Over the past decade, interest in elemental imaging by laser ablation coupled with ICP-MS (LA-ICP-MS) has grown in several areas such as geology, biomedicine and pharmacology. LA-ICP-MS has proven to be an interesting tool for imaging due to the reduced requirement for sample preparation, high throughput, wide dynamic range, microscopic resolution and isotopic and elemental capability. Though this tool has been used more over the past few years notably, for the analysis of biological tissues, it still suffers from several disadvantages that prevent it to be routinely used. The commonly used sample cells for laser ablation systems have washouts of a few hundred milliseconds meaning that ICP-MS data acquisition rates of about 10Hz are required to extract the optimum spatial resolution. The speed of data acquisition by quadrupole ICP-MS would then need to limit the number of elements to 5 to 15 to match this requirement. Time of Flight ICP-MS would provide data acquisition at even faster rates, but this has an even greater disadvantage of sensitivity, relevant to a quadrupole ICP-MS. The sensitivity of ICP-MS is critical when considering the spatial resolution, with each halving of the spot size the signal generated per ablation is reduced by 4x. Compromises of spatial resolution or detection limit must therefore be considered along with the speed of data acquisition.

The detection of nanoparticles which are small enough to penetrate cell walls and cause damage to proteins is of critical interest to researchers in the field of environmental toxicology and the biological impact of nanotechnology. Such nanoparticles are generally accepted to be those less than 10nm in size (Xia Q, et al. J Biomed Mater Res Part A: 105A: 710-719, 2017). The detection of these small nanoparticles is made more problematic when dissolved ionic concentrations for the element of interest elevate the background signals in the sample making it more difficult to distinguish particle signals. This work will describe how a nebuliser with a desolvation system can be used with Attom to improve the size detection limit through an increase in the ion transmission and particle signal to ionic background ratio.

When using ICP-MS for liquid samples, the sample is introduced as a fine aerosol through a pneumatic nebuliser. Typically, the liquid uptake flow is between 0.1 and 0.3mL/min with only a small proportion of that flow passing through a spray chamber and into the ICP torch. The plasma generated in the ICP torch, has a central channel with a temperature of 5000-6000K which is sufficient to desolvate the droplets, volatilise the solid compound, dissociate the molecules and then ionise the atomic species. The output from the ICP torch is positioned in close contact with the cooled cones of the mass spectrometer interface and this interface has a limit to the amount of condensing material that can be present in the output of the plasma before cone blockage occurs. The deposition of material on the cones leads to signal drift which can be gradual or less controlled as deposits build up and break off the skimmer cone particularly.

The Attom ES has well established performance and a track record of robust reliability for trace element and isotope ratio analysis used in a wide range of applications including nuclear applications.

In order to provide a safer working environment once the radioactivity in the samples exceeds a certain point, the Attom ES is available in a version compatible with fume hoods and gloveboxes. The design maintains the performance whilst the sample introduction, plasma and mass spectrometer interface remain within industry standard safety enclosures.

The Nu Instruments Calculations Editor (NICE) is a powerful tool that allows users to process numerical data in the way they want. Using NICE allows the calculation of results to be scripted and used over multiple samples easily and quickly. Scripts generated in one batch of samples are saved for global use in other batches and can even be exported for transfer to other computers when required.

The ICP-MS technique has promised to be a powerful analytical tool for the measurement of nanoparticles but has generally been found to be on the very edge of performance limitations for many applications, especially when measuring samples with ionic metal content. The continuous background signal from the ionic element degrades the analysis due in part to the reduced ability to distinguish background signals from nanoparticle signals and a level of uncertainty introduced by the required background signal subtraction.

A more robust method of distinguishing particle signals from background would open up greater possibilities for researchers in the field of nanoparticle analysis.

The ICP-MS technique has promised to be a powerful analytical tool for the measurement of nanoparticles but has generally been found to be on the very edge of performance limitations for many applications including where samples have a range of particle concentrations. Traditionally, ICP-MS signals for nanoparticles are integrated over fixed time periods and any signal measured within the fixed period is deemed to be due to a single particle. This has been highlighted as a large source of error by several researchers and a generally accepted upper limit of 100 measured particles per sec is used to determine sample dilutions. Whilst the use of dwell times significantly lower than the expected width of a nanoparticle peak does reduce the error, when using a fixed integration window there is still a measurable impact which must be accommodated by running samples diluted enough to prevent particle coincidence.

The ICP-MS technique has promised to be a powerful analytical tool for the measurement of nanoparticles but has generally been found to be on the very edge of performance limitations for many applications, especially when shorter dwell times are used to improve signal to background. An unfortunate outcome of using shorter dwell times is the reduced dynamic range that ICP-MS users have reported from their instrumentation. With a 10μs dwell, a single count is the equivalent of 100,000cps when the upper ceiling of most ICP-MS is 5e6 cps, this limits the range to little more than one decade allowing for a minimum detectable peak being a few counts. The common dead time of 30ns for ICP-MS detectors also introduces significant correction uncertainty at the highest count rates, especially when dwell times longer than the expected duration of a nanoparticle signal are used. As the diameter of a nanoparticle is related to the cube root of the mass or volume this means that the size dynamic range of current ICP-MS for nanoparticles is possibly only 3-4.

The ICP-MS technique has promised to be a powerful analytical tool for the measurement of nanoparticles but has generally been found to be on the very edge of performance limitations for many applications. Aspirating an aerosol of nanoparticles creates transient signals of 100-400μs in length which means that the commonly used millisecond data acquisition times for ICP-MS are not adequate. This has led some researchers to developing their own faster data acquisition hardware but this not possible for most users.

High spatial resolution measurement by laser ablation ICP-MS has continuously improved in recent years addressing challenges in depth and lateral resolution, especially for samples that require precise isotope ratio measurements. Such applications would include spatial discrimination of uranium/lead isotope ratios of zircons and single particle analysis for uranium ratios where the isotope ratios of a single laser shot need to be measured to the best possible precision. All aspects of instrumentation and methodology need to be optimised to improve performance and ease of use for this technique. This application note will discuss recent areas of improvement and show some characteristic performances for the Attom ES.

Currently, quantitative analysis of ²³⁷Np in U matrices is achieved with laborious and time-consuming sample preparation to separate the Np from the U. The analysis has traditionally required a high decontamination factor using a co-precipitation method with a processing time of 1-1.5 days, resulting in a relatively poor sample throughput and customer response times. High levels of decontamination from the uranium matrix are required as the tail of a strong ²³⁸U signal affects neighbouring masses, for example ²³⁷Np, increasing the baseline and showing an exponential-type curve when monitored at low resolution (300).

Attom can be used to analyse samples for quantitative measurements and highly precise isotope ratios. The processing of data for isotope ratios requires a variety of calculations depending on the type of correction needed and the analyst’s choice of calibration technique. Nu Instruments has always provided users with a flexible method of implementing customized calculation

The Attom from Nu Instruments is a high performance ICP-MS capable of undertaking work in both high precision isotope ratio analysis and high resolution elemental analysis. It is commonly used in laboratories where there is not one fixed application, so there is always a desire to have an instrument with the flexibility to switch easily between tasks without impairing the performance and ease of use. In order to confirm the ability of the Attom to conduct reproducible multi-element analysis over a long period whilst also being used for other applications, an experiment was devised where a set of samples previously analysed at British Geologica Survey (BGS), an accredited laboratory, were re-analysed on the Attom on several occasions over the period of a month.

High Resolution Magnetic Sector ICP-MS is established now as the go to method for unambiguous determinations of trace concentrations in complex matrices. The ability to physically separate the mass of an analyte from the interfering polyatomic species makes the technique robust and trustworthy for developing methods of analysis in a research or routine laboratory. This characteristic performance is achieved by physically restricting the ion beam with a slit on both the entrance and exit of the mass spectrometer itself. Until recently, there have been two approaches to this implementation; variable slits where two perfectly parallel blades are precisely controlled to impose a slit width in the path of the ion beam; and fixed slits laser cut into a thin sheet of metal and moved into the beam line.

The ICP-MS technique has become a powerful tool for a growing set of applications including isotope ratio and elemental determinations in a range of samples through laser ablation ICP-MS or the use of ICP-MS as an element specific detector for chemical speciation work with a variety of chromatography techniques. Compared to quadrupole ICP-MS, magnetic sector instruments offer generally better signal-tonoise ratios along with flat-topped peak profiles that yield much better measurement precisions, especially when dealing with signals that are not at steady state as seen with laser ablation and chromatography applications.

Quadrupole ICP-MS is a widely used and well accepted technique for the rapid quantification of a large number of elements in a single sample. However, high resolution ICP-MS (HR-ICP-MS) instruments also have a role to play due to their superior detection limits, better sensitivity and ability to resolve isobaric interferences.

High resolution instruments such as the Attom from Nu Instruments are a powerful tool for the fast quantification of a large number of elements at varying concentrations in a variety of sample materials. Generally, samples analysed with such instruments can have very low concentrations of trace and ultratrace elements but at the same time, some of the major elements may be of interest too. Therefore, it is important to be able to analyse these in the same sample dilution without prior knowledge of the concentrations with a versatile detector system which is able to automatically cope with the varying signal intensities.

High resolution instruments such as the Attom from Nu Instruments are a powerful tool for the identification of a large number of elements at varying concentrations. The samples analysed with such instruments can have very low concentrations of trace and ultra-trace elements but at the same time, some of the major elements may be of interest, too. Therefore, it is important to be able to analyse these at the same sample dilution without prior knowledge of the concentrations with a versatile detector system that is able to cope with the varying signal intensities.

Since the commercial introduction of ICP-MS during the 1980s, the technique has evolved into a well-established method for quantitative and semi-quantitative trace and ultra-trace element measurement as well as isotope ratio determination.

The ICP-MS technique has become a powerful tool for a growing range of organic and inorganic applications including isotope ratio measurements. Compared to quadrupole ICP-MS, magnetic sector instruments (multi- or single-collector) offer higher sensitivity and better signal-to-noise ratios as well as flat-topped peak profiles that yield much better isotope ratio precisions.

Modern high resolution ICP-MS (HR-ICP-MS) instruments offer a number of performance advantages compared to more widely used quadrupole ICP-MS instruments, including increased sensitivity, superior detection limits and faster scan speeds. For laser ablation acquisition, rapid peak scanning is a distinct advantage, as it allows for increased temporal resolution of time-resolved data. The advantage of single-collector ICP-MS over multi-collector ICP-MS, is that a wider mass range can be scanned in a single analysis. This means that a range of elemental concentrations can be determined, as well as precise isotope ratios.

Fast, multi-elemental analysis for preliminary evaluation of sample concentrations is a must in routine laboratory work. This kind of screening has been proven to be a useful tool to help choose the best analytical technique or as a “ballpark” figure to determine approximate concentration figures for further analytical investigation (i.e. determination of required dilution factors, concentration calibration standard range, or for spiking for IDTIMS analysis).

Plutonium is a radiogenic element that is principally of anthropogenic origin, though it does occur naturally in minute quantities (for example in concentrated uranium ores). Most Pu present in the environment originates from nuclear weapons tests and to a lesser degree from nuclear power station incidents. Measurement of the isotopic composition of Pu may help identify the origin.

Modern high resolution ICP-MS (HR-ICP-MS) instruments offer a number of performance differentiators compared to more widely used quadrupole ICP-MS instruments. Better sensitivity, superior detection limits and faster scan speeds all offer distinct advantages in addition to the more obvious advantage of higher resolution analysis.