Vortex-Assisted Liquid-Liquid Microextraction for Steroid …
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using an ultrasonic probe, and the dispersion formed under vortex-mixing is thermodynamically unstable, which means the extraction phase that contains the target
analyte can be easily separated (Papadopoulou et al. 2011). Thus the major aim of this
study is to discuss a simple and rapid sample preparation technique using VALLME
in determination of ‘steroid profile’ in urine samples using Liquid Chromatography
tandem mass spectrometry (LC-MS/MS).
6 LC-MS/MS Technique as Instrument Analysis
LC-MS/MS is a powerful analytical technique that combines the separating power
of liquid chromatography with the highly sensitive and selective mass analysis capability of triple quadrupole mass spectrometry. A sample solution containing analytes
of interest are pumped through a stationary phase (LC column) by a mobile phase
flowing through at high pressure. Chemical interaction between the components of
the sample, the stationary phase and the mobile phase affects different migration
rates through the LC column affecting a separation. The wide variety of stationary
phase and mobile phase combinations allow for customizing a separation to suit
many complex solutions.
After elution from the LC column, the effluent is directed to the mass spectrometer.
The mass spectrometer for an LC-MS/MS system has an ionization source where the
LC column effluent is nebulized, desolvated and ionized creating charged particles.
These charged particles then migrate under high vacuum through a series of mass
analyzers (quadrupole) by applying electromagnetic fields. A specific mass/charge
precursor ion (or parent ion) is targeted to pass through the first quadrupole, excluding
all other mass/charge ratio particles. In the collision cell, the selected mass/charge
ions are then fragmented into product ions (or daughter ions) by collision with an
inert gas. The third quadrupole is used to target specific product ion fragments. The
resulting isolated product ions are then quantified with an electron multiplier. This
transition of ions from the precursor to product ion (also referred to as MS
2 ) is highly
specific to the structure of the compound of interest and therefore provides a high
degree of selectivity. The strength of this technique lies in the separation power of LC
for a wide range of compounds combined with the capability of the MS to quantify
compounds with a high degree of sensitivity and selectivity based on the unique
mass/charge (m/z) transitions of each compound of interest.
Green chemistry which was introduced in the 1990s, aimed to minimise the environmental impact of diverse chemical activities, including those used in research
(Shaaban and Gorecki 2015; Farré et al. 2010). In this scenario, green analytical
chemistry plays an important role, e.g., by reducing hazardous wastes, using reusable
materials, and/or employing eco-friendly solvents or green solvents. The last two
terms refer to solvents that have a lower environmental impact resulting from their
production, use, and disposal (life cycle assessment), and/or that allow health and
safety impacts to be minimized (Pena-Pereira et al. 2015). The main goals of green
analytical chemistry include the multi-analyte determination and the development of
753
using an ultrasonic probe, and the dispersion formed under vortex-mixing is thermodynamically unstable, which means the extraction phase that contains the target
analyte can be easily separated (Papadopoulou et al. 2011). Thus the major aim of this
study is to discuss a simple and rapid sample preparation technique using VALLME
in determination of ‘steroid profile’ in urine samples using Liquid Chromatography
tandem mass spectrometry (LC-MS/MS).
6 LC-MS/MS Technique as Instrument Analysis
LC-MS/MS is a powerful analytical technique that combines the separating power
of liquid chromatography with the highly sensitive and selective mass analysis capability of triple quadrupole mass spectrometry. A sample solution containing analytes
of interest are pumped through a stationary phase (LC column) by a mobile phase
flowing through at high pressure. Chemical interaction between the components of
the sample, the stationary phase and the mobile phase affects different migration
rates through the LC column affecting a separation. The wide variety of stationary
phase and mobile phase combinations allow for customizing a separation to suit
many complex solutions.
After elution from the LC column, the effluent is directed to the mass spectrometer.
The mass spectrometer for an LC-MS/MS system has an ionization source where the
LC column effluent is nebulized, desolvated and ionized creating charged particles.
These charged particles then migrate under high vacuum through a series of mass
analyzers (quadrupole) by applying electromagnetic fields. A specific mass/charge
precursor ion (or parent ion) is targeted to pass through the first quadrupole, excluding
all other mass/charge ratio particles. In the collision cell, the selected mass/charge
ions are then fragmented into product ions (or daughter ions) by collision with an
inert gas. The third quadrupole is used to target specific product ion fragments. The
resulting isolated product ions are then quantified with an electron multiplier. This
transition of ions from the precursor to product ion (also referred to as MS
2 ) is highly
specific to the structure of the compound of interest and therefore provides a high
degree of selectivity. The strength of this technique lies in the separation power of LC
for a wide range of compounds combined with the capability of the MS to quantify
compounds with a high degree of sensitivity and selectivity based on the unique
mass/charge (m/z) transitions of each compound of interest.
Green chemistry which was introduced in the 1990s, aimed to minimise the environmental impact of diverse chemical activities, including those used in research
(Shaaban and Gorecki 2015; Farré et al. 2010). In this scenario, green analytical
chemistry plays an important role, e.g., by reducing hazardous wastes, using reusable
materials, and/or employing eco-friendly solvents or green solvents. The last two
terms refer to solvents that have a lower environmental impact resulting from their
production, use, and disposal (life cycle assessment), and/or that allow health and
safety impacts to be minimized (Pena-Pereira et al. 2015). The main goals of green
analytical chemistry include the multi-analyte determination and the development of