SPECTRO ARCOS

MultiView Q&A

Is there any sort of optical alignment necessary when switching from axial- to radial-view?

No, the system is self-aligning.

Is viewing height adjustable in radial-view instruments or in MultiView running in radial mode?

The view height in radial mode is factory-optimized for best SNR.

How can you do without an external cooling system in an axial view?

The axial interface is surrounded by cooling fins that dissipate the heat via a stream of forced air.

Is a dedicated axial-/radial-view ARCOS upgradable to MultiView?

Yes, in principle it is possible. However, it would require changing the instrument’s entire single-view mechanics to a MultiView mechanism.

With the parts disassembled and reassembled to change the orientation of the plasma, how do you ensure the precision of a measurement?

The mechanical construction is such that optimal alignment is fully maintained. Thus the unit’s measurement precision is not affected by the disassembly/assembly of the interface and sample introduction components.

When switching axial to radial, is the same torch required? Or is there a different torch for the axial and radial viewing modes?

Radial and axial torches are different. A radial torch uses a straight glass body and typically a 1.8 mm injector tube. The axial torch has a slightly longer glass body, with a tulip-shaped end. Typically it uses a 2 mm injector tube.

Is there something to be done to realign the torch after rotating the load coil? Is it possible to run the instrument with a nonaligned torch?

The torch is self-aligning using a bayonet coupling. When the coupling is fully engaged, the torch is fully aligned. Plasma start is only possible when the coupling is fully engaged.

How do you bracket in high-precision analysis for major components?

Bracketing can be performed using the Smart Analyzer Vision instrument software. The concentration of bracketing element defines the standards to be used. The bracketing measurements are performed per the defined number of cycles. After that, the bracketing correction is automatically calculated and applied to the unknown sample.

For the MultiView instrument, is torch alignment within the software using an Mn standard required each time you change the orientation of the torch?

No. An optimization, which can be performed automatically, is only required if sample introduction components are changed — e.g. if a different nebulizer or spray chamber is used.

Does the sample have to be solubilized into a solution for ICP analysis?

Yes — in general ICP is a solution technique.

What is the effect of the type of spray chamber used on sensitivity … and the results presented?

Sensitivity is mainly affected by the nebulizer and only to a lesser extent by the spray chamber. The type of spray chamber used influences washout and precision, however. For example, plastic spray chambers do not drain very well, which has a negative effect on precision; small cyclonic spray chambers have a faster washout; large-volume spray chambers have the best long-term stability.

Is it possible to use MultiView with all available sample introduction systems?

Yes, absolutely. There are no limitations in this regard.

Is your torch one-piece or demountable?

One-piece and demountable torches are available.

Is a dual-view axial analysis equivalent to axial-only instrumentation? If it is, wouldn’t it be a better choice when choosing between axial- and dual-view?

Sensitivity-wise, there is no difference between axial dual-view and dedicated dual-view. A dedicated axial system is typically less expensive, however. So when a radial mode is not needed, money can be saved. Should it be necessary, the SPECTRO dual-view (Twin Interface) is field-upgradable at any later point in time.

In a dual-view system, what is the approximate loss of performance in the radial view?

In the wavelength range between 165 and 285 nm, sensitivity is about a factor of 2 lower compared to a dedicated radial view. Above 285 nm, there is no difference in sensitivity.

Is it necessary to optimize the torch’s positions or does it use fixed positions?

The system uses fixed, factory-optimized positions.

Is there any disadvantage to axial-view when analyzing high HF solutions?

No, high HF solutions do not affect the axial interface.

What are the cost comparisons of dual/radial/axial/MV?

Radial and axial are about the same price. Dual-view adds about 5% to the overall cost. MultiView also adds about 5% to the cost of the ARCOS system.

When calibrating using a multi-element mix, is there a choice of selecting radial view for alkali metals and axial for the rest of the elements?

When using an ICP with dual-view plasma observation, the typical method of operation is to analyze wavelengths below 285 nm using the axial mode, because metals have their most prominent lines in this wavelength range. This provides the highest sensitivity. Also, those elements/lines are not affected by the EIE effect. Wavelengths above 285 nm are typically analyzed using the radial mode. For the group 1 and 2 elements, there is little need to analyze trace levels, and even in radial mode the sensitivity is still high. While those elements are strongly affected by the EIE effect, the radial mode is beneficial since it greatly reduces the effect. Certainly, if desired, the entire spectrum can be analyzed radially as well as axially.

What is the detection limit with MultiView?

It is the same as with a dedicated axial or a dedicated radial.

Can the same sample be run in both views on the MultiView? If so, do you need to run calibration standards for each view or is a common one enough for both views?

That is certainly possible. Calibration standards can be the same, but since the plasma view is completely different, radial- and axial-view require different calibrations.

Will you please explain a little more about the effect of the nebulizer and its relevance to the particular view mode?

The nebulization of the sample is independent of the viewing mode. Using a pneumatic nebulizer, the efficiency is between 2% and 5%, so the same amount of sample enters the plasma. What is different is that in radial mode only a cross section of the plasma is viewed, while in axial mode the entire excitation zone is viewed and more light is transferred into the optic. Therefore, sensitivity is higher compared to the radial mode.

Which mode would you recommend for S measurements at 182 nm?

Both modes are suitable. The observation direction really depends on the application. E.g., for analyzing sulfur in organic solutions, radial is preferred; however, traces of sulfur in an aqueous matrix are better analyzed using the axial mode. Axial provides better LODs.

Does dual-view mean that there are two light beams?

Yes, that is true. For highest performance, dual-view systems use an automatic sequential measurement to analyze the sample using an axial and a radial light path. Simultaneous dual-view also exists; however, this capability comes at the cost of a compromised performance.

For chlorine (Cl) analysis, which view mode is best? What are the detection limits?

For the analysis of Cl in a clean aqueous matrix, an LOD of 30 ppb can be achieved with axial and 100 ppb with radial plasma observation. Which is more suitable depends on the application and the required sensitivity. For an application with higher amounts of totally dissolved solids and for organic solutions, radial plasma observation is preferred.

What is the key consideration between dual-view and MultiView?

Dual-view is a performance expansion for a dedicated axial instrument. MultiView is a performance expansion for a dedicated radial instrument, and is in fact a 2-in-1 instrument without any compromise.

What is the approximate time required to change MultiView from axial to radial view?

Without rushing, approximately 90 seconds.

Would you suggest specific nebulizers for applications in which sensitivity is desired?

Absolutely. Nebulizers with higher sensitivity would be, for example, Modified Lichte and Seaspray. An average sensitivity is typically obtained with Cross Flows and Conicals. V-Groove and Babington nebulizers are often of lower sensitivity. In addition to the sensitivity of the nebulizer, the matrix tolerance must also be taken into consideration. High efficiency also means high plasma load. This may lead to signal depression, so the gain on one side turns into a loss on the other. The same applies to stability. If a sensitive nebulizer is no longer stable with higher matrix concentrations, this may also negatively influence the achievable limits of detection. As a rule of thumb, we suggest using more efficient nebulizers up to TSD concentrations of 2%. Cross Flows are usable up to 20 % TDS (requires the use of an argon humidifier). V-grooves and Babingtons are suitable for solutions containing undissolved particles, since they do not plug so easily.

What view is better when analyzing iodine?

When sensitivity is paramount, TDS is < 5%, the sample is aqueous, and the accurate determination of alkali elements is not important, then it is axial. If alkali elements are important, a dual plasma observation system is better suited. Once TDS is >5%, the sample is an organic solution, high linearity, high accuracy, or high stability is needed, then likely a radial system provides the higher performance.

How much argon is used for one analysis?

A low-power application (900-1000 W) will run with 10 l/min coolant, 0.6 l/min auxiliary, 0.6 l/min nebulizer flow, 1 l/min light path flow, and 0 l/min optic purge (the optical system is hermetically sealed and uses UV-Plus). A standard power application (1200 W) will use 12-13 l/min coolant, 0.6-0.8 l/min auxiliary, 0.7-0.8 l/min nebulizer flow, 1 l/min light path flow, and also 0 l/min optic purge.

When the operator changes the view of the torch, do they have to recalibrate the torch again?

There is no optimization for the torch required. However, because of the different plasma views (radial and axial), they each have different calibrations.

White Paper

Selecting your ICP-OES analyzer's plasma interface: axial-view, radial-view, dual-view or new MultiView.

download »