Positive interference in lithium determinations from clot activator in collection container.

Author(s): Sampson M, Ruddel M, Albright S, Elin RJ

Publication: Clin Chem, 1997, Vol. 43, Page 675-9

PubMed ID: 9105272 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to assess the effects of specimen volume, pH, storage time, and storage container on ion selective electrode determination of Li concentration in serum.

   Summary of Findings:

   Interference in the measurement of Li in serum by ISE was observed when either whole blood or pooled Li-free serum specimens were stored in BDP. Specimens in BDP consistently gave positive readings by LSE, but no Li was detected in the same specimens by flame atomic absorption spectroscopy or in specimens stored in BDG. Lower specimen volumes and pH led to higher apparent Li concentrations for specimens stored in BDP, while storage time had no effect on measured Li concentration. Specimens in BDP-2 gave Li measurements that were lower than those in BDP, however, a small false elevation in Li persisted. The authors determined that short-term exposure of the Lytening 2Z ISE to the silica clot activator with silicone surfactant (SCA) found in BDP resulted in falsely increased Li readings, while long-term exposure of the ISE to SCA resulted in a decrease in the falsely elevated Li measurements and a decrease in Li measurements for specimens not exposed to SCA.

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Serum

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Electrolyte/Metal	Atomic absorption spectroscopy
   Electrolyte/Metal	Ion selective electrode

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Aliquots and Components	Aliquot size/volume	1 mL 1.25 mL 2 mL 3 mL 4 mL 5 mL
   Biospecimen Aliquots and Components	pH	6 6.6 7 7.4 7.8 8.5
   Storage	Type of storage container	Plastic Vacutainer Plus (BDP) Plastic Vacutainer Plus, less silicone surfactant (BDP-2) Glass Vacutainer Tube (BDG)
   Biospecimen Aliquots and Components	Blood and blood products	Serum Whole blood
   Storage	Storage duration	0 min 10 min 30 min 1 h 2 h 4 h 1 d 2 d 3 d 4 d
   Ion selective electrode Specific	Technology platform	Atomic absorption spectroscopy
   Biospecimen Aliquots and Components	Centrifugation	Centrifugation delays investigated

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