- Coulometric Reagents
- Volumetric Reagents
- Water Standards
- Karl Fischer Method
- Scope of Applications for Karl Fischer Method
Coulometric Reagents
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.
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
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.
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.
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
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
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
Figure1:Electrolysis cell of Coulometric Moisture Meter
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.
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.
Figure2:Volumetric Moiture Meter
Scope of Applications for Karl Fischer Method
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 |