DE699238C - Process for the determination of ash from organic substances - Google Patents

Description

Process for the ash determination of organic substances of organic substances, for example carbohydrates, are the substances to be analyzed heated in bowls made of porcelain, quartz glass or platinum, for example using an electrically heated muffle furnace. If the temperature here is worse than 7000 are increased in the presence of certain ash components, such as compounds of phosphorus, Arsenic and the like, even quartz glass and platinum, which are considered to be exceptionally resistant Materials are known to be more or less severely corroded. The corrosion leaves Avoid with certainty only if the incineration is below 700 °, so at relatively low temperatures. This, however, is the Time to perform an analysis increased many times.

It has now been found that ash determinations of the organic Carry out substances without corrosion of the vessel material even at temperatures above 700 ° leave if, according to the invention, the AiiaWsensubstanz on one in the incineration vessel extensive layer of oxides, preferably of elements of the 2nd to 4th main group of the penodic system or those compounds that operate at higher temperatures in these - oxides pass over, gives up.

The incineration of the organic matter takes place, for example, in the presence carried out by oxides of the earth metals, especially of alumina; next to these Oxides with amphoteric character have found basic oxides, e.g. the oxides of alkaline earths and especially calcium oxide and beryllium oxide, and also oxides with weakly acidic Character, such as B. the silica, proven. For some oxides there is a previous one Glowing recommended to avoid absorption of water from the atmosphere; so alumina and silica lose their hygroscopicity, welm they are heated to temperatures above 1000 ° for a longer period of time.

Corrosion is further avoided according to the invention by the Analytical substance is applied to compounds that are in Foul oxides, e.g. B. Alkaline earth carbonates. Mixtures can be used with equal success use that contain the substances mentioned. The amount of additive depends according to the amount and type of ash constituents.

The oxides or carbonates are on the bottom and walls of the Incineration vessel spread out in the form of an even layer on which the Analysis substance, if necessary with a further addition of oxides and carbonates, is abandoned.

The described additions have been made to avoid corrosion of the vessel materials in ash determinations of the most varied organic Tried and tested substances, for example in the determination of the ash of substances of vegetable origin Origin. The additives prevent corrosion when organic substances are incinerated of the most varied of materials; vessels made of platinum are particularly cheap Results with the addition of silica, clay, or a mixture of both achieved, in the case of quartz glass, the addition of silica has proven particularly useful.

If the analysis substance is spread on the named substances, so the incineration can be carried out at temperatures above 7000 without that corrosion of the vessel material is observed.

This work at higher temperatures increases the duration of the analysis abbreviated considerably.

In the case of corrosion of the. Vessel materials when incinerating organic Substances also play a role - the metaphosphates contained in the ashes of these substances Role; flour ash consists of 8-85% potassium metaphosphate.

It is possible that the described effect of the oxides is partly due to this is based on the fact that the metaphosphates in harmless complex or aluminum storage compounds be transferred.

For the determination of organic substances, use quartz sand to mix and then incinerate is known.

According to the known method, as a result of the mixing of the analysis substance with the quartz sand and the resulting lack of a protective layer between the substance to be analyzed and the incineration vessel adequate protection of the latter against corrosion not achieved.

Examples I. 1 g of silica or 1 g of clay or 1 g of a mixture both are shaped on the bottom and the walls of a tared platinum dish linen spread evenly; then add 3 g of flour with an approximate Ash content of 0.5% abandoned. Now is in an electrically heated flour incinerator with unhindered air access and dark red embers slowly charred and then with closed oven the temperature increased to 920 ° and at this temperature Heated until the flour is completely ashed. The entire operation takes time about is / 2 hours.

The residue obtained in this way is completely white and loose. The platinum peeling shows no changes after cleaning with hot, dilute hydrochloric acid; it has remained constant in weight, its polish is completely preserved.

Will incineration under exactly the same conditions without addition made of silica or alumina, the ashes melt into droplets. After cleaning, the areas covered by droplets are typical Corrosion phenomena; they are covered with glittering crystal surfaces, the polish has disappeared.

2. 3 g of flour in the presence of 1 g of silica in the example In the manner I described, incinerated in a quartz glass bowl.

Here, too, no change can be observed after cleaning the bowl; the glaze is perfectly preserved and the weight of the bowl unchanged.

If the same experiment is carried out without the addition of silica, so the ashes melt into droplets. After cleaning the bowl with diluted With hot hydrochloric acid, the areas covered by the droplets show signs of corrosion; they are completely cloudy and roughened, their glaze is destroyed.

Claims (1)

PATENT CLAIM: Method for determining the ash of organic substances, for example carbohydrates, characterized in that the analysis substance on a layer of oxides, preferably elements, spread out in the incineration vessel the 2nd to 4th main group of the periodic system, for example of clay or its mixture of silica and alumina, or of such compounds as lead higher temperatures pass into these oxides, is abandoned.