DE2143415A1 - Sample vaporizer - Google Patents

Description

DR. MÜLLER-BüFf? OIPL-PHYS. DR. MAN ITZ DIPL.-CHEM. DR. DEUFEL DIPL.-ING. FINSTERWALD DIPL-ING. GRÄMKOW

30. NK.

Ph / th - λ 2167

ATOIiIC MTEIiGX GI? G-aljADA LIhITED Ottawa, Ontario, Lanada

Jf rob evaporator

Priority: Canada from October 16, 1970, No. 095 770

The invention "relates to a liquid sample vaporizer, in particular a vaporizer for water samples, to the J3estirar: iun £ of their douterium content by mass speiet ιό-metric Facilitate analysis.

commonly known method for the preparation of liquid samples for the liiassenspektrometrisclie analysis is' in the complete vaporization of a limited hours-Is ₁ J th hen ^ e a liquid in a closed Behäl- ® ter Lind followed by introducing the steam into a hossenspektrometer for analysis by procedures similar to <»Aen how they are used for gas analysis.

! f Hit the previous * procedure, it is difficult to get a bigger one

Analyze ^"1 J number of samples sclmell" In the production voii heavy water it is desirable to a large number

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of samples from a variety of water sources quickly to analyze to determine the deuterium content in it.

The Canadian registration number SO? 635 describes one Vaporizer that facilitates automated analysis and a tubular member for insertion into the sample with a reduced inlet bore, a narrowing evaporation part and an outlet for connection with a mass spectrometer and a Valoium source. This device is suitable for the rapid analysis of liquid samples that are relatively clean. rehearse with a significant amount of contaminants, such as dissolved salts and suspended solids, require time consuming cleaning operations before this method can be successfully applied.

The invention provides a sample vaporizer which is suitable for liquid samples with impurities such as, for example, dissolved salts and suspended solids, such as are found, for example, in seawater. The invention uses the Leidenfrost ¹ see phenomenon, characterized by a boiling film of a liquid near a metal surface heated above the Leidenfrost point (this is the temperature above which the liquid no longer wets the metal). Impurities in the liquid sample near the heated metal surface remain in the liquid phase and a representative vapor sample can be withdrawn for analysis.

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The invention "consists in a sample evaporator apparatus, characterized by a sample evaporation and a Steam receiving chamber, a device for heating a Part of the surface of the chamber via the Leidenfrost point and a steam pipe extending from a practically central one Part of that portion of the surface up to an outlet for connection to a vacuum source and sample analyzer extends.

Compartment of one embodiment comprises the sample vaporizer- apparatus a tubular evaporation chamber with a convex, vapor-absorbing end, a device for Heating of the convex end above the Leidenfrost point, ■ whereby the tubular chamber encloses a steam line, which extends from a practically central part of the vapor-absorbing part End extends to an outlet for connection to a vacuum source and a sample analyzer.

The vaporizer preferably comprises at least one sample container with devices for heating the sample to a temperature below the boiling point, for degassing.

According to a further embodiment, the invention exists in a sampling device with a plate-like Evaporation member with a concave, the sample receiving part, means for heating the plate over the Leidenfrost point, a steam exhausting point in the plate lying line extending from a practically central part of the part receiving the sample to an outlet for "connection to a vacuum source and a sample analyzer extends.

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Embodiments according to the invention are below Described with reference to the figures; show:

Fig. 1 to 3 partial views of three Ausfu.hrungsfor.men the Invention, in cross section and

Fig. 4- is a schematic view of an embodiment for automated sampling.

According to Fig. 1, the evaporator comprises a tubular one Evaporation device 10 with a convex, vapor-absorbing end 11. The device 10 has heating devices in the form of an electrical heating element 15 for heating the end 11 above the Leidenfrost point. The tubular device 10 encloses a conduit 12 which extends from a practically central part of the end 11 extends to an outlet 14. The line 12 encloses a recess for receiving a capillary suction probe 16, those with a vacuum source and an analyzer such as a mass spectrometer or otromatograph (not shown) is connected.

The sample 17 is contained in .einer recess 8 in a sample receiver 18, which heating devices 1J for heating the sample has a temperature below the boiling point for degassing.

The embodiment according to JPig. 2 has a direct connection from line 22 to the vacuum source and to the analyzer in the form of line 26. A constriction 29 at the end of the line limits the absorption of steam · -.-. "■

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ITael·L i'ig. 3 ″, the device vaporizing and receiving the sample has the i ⁽¹ form of a plate 30 with a concave, sample receiving part 31 for receiving a sample 37. A heating device 35 holds the surface 31 above the Leidenfrost point. The steam is over the capillary probe 36 is withdrawn through a line leading away the steam, which line is formed by a narrowed part 39 and a bore 32.

Preferably, the plate 30 has a sloping degassing belt 3Ö. An insert made of non-corrosive limaterial such as for example gold 33 covers those in contact with the sample Surfaces.

Ji ¹ Ig, 4 shows a schematic view of a device for automated sampling including a rotatable sample changer 48, a sample evaporator 40, a sample analyzer ^ O such. B. a Hass spectrometer, a control valve 5-2 uJid of a vacuum pump 31

In operation, according to i ^r ig. 1 brought the sample 17 into the receiving device 18, which is ^{heated by heating devices 13 to a temperature of approximately 90 0} O in order to degas the sample to remove dissolved air or gases which could otherwise prevent smooth operation. The degassing occurs through bubbles appearing in the sample,

Then the tubular evaporation device 10 is on heated to a temperature of 300 to 400 ° 0, in sample 17 lowered. A stable vapor film forms at the end 11 7 · ^ he liquid 17 is from the end by laminar

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^ Flow _it held vapor 7, which is durci_ the heat of evaporation device 10 testifies ei. The laminar vapor flow prevents the mechanical "transfer;" of particles of the impurities into the line 12. If the sample is properly degassed, the vapor film 19 is stable and vapor is formed without the ejection of salts which are in solution in the liquid phase stay.

A vacuum applied to the capillary probe 16 draws a portion of the generated vapor towards the analyzer. The outlet opening 14 - of the evaporation device 10 is larger than the capillary probe 16 to allow the vaporized samples to flow freely through the conduit.

After i? 2 the sample 17 is from a conventional one Container 28 added. The sample can be heated by heating prior to placing it in the container 18 or in the container be degassed by any suitable device. In this embodiment, the vacuum source is direct with the line 22 connected. The evacuation of steam is restricted by the constriction 29 to prevent air from entering is also sucked into the line 25. Can also be a rapid removal of the steam interfere with the formation of a stable steam film.

After I ¹ Xg. 3 , a drop of the sample is brought into the degassing channel 38 on the outer edge of the plate 30 '. If the sample touches the heated device 30, it is heated and the dissolved gas is expelled, so that the sample is clear and stable when it lies in the concave sample receiving part 31. The sample drop 37 floats on a steam cushion. The vapor sample to be taken is down

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guided through a constriction 39 and a line 52. The steam sample is passed through a capillary probe 36 in a similar hole as above with reference to I ¹ Xg. 1 "is deducted.

I'ig. 4 shows schematically]! a device for automated sampling including a rotatable sample changer "48. The sample changer 48 comprises a plurality of wells 41 for receiving the samples. The samples can be degassed before being applied to the sample changer 48 -....-" or the sample changer can open approximately 90 ^° C. in order to degas the samples when they are brought into the wells 41. The automated cycle begins with switching on the vacuum pump with the control valve 52 open. The evaporation device is lowered into one of the samples, and after a time sufficient for the formation of a uniform vapor flow, the valve 52 is closed and metered for the analyzer 50. The evaporator 40 is then withdrawn and the valve 52 opened to clean the evaporator and analyzer 50. The sample changer is rotated to place a new sample in position and the above cycle is repeated.

example 1

According to Fig. 1, the preferred embodiment is the Invention in an evaporation device 10 from ITiekel with a diameter of 6 mm and a steam inlet 9 of 0.5 well. The end 11 is hemispherical, but above that central rope slightly flattened to create the best stability for the steam film 7.

The maximum water penetration of the evaporation device 10 before the breakdown of the vapor film is approximate

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equal to the diameter of the evaporation device 10. Any visible penetration is sufficient to exclude the suction of air with the steam. Total exclusion of air occurs before a surface defect is visible.

With the one that receives the sample and is heated to 90 ° C Device 18 and with a sample amount of 0.5 ecm, the degassing time is approximately 10 seconds.

The optimal operation st emp.era door of the end of the evaporation facility was determined to be 300 to 400 ° ö.

The tip of the capillary aspiration probe 16 preferably has a diameter between 0.020 and 0.030 mm. The vacuum applied is preferably between 0.04 and 15 mm Hg. This Values can be changed provided that steam is not removed from outlet line 14 any faster when it can enter line 9.

It has been found that the accuracy of the system a standard comparison better than - 0.1 ppm was at natural deuterium concentration. There was an absolute error of about 0.3 ppm when compared with total sample evaporation. However, this error is a constant percentage at a given temperature of the water sample and, along with other errors that occur with the mass spectrometer approximation to the D / H analysis (e.g. Hj. ⁺ Ion formation), can be corrected by standard comparison.

The device described above was found to be suitable for salt concentrates up to 10 %.

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Example 2

According to FIG. J, the evaporator plate 30 has an insert made of gold to prevent corrosion. For the plate temperatures proved -from 175 ° "to 350 ⁰ C to be suitable. A suitable diameter for the conduit constriction 39 was" 0.1 to 0.6 mm.

The degassing of the sample by introducing the drop into the degassing channel 38 takes place within 0.5 to 2.0 seconds. If the drop is in the sample receiving part 31 ₅ , one finds that the temperature of the drop ^{is stable at about 88 to 90 °} C., regardless of the size of the drop or the temperature of the hot plate.

Satisfactory results have been / o achieved with salt concentrations up to 1 °. However, it was found necessary to clean the plate after 40 to 60 contaminated samples due to deposits on the degassing channel 38. Multiple degassing troughs can be used to extend the sampling time. Stainless steel is suitable in place of gold, but requires an increase in operating temperature of 100 ° 0 to develop good degassing properties due to its poor thermal conductivity.

It is understood that changes to the embodiments set forth can be made without departing from the scope of the invention. For example, the heating devices not necessarily as shown in the figures, but can be any suitable Be a facility that creates the required temperature. A linear sample changer can also be used instead of the rotatable sample changer shown in FIG.

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Furthermore, according to FIG. 3, a direct connection from the Line 32 to the vacuum source as in Fig. 2 against the Suction probe 26 must be replaced.

-Patent claims-

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Claims (6)

Patent claims . Sample evaporator apparatus, g e k e η η ζ calibrated through, a sample vaporizer and. a steam receiving chamber, means for heating part of the surface of the chamber above the Leidenfrost point and a steam line, extending from a practically central part of the part of the surface to an outlet for "connection." with a vacuum source and a prob enan'alysa tor extends. 2. sample evaporation apparatus according to claim 1, characterized through a tubular evaporation chamber with a convex, vapor-receiving end, a Means for heating the convex end above the Leidenfrost point, the tubular chamber being a Steam line encloses, which extends from a practically central part of the steam-absorbing end to a Extends outlet for connection to a vacuum source and a sample analyzer. 3. Prob enverdampfungs-Appara door according to claim 2, characterized by at least one sample container with a device for heating the sample to a Temperature below the boiling point for degassing. 4-, apparatus according to claim 3jgekennzeich.net through a variety of sample containers, one facility for advancing the containers for successive sampling and means for lowering and raising the tubular chamber simultaneously with the advancing container. 209817/0767 5 * apparatus according to claim 2, characterized net that the line of the tubular chamber a Recess to accommodate a capillary suction probe comprises, the probe not sealing to the opening arranged and with the vacuum source and the sample analyzer connected is" 6. Apparatus according to claim 2 »characterized in that the line has a flow-restricting device having near the end. 7 * Apparatus according to claim 1, characterized by an evaporator plate with a concave, the Sample receiving part, a device for heating the plate above the Leidenfrost point, a steam line in the plate, which extends from a practically central part of the part receiving the sample to a Outlet for connection to a vacuum source and a Sample analyzer extends. 209817/0757