LC-MS innovation: Improve your analytical
accuracy and maximize sensitivity
Liquid chromatography–mass spectrometry (LC-MS) is a powerful analytical technique
commonly used for separation, identification, and quantification of both known and unknown compounds. LC-MS is
widely recognized as a specialized tool that generates highly accurate results with enhanced sensitivity and
precision, as well as a large dynamic range of detection. This technique is becoming the preferred tool to use
by many liquid chromatographers, since it combines the physical separation capabilities of liquid
chromatography, along with the detection specificity of mass spectrometry – which creates and also detects
charged ions. LC-MS now means that the analysis of complex biological samples that once were difficult to
analyze have become a thing of the past.
Selecting an appropriate LC-MS solution to meet your needs can be a challenge.
Users need to consider sample type and application, and find out how to best optimize their sample preparation
processes. The level of LC-MS performance must be suitable to meet user needs, while also considering particle
and stationary phases, LC accessories, and reference materials. There are many ways to identify whether you
need to consider buying a new LC-MS instrument, and this choice should be application driven. For instance –
if an instrument has not been refurbished, sensitivity and speed can be lost overtime – since internal
components age, which makes it difficult to keep up with newer technologies. Plus, if an instrument is not
sensitive enough to detect or quantitate the levels you require, then it is likely time to consider an
upgrade. If a user needs faster speed to improve productivity or throughput, then they may need to consider an
LC-MS instrument that has been introduced within the past year – since speed has been a key focus in the
development of the majority of state-of-the-art LC-MS instruments.
To help overcome these issues, Restek have been working to perfect the art and
science of liquid chromatography by creating a range of specialized tools designed to streamline analyses, and
help users master their analytical results.
Hear from Jeanette Langner, head of the department of pesticides in food at PiCA
Prüfinstitut Chemische Analytik GmbH as she explores the challenges she faced when detecting polar
compounds in food matrices, and why she chose Restek Polar X LC Columns to streamline these analyses.
Read article
Assay optimization can be challenging, particularly for those working within
therapeutic drug monitoring(TDM). TDM is a clinical practice used to measure drugs at designated intervals to
maintain a constant concentration in the bloodstream, in order to optimize individual dosage regimens and
avoid patient toxicity. New and improved pain management medications are consistently being developed and
released onto the market on a regular basis. The steady increase of pain medication has led to many hospital
and reference labs working tirelessly to screen more patients.
Patient samples must be screened to prevent drug misuse and to ensure patient
safety. The tests needed to monitor therapeutic drugs can be challenging, whereby technicians need to manage
low cut-off levels, matrix interferences, and isobaric drug compounds. LC-MS/MS tools can be used to address
these challenges, by delivering increased speed, sensitivity, and specificity.
The Raptor™ Biphenyl column from Restek has proven as an ideal tool for developing
successful LC-MS/MS pain medication screening methodologies, since the column has been designed with high
retention and unique selectivity. The column has enabled 231multiclass drug compounds and metabolites –
including over 40 isobars to be analyzed within 10 minutes, as shown in Figure 1. In addition, separate panel
shave also been optimized on the Raptor Biphenyl column for use with arange of specialized drugs, including
opioids, antianxiety drugs, barbiturates, and analgesics – for use during confirmation and quantitative
analyses.
Figure 1: Multiclass Drug Panel on Raptor Biphenyl by
LC-MS/MS
In the key resources below, we explore pain management using the Raptor
Biphenyl LC columns, and explain how these columns enable fast separation in bioanalytical testing applications,
such as pain panels. We also reveal the importance of mycotoxin detection in raw plant materials and cannabis
products, and present a simple pass-through solid phase extraction (SPE) sample clean-up method, which was
applied to CBD oils using the Raptor Biphenyl column.
LC-MS is a powerful separation technique and is also the preferred tool used to
separate large non-volatile molecules, such as complex peptides and proteins. C18, along with C8 and C4 are all
linear alkylsilane phases. C18 is octyldecylsilane and contains 18 carbons bound to silica. C18 analytical columns
are the cheapest and most common form of column used for reverse-phase chromatography. These columns comprise of a
hydrophobic surface, and a large surface area, due to their large number of carbons. These columns are available
with a range of characteristics to meet the unique needs of the user, and can be used across many disciplines,
from pharmaceuticals to environmental science.
Despite the popularity of C18 columns, they do not work effectively for every
compound. As an alternative, users can opt to use the Raptor™ FluoroPhenyl column, a column which has been
developed to deliver greater selectivity and retention for analytes that are not easily separated by C18 phase
chemistry. For instance, C18 columns cannot effectively separate isobaric epimers, while the FluoroPhenyl column
provides chromatographic resolution to ensure accurate results are generated.
Figure 2: 25-HydroxyvitaminD2/D3 and
3-Epi-25-Hydroxyvitamin D2/D3 on Raptor™ ARC-18 by LC-MS/MS
Figure 3: 25-HydroxyvitaminD2/D3 and
3-Epi-25-Hydroxyvitamin D2/D3 on Raptor FluoroPhenyl by LC-MS/MS
Raptor FluoroPhenyl LC Column
Figure 2 and Figure 3 present a comparison between the C18 and the Raptor
FluoroPhenyl column and demonstrates their ability to separate the epimers of vitamin D2 and D3
25-hydroxymetabolites. For additional information on the analysis of epimers of 25-hydroxyvitamin D in
serum, look at the resource below.
The retention and separation of challenging compounds can be laborious,
time-consuming, expensive, and above all, complex. Therefore, the most appropriate technology must be selected to
ensure the most accurate results are generated as simply as possible. Restek have created a range of bespoke LC-MS
tools designed to help users easily master their analytical results.
In the resources below, hear from the experts at Restek as they introduce a simple
approach to the retention and separation of challenging compounds, including a unique stationary phase created to
selectively retain polar analytes. Plus, find out more about how to best monitor biomarkers, and learn how methods
for monitoring alcohol consumption biomarkers (EtG and EtS) are limited by poor retention and coelution, and how
the dilute-and-shoot EtG/EtS LC-MS/MS analysis method was established. Discover how this method was developed
using the Raptor™ EtG/EtS column, designed to resolve EtG and EtS from matrix interferences, and provides
consistent, accurate results for high-throughput lab testing. These resources will also explore reference
standards and the key steps needed to build a solid analytical foundation.
EtG/EtS LC-MS/MS Analysis
Raptor Polar X LC Columns
To help take your analysis to the next level, discover the Force LC column, with
Time-Tested Restek Biphenyl Phase. This tool has been designed to separate compounds that other phenyl and C18
chemistries cannot perform, including the use of simple, MS-friendly mobile phases. The Force LC column is
particularly valuable for those working within therapeutic drug monitoring or toxicology. For instance, Figure 4
outlines how the Force Biphenyl columns were created for applications where fast, reliable identification of drugs
and metabolites are necessary.
Figure 4: Morphine and Metabolites on ForceBiphenyl
by UHPLC-MS/MS
Additionally, the Force LC columns also have a General-Purpose Restek C18 Phase,
designed to offer high hydrophobic retention, along with a wide pH range, which delivers excellent data quality
over a range of applications. This phase is compatible with moderately acidic-to-neutral mobile phases, and
generates excellent data quality in food, environmental, and bioanalytical applications.
In-line sample preparation (ILSP) uses LC-MS/MS to streamline and automate sample
extract clean-up, which, in turn, reduces cost, sample preparation time, and also eliminates downtime between
samples.
For those working within the food safety sector, the Revive ILSP Pesticides cartridges
from Restek are an ideal sample preparation alternative for researchers who need to spend less time and money on
multiresidue pesticide samples, without sacrificing performance. These cartridges function by effectively
separating analytes from potentially interfering matrix components, like conventional SPE and QuEChERS, but it
also replaces the time-consuming manual procedures via an automated clean-up process of complex samples. Figure 6
presents a comparison between the Revive ILSP Pesticides workflow and a QuEChERS workflow for the analysis of
pesticide residues in spinach.
This diagram demonstrates that the ISLP method resulted in a time saving of 1.5
hours, with fewer sample transfers, and also minimized the risk of introducing error through manual steps.
Figure 7 provides more information on how Revive In-Line Sample Prep operates to deliver superior analytical
results.
Figure 5: An image to illustrate the Revive in-line sample
preparation system – operating 1.5 hours faster than a traditional QuEChERS workflow for 14 spinach
samples.
Figure67: A diagram to demonstrate how In-Line Sample Preparation
operates.
Revive In-Line Sample Preparation
Raptor™ EXP® Guard Column
Cartridges
Raptor™ ARC-18 LC Columns
The Raptor™ARC-18 Column is made specifically for high-throughput,
low–sample prepLC-MS/MS applications. A well-balanced retention profile offers betterdetection and integration
of large, multiclass analyte lists, and stericprotection helps this SPP column endure the harsh, low-pH mobile
phases neededfor mass spec without sacrificing retention or peak quality.
Raptor™ Biphenyl LC
Column
With Raptor™ LC columns, Restek chemists became the first to combine the
speed of superficially porous particles (also known as SPP or “core-shell” particles) with the resolution of
highly selective USLC® technology. This new breed of chromatographic column allows you to more easily achieve
peak separation and faster analysis times without expensive UHPLC instrumentation.
*Certain images and/or photos on this page are the copyrighted property of 123RF.com,
its contributors or its licensed partners and are being used with permission under the relevant license. These
images and/or photos may not be copied or downloaded without permission from 123RF.com. Other images courtesy
of Restek..
