Pre-analytical conditions influencing analysis of folate in dried plasma microsamples

Christopher M Shuford; Evan W McConnell; Stacy Dee; Russell P Grant

doi:10.1016/j.jmsacl.2023.01.003

Pre-analytical conditions influencing analysis of folate in dried plasma microsamples

J Mass Spectrom Adv Clin Lab. 2023 Jan 24:28:1-8. doi: 10.1016/j.jmsacl.2023.01.003. eCollection 2023 Apr.

Authors

Christopher M Shuford¹, Evan W McConnell¹, Stacy Dee¹, Russell P Grant¹

Affiliation

¹ Laboratory Corporation of America Holdings, Center for Esoteric Testing, Burlington, NC, United States.

Abstract

Introduction: Determination of folate insufficiency is of considerable interest given its importance in fetal development and red blood cell formation; however, access to blood tests may be limited due to the requirement for phlebotomy as well as controlled temperature shipping of blood specimens to laboratories for testing due to the inherent instability of folate and its vitamers.

Methods: An LC-MS/MS test was developed and validated for the measurement of 5-methyltetrahydrofolate (5MTHF) in dried plasma specimens collected from fingerstick blood using a laminar flow blood separation device, as well as liquid venous plasma for comparison. Two pre-analytical factors investigated influencing the measurement of 5MTHF in dried plasma were hemolysis of the fingerstick blood during collection and storage/shipment of the dried plasma.

Results: Although observed infrequently, hemolysis >10 % resulted in elevated 5MTHF measurements, but hemolysis >1 % resulted in elevated chloride measurements, which were necessary to normalize 5MTHF measurements for variation in volume of dried plasma specimens. Stability of 5MTHF was improved in dried plasma relative to liquid plasma at ambient temperatures, but not sufficiently to allow for uncontrolled temperature shipping despite controlling for humidity and light exposure. Shipping studies emulating ISTA procedure 7D were conducted with a reusable cold packaging solution. The packaging failed to stabilize 5MTHF in dried plasma specimens during a 2-day summer shipping evaluation, but did provide sufficient temperature control to stabilize 5MTHF during the overnight shipping evaluation.

Conclusion: Our studies provide boundary conditions with respect to hemolysis, storage, and shipping for successful analysis of 5MTHF from dried plasma specimens.

Keywords: 5-Methyltetrahydrofolate; 5MTHF, 5-methyltetrahyrofolate; CLSI, Clinical Laboratory Standards Institute; DBS, dried blood spot; FDA, Food and Drug Administration; Folate; ISTA, International Safe Transit Association; LC-MS/MS, liquid chromatography tandem mass spectrometry; Liquid chromatography; Mass spectrometry; Microsample; PCM, phase change material.