WO2001044803A2

WO2001044803A2 - Rapid test for formaldehyde determination

Info

Publication number: WO2001044803A2
Application number: PCT/EP2000/012334
Authority: WO
Inventors: Adalbert Prior; Michael GRÜNWALD; Thomas Kestler
Original assignee: Zivilingenieur Für Techn. Chemie
Priority date: 1999-12-13
Filing date: 2000-12-07
Publication date: 2001-06-21
Also published as: AT4098U1; WO2001044803A3

Abstract

The invention relates to a test kit for the rapid determination of formaldehyde in textile materials, which comprises; a sealed ampoule, filled with a defined volume of a reagent mixture, which produces a colour change on reaction with formaldehyde; a test-tube for mixing the reagent mixture and a defined volume of an extract from the textile material; and a reaction vessel, or a measuring cuvette for the mixture of extract and reagent mixture and subsequent carrying out of a colour reaction at elevated temperature.

Description

QUICK TEST FOR DETERMINING THE FORMALDEHYDE

The present invention relates to an improved method for determining formaldehyde from textile fabrics, and to a test kit for carrying out this method.

The determination of formaldehyde from textile fabrics according to the standards EN ISO 1 41 84-1 and 1 41 84-2 is carried out according to a complex laboratory procedure with preceding, time-consuming, several-hour extraction. Thanks to the MORAPEX ^® extraction apparatus, which is described in detail in EP 0 640 825, the extraction process can be shortened to 5-1 0 minutes.

The aim of the present invention is to provide a method and a test kit with the aid of which an extract from a textile sample obtained by a MORAPEX® device can be examined for ingredients, in particular formaldehyde, as quickly and without loss as possible.

The formaldehyde determination according to the method according to the invention is carried out as follows:

A defined volume of an extract obtained by the MORAPEX ^® method is transferred, preferably already during the extraction process and under essentially airtight conditions, into a test tube which already contains a defined volume of a reagent mixture suitable for the determination of formaldehyde. The test tube is then sealed airtight and shaken vigorously to mix the extract and the reagent well. This mixture or a part thereof is then transferred to a measuring cuvette and heated at 60 ° for 10 minutes. Depending on the formaldehyde concentration, this results in a color change, which, after the mixture has cooled to room temperature, is then measured in a spectrophotometer and the formaldehyde content is determined quantitatively therefrom. The formaldehyde content determined is output directly from the photometer or can be read on a display.

In principle, any reagent mixture can be used as the reagent mixture which causes a color reaction with formaldehyde. According to the invention, however, a non-hazardous reagent mixture is preferred, which consists of ammonium acetate, acetylacetone, concentrated acetic acid and demineralized water, preferably with the following composition: Make up 1 50 g ammonium acetate, 2 ml acetylacetone, 3 ml concentrated acetic acid with demineralized water to a total volume of 1 liter. Deviations from this mixing ratio, in particular a higher concentration of the ingredients, are possible and are within the scope of the present invention.

This solution is then filled, in particular for the production of a test kit, in precisely defined amounts, preferably in portions of exactly 5 ml, into sealable plastic ampoules (e.g. volume 5-6 ml).

It is preferred that the test tubes, which contain a defined amount, e.g. B. with exactly 5 ml, the reagent mixture are also part of the test kit according to the invention. It is further preferred that these test tubes are matched to the commercially available MORAPEX® extraction device and can be connected in an airtight manner to the extract outlet connector of this MORAPEX® extraction device. The test tubes, for example commercially available test tubes with the dimensions 1 80 * 1 8 mm and smooth rim, can be against a conical stopper, e.g. B. rubber stopper that surrounds the extract outlet of the MORAPEX® extraction device can be attached and fixed. But you can also e.g. Have threads that can be closed with screw caps, that have a perforated membrane and that can be attached to the outlet port of the MORAPEX® extraction device (in one embodiment without rubber plugs or other sealing sleeves). But it can also, for. B. flange-like plug-in connections may be suitable, as well as any other type of essentially air-tight connection via sealing rings or sealing sleeves and the like. The aim of this measure is to keep evaporation losses as low as possible and thus to make the rapid test as accurate as possible.

Suitable measuring cuvettes, which are preferably also part of the test kit, are both those which can be heated and cooled directly with bath fluid, in particular via a double jacket, and those which are tempered by means of an electrical heating device, for example a water bath. It goes without saying that the Measuring cuvettes must be matched to the heating device to be used and in particular to the photometer to be used. Within the scope of the test kit according to the invention, suitable measuring cuvettes are therefore provided for a number of known, preferably portable and mostly portable, heating devices or water baths and photometers.

The present invention is explained in more detail below with the aid of figures. Fig. 1 schematically shows an embodiment of the rapid test method according to the invention; and FIG. 2 shows a comparison of the analysis results from three different ones

Formaldehyde determination methods.

In FIG. 1, step 1 shows the collection of the extract obtained by means of a MORAPEX® extraction device in a test tube which is filled in advance with the reagent mixture composed according to the invention. This test tube is attached to the extract outlet of the MORAPEX® extraction device essentially airtight before the actual extraction, so that the resulting extract can drip directly into the reagent mixture. Compared to other methods, this has the advantage that the chemical reaction between the reagent and extract in the test tube begins during the extraction process and complex formation begins, which is then continued and completed at a higher temperature, separately from the extraction apparatus. The result is a considerable saving of time.

An essentially airtight seal is particularly important when using volatile organic extractants.

The MORAPEX® extraction device delivers 5 ml extract per extraction cycle (duration 1-2 min); after 5 extraction cycles, ie after approx. 5-10 minutes, the extraction is complete and the accumulated extract volume is 25 ml. When using the reagent mixture with the preferred composition, the test tube is filled with 5 ml of reagent mixture, so that together with the extract gives a total volume of 30 ml. In this case, the test tube must have a capacity of at least 30 ml. It is a further advantage of the present invention that, in contrast to the standard method in which the reagent and extract are reacted in a ratio of 1: 1, a ratio of only 1: 5 must be used when using the preferred reagent mixture, to still deliver accurate results. It goes without saying that when using a different, for example more highly concentrated, reagent mixture or a different, for example smaller, amount of extract, the corresponding amount of reagent has to be adapted accordingly, which can easily be accomplished by a person skilled in the art.

After the extraction is complete, the test tube is removed from the extraction device, closed with a suitable cap or stopper and - as shown in step 2 - shaken vigorously. The mixture is then transferred, if appropriate using a funnel as shown in step 3, into a reaction vessel, preferably into a measuring cuvette to be used later for the photometric evaluation. This reaction vessel or the measuring cuvette (e.g. a round cuvette with the dimensions 90 * 13 mm) is then, preferably after being covered with a suitable closure, used in step 4 in a heating device, for example a preheated electric oven or a preheated water bath, and preferably tempered at 60 ° C for a period of 10 minutes. In principle, it is also possible to carry out the color reaction at a different temperature and corresponding reaction time, in particular within a range from 40 to 90 ° C. and corresponding reaction times from approx. 30 to approx. 5 minutes (ie 30 minutes at 40 ° C. or 5 minutes at 90 ° C), but the reaction at about 60 ° C and a duration of about 1 0 minutes has been found to be the most practical. Lower reaction temperatures lead to an undesirable increase in the duration of the analysis, while higher temperatures save time, but at the same time provide less precise and more scattering analysis results.

As an alternative to the use of a heating device mentioned above, a reaction vessel or a measuring cuvette with a double jacket can of course also be used in order to heat and subsequently cool down via the double jacket by means of a temperature control medium, e.g. B. water to accomplish. In order to achieve the highest possible measurement accuracy, it is preferred that the reaction cover or cover the measuring cuvette during the reaction at 60 ° C or close it in such a way that no evaporation losses can occur in order to avoid incorrectly high analysis values. As an alternative, you can also use a mathematical correction factor under constant analysis conditions to compensate for evaporation losses in the case of open measuring cells or reaction vessels.

After the reaction of the reagent mixture with the extract, which, depending on the formaldehyde content, results in a color change from colorless to yellowish to orange-yellow or orange, the cuvette is cooled either passively (via ambient air) or actively (using coolant) to room temperature and then in measured with a photometer as shown in step 5. To carry out the photometric measurement including zeroing, the regulations of the device manufacturer must be taken into account accordingly. It is preferred that the photometer be adjustable to provide the desired analysis value, i.e. can output the formaldehyde content directly in ppm per unit mass or area of the textile sample.

It can be seen in FIG. 2 that the rapid test according to the invention (referred to as "MORAPEX Rapid Test"), which takes only about 20 to 30 minutes from the extraction of the sample to the present final result and manages with a fifth of the amount of reagent, compared to the standardized Determination method according to EN ISO 141 84-1 and 1 41 84-2, which takes 3-4 hours, provides sufficiently consistent results. The method called "Morapex Mop 6a" is also based on an extract that was obtained with the MORAPEX® extraction device, however, the reagent was added and the color reaction was carried out in accordance with the standards and separately from the extraction device.

Thanks to the rapid test according to the invention, it has now become possible for the textile industry to react much more quickly to certain workflows in textile production or treatment processes and thus to avoid undesired high formaldehyde concentrations in fabrics better than hitherto.

Claims

claims

1 . Test kit for the rapid determination of formaldehyde in textile fabrics, characterized in that it contains the following components: - a sealed ampoule filled with a precisely defined volume of a reagent mixture, which causes a color change when reacted with formaldehyde; a test tube for receiving and mixing the precisely defined volume of the reagent mixture and a precisely defined volume of an extract obtained from a textile fabric by means of an extraction device; and a reaction vessel or a measuring cuvette for holding at least a portion of the mixture of extract and reagent mixture.

2. Test kit according to claim 1, characterized in that the reaction vessel or the measuring cuvette can be tempered, preferably have a double jacket, and can be heated and cooled by means of a liquid.

3. Test kit according to claim 1, characterized in that it also contains a heating device, in particular an electric oven or a water bath, and the reaction vessel or the measuring cuvette are matched to the heating device.

4. Test kit according to claim 1 or 3, characterized in that it also contains a spectrophotometer, and the reaction vessel or the measuring cuvette are matched to the photometer.

5. Test kit according to claim 1, characterized in that the test tube for receiving the extract in one versus one

Outlet connector of the extraction device is designed in an essentially airtight sealing form, and can preferably be connected to the outlet connector by simply plugging, screwing or clamping against a sealing element.

6. Test kit according to claim 5, characterized in that the sealing element is a perforable membrane, a sealing ring, a sealing sleeve, a flat seal or a cone.

7. Test kit according to one of the preceding claims, characterized in that the reagent mixture consists of an aqueous solution which contains 1 50 g of ammonium acetate, 2 ml of acetylacetone and 3 ml of concentrated acetic acid per liter.

8. Test kit according to one of the preceding claims, characterized in that the defined volume of the reagent mixture is 5 ml and the test tube has a capacity of at least 30 ml.

9. Method for the rapid determination of formaldehyde in textiles

Tissue samples, characterized in that a defined volume of an extract obtained from a tissue sample is introduced during the extraction into a test tube filled with a defined volume of a test mixture, the test tube is then closed and shaken, the resulting mixture or a part thereof in a reaction vessel or a measuring cuvette is transferred and heated, and then a color change resulting from the reaction between formaldehyde and reagent mixture is measured photometrically and evaluated quantitatively.

10. The method according to claim 9, characterized in that the extract flows or drips directly into the test tube from an extraction device during the extraction process, preferably under essentially airtight conditions.

1 1. A method according to claim 9 or 10, characterized in that the reagent mixture consists of an aqueous solution which contains 1 50 g of ammonium acetate, 2 ml of acetylacetone and 3 ml of concentrated acetic acid per liter.

1 2. The method according to claim l 1, characterized in that 5 ml of extract are introduced into the test tube per 1 ml of the reagent mixture.

1 3. The method according to claim 1 1, characterized in that the defined volume of the reagent mixture is 5 ml and is preferably taken from a prefabricated ampoule, which contains precisely these amounts, and transferred to the test tube.

1 4. The method according to any one of claims 9 to 1 3, characterized in that the reaction vessel or the measuring cuvette to a temperature between 40 and 90 ° C for a period of 30 to 5 minutes, preferably to a temperature between 55 and 65 ° C. for a period of 1 2 to 9 minutes.

1 5. The method according to claim 1 4, characterized in that the reaction vessel or the measuring cuvette is heated to a temperature of 60 ° C for a duration of 1 0 minutes.

1 6. The method according to any one of claims 9 to 1 5, characterized in that the reaction vessel or the measuring cuvette are actively or passively cooled to room temperature before the photometric measurement.

1 7. The method according to any one of claims 9 to 1 6, characterized in that the temperature control of the reaction vessel or the measuring cuvette via a double jacket system with bath liquid or by means of a heating device, in particular an electric oven or a water bath.