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n Medical Technology SA - Red blood cell folate stability study : stability of whole blood prior to haemolysate preparation and stability of the haemolysate at various temperatures
Introduction : Folate is an essential vitamin vital for normal cell growth and DNA synthesis. A folate deficiency can lead to megaloblastic anaemia and severe neurological problems. Samples received at our laboratory often have long transit times as they are sent from peripheral clinics; therefore we determined sample stability. An accreditation non-conformance for the storage temperature of prepared haemolysate led to this haemolysate stability study.
Methods : Fasting blood samples were drawn from 40 healthy volunteers. Baseline RBC folate was performed in duplicate on each sample. Half the whole blood was then stored at various temperatures for 72 hours prior to haemolysate formation and RBC folate was determined every 24 hours. The other half was haemolysed, the haemolysate stored at various temperatures and analysed at 4-hourly intervals for 12 hours.
Results: Using the 15% acceptable assay imprecision allowed for RBC folate determination, it was found that whole blood was stable at room temperature unprotected from light for 72 hours. Taking the manufacturers 10% allowable degradation of the haemolysate and 15% acceptable assay imprecision into consideration, haemolysates may be stored for up to 12 hours at -20°C.
Conclusions : Samples transported from distant clinics for RBC determination are stable for up to 72 hours at room temperature even if unprotected from light. Haemolysates prepared for RBC folate determination may be stored at -20°C.
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