卡尔·费希尔法可用于广泛的物质。然而,该方法依赖于一种基于卡尔·费舍尔试剂与水之间反应的碘量测定法。因此,如果样品中含有与碘反应的物质,则结果误差为正;如果样品中含有氧化碘化物产生碘的物质,则结果误差为负。下表列出了可以用卡尔·费歇尔试剂直接滴定的物质,不能直接滴定但可以根据适当的化学反应或过程通过调整滴定的物质,以及与卡尔·费歇尔试剂反应因而不适合直接滴定的物质。即使一种物质不能直接滴定,它的含水量也可以通过间接的方法测量,如水蒸汽法。
Compounds that can be titrated directly
Organic compounds |
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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<br=””> 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 compounds |
Inorganic salts and their hydrates Inorganic acids Chelate compounds Fertilizers Calcium carbonate Polytungsten salts |
Compounds that can be titrated directly after special processing or under certain conditions
经过特殊处理或在一定条件下可直接滴定的化合物
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.
对下列化合物进行检查是必要的,尽管在以前的文献中说这些化合物可以通过下列处理直接滴定。
Compound | Treatment |
---|---|
Ammonia | Add acetic acid. |
Ferric salts | Add 8-hydroxyquinoline. |
Hydrazine derivatives | Add acetic acid. |
Hydroxylamine salts | Add sulfur dioxide: pyridine solution (1:1). |
Thiol(mercaptan) | Prevent interference by adding olefins(octene, etc.). |
Sulfuric acid | If the sulfuric acid is 92%pure or higher, add a large surplus of pyridine and titrate it as a salt. |
Thioacid | Prevent interference by adding olefins(octene, etc.). |
Thiourea | Prevent interference by adding olefins(octene, etc.). |
Compounds that react with Karl Fischer reagents and cannot be titrated directly
与卡尔·费舍尔试剂反应而不能直接滴定的化合物
Organic compounds |
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Ascorbic acid, Diacyl peroxides Peracids, Quinone |
Inorganic compounds |
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 |