AACC 2019 | Evaluating 7-day Stability of Lipid and Metabolic Analytes in Plasma Samples Prepared at the Point of Draw with the Torq™ Zero Delay Centrifuge System

Gabriella Iacovetti, Ali Rahimian, Kyungjin Hong, Kory Melton, Anjali Parikh, Greg Sommer, Ulrich Schaff

Sandstone Diagnostics Inc., Pleasanton, CA


Hemolysis is a leading contributor to preanalytical errors, which account for up to 75% of all diagnostic errors. Blood samples not promptly centrifuged are susceptible to hemolysis and other degradation in vitro, however centrifuges are often not available at the point of blood draw. Therefore, sample quality is often compromised and access to tests remains limited.

The Torq™ zero delay centrifuge system is a lightweight, hand-portable device for immediately separating and stabilizing plasma at the point of collection. The Torq system is comprised of the ZDrive™ – a CLIA-waived, 4” diameter, battery-powered centrifuge – and of ZDiscs™ – evacuated and anticoagulated cartridges designed to collect blood and isolate liquid plasma from cells following a brief (1-4 minute) spin upon collection. Torq enables shipment of stable plasma to centralized laboratories without the degradation that occurs in whole blood.


The objective of this study was to determine if separation and storage of blood using the Torq system provides equivalent results to separation and storage in sterile control tubes for a variety of lipid and metabolic analytes.


Lipid panels (cholesterol, triglyceride, HDL, LDL) were run on samples from five donors with blood separated in ZDiscs and blood separated in BD Vacutainer® plasma separation tubes (PSTs). Plasma was aliquoted into sterile storage tubes and stored at room temperature for 1 day, 3 days, and 7 days prior to testing at an external independent laboratory (InSource Diagnostics, Monrovia CA). Additionally, metabolic analytes (BUN, Na, K, Cl) were run on samples from three donors with plasma that was stored at room temperature in both ZDiscs and in sterile control tubes for 1 day, 3 days, and 7 days prior to testing. The results of ZDisc samples vs. control samples for each analyte at each time point were averaged and compared.


Percent differences at day 1, day 3, and day 7 for each analyte were as follows: cholesterol: 2.67%, 1.67%, and 2.54%; triglyceride: 1.83%, 2.98%, and 2.57%; HDL: 2.96%, 1.56%, and 2.86%; LDL: 2.06%, 2.81%, and 5.08%; BUN: 2.02%, 2.5%, and 5.78%; Na: 1.96%, 3.10%, and 3.05%; K:1.53%, 3.13%, and 3.38%; Cl:1.76%, 2.70%, and 2.68%.


Differences in results of lipid panel in ZDisc samples and control samples were not clinically significant at any time point tested. Differences in metabolic analyte results from blood stored in ZDiscs and control samples were not statistically significant at any time point tested. These results indicate that the Torq system is suitable for plasma separation at the point of care for lipid panel analysis and that storage in ZDiscs is not a significant factor in metabolic analyte results.