A more secure and efficient screening technique for foracylcarnitines, amino acids and steroids in newborns by LC-MS
In Switzerland, 84’000 newborns are screened by dried blood spot analysis for innate errors every year [1-3]. However, traditional methods in this field are laborious as they are based on punching and offline extraction. Even more critically, sometimes sample confusion is caused electrostatic effects, which direct punched samples into the wrong tube or well. A method using steroids, acylcarnitines and amino acid based on the DBS-500 is presented here.
Workflow
Classical DBS punching versus online CAMAG DBS-500. The classical workflow includes a semi-automatic punch-out step whereas the automated DBS-500 allows direct extraction of blood spots into the mass spectrometer.
Materials and methods
A fully automated dried blood spot sampler, the DBS-MS 500,(CAMAG, Muttenz BL, CH) and a 6410 triple quadrupole mass spectrometer (+ESI) equipped with a 1100 series quaternary HPLC pump (Agilent, Santa Clara CA, USA) were used. Solvents and additives were provided by Sigma-Aldrich (Buchs SG, CH). Standards for amino acids and acylcarnitines were provided by Chromsystems (München, D). The method was validated according to ICH guidelines [4].
Results and discussion
Extraction conditions
An optimum extraction is achieved by a mixture of methanol / water 7:3, which is the best compromise of extracting the analytes, extracting low amounts of suppressant and minimum interference with the chromatographic separation.
Chromatography
Most compounds are separated by MRM only. Deoxycorticosteron and 17 OHP, which have the same MRM, are separated by chromatography.
Validation
The averaged CV of the amino acids and acylcarnitines was 4.2 % within one day and 7.2% for several days using the automated method. This was comparable to the established routine method, which was found to be 5.6% CV for one day and 6.3% CV for several days.
Conclusions
It has been shown that the new direct elution method has significant advantages compared to the traditional method. The combination of the 25 markers allows fully automated screening of several diseases in less than 2.5 minutes per sample.
Outlook
This new direct extraction approach significantly improves not only newborn screening programs, but also opens new avenues for dried blood spot analysis in other fields such as screening for doping, therapeutic drug monitoring, or point of care analytics.
References
[1] Dried Blood Spots: Applications and Techniques ISBN: 9781118054697
[2] Neugeborenscreening Kinderspital Zürich http://www.neoscreening.ch
[3] Fingerhut et al. Rapid Commun. Mass Spectrom. 2014, 28, 965–973
[4] ICH Validation Guidelines http://www.ich.org
Project details
- Type
- Research project
- Research areas
- Instrumental analytics
- University
- FHNW School of Life Sciences / Institute for Chemistry and Bioanalytics
- Partner
- CAMAG Chemie-Erzeugnisse & Adsorptionstechnik AG; University Children's Hospital, Children’s Research Center, Swiss Newborn Screening Laboratory
- Collaboration
- Christian Berchtold, Irene Wegner, Stefan Gaugler, Tamara von Däniken, Markus Wyss, Ralph Fingerhut, Götz Schlotterbeck
Contact
Prof. Dr. Stefan Gaugler
- Phone
- +41 61 228 50 98
- stefan.gaugler@fhnw.ch