Lab Manager's Independent guIde to purchasIng a Mass spectroMeter July/august 2011 Copyright © lab manager magazine®

a number of techniques are available to ionize the sample as it is introduced into the mass spectrometer. Different ionization techniques are available, and the appropriate method should be selected based on the properties of the sample.

Standalone SyStemS

a Inductively Coupled Plasma Mass Spectrometry (ICP-MS)iCp-ms is a highly sensitive type of mass spectrometry

widely used for the determination of a range of metals and non-metals at concentrations below one part in 1012.

C Fourier Transform Ion Cyclotron Resonance (FTICR) Mass Spectrometry

FtiCr is a very high resolution technique in that mass can be determined with very high accuracy. many applications of FtiCr-ms use this mass accuracy to help determine the composition of molecules based on accurate mass. this is possible due to the mass defect of the elements.

d Thermal Ionization Mass Spectrometry (TIMS)tims relies on the thermal ionization of samples prior to

detection and is widely used in radiometric dating, geochemistry, geochronology, and cosmochemistry. the sample is ionized under vacuum. the relative abundance of different isotopes can then be measured, yielding isotope ratios.

Agilent7700x

Thermo ScientificArgus VI

Agilent7700e

BrukersolariX

Thermo ScientificLTQ FT Ultra

Thermo ScientificGas Bench II

Bruker820

Thermo ScientificTRITON Plus

SpectroSpectrogenesis

Thermo ScientificElement 2

Thermo Scientific Element XR

Thermo Scientific NEPTUNE Plus

Agilent7700s

Thermo ScientificDelta v

Bruker810

Thermo ScientificMAT 253

Brukeraurora M90

SpectroArCOS 165

Thermo ScientificElement GD

Thermo ScientificXseries 2

B Matrix-Assisted Laser Desorption/Ionization (MALDI) malDi is a gentle ionization technique that allows the analysis

of biomolecules, such as proteins and peptides, and large organic molecules, such as polymers and dendrimes. molecules of this type tend to be too fragile to be analyzed by conventional ionization methods, fragmenting when ionized.

BrukerAutoflex III

BrukerUltrafleXtreme

ShimadzuAxima Confidence

Shimadzu Axima Resonance

Waters MALDI SYNAPT™ G2 HDMS

Thermo ScientificMALDI LTQ Orbitrap

BrukerMicroflex

ShimadzuAxima Assurance

ShimadzuAxima Performance

ShimadzuMegaDalton

WatersMALDI SYNAPT™ G2 MS

mass spectrometry (ms) involves the

ionization of chemical samples to

generate charged molecules or molecular

fragments and measuring their mass-to-

charge ratio. ms is used for determining

the elemental composition of a sample

and the chemical structures of molecules,

such as peptides and other compounds.

the first stage in selecting a mass

spectrometer is to decide whether

you need a standalone instrument or

an integrated system that combines

mass spectrometry with other analytical

techniques, such as gC or lC.

IntroduCtIon:

BrukermicrOTOF II

Agilent6200 Series Accurate-Mass Time-of-Flight (TOF) LC-MS

BrukermicrOTOF-Q II

mass spectrometry is frequently combined with separation techniques to form powerful and widely used integrated systems such as gC-ms, lC-ms or ms-ms-gC. the appropriate choice of a system depends on the properties of the sample.

a GC-MS gC-ms is considered the gold standard for many analytical processes, including forensic substance identification. other applications include drug detection, fire investigation, environmental analysis, explosives investigation, and identification of

unknown samples. in addition, it can identify trace elements in disintegrated materials.

gC-ms instruments are available with a number of different mass analyzers, of which time-of-flight (toF) and quadrupole are the most common.

1 GC-MS –Time-of-Flight

gC-ms-toF delivers faster results and a greater sensitivity compared with quadrupole systems. gC-toF instruments are found in environmentally focused and material analysis labs for organic analysis and large molecule screening applications. they are also used in advanced life science research.

3 GC-MS (Ion Trap)

the ion-trap mass spectrometer uses three electrodes to trap ions in a small volume. the advantages of the ion-trap mass spectrometer include compact size and the ability to trap and accumulate ions to increase the signal-to-noise ratio of a measurement.

• High Resolution TOF GC-MS

high resolution mass spectrometry techniques allow molecular fragments that are close together in m/z to be successfully separated.

• Electron Ionization (EI)

ei is by far the most common and perhaps standard form of ionization. molecules are bombarded with free electrons emitted from a filament, causing the molecule to fragment in a characteristic and reproducible way.

• Electron Ionization (EI) or Chemical Ionization (CI)

some mass spectrometers offer a choice of ei or Ci. in Ci, a reagent gas is introduced into the mass spectrometer to interact with the analyte and cause a 'soft' ionization of the molecule of interest. in positive chemical ionization (pCi), the reagent gas interacts with the target molecule, most often with a proton exchange. this produces the species in relatively high amounts.

• Electron Ionization (EI) or Chemical Ionization (CI) (PCI or NCI)

in negative Chemical ionization (nCi), the reagent gas decreases the impact of the free electrons on the target analyte. this decreased energy typically leaves the fragment in great supply.

External Ionization Source

Integrated SyStemS

WatersGCT premier

AgilentMS -210

Agilent240-MS

Thermo ScientificDFS

Thermo ScientificITQ

LECOPegsus GC-HRT

LECOPegasus HT TOFMS

B LC-MS

lC-ms is a powerful technique used for many applications that has very high sensitivity and selectivity. generally, its application is oriented towards the specific detection and potential identification of chemicals in the presence of other chemicals (in a complex mixture).

1 Quadrupole

Quadrupole mass spectrometers use oscillating electrical fields to selectively stabilize or destabilize the paths of ions passing through a radiofrequency field created between 4 parallel rods.

5 Orbitrap

orbitrap lC-ms technology routinely delivers high resolution and mass accuracy through an extended dynamic range and high sensitivity. orbitrap mass spectrometers are often used in protein and metabolite identification, characterization and quantitation, among many other applications.

6 Quadrupole Orbitrap

the Quadrupole orbitrap mass spectrometer combines both quadrupole precursor selection and high-resolution accurate mass (hr-am) orbitrap mass analysis in one system.

2 Ion Trap

the quadrupole lC-ms is a particularly popular instrument due to its reliability, cost advantage, ease-of-use, versatility, and high sensitivity. however, this technique is not typically used for unknown or new compound identification, due to its nominally unit mass resolution and lack of tandem ms capabilities.

3 Time-of-Flight (TOF)

toF analyzers use an electric field to accelerate the ions through the same potential, and then measure the time they take to reach the detector. lighter ions will reach the detector first.

4 Quadrupole Time-of-Flight (Q-TOF)

Q-toF mass spectrometers are a hybrid quadrupole and time-of-flight (toF) mass spectrometer that also include ms-ms capability. in ms mode the ion guide is operated by the quadrupole, in ms-ms mode the quadrupole functions as the mass selection device. in both ms and ms-ms mode the toF analyzer acts as the mass resolving device. During ms-ms usage a collision cell placed between the quadrupole and toF analyzer induces fragmentation, while final detection is achieved with a mirochannel plate.

Thermo ScientificMSQ Plus

Thermo ScientificExactive

Thermo ScientificQ Exactive

Thermo ScientificLCQ Fleet

Agilent6500 Series Accurate-Mass (Q-TOF) LC/MS

Agilent6500 Series iFunnel Q-TOF LC-MS

Thermo ScientificTSQ Quantum Ultra

ShimadzuLCMS-8030 Triple Quadroupole

Thermo ScientificLTQ Orbitrap XL

Thermo ScientificLTQ XL

BrukermaXis 4G

WatersXevo G2 Qtof

BrukermaXis impact

PerkinElmerAxION ™ 2 TOF MS

BrukermicrOTOF-Q II

Hitachinanofrontier_nlc

BrukeramaZon SL

Thermo ScientificTSQ Vantage

Thermo ScientificOrbitrap Velos Pro

Thermo ScientificOrbitrap Elite

Hitachinanofrontier_eld

BrukeramaZon ETD

Thermo ScientificTSQ Quantum Access

Thermo ScientificLTQ Orbitrap Discovery

Thermo ScientificLCQ Velos Pro

C GC-MS-MS

ms-ms, also known as tandem ms, is achieved by adding a second ms to the output of the first system. this technique reduces sample prep, shortens analysis cycles, eliminates false results, and simplifies data review for improved productivity.

Agilent7000B GC system

AB SCIEX3200

LECOPegasus 4D

AB SCIEX4000

AB SCIEX5600

AB SCIEX5500

Thermo ScientificTSQ Quantum XLS Ultra

LECOTruTOF HT TOFMS

ZoexFas TOF

Agilent220 Ion Trap

Agilent240 Ion Trap

2 GC-MS (Quadrupole)

the quadrupole gC-ms is a particularly popular instrument due to its reliability, cost advantage, ease-of-use, versatility, and high sensitivity. however, this technique is not typically used for unknown or new compound identification due to its nominally unit mass resolution and lack of tandem ms capabilities.

• GC-MS (Quadrupole) - Portable

portable gC-ms are ideal for use in the field or where space in a laboratory is limited. these instruments can be highly accurate and versatile.

Agilent5975T LTM GC/MSD

• GC-MS - Quadrupole Standard

gC-ms instruments offer a range of ionization techniques.

Perkin-ElmerClarus 600 D

Perkin-ElmerClarus 560 D

Perkin-ElmerClarus 600 C

Agilent5975E GC/MSD

Perkin-ElmerClarus 600 T

Bruker320-MS

Agilent5975C GC system

Perkin-ElmerClarus 600 S

Bruker300-MS

Agilent7000A

WatersAPCG

Perkin-ElmerClarus 560 S

Thermo ScientificISQ

ShimadzuGCMS-QP2010

WatersAutospec premier

• Electron Ionization (EI)

ei is by far the most common and perhaps standard form of ionization. molecules are bombarded with free electrons emitted from a filament, causing the molecule to fragment in a characteristic and reproducible way.

• Electron Ionization (EI) or Chemical Ionization (CI) (PCI or NCI)

in negative Chemical ionization (nCi), the reagent gas decreases the impact of the free electrons on the target analyte. this decreased energy typically leaves the fragment in great supply.

• Electron Ionization (EI) or Chemical Ionization (CI)

some mass spectrometers offer a choice of ei or Ci. in Ci, a reagent gas is introduced into the mass spectrometer to interact with the analyte and cause a 'soft' ionization of the molecule of interest. in positive chemical ionization (pCi), the reagent gas interacts with the target molecule, most often with a proton exchange. this produces the species in relatively high amounts.

STARTHERE

Author: John Buie

LAB MANAGER MAGAZINE’S INDEPENDENTGUIDE TO PURCHASING A

MASS SPECTROMETERwww.labmanager.com

PRODUCT FOCUS: SamPle PReP FOR HPlC

CRiTiCal FiRST STePS in lC analySiSby angelo DePalma, Ph.D.As HPLC systems become faster and em-ploy increasingly exotic stationary phas-es, sample preparation becomes essential for reliable, reproducible analyses.

Biological samples generally require concentration in the target analyte and, in the case of proteins, depletion of high-concentration interfering ma-terials. The value of concentration/depletion is illustrated by the dilemma facing proteomic analysis, particu-larly using blood-derived samples. In plasma, the concentration dynamic range between the most abundant protein, albumin, and the protein of interest may be as high as 10-13. Sam-ple concentration may be carried out through dialysis or with specialized evaporation systems. Porvair Sciences (Leatherhead, UK) and other vendors sell devices that blow heated nitrogen into individual microwells to speed up evaporation and sample concentration. Depletion is somewhat more difficult to achieve, particularly when purifying a low-abundance protein in the pres-ence of high-concentration species.

Depending on the sample type, com-mon prep methods may include solid phase extraction (SPE), centrifuga-tion, or liquid-liquid extraction. SPE is straightforward and available as single disposable cartridges filled by hand or through automated instruments. Protein prep for most LC-MS often involves an additional step, proteoly-sis, which breaks large molecules into smaller, more manageable peptides.

Filtration is the simplest and perhaps most essential of LC sample prep techniques. Schleicher & Schuell Mi-croScience (S&S; Dassel, Germany) suggests filtering through a 0.45-mi-cron microporous syringe membrane filter to break up emulsions and retain particulates that clog columns.

S&S recommends regenerated cel-lulose (RC) membranes, which are hydrophilic, are highly resistant to HPLC solvents, and show very low extractables. According to the compa-ny, RC is one of the weakest protein-binding membranes, which means it’s suitable for proteomic analysis.

automation: not just for high throughputSample preparation is an oft-over-looked source of error and inconsis-tency in HPLC analysis. Column and mobile phase conditions may be opti-mal and steady from run to run, but if samples are prepared differently, they will run differently as well.

That is why Simon Robinson, HPLC product manager at Shimadzu (Co-lumbia, MD), recommends automating sample prep whenever possible. “Oth-erwise, reaching a point where data becomes untrustworthy is quite likely,” he says. “Automated sample prepara-tion eliminates human error.” It also works unattended, freeing up modest chunks of time for occasional chro-

matographers and several hours per day for heavy users. Automated sample prep may be integrated directly with an auto-injector for overnight operation.

One drawback of automated sample prep is that standards and samples need to be refrigerated, which introduces schedul-ing issues and somewhat reduces the at-tractiveness of hands-off operation.

Shimadzu has been working closely with Perfinity Biosciences (West La-fayette, IN) on a next-generation LC sample prep system. Through this collaboration, Shimadzu provides the LC hardware while Perfinity supplies the Perfinity Workstation, workflow, methods, user interface software, col-umn technology, and reagents. Shi-madzu is responsible for marketing, sales, installation, and hardware sup-port, while Perfinity provides applica-tions support and consumables.

The companies share more than a common product. Both agree that thinking in terms of throughput thresholds before adopting automa-tion is a mistake. “We believe that au-tomation is appropriate for all sample prep methodologies regardless of throughput demands,” says Nicholas Herold, research scientist at Perfinity. “With conventional prep, sample loss and contamination can be significant. Not so with direct, automated transfer between steps in a closed system. Au-tomation keeps the focus on answers instead of workflows.”

So far, dual-mode homogenization has received attention from a wide range of end users, according to Ms. Archibald, in-cluding those involved with food testing, wastewater treatment, and plant pathology.

The smaller the sample, the more critical the homogenizerSmaller sample volumes and high throughput are recurring trends in ho-mogenization, not only in biology but also in food, materials, and environmen-tal testing. “Until fairly recently, sample sizes ranged from about fifteen millili-ters up to a few hundred milliliters, and samples were processed in glass,” notes Reed Barrickman, marketing communi-cations manager at Omni International, Inc. (Kennesaw, GA). The widespread adoption of 2 mL plastic microtubes now enables homogenization and analy-sis of hundreds of samples per day. Ho-mogenization has become so efficient, in fact, that downstream analysis has become a workflow bottleneck, which according to Mr. Barrickman presents serious workflow and throughput chal-lenges to analytical laboratories.

Omni specializes in multi-sample sys-tems that even in relatively low-volume formats (e.g., the six-sample Omni-Prep rotor-stator homogenizer and the

24-sample Omni Bead Ruptor 24 bead mill) provide a decent level of automa-tion for medium-throughput labs. Om-ni’s LH-96 model, a high-throughput fully automated system, can rightly be termed the Cadillac of homogenizers. This model handles up to 192 samples in full walk-away mode. With the LH-96, Omni has introduced a “smart” and familiar Microsoft Windows touch-screen-based interface and an option to interface directly with microtiter plates.

One of the more interesting recent developments in homogenization has been the Ultra Turrax Tube Drive (UTTD) from IKA Works (Wilming-ton, NC). The system consists of sin-gle-use, hermetically sealed tubes, each fitted with a reusable, sterilizable grind-ing element (a stirrer, glass or stainless steel balls, or a rotor/stator assembly). Special tube designs accommodate ho-mogenization of drugs, plant or animal tissues, and sterile samples, with an op-tion for piercable covers for easy sam-ple withdrawal. Tubes are available in two capacities: 2-15 mL and 15-50 mL.

“The UTTD’s disposable tubes elimi-nate sample vial cleaning and practi-cally reduce cross-contamination to zero,” says Tracy Christian, marketing coordinator at IKA.

The UTTD satisfies two goals of mod-ern homogenization equipment: repro-ducibility and compressed workflows.

What to look for“Users should consider what they are trying to homogenize, and how small they need their samples to be,” she tells Lab Manager Magazine. Achieving submicron particle sizes involves either ultrasonic disruption or bead milling. The former is faster but is noisy, tends to heat the sample, and in some instanc-es can alter its chemical characteristics.

According to Ms. Christian, other de-sirables include:

• easy cleaning of product-contact surfaces

• a low motor noise, since homogenizers are usually located on workbenches in close proximity to operators

• ease of use

• rapid homogenization

• user control over homogenization parameters through a familiar digi-tal display

• low heat generation, which is particu-larly important for labile tissue samples

• a programmable library of methods

Angelo DePalma holds a Ph.D. in organic chemistry and has worked in the pharma-ceutical industry. You can reach him at an-gelo@adepalma.com.

FOR ADDITIONAL RESOURCES ON HOMOGENIZERS, INCLUDING USEFUL ARTICLES AND A LIST OF MANUFACTURERS, VISIT WWW.LABmAnAgEr.COm/HOmOgEnIZErS

, INC.www.kinematica-inc.com

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