Instrumentation
The Aga lab is equipped with the necessary instruments to perform top-of-the-line analytical/environmental research.
Agilent 6410 LC/MS/MS
Triple Quadrupole Mass Spectrometer with Agilent 1100 HPLC
The Agilent 6410 offers precision and sensitivity to LC/MS/MS analysis. After separation of sample components by HPLC, the analytes desolvated and ionized by an ESI source. Triple quadrupole mass spectrometers consist of two mass filtering quadrupoles centered by a quadrupole that acts as a collision cell. As collisions occur with an inert gas, typically nitrogen or argon, the molecular ions become fragmented, which provides structural information. Fragments are characteristic to each analyte and provide enhanced specificity when identifying analytes. Triple quadrupole mass spectrometers also have much reduced noise versus a single quadrupole resulting in improved sensitivity.
Our group has used the 6410 to transition many of our previous LC/MS methods to new levels of sensitivity and confidence. The following projects have benefitted recently:
- The analysis of pharmaceuticals and personal care prodects in surface water and waste water.
- Studies of the fate of hydroxylated PBDEs in human liver extracts.
Thermo Scientific TSQ Quantum XLS
Triple Quadrupole Mass Spectrometer with Trace QC Ultra Gas Chromatograph
The Thermo Scientific TSQ Quantum XLS offers maximum precision and sensitivity to gas chromatography (GC)/MS analysis. After separation of a sample into its components by GC, the components are transferred to a triple quadrupole mass spectrometer through an electron ionization (EI) or chemical ionization (CI) source. Furthermore, this instrument contains an electron capture detector (ECD), which is beneficial for detecting halogenated compounds in addition to MS.
Our group has used the TSQ to replicate the capabilities of much more expensive instrumentation. The following projects have benefitted recently:
- The analysis of PBDEs in the aquatic food chain of Lake Erie.
- Studies of the fate of PBDEs in human liver extracts.
- Studies of PCBs and PBDEs from PM10 particulates and fish from the Philippines.
Thermo Scientific XSERIES 2 ICPMS
Single Quadrupole Mass Spectrometer with Inductively Coupled Plasma Source
Inductively coupled plasma mass spectrometry (ICP-MS) is an analytical technique that enables the determination of trace elements. It is known for its wide elemental coverage, low detection limits, fast analysis times, wide analytical working range, and isotopic capabilities. The ICP/MS in the UB Chemistry Department has a Thermo X-Series II quadrupole mass spectrometer acquired through the NSF MRI Program CHE 0959565, with Dr. Aga as PI. The ICP/MS is equipped with an advanced H2/He collision cell technology (CCT). This instrument enables the analysis of a wide range of elements, with detection limits ranging from ppt to ppm concentrations. With the inclusion of CCT, elements that are traditionally difficult to analyze (i.e., Mg, K, Ca, Fe, As, Se, S, etc.) can be detected at very low levels by removal of gas-based and matrix-based polyatomic interferences through collisional retardation / differential transmission (kinetic energy discrimination). Our ICP-MS is also equipped with a 213 nm laser ablation system from New Wave Research (NWR-213 third-generation, high-performance Nd:YAG deep UV) for direct analysis of solid samples, such as geological samples or biological tissues. In addition, we have an HPLC system that can be coupled with the ICP-MS for applications requiring online metal speciation and separation.
Currently, our group has used the ICP-MS to support the project: Environmental transport, biodegradation and bioaccumulation of CdSe quantum dots and HfO2 and ZrO2 metal oxide nanoparticles (EPA STAR funded), specifically in:
- The analysis of total Cd, Se, Hf, and Zr.
- The mapping and distribution analysis of Cd, Se, Hf, and Zr in plant and earthworm tissues.
- The development of CE-ICP/MS interface for the simultaneous analysis of intact and degraded nanoparticles.
Thermo Finnigan LCQ Advantage
Ion Trap Mass Spectrometer with Thermo Finnigan Surveyor HPLC
The Thermo Finnigan LCQ Advantage ion-trap mass spectrometer, equipped with a Surveyor high performance liquid chromatograph (LC-IT/MS), is used in our laboratory for structural characterization of unknown organic pollutants and their metabolites. The LC-IT/MS uses either an electrospray ionization (ESI) source or an atmospheric pressure chemical ionization (APCI) source. In general, ESI is used to ionize the more polar compounds, such as many antibiotics and other pharmaceuticals, while APCI is used for relatively non-polar compounds, such as the hydroxylated metabolites of polybrominated diphenyl ethers. The IT/MS consists of three electrodes with hyperbolic surfaces where the ions are trapped within the system, the central ring electrode, and two adjacent endcap electrodes of hyperbolic cross-section. High resolution (>106 at m/z >1000) is accessible through slow scans, but mass measurement accuracy is relatively poor in IT-MS. The principal advantages of the IT/MS over the quadrupole MS is the higher sensitivity of IT/MS under full scan mode, and the ability of the latter to perform multiple stage mass spectrometry (MSn) simply by the use of additional operations which are performed sequentially in time. The MSn fragmentation provides enhanced structural information for qualitative analysis. A unique mass spectral fingerprint obtained by MSn can be used in structure elucidation of unknown metabolites even in complex environmental matrices. The LCQ Advantage LC-IT/MS in our laboratory is also equipped with an on-line diode array detector; therefore, the UV spectral information can be used as additional confirmatory tool to match the chromatographic peaks with the mass spectral information.
Beckman Coulter P/ACE MDQ
Capillary Electrophoresis with Diode Array Detector
The Beckman Coulter P/ACE MDQ capillary electrophoresis (CE) allows for high-resolution separation of ions in solution under an electric field. The use of an open tubular fused silica capillary reduces plate height and increases theoretical plates when compared to high pressure liquid chromatography (HPLC). Theoretical plates of greater 100,000 are not unusual for CE, which is at least 10 times greater than HPLC.
Currently, the CE is being coupled to an inductively coupled plasma-mass spectrometer (ICP-MS) for investigating the speciation of free metal ions in solution versus what is intact in quantum dot nanoparticles. Quantum dots continue to gain interest in the scientific and medical field, due to their potential use in biological imaging, sensors, and solar energy harvesting. Unfortunately, quantum dots may also be released into the environment as waste, potentially releasing toxic materials such as cadmium, selenium, and zinc. These elements are often used in the core or shell of the quantum dots.
Therefore, coupling the CE to ICP-MS allows for:
- detection of free metal ions, which cannot be detected by traditional optical detectors (UV or fluorescence)
- low detection limits of the ICP-MS for metal ions
- selectively scanning for individual metal ions in environmental matrices
DIONEX ASE 200
Accelerated Solvent Extraction System
The Dionex ASE 200 allows for extractions that would otherwise take hours to be completed in minutes, while greatly reducing solvent consumption. The instrument regulates temperature and pressure, which lead to the completion of rapid and efficient extractions. An increase in temperature results in accelerated extraction kinetics, while increased pressure prevents the solvent from reaching its boiling point.
