Tag Archives: ionization efficiency

International Conference on Non-Targeted Screening. It was finally time to get back to in-person conferences! 

After almost two years of zoom-only meetings, it was my great pleasure to last week get back to meeting fellow scientists in person at Intentional Conference on Non-Targeted Screening, Erding, Germany. The meeting was held in parallel in-person and online. The conference ran over four days with talks covering computational mass spectrometry, instrumental techniques for […]

What is the potential risk of the compounds detected in water samples? Combining concentration and toxicity

How do you know which of the compounds detected in suspect or non-targeted screening is most likely to cause an adverse effect? Which is most toxic? Which is present in the highest concentration? Which is having a concentration close to a toxic endpoint? This is exactly what we are answering in our latest research in […]

Thesis-Thesis-Thesis: From PCB Metabolites Through PFOS to Reactions in Charged Droplets

The last two weeks have been going under the title “thesis-thesis-thesis” in our group. This spring one BSc student and two MSc students from our group have defended their thesis: Sara Khabazbashi, Helen Sepman, and Thomas Ledbetter. Both Sara and Thomas have dug into the analytical standard free quantification for pollutants. Sara specifically focussed on metabolites of […]

Benchmarking of the quantification approaches for the non-targeted screening

Non-targeted screening with liquid chromatography-electrospray high-resolution mass spectrometry (LC/ESI/HRMS) is revealing hundred to thousands of contaminants in the water. We have recently proposed a way to quantify these contaminants based on the estimated LC/ESI/HRMS ionization efficiencies. But how to know how well such tools are performing? Well, we need to compare with classical methods that are […]

NORMAN interlaboratory comparison on semi-quantitative LC/HRMS

The difficulty in quantifying compounds in LC/ESI/HRMS arises from vastly different responsiveness of the compounds. At the same concentration, two compounds may yield very different signals due to the differences in the ionization efficiency of the compounds. The different responsiveness has made semi-quantitative non-targeted screening challenging. Still, research has been increasingly focussing on enabling the semi-quantification […]

Quantification for non-targeted LC/MS screening without standard substances

Recently we have published a paper on advancement in predicting ionization efficiency in ESI and using this for estimating the concentration of pesticides in cereal samples without the need for analytical standards. In this paper, we explored the possibility to use machine learning for fast and accurate prediction of ionization efficiency. Previously we have carefully […]

What is non-targeted analysis and why it should go quantitative?

In June at HPLC conference I had a super nice possibility to explain what is non-targeted screening and why it should be developed into a quantitative method. Now, this video is available for all of you. I thank a lot Alasdair Matheson from LC&GC, who invited me to do the video, LCGC video teem, and HPLC […]

Ionization efficiency of an oligopeptide can be predicted based on its amino acid composition

Ionization efficiency of oligopeptides does depend on the chemical composition of the peptide. Longer oligopeptides generally obey higher ionization efficiency; however, for peptides containing more than seven amino acid the ionization efficiency values are relatively similar. Also, the ionization efficiency values of the amino acids can be used to estimate the ionization efficiency of a […]

We presented standard substance free quantitation in HPLC2019

Last Thursday the HPLC2019 meeting finished. The conference was this year held in Milano, Italy and incorporated more then 300 talks. I had a chance to give a keynote lecture on the quantification of metabolites from green tea with LC/MS without the need for standard substances. The main focus of the conference was on the […]

67th ASMS Conference on Mass Spectrometry and Allied Topics

From 1st to 6th of June, two PhD fellows Piia Liigand and I presented our recent results at 67th ASMS annual conference in Atlanta, USA. The conference was kicked off with a plenary lecture by Prof. Mark Z. Jacobson on the topic of “Transitioning the World Energy for All Purposes to Stable Electricity Powered by […]