Comparative study on microsampling techniques in metabolic fingerprinting studies applying gas chromatography-MS analysis.

AIM: Sample collection and preparation are important steps in the metabolomics workflow. Any improvement should be aimed toward making them simpler, faster and more reproducible. This paper describes the evaluation of different types of whole blood microsampling techniques applied in a metabolic fingerprinting study of breast cancer patients. RESULTS: A total of 139, 124 and 128 metabolites were identified in protein precipitation, dried matrix on paper discs and Mitra® volumetric absorptive microsampling, respectively in 80% of the sample sets, where the quality control samples had a relative standard deviation of <30%. Ten metabolites in breast cancer samples were detected as being altered significantly (p < 0.05). CONCLUSION: Our results suggest that whole blood microsampling techniques do not obtain statistically different results in comparison with the metabolomics applied standard reference method of protein precipitation, in terms of the number of detected compounds, the reproducibility and modeling of differences between the groups.

State-of-the-art dried blood spot analysis: an overview of recent advances and future trends.

Dried blood spots have become a popular method in a variety of micro blood-sampling techniques in the life sciences sector, consequently competing with the field of conventional, invasive blood sampling by venepuncture. Dried blood spots are widely applied in numerous bioanalytical assays and have gained a significant role in the screening of inherited metabolic diseases, in PK and PD modeling; in the treatment and diagnosis of infectious diseases; and in therapeutic drug monitoring. Recent technological developments such as automation, online extraction, mass spectrometric direct analysis and also conventional dried blood spot bioanalysis, as well as future developments in dried blood spot bioanalysis are highlighted and presented in this article.

Bioanalytical LC separation techniques for quantitative analysis of free amino acids in human plasma.

The quantitative analysis of free amino acids in human plasma has become an important and essential analysis parameter in different areas of life sciences. Free amino acid concentrations in human plasma samples are generally determined by means of GC or LC after chemical derivatization followed by UV, fluorescent or MS detection of the amino acid derivatives. Derivatization of free amino acids is done either pre- or post-column, and the amino acid derivatives obtained posess improved chromatographic behavior, increased detection sensitivity and selectivity compared with non-derivatized free amino acids. This work gives an overview of different chemical derivatization methods applied and their liquid separation techniques in bioanalytical assays for quantitative free amino acid analysis in human plasma samples. Important plasma preparation procedures, pre- and post-column derivatization, and different LC separation techniques are presented.

Dried matrix on paper disks: the next generation DBS microsampling technique for managing the hematocrit effect in DBS analysis.

BACKGROUND: The hematocrit effect is a hurdle for successful introduction of the dried blood spot (DBS) in a regulated environment. Recently, attempts were taken to overcome the hematocrit effect by whole-cut DBS analysis. This paper presents the next-generation whole-cut DBS; dried matrix on paper disks (DMPD). RESULTS: DMPD eliminated the hematocrit effect and demonstrated better accuracy and precision than regular DBS with partial punching. Observed accuracy and precision were 6.0 and 2.3% for DMPD, respectively, and -10.4 and 17.1%, for DBS, respectively. CONCLUSION: The DMPD technique performed better than regular DBS by eliminating the hematocrit effect related blood volume bias. Although this effect was not observed with DMPD, a systematic error of 6.0% was detected and further technical development of DMPD could improve the performance.