CHROMATOGRAPHY 47
Fig.2. Labs reporting PFOA and PFOS alone can increase sample throughput with a <2 minute analysis (4.5 minute total cycle time)
analytical processes (including HPLC solvent inlet tubing) is essential for accurate analysis. Typically, perfluorinated alkyl acids are analysed by LC-MS/ MS methods, but some methods (e.g. ISO 25101 or DIN 38407- 42) require long analysis times (>20 min) that can greatly limit sample throughput. Te method developed here offers a fast analysis that still ensures sufficient resolution for the MS dwell time for all compounds within a specific retention time window. In the chromatogram shown in Fig.1, all target perfluorinated alkyl acids were analysed on a Raptor C18 column in under eight minutes with a total cycle time of 10 minutes. In addition to
providing a fast analysis that supports sample throughput, there is no sacrifice in peak resolution or selectivity, meaning all fluorochemicals are easily identified and they elute as highly symmetrical peaks that can be accurately integrated and quantified by MS/MS. If PFOA and PFOS are the only target fluorochemicals of concern, the analysis can be further optimised, which results in a fast, <two-minute separation with a total cycle time of just 4.5 minutes, as shown in the Fig.2 chromatogram.
Te Raptor C18 5 µm
particle column used here offers excellent resolution for fluorochemicals with short total cycle times in part because it is
a superficially porous particle (SPP) column. Tese particles, which are also commonly known as “core-shell” particles, have been proven to produce faster, more efficient separations than fully porous particles (FPP). Tis is due to the shorter diffusion path and reduced peak dispersion that result from the solid core that is characteristic of SPP particles and that differentiates them from FPP particles. If desired, even faster analysis times could be obtained by using a Raptor C18 SPP column with 2.7 µm core-shell particles.
Whether labs conducting perfluorinated alkyl acid analysis by LC use longer target analyte lists or focus just on PFOA and
PFOS, the excellent peak shapes and separations achieved here result in consistent, accurate quantification with much shorter analysis times. As increased regulatory interest and human health and environmental concerns drive up demand for efficient, effective perfluorinated alkyl acid analyses, methods such as the one presented here can help labs report results quickly and accurately.
For more information ✔ at
www.scientistlive.com/eurolab
Dr Shun-Hsin Liang is senior LC applications chemist with Restek.
www.restek.com
Preparative chromatography materials launched The well-regarded EternityXT family
A
kzoNobel recently announced that its Kromasil EternityXT 10 µm C8 bulk material is now shipping. Kromasil EternityXT 10 µm materials are used in reversed phase chromatography, they are end capped and now delivered in both C18 and C8 derivatisations, providing the flexibility needed for small, medium and large-scale preparative chromatography. This family of Kromasil EternityXT stationary phases supports scientists working in purification under extreme conditions that may be challenging to the mechanical and chemical stability of the stationary phase.
of products is based on advanced technology where the material can operate under extremely demanding conditions, including extended pH range. In fact, Kromasil EternityXT stationary phases can operate beyond the pH window of Kromasil Classic materials, which is the recognised standard in purification for a variety of applications worldwide, including pharmaceutical, peptides and oligonucleotides. Kromasil EternityXT 10 µm C8 and C18 materials can withstand pH 12 and as many
compounds used by the pharmaceutical industry are basic in nature, it is possible to run them under strong basic conditions with EternityXT to increase loading onto the column to improve productivity and to reduce purification costs. The structure of Kromasil EternityXT C18
and C8 materials is such that it is possible to sanitise or regenerate them in-column, carrying out cleaning in place (CIP) even at 1 M NaOH, if so required.
For more information visit
www.kromasil.com
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