JPH07123035B2 - High frequency inductively coupled plasma / mass spectrometer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-frequency inductively coupled plasma / mass spectrometer in which a high-frequency inductively coupled plasma and a mass spectrometer are combined, and more specifically, measurement of an unknown sample. Also in this case, high frequency inductively coupled plasma that can accurately measure the element to be measured contained in the unknown sample without detecting salt in the small hole of the nozzle.
The present invention relates to a mass spectrometer.

<Prior Art> A high-frequency inductively coupled plasma / mass spectrometer uses a high-frequency inductively coupled plasma to excite a sample, and guides generated ions to a mass spectrometer through an interface composed of a nozzle and a skimmer to measure a specific mass. The element to be measured in the sample is analyzed by electrically detecting only the ions. Further, the sample is sent from a sample tank to a nebulizer for atomizing the sample to be an aerosol sample, and then sent to the inner chamber of the plasma torch by argon gas. The sample introduced in this way is excited by the high frequency inductively coupled plasma as described above, and the generated ions are detected by the mass spectrometer detector such as a quadrupole mass filter through the interface including the nozzle and skimmer. Based on the detection signal, a mass spectrum is drawn on the display unit such as a recorder to analyze the element to be measured in the sample.

<Problems to be Solved by the Invention> However, in the above-mentioned conventional example, the salt concentration in the sample tank is 0.
When 1% or more of the sample is stored and introduced into the plasma, salt is deposited in the small hole of the nozzle (small hole of the orifice structure) and the small hole is blocked, so that analysis cannot be finally performed. was there. If such a blockage occurs, there is a drawback in that it is necessary to once digest the high frequency inductively coupled plasma to remove the blockage, which consumes a lot of time and labor.

The present invention has been made in view of the drawbacks of the conventional example, and its object is to accurately measure the element to be measured contained in the unknown sample without salt precipitation in the small holes of the nozzle when measuring the unknown sample. An object of the present invention is to provide such a high frequency inductively coupled plasma / mass spectrometer.

<Means for Solving Problems> In order to achieve such an object, the present invention guides an aerosol sample atomized by a nebulizer from a nozzle to plasma and excites it, and guides generated ions to a mass spectrometer. In a high-frequency inductively coupled plasma / mass spectroscope for analysis, a controller that controls the dilution ratio of the sample supplied to the nebulizer, and a controller that controls this controller and is diluted in advance to a concentration at which salt is not detected in the nozzle. The concentration of the sample is obtained from the sum of the count numbers of elements having a predetermined count number or more obtained by scanning with the mass spectrometer using, and the dilution ratio of the sample is calculated to be suitable for the measurement sensitivity of the mass spectrometer. , And the computer is provided, and the controller is controlled based on the dilution ratio determined by the computer to obtain an appropriate concentration. Interpretation was qualitative scan performed prescribed number of times in the sample, it is characterized by analyzing the elements of the sample.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. First
The figure is a configuration explanatory view of an embodiment of the present invention, in the figure, 1a is a tank storing a sample, 1b is a tank storing a solvent such as pure water, 2a, 2b is a sample or a solvent A peristaltic pump for feeding a liquid, 3 a controller for controlling the flow rate of these 2a, 2b, 4 a computer for sending a command signal to the controller 5, 5 a nebulizer for atomizing a sample into an aerosol sample, and 6 an outermost A plasma torch having, for example, a triple-tube structure having a chamber 6a, an outer chamber 6b, and an inner chamber 6c, 7a is an argon gas supply source, 7b is a pressure regulator for adjusting the pressure of argon gas delivered from the supply source, and 8 is High frequency induction coupled plasma, 9 high frequency induction coil, 10 high frequency induction coil 9
A high-frequency power supply for supplying high-frequency energy, 11 is a nozzle, 12 is a skimmer, 13 is a fore chamber, 14 is a vacuum pump for sucking the inside of the fore chamber 13 to 1 torr., 15 is a center chamber, 16 is a center chamber
For example, a vacuum pump that sucks the inside of 15 to 10 ^-2 torr., 17 is a pole such as a quadrupole mass filter, 18 is a rear chamber, and 19 is a vacuum that sucks the inside of the rear chamber 18 to, for example, 10 ^-4 torr. A pump, 20 is a secondary electron multiplier, and 21 is a signal processing unit such as a microcomputer.
An ion lens may be provided in the center chamber 15.

In the embodiment of the present invention having such a configuration, the controller 3 causes the first peristaltic pump 2a and the second peristaltic pump to operate in response to a command from the computer 4.
The rotation of 2b is controlled, and the flow rate from the sample tank 1a is l ₁ (eg 0.05 ml
/ min.) and the sample flows from the solvent tank 1b at a flow rate of l ₂ (eg 2.5 ml
/ min.) and the solvent starts to flow. Therefore, these samples and the solvent are mixed and then atomized by the nebulizer 5 to form an aerosol sample. The aerosol sample is conveyed to the argon gas sent from the argon gas supply source 7a through the pressure regulator 7b, and the inner chamber of the plasma torch 6
Introduced in 6c. Further, argon gas is sent from the gas supply source 7a to the outermost chamber 6a and the outer chamber 6b of the plasma torch 6 via the pressure regulator 7b. On the other hand, high frequency energy is supplied to the high frequency induction coil 9 from a high frequency power source 10, a high frequency magnetic field (not shown) is formed around the coil 9, and a plasma 8 is generated by the action of the magnetic field. The ions in the plasma 8 are extracted into the center chamber 15 through the nozzle 11 and the skimmer 12, and then the pole 17
Detected in. The detection signal is amplified by the secondary electron multiplier 20 and then sent to the signal processing unit 21, where it is subjected to predetermined signal processing so that a mass spectrum is drawn on a recorder (not shown) to give an analysis value of the sample. Become. By the way, the sample is diluted with the solvent as described above in the following manner.
According to the analysis program by. First, a sample having a salt concentration of 5% or less is put in the sample tank 1a. This is because in a sample having a salt concentration of more than 5%, salt is deposited on the nebulizer or plasma torch. In addition, the liquid delivery flow rates of the first peristaltic pump 2a and the second peristaltic pump 2b are respectively l ₁ (for example, 0.05
ml / min.) and l ₂ (eg, 2.5 ml / min.) are controlled by the controller 3, so even if the sample has a salt concentration of 5%. That is, it will be diluted to 0.1%. Since the 50-fold dilution is first performed in this manner, it is possible to prevent the salt from precipitating in the small holes of the nozzle 11 from the beginning. Next, a high-speed qualitative scan (for example, a scan of 16 channels per mass unit is performed up to a mass of 250 for about 400 μsec per channel) is performed once, and for example, 1000 or more counts of elemental signals obtained by the signal processing unit 21. Calculate the sum S ₅₀ of the count numbers for the element. When the value of S ₅₀ satisfies the equation (1), the values of l ₁ and l ₂ are 0.05 ml / min. And 2.5 ml / mi, respectively.
The state of n. is maintained, and the sample is diluted about 50 times as described above. Also, when the value of S ₅₀ above satisfies the equation (2), the above l
The values of ₁ and l ₂ are 0.1 ml / min and 1.9 ml / min, respectively, Samples are diluted by a factor of 2, or 20. The value of S ₅₀ above is (3)
When the equation is satisfied, the above l ₁ and l ₂ values are 1.0 ml / min, respectively.
And 1.0 ml / min, Samples are diluted by a factor of two. Further, when the value of S ₅₀ satisfies the equation (4), the values of l ₁ and l ₂ are 1.0 m respectively.
1 / min. and 0 ml / min., and the sample is delivered to the nebulizer 5 without being diluted.

S ₅₀ ≧ 100.000 (1) 10.000 <S ₅₀ <100.000 (2) 2.000 <S ₅₀ <10.000 (3) S ₅₀ ≦ 2.000 (4) Thus, the dilution ratio of the sample is determined according to the above S ₅₀ value. It After that, the qualitative scan is performed a predetermined number of times (so-called a prescribed number of times), and finally the analysis value of the element to be measured is shown and the qualitative analysis is completed. The present invention is not limited to the above-mentioned examples, and various modifications can be made.For example, the dilution ratio is set more finely in accordance with the value of S ₅₀ , and the salt concentration in the sample is 0.1% at the maximum.
It may be as follows.

<Effects of the Invention> According to the present invention as described in detail above, a high-frequency wave capable of accurately measuring an element to be measured contained in an unknown sample without causing salt to be deposited in a small hole of a nozzle when measuring an unknown sample. An inductively coupled plasma / mass spectrometer is realized. Also, with such an analyzer, the computer determines the dilution ratio and automatically dilutes the new dilution ratio for qualitative analysis, so there is no precipitation of salt on the nozzle and complicated manual dilution operations, etc. There is an advantage that can be omitted.

[Brief description of drawings]

The figure is a diagram for explaining the configuration of the embodiment of the present invention. 2a, 2b ... peristaltic pump, 3 ... controller, 5 ... nebulizer, 11 ... nozzle, 12 ... skimmer.

Claims (1)

[Claims] 1. A high frequency inductively coupled plasma-mass spectrometer for guiding an aerosol sample atomized by a nebulizer to a plasma from a nozzle to excite it, and guiding the generated ions to a mass spectrometer for analysis. A sample supplied to the nebulizer. And a controller for controlling the dilution ratio of the element, and an element having a predetermined count number or more obtained by scanning with the mass spectrometer using a sample diluted in advance with a concentration that does not detect salt in the nozzle while controlling the controller. The concentration of the sample is obtained from the sum of the count numbers of, and a computer for calculating the dilution ratio of the sample so as to be suitable for the measurement sensitivity of the mass spectrometer is provided, and based on the dilution ratio determined by the computer. By controlling the controller and performing a qualitative scan a specified number of times with a sample diluted to an appropriate concentration, the elements in the sample are Inductively coupled plasma mass spectrometer which is characterized in that analysis.