CS258160B1 - Method for identification of β semiquantitative determination of monoathylanglycol in engine oil - Google Patents

Abstract

The solution oe concerns the determination of the quality of engine oil in internal combustion engines, contaminated with a coolant consisting of monoethylene glycol. The oil sample is mixed with ethanol after homogenization and a reagent is added to the mixture. This mixture is applied to a plate with a thin layer of sorbent and a standard solution next to it. This consists of monoethylene glycol dissolved in ethanol in the presence of a reagent. The plate is subjected to the action of the mobile phase and after a period of time, the spots of the mixture and the standard solution are compared. The reagent used is p-/N,N-dimethylamino/benzene-p'-azobenzoyl chloride.

Description

The invention relates to a method for the identification and semi-quantitative determination of monoethylene glycol in engine oil by thin-layer chromatography.

The essential component of the coolant used in internal combustion engines is monoethylene glycol. When the coolant enters the engine oil, unwanted reactions with additives occur and, on the other hand, condensation reactions can occur, the products of which can cause so-called engine sticking. It is therefore desirable to monitor the presence of monoethylene glycol in engine oils. It is known to use either azeotropic distillation followed by oxidation with nitric acid or infrared spectrometry. These procedures are time-consuming and costly in terms of instrumentation and in no way can they be used in operating conditions outside a special laboratory.

Further, it is known from U.S. Pat. No. 3,635,677 to detect glycol in oil by shaking the oil sample with an aqueous solution of an oxidizing agent, and then allowing the aqueous phase to act on the sorbent with a color-reactive aldehyde reagent. According to German Pat. No. 2,261,200, the alcohol content of the fuel is determined. O-vanadic acid 8-hydroxyquinolinester is deposited in a tube on a silica gel support or laumina, and the color zone length is proportional to the alcohol content after a given amount of sample has flowed.

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These methods are also labor-intensive.

These drawbacks are overcome by the method of identification and semi-quantitative determination of monoethylene glycol in engine oil by the thin-layer chromatography method of the invention.

It consists in homogenizing the oil sample and mixing it with ethanol and shaking, followed by the addition of a reagent consisting of p- / N, N-dimethylamino / benzene-p'-azobenzoyl chloride dissolved in benzene, to the ethanol layer. apply the mixture to a thin sorbent plate and next to a standard solution consisting of monoethylene glycol dissolved in ethanol and mixed with the reagent in benzene. Thereafter, the thin-bed plate of the sorbent is treated with a 3: 2 hexane-ethyl acetate mixture, and after a period of time, the stains of the mixture and the standard solution are compared.

The main advantage of the process according to the invention is that it makes it possible to easily identify monoethylene glycol in engine oil under operating conditions without the need for complex instrumentation. Furthermore, the amount of monoethylene glycol in the engine oil can be determined semi-quantitatively. The limit of detection is 0.1% by weight. glycol.

The method is described in more detail below on a specific embodiment.

Example

The oil sample was homogenized and 5 ml was collected into a wider tube. Then 2.5 ml of ethanol was added, the mixture was shaken vigorously and allowed to stand. Then, 0.5 ml of the ethanol layer was collected into a smaller tube and 0.5 ml of a reagent consisting of 0.1 g of p- / N, N-dimethylamino / benzene-p'-azobenzoyl chloride dissolved in 50 ml of benzene was added. This mixture was mixed again. Then, 5 µl of this mixture was applied to the start of a thin sorbent plate. Next, a standard solution of monoethylene glycol, consisting of mixing 0.5 ml x% rotocumonoethylene glycol in ethanol with 0.5 ml of the above reagent, was applied. The thin sorbent plate thus treated was placed in a beaker with a mobile phase such that the mobile phase reached about 0.5 cm below the start. The beaker was covered with a watch glass. It was then developed until the mobile phase reached a distance of 10 cm behind the launch. If there was monoethylene glycol in the engine oil sample to be tested, the spot appeared at the same distance from the start as the closest spot from the start of the standard solution.

The total time for one separate assay was approximately 30 minutes. For a semi-quantitative assay, it is necessary to apply an accurate volume of the engine oil sample to the plate with a thin sorbent layer and at the same time to apply standard solutions with graduated amounts of monoethylene glycol.

Since the sample is shaken to half the amount of ethanol, the result should be divided by two.

Claims (1)

SUBJECT OF THE INVENTION Method for the identification and semi-quantitative determination of monoethylene glycol in motor oil by thin-layer chromatography, characterized in that the oil sample is homogenized and mixed with ethanol and shaken, followed by the addition of a p- / N, N-dimethylamino / benzene-p 'reagent. -azobenzoyl chloride dissolved in benzene, then this mixture is applied to a thin sorbent layer plate and next to a standard solution consisting of monoethylengylcol dissolved in ethanol and mixed with the said reagent in benzene, the thin layer of rosbent is treated with a hexane mobile phase : ethyl acetate in a ratio of 3: 2, and after a period of time, the spots of the mixture and the standard solution are compared.