Benefits

•Column diameter ≤2.1 mm
•Rapid analysis
•Characterisation technique
•High sensitivity
•Quantitative analysis
•Peak deconvolution ability
 

Introduction

Traditional problems associated with the inherent incompatibility of HPLC (high liquid pressure) and mass spectrometry (low vapour pressure) have been largely overcome. LC-MS has become a leading technique offering characterisation of solute molecules.

Column Dimensions

LC-MS interface techniques such as Atmospheric Pressure Chemical Ionisation, Electrospray, Particle Beam or Thermospray can typically handle maximum flow rates of 200µl/min. As microbore columns (2 mm i.d.) utilise such flows they are commonly used in LC-MS applications.

A 50 x 2.1 mm i.d. column is used for fast speed analysis applications whilst a 250 x 2.1 mm i.d. column will be the one of choice for more complex separations.

Where sensitivity is an issue, as in the analysis of peptides and proteins, 1mm i.d. columns are available. 

Availability

We offer a range of ACE, Hichrom, Hypersil, Inertsil, Kromasil, NUCLEOSIL, Vydac, YMC and Zorbax LC-MS columns, in lengths from 10 to 250mm and 1.0 and 2.1mm i.d. Alternative materials and dimensions can readily be supplied. Please enquire for details. 

Applications

LC-MS has numerous applications. These include:

•Drug metabolism structure elucidation and quantitative studies
•Protein and peptide identification and sequencing
•Combinatorial chemistry
•Agrochemical identification and quantitative studies
 

Figure 1 shows the use of single-ion monitoring to analyse a mixture of benzodiazepines. Although the total ion current chromatogram (A) obtained on a 150 x 2.1 mm i.d. column only resolves Oxazepam (D), Lorazepam (G) and Estrazolam (C), the four remaining unresolved benzodiazepines can be analysed using a single-ion monitoring technique (Diazepam m/z 285 (B), Clobazam m/z 301 (E), Alprazolam m/z 309 (F) and Triazolam m/z 344 (H)).
Although the assay is complete in under 5 minutes, use of a 50 x 2.1 mm rapid analysis column will reduce the analysis time to under 2.5 minutes.