
Prevent interference by adding olefins(octene, etc.).
If the sulfuric acid is 92%pure or higher, add a large surplus of pyridine and titrate it as a salt.
Prevent interference by adding olefins(octene, etc.).
Prevent interference by adding olefins(octene, etc.).



Examples of how AQUAMICRON® can be used with compounds that cause interference

Compound

Interference reaction

Treatment

Volumetric titration

Coulometric titration

Ketones

React with methanol to produce ketal and water

Titrant SS-Z + Solvent KTX

AKX + CXU

Titrant SS + Solvent CP

Aldehydes

React with methanol to produce acetal and water React with sulfur dioxide and water

Titrant SS-Z + Solvent KTX

AKX + CXU
(suitable only for a certain aromatic aldehydes)

Titrant SS + Solvent CP

Lower carboxylic acids

React with methanol to produce ester and water

Titrant SS-Z + Solvent KTX

AKX + CXU

Titrant SS + Solvent CP

Amines above pKa 9

Consume iodine gradually and the end-point becomes unstable

Titrant SS-Z + Solvent GEX
salicylic acid 10g

AXI or AX +CXU
salicylic acid 10g

Titrant SS + Solvent MS
salicylic acid 10g


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