ICPMS.qmd

# ICP-MS

Inductively-coupled plasma mass spectrometry

Intro - Plasmas are incredibly efficient ionizers. We can access a large portion of the periodic table. Thus, many types of samples can be analyzed (solids, liquids, and gases), elemental compositions an isotope ratios - the decisions that you make about treating those samples beforehand are really important. 

## Sample introduction for ICP-MS
Because we can analyze solids, liquids, and gases, there are a lot of different sample introduction methods. 

### Solids
crushed and picked (and/or mineral sep) vs in situ

### Liquids
dilute and shoot vs chemical separation

Spray chambers, desolvating nebulizers

### Gases
some things travel in the gaseous phase when they're introduced. For instance, mercury, sulfur

## Inductively Coupled Plasma
how a plasma is generated
gen schematic fig

### Plasma types
Ar plasmas are the most common
Links to other types of plasmas (i.e., Ne, N) 

### Plasma state
The plasma can exist at a range of temperatures, controlled by gas flows and RF
Those choices are made based on the type of analyses and/or the sample introduction system

## The interface
The interface is like the vestibule of the ICP-MS. You have to get through the door, take off your shoes, hang up your coat. 
This is where we're moving toward higher vacuum, getting the ions into the instrument

Schematic of the interface region (cones + whatever for different types of instruments). Have pictures of the parts too
torch
>quartz or ceramic
guard electrode - some steel, some platinum
bonnet - the purpose of the bonnet is to try to limit the amount of atmospheric gases that you are drawing into your ICP

Cones - all differnt types of cones

Ion Extraction Lenses

>low vs high voltage extraction - is this where we introduce the concept of quads vs multicollectors? 

## Ion optics
Beyond the interface, we have an ion beam that needs to be steered and shaped within the ion optics of any given instrument. Because of the range of isobaric interferences present in ICP-source mass spectrometers, they often have extensive ion optics packages to mitigate the heterogeneous nature of the ion beam. 

::: {.callout-tip title="Interferences in ICP-MS"}
Plasma source mass spectrometers have a more heterogeneous ion beam than some other mass spectrometers because the ion source is an Ar plasma. Thus, there are inevitably more species that can be created from the components of the plasma (i.e., Ar interferences), from the sample matrix (either the sample itself or the reagents used to prepare the sample), and also those that are created in the plasma from atmospheric gases that transmit through the interface (i.e., oxide interferences, hydride interferences). For instance, the $^{40}$Ar$^{16}$O interference at mass 56 is created by a combination of Ar from the plasma and O from the atmosphere, and is a significant interference on $^{56}$Fe. 

Link to [A Table of Polyatomic Interferences in ICP-MS](https://dl.icdst.org/pdfs/files3/6614fc08aaf965e51d9f3c08cf3db8ed.pdf)

:::

Different types of ion optics and their functions:

>appertures and defining slits

>lenses

>steering plates

>Wien filters

## Ion separation

### Collision/reaction cells

### Quadrupoles

### Magnets

### ESAs

### Tandem mass spectrometry

### TOF

## Ion detection

different detector types

quadrupoles/TOFs have SEMs (with pulse and analog modes)

Sector field instruments - all the options

## Environmental considerations
It's really important to control the temperature and humidity of the room because you're going from atmospheric pressure into a high vacuum environment

## Examples of ICP Mass Spectrometers

### Quads

### TOFs

### Magnetic sectors

### Tandem (MS/MS) machines