JP2794903B2 - Atomic absorption spectrometer atomizer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an atomization apparatus for atomizing a sample by a flame method in an atomic absorption spectrometer.

(Prior Art) In an atomizing device of a flame type atomic absorption spectrometer, a liquid sample sucked up through a sample sucking capillary is sprayed by a so-called atomizing mechanism. The sprayed sample collides with a ball-shaped disperser provided in the atomization chamber and is pulverized, and further atomization proceeds.
In the atomizing device of that type, the amount of atomization is basically determined by the performance of the atomizer which is the atomizing mechanism. Therefore, in order to increase the amount of atomization, a mechanically high-performance and expensive atomizer is required.

As an atomization device improved to increase the amount of atomization, the atomizer has a two-stage nozzle structure, and the primary nozzle spirally jets the sample suction gas to suck the sample and aspirates the sample with swirling force. In some cases, the amount of atomization is increased by miniaturizing the atomized droplets and further swirling and ejecting gas from the secondary nozzle immediately after the outlet of the primary nozzle, thereby promoting the miniaturization of the atomized droplets with the energy.

As another improved atomizing apparatus, an atomizing chamber is heated by an electric heater, hot water, or the like to reduce the aggregation of atomized droplets and to improve efficiency.

Still other improved atomization devices have attempted to increase the amount of atomization using auxiliary energy such as ultrasound or static electricity.

(Problems to be Solved by the Invention) Even in the above-described improved atomizing device, the amount of atomization is not yet sufficient. Moreover, increasing the amount of atomization requires extremely expensive equipment.

The amount of atomization and the size of the atomized droplet vary every time spraying is performed, and the reproducibility is not good. The atomization fluctuates due to the non-uniform size of the droplets.

An object of the present invention is to solve these problems and to provide an inexpensive and highly reproducible atomizing apparatus.

(Means for Solving the Problems) According to the atomization device of the present invention, the liquid sample is sucked and atomized by a nebulizer in the same manner as the conventional device, but heated as a pressurized gas that gives energy for atomization. A high temperature gas oxidizer is used and the atomization chamber is also heated to keep it high. Therefore, the atomization device of the present invention is provided with only an atomizer that sprays a sample sucked by a capillary with a pressurized gas containing an oxidant as an atomizing means in an atomization chamber connected to a burner head, and sprays the oxidant with the atomizer. A heating means is provided in a flow path for supplying the gas to the chamber, and a heating means is also provided in the atomization chamber.

(Operation) The energy of the gas for spraying is mechanical energy by pressure and thermal energy by heating. Since the sample is mechanically finely divided, the surface area per weight increases, and the heat transfer coefficient improves. Since the sample exiting the atomizer and the high-temperature gas are well mixed by the spray effect, the sample is sprayed for atomization, and at the same time, efficient heat transfer is performed, and the sample is vaporized.

Furthermore, since the atomization chamber is heated and the sample is atomized, the heat is efficiently transferred to the sample and the vaporization of the sample is promoted.

As a result, most of the sample sent from the atomization chamber to the burner is vaporized. In this way, the amount of atomization that reaches the burner will depend on the amount of heat applied to the sample. If the heat supply is sufficient, atomization up to an amount corresponding to the saturated vapor partial pressure of the sample in the atomization chamber is expected.

(Embodiment) FIG. 1 shows an embodiment.

Reference numeral 2 denotes an atomization chamber, and the outlet is connected to a burner head 4. A sprayer 6 is provided at the base end of the atomization chamber 2. The sprayer 6 has a structure in which the tip of the capillary 10 is positioned at the center of the cone-shaped nozzle 8, and the base end of the capillary 10 is guided to a sample bottle so that a liquid sample can be sucked. A mixed gas of a gas oxidant and a fuel gas is supplied to the outside of the capillary 10 under pressure by the nozzle 8, and the sample is sprayed from the capillary 10 by being ejected from the nozzle 8. A heater 16 is provided in the mixed gas supply flow path 14 of the oxidant and the fuel gas, and heats the gas supplied to the nozzle 8. The heater 16 is, for example, an electric heater. Air is used as the oxidizing agent supplied to the nozzle 8 as in the conventional atomizing device, and acetylene gas is used as the fuel gas as in the conventional case.

A heater 18 is provided for heating the atomization chamber 2. The heater 18 is, for example, a tape heater and is wound around the outside of the atomization chamber 2.

A drain 20 is provided at a lower portion of the atomization chamber 2 to discharge a sample which has been sucked and not atomized.

In this embodiment, air and fuel gas are supplied under pressure, and the mixed gas is heated by the heater 16 and supplied to the atomizer 6. The atomization chamber 2 is also heated by the heater 18. The sample is sucked from the sample bottle by the capillary 10 and sprayed from the sprayer 6. At this time, the sample fine particles are heated and vaporized by the heated air and the fuel gas, and further heated and vaporized in the atomization chamber 2. The vaporized sample gas is mixed with air and a fuel gas and guided to the burner head 4 to form a flame 22. Light for measurement passes through the flame 22, and is spectrally analyzed by a spectrophotometer.

In this embodiment, in order to measure the amount of atomization, the nozzle structure of the atomizer 6 is changed as shown in FIG.
1.5 mm, the outer diameter of the capillary 10 is 0.6 mm, the inner diameter of the capillary 10 is 0.34 mm, and the inclination angle θ of the nozzle cone is 39.
Degree. However, since the amount of atomization is not greatly affected by θ, θ may be set to an easy angle such as 45 degrees. Capillary 10 is a platinum iridium tube. When the mixed gas flow rate of the air and the fuel supplied to the atomizer 6 having such dimensions is 10 Nl / min and the total pressure is 0.5 kg.f / cm ² , the sample suction amount is 4 cc / min. The nozzle 8 was adjusted.

When the amount of atomization was measured using this atomizing device while changing the heating power, the results as shown in FIG. 3 were obtained. In FIG. 3, the portion indicated by A is a portion which is formed as water droplets by mechanical spraying and exits from the burner head, and the portion indicated by B is a portion which is vapor and exits from the burner head. When heated to a high temperature, everything vaporizes and exits the burner head, and the amount of atomization is proportional to the heating energy. However, this does not mean that the power of the electric heater and the amount of atomization are proportional, but it can be considered that the amount of heat given to the steam and the amount of atomization are almost proportional.

In this measurement, the maximum amount of atomization was about 1.3cc / min. This indicates that the atomization rate is 30% or more for a suction rate of 4 cc / min.

On the other hand, when the supply amount of air and fuel gas, the gas pressure, and the sample suction amount are equivalent to the numerical values shown in the examples in the conventional atomization device, the atomization amount is about 0.4 cc / min, The atomization rate is about 10%.

In this embodiment, the air and the fuel gas are simultaneously heated through the heater 6 after the air as the oxidant and the fuel gas are mixed. However, only the air may be heated by the heater 16 and the fuel gas may be mixed by the nozzle 8. In this case, the temperature of the heated air decreases due to the mixing of the fuel gas, so the air temperature must be raised accordingly.

(Effect of the Invention) In the present invention, the heating means is provided in the flow path for supplying the oxidizing agent to the atomizer, and the heating means is also provided in the atomization chamber. It is only necessary to spray with a particle size as large as necessary to maintain transmission efficiency, and high mechanical performance is not required. Therefore, the nebulizer is relatively simple and cheap.

Even if the atomizer is disassembled, washed, and reassembled, the structure can be made such that the amount of heat transfer does not change, so that it is possible to supply an atomizing device with a reproducible amount of atomization.

Due to the above effects, maintenance such as disassembly and cleaning is easy. The fact that the user can easily clean the nebulizer means that the analysis accuracy can be prevented from deteriorating due to the residue of the previous analysis sample.

Because the amount of atomization is determined by the amount of heat transfer, even if the sprayer becomes dirty due to repeated use and the suction amount fluctuates,
The change in the amount of atomization is small, and stable and reproducible analysis is possible.

Since the mist of the sample reaching the burner is vaporized, the uniformity of the particle size is good, the atomization in the flame can be stabilized, and the analysis with less noise can be performed.

The sample is not only sent into the flame at a high concentration, but is also finer particles than in the case of a droplet because it is vaporized, so that efficient atomization is performed and analysis sensitivity is improved.

Since the sample supplied in the flame is vaporized, it does not take away the heat of vaporization from the flame as when the sample is in the form of droplets. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment, FIG. 2 is a cross-sectional view showing a nozzle portion in one embodiment, and FIG. 3 is a diagram showing the relationship between the amount of heating heat and the amount of atomization in one embodiment. 2 atomizing chamber, 4 burner head, 6 atomizer, 8 nozzle, 10 capillary, 14 gas supply passage, 16, 18 heater.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 21/00-21/74

Claims (1)

(57) [Claims] 1. An atomization chamber connected to a burner head,
Only a sprayer for spraying a sample sucked by a capillary with a pressurized gas containing an oxidant as atomization means is provided, and a heating means is provided in a flow path for supplying the oxidant to the sprayer, and the atomization chamber is also heated. Means for heating the sample from the burner head to a temperature at which all of the sample exiting from the burner head is vaporized.