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Short-Term Stability of Whole Blood Polyunsaturated Fatty Acid Content on Filter Paper During Storage at -28 °C
Daniele Pupillo1, Manuela Simonato2, Paola E Cogo3
1Division of Neonatology, Polytechnic University of Marche and Salesi's Children Hospital, Via Corridoni 11, 62123, Ancona, Italy.
Insights
Dried blood spot analysis of long-chain polyunsaturated fatty acids (LC-PUFA) in newborns is feasible. For accurate LC-PUFA measurements, analysis should occur within one week of collection due to potential degradation over time.
Area of Science:
- Biochemistry
- Neonatal Research
- Analytical Chemistry
Background:
- Umbilical cord blood offers a valuable source for neonatal fatty acid analysis.
- Dried blood spot sampling presents a minimally invasive alternative to traditional phlebotomy, particularly in infants.
- Assessing the stability of long-chain polyunsaturated fatty acids (LC-PUFA) in dried blood spots is crucial for reliable research.
Purpose of the Study:
- To evaluate the stability of LC-PUFA in dried umbilical cord blood samples stored at -28 °C.
- To determine the optimal storage duration for dried blood samples intended for LC-PUFA analysis.
- To assess the impact of storage on both fatty acid composition and isotopic enrichment.
Main Methods:
- Collected 12 umbilical cord blood samples, analyzing some immediately and others after drying on filter paper.
- Stored dried samples at -28 °C for up to 6 months, with analyses at 7 days, 1, 3, and 6 months.
- Measured fatty acid composition (mol%) and carbon-13 ((13)C) enrichment using gas chromatography and gas chromatography-isotope ratio mass spectrometry.
Main Results:
- LC-PUFA composition (mol%) showed no significant difference at 7 days compared to baseline (time 0).
- A statistically significant decrease in LC-PUFA values was observed by the first month of storage.
- Carbon-13 ((13)C) enrichment for 20:4n-6 and 22:6n-3 remained stable throughout the 6-month study period.
Conclusions:
- Dried umbilical cord blood is suitable for LC-PUFA analysis in neonates if performed within one week of collection.
- Subsequent storage leads to significant losses of LC-PUFA, compromising compositional accuracy.
- Dried blood samples retain (13)C enrichment for up to 6 months, making them valuable for natural abundance isotopic studies.
Abstract:
Finger or heel-pricked blood sampling for fatty acid analysis is suitable especially in newborn infants where blood sampling is difficult and phlebotomy for research can be unethical. The aim of this study was to evaluate dried blood long chain polyunsaturated fatty acids (LC-PUFA) stability during storage at -28 °C. We collected 12 blood cord samples that were analyzed immediately after blood drawing, with and without drying the blood on filter paper. Dried samples were then analyzed 7 days and 1, 3, and 6 months after collection. Butylated hydroxytoluene was added to all samples. Fatty acid composition and (13)C enrichment were measured by gas chromatography and by gas chromatography-isotope ratio mass spectrometry, respectively. The fatty acid composition, expressed in mol%, of the major LC-PUFA at day 7 was not statistically different from time 0, however lower values were found by the first month of storage. The (13)C enrichment of 20:4n-6 and 22:6n-3 did not differ during the whole study period. LC-PUFA analysis from dried umbilical cord blood in neonates should be performed within a week, major losses of LC-PUFA occur afterwards. However, fatty acids obtained from dried blood maintain their (13)C enrichment value for up to 6 months and thus these samples are suitable for natural abundance isotopic studies.
