Glossary
8800 ICP-QQQ Shorthand for Agilent 8800 Triple Quadrupole ICP-MS.
A
Agilent 8800 Triple Quadrupole ICP-MS
Official name of the Agilent Triple Quadrupole ICP-MS. It is also referred to as the 8800 ICP-QQQ or 8800. The 8800 ICP-QQQ possess two separate quadruople mass filters, Q1 and Q2, one before and one after the collision/reaction cell. The term “triple quadrupole”or "triple quad" follows the same naming convention as LC-QQQ and GC-QQQ, used in organic mass spectrometry to describe a tandem mass spectrometer with two quadrupole mass analyzers separated by a chamber (or cell) containing an ion guide.
Agilent 8800 #100 The standard configuration instrument: Equipped with an x-lens, Ni cones, a 2.5mm injector quartz torch and a glass concentric nebulizer. It includes 4 cell gas mass flow controllers and 5 plasma gas mass flow controllers.
Agilent 8800 #200 The semiconductor configuration instrument: Equipped with an s-lens, Pt cones, a 2.5mm injector quartz torch and a PFA concentric nebulizer. All other parts of the instrument are the same as the standard configuration (option #100).
Acquisition conditions
Parameters including: Peak profile, mass, integration time, scan number and replicate.
Ammonia, NH3
A reaction gas used in the collision/reaction cell. NH3 is a very reactive gas, which is used both in on-mass methods and mass-shift methods to remove/avoid interferences.
amu
Atomic mass unit. An obsolete, non-SI unit that is still in common use in its abbreviated form "amu", meaning the same thing as "unified atomic mass unit" (u) or dalton (Da). All are used to indicate the atomic mass of ions, atoms or molecules, based on the carbon 12 standard.
AS, abundance sensitivity
The measure of an analyzer’s ability to separate adjacent peaks differing greatly in intensity. The 8800 ICP-QQQ with MS/MS operation delivers unmatched peak separation (abundance sensitivity <10-10), as the resolution performance is the product of the abundance sensitvitiy of the two quadrupoles.
ASX-520
Autosampler suitable for medium to high sample throughput applications, with rack configurations providing up to 360 vial positions (up to 720 with the extended rack XLR-8 version).
B
Bandpass
Mode of operation of a multipole ion guide, where both a low-mass cut-off and high-mass cut-off are applied, rejecting ions below and above a certain m/z. A bandpass filter passes a "window" of masses (typically covering a 20-30 m/z range) through the ion guide, and is therefore distinct from a mass filter, which is capable of unit mass resolution (single m/z mass selection).
Batch
The acquisition batch contains all the information required for a sample analysis or experiment, including peripump program, tuning conditions, acquisition parameters, sample list and data analysis (calibration) parameters. The data analysis (DA) batch contains the measured results for the batch of samples, and includes the calibration plots, internal standard signals and QC flags
BEC, Background equivalent concentration
The magnitude of a signal in a blank, expressed as a concentration.
C
CRGS, Carrier gas
Carrier gas is an Ar gas supply flowing through the nebulizer to convert a liquid sample into a fine aerosol. It is a tuning parameter of the plasma.
CRC conditions (collision/reaction cell)
Parameters that affect collision/reaction cell performance such as cell gas, cell gas flow rate, octopole bias voltage, KED bias and deflection lens.
Charge transfer
A reaction mechanism that relies on the exchange of charge between ions and cell gas molecules, e.g., Ar+ + NH3 → Ar + NH3+
Collision mode
A cell mechanism to remove interferences either by collisional dissociation or by kinetic energy discrimination (KED). With KED, ions entering the collision/reaction cell collide with the cell gas (such as helium). Since polyatomic ions have a larger ionic cross-section than mono-atomic analyte ions at the same mass, the polyatomic ions undergo more collisions than the analyte ions, and so lose more energy. By the cell exit, the lower energy ions (the polyatomics) can be separated from the higher energy (analyte) ions by applying a bias voltage "step". This is known as kinetic energy discrimination (KED).
Cool plasma
A technique used to reduce interferences. Under low temperature plasma (cool plasma) conditions, the formation of interferences such as Ar+, ArO+ and ArH+ is suppressed, allowing the detection of Ca+, Fe+ and K+ at the trace level. Typical RF power for cool plasma is 600-900 W.
CRC
Abbreviation of Collision Reaction Cell.
D
DL
Abbreviation of Detection Limit. Also called LOD (limit of detection). It is the concentration that is equivalent to 3 times the standard deviation (SD) of the background signal.
Dynamic range or analytical working range
The range of linearity of an analytical instrument. The 8800 ICP-QQQ is fitted with an advanced, dual-mode, discrete dynode electron multiplier (DDEM) that provides a full nine orders dynamic range under standard operating conditions.
DiGS, Dilution gas
Argon gas flow added to the carrier gas via a dilution gas port located between the torch and the spray chamber. A dilution gas is used for Aerosol Dilution with HMI. The gas supply used for the DiGS can also be switched automatically to add the gas flow to the spray chamber instead (known as make-up gas or MUGS). It is a tuning parameter of the plasma.
E
Enthalpy of reaction, ΔHr
Amount of energy (heat) absorbed or released by a reaction. When ΔHr is positive (ΔHr > 0), the reaction is endothermic, meaning energy is required (absorbed) for the reaction to occur. When ΔHr is negative (ΔHr < 0), the reaction is exothermic, meaning energy is released by the reaction, which is spontaneous.
G
GC Interface kit
Agilent's GC-ICP-MS interface features a fully heated inert transfer line and separately heated inert torch injector that provides reliable separation of volatile compounds.
H
HMI, High Matrix Introduction
HMI Aerosol Dilution technology is standard on the 8800 ICP-QQQ, extending the TDS range to % level, while eliminating the added cost, time and potential errors of conventional liquid dilution.
Hard extraction
A tuning condition when a negative voltage is applied to the extraction lens. Hard extraction provides higher sensitivity at lower plasma temperature than soft extraction. Cool plasma conditions require hard extraction.
Helium mode, He mode
See collision mode.
HR-ICP-MS, high-resolution ICP-MS
Also known as magnetic sector, sector field or double focusing. Magnetic sector based ICP-MS instruments are capable of resolution (M/ΔM) of up to 10,000 and are able to resolve most polyatomic species from analytes at the same nominal mass.
I
I-AS, Integrated Auto sampler
Integrated, covered auto sampler with pumped rinse station; ideal for ultra-trace analysis and small sample volumes (as low as 0.5 mL). Flexible rack configurations offer a maximum capacity of 89 vials, plus 3 rinse vials.
ICP
Inductively coupled plasma, generated by applying a high-power radio frequency (rf) field to a flow of argon gas. The plasma is a high temperature ion source, up to 10,000 K maximum and around 7,500 K in the central channel.
ICP-MS
Inductively coupled plasma mass spectrometer or spectrometry.
ICP-QQQ
Abbreviation for triple quadrupole ICP-MS.
IDA, ID, ID-MS
Isotope Dilution Analysis or Isotope Dilution Mass Spectrometry is a highly accurate method to quantify elements based on the change in isotope ratio that results from the spiking of an unknown sample with a spike enriched in one isotope of the target analyte. Because each sample result is based on the measurement of the change in ratio in that sample, rather than relative to a response in a separate calibration standard, IDMS results are also directly traceable to certified standards, which reduces uncertainty.
Inert Sample Introduction kit
O-ring-free and manufactured from PFA for the lowest contamination levels. Demountable torch with Pt or sapphire injector options. HF resistant, and suitable for high-purity reagents.
Interferences - spectral
Direct overlap from a different element with an isotope at the same nominal mass (isobar), or overlap from a polyatomic ion, or doubly-charged ions resulting from the loss of two electrons instead of just one. Because the quadrupole separates ions based on m/z (mass over charge ratio), a doubly-charged ion (M2+) will appear at mass M/2.
Ion guide
Operation of an ion lens where no mass rejection is performed. Applies to simple electrostatic ion lenses, and also to multipole ion guides operated with no low- or high-mass cut-off.
IP, Ionization potential
The first ionization potential of the element is the energy required to remove one electron from a neutral atom and is specific for each element. Most elements are largely converted (>90%) to singly-charged ions in an argon plasma. Elements with a low second IP will also form some doubly-charged ions.
IR, isotope ratio
Ratio of abundance of two isotopes of an element.
Isobar
Refers to isotopes of different elements that appear at the same nominal mass. These overlaps occur when atoms of two different elements (i.e. different number of protons in the nucleus, so different atomic number) each have an isotope with the same atomic weight (same total number of protons plus neutrons in the nucleus, e.g. 204Pb and 204Hg).
Isobaric interferences
Overlaps that occur at the same mass (see isobar). These overlaps/interferences can be resolved by reaction chemistry (e.g. NH3 is used to separate Pb from the Hg overlap), but cannot be separated by high-resoluton ICP-MS; separation of 204Pb from 204Hg would require a resolution of around 500,000 (50x higher than can be achieved by any commercial high-resolution ICP-MS).
Isotope
A specific form (atomic weight) of an element. Many elements have atoms with different atomic weights, such as Pb 204, 206, 207 and 208; these are called isotopes. The different isotopes of Pb all have 82 protons in the nucleus (Pb has atomic number 82) but a different number of neutrons, so the atomic weight is different for each isotope.
ISTD, internal standard
Internal standards are commonly used in ICP-MS, particularly where samples vary in composition from the calibration standards. Changes in sample transport, nebulization efficiency and signal intensity (long-term drift) would all lead to errors, which may be corrected if an ISTD element with similar behavior is used as a reference.
K
KED, Kinetic Energy Discrimination
KED is used to discriminate the analyte ion of interest from interfering ion(s) by the difference of kinetic energy. Refer to collision mode. KED is also used as a tuning parameter of CRC conditions: KED = (Q2 bias voltage) - (octopole bias voltage).
L
LA, Laser ablation
Method used for the direct analysis of solid samples using a laser to vaporize the sample before introduction to the plasma.
LC Speciation kits
Sample introduction kits to facilitate LC coupling and provide turn-key methods for common speciation applications. A Capillary-LC connection kit is also available.
M
MUGS, Make-up gas
Make-up gas refers to Ar gas applied to the spray chamber to increase/adjust total injector gas flow rate. It is a tuning parameter of the plasma.
MS/MS mode
Acquisition mode unique to 8800 ICP-QQQ. MS/MS mode operates Q1 as a unit (1 amu window) mass filter and Q2 is also set to the single mass of the target ion or reaction product ion.
Mass pair
MS/MS mode requires a mass setting for Q1 and Q2. The selected mass settings for Q1 and Q2 are known as the mass pair. For example when As is measured in O2 mode, Q1 is set to the precursor ion (As+) at m/z 75 and Q2 is set to the product ion (AsO+) at m/z 91. 75 --> 91 is the mass pair for As in O2 mode.
Mass filter
Generic term for any mass analyzer cabable of unit mass resolution. Note that the ion guide used in the CRC of some quadrupole mass spectrometers appears physically similar to a quadrupole mass filter. However, these ion guides cannot provide unit mass resolution because of the ion scattering effect at the higher pressures present in the CRC.
Mass spectrum
See spectrum.
Mass-shift method
A method where the analyte ion is reactive and is moved to a new mass free from the original interference. Sometimes referred to as "indirect" measurement, e.g. Se+ reacts with O2 in the cell and is converted to SeO+. It can then be detected free from the original interference of ArAr+.
MH, Mass Hunter software
Software package that provides comprehensive instrument control for the 8800 ICP-QQQ and accessories, and integrated data processing.
MSA, Method of Standard Additions (also known as StdAdd)
A calibration solution is spiked at multiple levels directly into the unknown sample, giving a calibration of response against added concentration. MSA eliminates matrix effects by calibrating in the sample matrix.
N
Neutral Gain Scan
Q1 and Q2 scan together, a fixed mass-shift apart. For example Q2 scans at Q1 + 16 amu for O-atom addition reactions.
O
O2, oxygen
A reaction gas used with the 8800 ICP-QQQ. A number of elements can be measured in mass-shift method using O2, e.g. Se+ can be measured as SeO+ using O2 cell gas. O2 is also added to the plasma carrier gas to decompose the carbon matrix when organic solvents are analyzed.
Octopole bias (OctP Bias)
A CRC parameter. It is the bias voltage applied to the octopole ion guide, which determines the collision energy of analyte ions with cell gas molecules.
OIDA, on-line isotope dilution analysis
A very powerful and useful development of traditional isotope dilution, using on-line addition of the isotope spike. Removes the time consuming step of spiking enriched-isotope standards into each separate sample.
On-mass method
A method where reactive interferences are removed to allow an unreactive analyte to be measured at its original mass. Sometimes referred to as "direct" measurement, e.g., the interference of GdO+ on Yb+ can be removed by the reaction of GdO+ with NH3.
Organics kit
Contains the sample introduction parts needed to run volatile organic solvents. Includes organics torch, solvent-resistant drain kit and uptake tubing.
ORS
Agilent's CRC design is known as the Octopole Reaction System. It is a temperature-controlled collision/reaction cell with octopole ion guide and four cell gas lines as standard on the 8800 ICP-QQQ. Provides maximum flexibility in collision and reaction modes, and uses a small internal volume cell to ensure rapid cell gas switching and high ion transmission.
ORS3
Third generation Octopole Reaction System.
Oxygen atom abstraction or oxygen atom transfer
Reaction mechanism associated with the use of oxygen in the collision reaction cell.
P
Preset method
Preset methods are provided in the ICP-MS MH software. These built-in methods cover a range of predefined operating conditions to suit different applications. Using a preset method, a user can create a new batch with minimum or no customization.
Preset plasma
Preset plasma conditions are a function of ICP-MS MH software. The software provides several predefined plasma conditions that users can select according to the application. This greatly simplifies system optimization by automatically tuning and calibrating the plasma parameters, rather than the user having to set a number of individual plasma tuning parameters. There are three preset plasma conditions that can be selected depending on the sample matrix: Low matrix, general purpose and HMI.
Polyatomic, Polyatomic ion
A molecular ion (an ion composed of more than one atom) that arises in the plasma or during ion extraction, and can appear at the same nominal mass as analyte ions. Polyatomics are usually interferences (such as ArO+).
Precursor Ion Scan
Q1 scans a user set mass range, while Q2 is set to a single fixed mass, measuring all the reaction product ions at that mass, formed from the different ions entering the cell as Q1 scans the mass range.
Product Ion Scan
Q1 is set to a fixed precursor ion mass, while Q2 scans a user set mass range measuring all reaction product ions formed from that single precursor ion.
Q
Quadrupole bias (QP Bias or Qpole Bias)
Bias voltage applied to the Q2 rods. Used in conjunction with the Octopole bias to provide a bias voltage "step" at the cell exit, usually to reject unwanted low energy ions from the ion beam.
Quantitation or quantification
Quantitative results are produced by comparing signal intensities of elements in the sample to those generated by calibration standards.
Q1
First quadrupole in the configuration of the 8800 ICP-QQQ. Q1 is positioned in front of the ORS3, to control the ions that are passed to the cell and enable MS/MS operation.
Q2
Second quadrupole in the configuration of the 8800 ICP-QQQ. Q2 filters the ions that emerge from the cell exit, passing only the target analyte ions to the detector.
R
Resolution (R)
The ability of a mass filter to separate adjacent masses. Defined as M/ΔM; the mass of the target peak/the mass difference to the nearest adjacent peak that can be separated. Sometimes also quoted as the width of the peak at a given peak height (e.g. 0.75 amu at 10% peak height).
S
Single Quadrupole MS, ICP-QMS
Conventional ICP-MS containing a single quadrupole mass filter.
Single Quad mode, SQ mode
Q1 operates as a wide band mass filter. SQ mode emulates conventional quadrupole ICP-MS.
Speciation measurement
Combination of chromatographic techniques with ICP-MS as a detector to determine the chemical form of elements in the sample.
Spectrum (Mass Spectrum)
After separation by the final mass filter (Q2), the ions are detected by an electron multiplier. The detector electronics count and store the total signal for each mass (m/z), creating a mass spectrum. The spectrum that is produced provides a simple and accurate qualitative representation of the sample. The magnitude of each peak is directly proportional to the concentration of an element in a sample.
STS, ShieldTorch System
A technique to eliminate capacitive coupling between the RF coil and plasma, keeping the plasma potential low and energy distribution of ions narrow. The technique is crucial for cool plasma and collision mode.
T
TDS, total dissolved solids
The total summed concentration of all non-volatile, dissolved inorganic and organic substances in a liquid. The matrix tolerance of Agilent ICP-MS instruments is 0.2–2 % TDS.
Triple quadrupole ICP-MS
ICP-MS with a tandem MS configuration, featuring a quadrupole mass filter (Q1) in front of the collision/reaction cell (CRC) followed by a second quadrupole mass filter (Q2).
U
UPW
Ultra Pure Water, purified by ion exchange to remove trace contaminants. Used for preparation of standards and for sample dilution for ultra-trace analysis