MSACL 2016 EU Abstract

Metrological Traceability of a New Waters MassTrak™ Vitamin D Assay

Norma Breen (Presenter)
Waters Technologies Ireland Limited

Bio: Norma Breen a Senior Product Development Chemist with Waters Technologies Ireland.

Authorship: Norma Breen (1), Leanne Davey (1), Lisa Calton (2), Philip Lambert (1), Declan Roche (1) Danielle Cullen (1), Robert Wardle (2)
(1) Waters Technologies Ireland Ltd, Wexford, Ireland, (2) Waters Corporation, Wilmslow, UK

Short Abstract

Robust metrological traceability has been incorporated in to the design, development and manufacture of the Waters MassTrak™ Vitamin D kit, to meet the requirements of ISO 17511:2003. The MassTrak™ Vitamin D kit calibrator materials are traceable to NIST SRM2972 via a documented unbroken chain of calibrations. The accuracy of this traceability to NIST SRM2972 has been verified through participation of the Vitamin D Standardisation Certification Program (VDSCP) in which the MassTrak™ Vitamin D Assay achieved a mean % bias of 0.6 % from the VDSCP reference values and an imprecision of 4.9%.

Long Abstract

Introduction: Robust metrological traceability has been incorporated in to the design, development and manufacture of the Waters MassTrak™ Vitamin D kit. The kit metrological traceability has been designed and developed to meet the requirements of ISO 17511:2003: In vitro diagnostic medical devices – Measurement of quantities in biological samples – Metrological traceability of values assigned to calibrators and control material. Traceability is further assured through participation in the Vitamin D Standardisation Certification Program (VDSCP). The robust metrological traceability of the MassTrak™ Vitamin D kit as well as a comprehensive review of the kit performance characteristics will be presented.

Metrological Traceability

Metrological traceability of the MassTrak™ Vitamin D kit to NIST SRM2972 has been established. Primary calibrators were prepared using certified reference materials and assigned 25(OH)D2 and 25(OH)D3 concentrations using reference measurement procedures at the University of Ghent which are traceable to NIST SRM2972.

All MassTrak™ Vitamin D kit calibrators and quality control lots are value assigned using primary calibrators and the certified values from the University of Ghent. The concentration values assigned to the MassTrak™ Vitamin D Kit calibrators and quality controls are verified in a value confirmation process. The value confirmation of the calibrators involves the measurement of independently assigned quality control material.

VDSCP

To further assess the accuracy of the metrological traceability and performance of the MassTrak™ Vitamin D kit assay, Waters enrolled in the CDC Vitamin D Standardisation Certification Program (VDSCP) for 25(OH)D in serum, which assesses bias and precision of assays relative to reference measurement procedures.

The VDSCP Certification phase consists of 10 blinded patient samples distributed quarterly. Each quarter the 10 samples are analysed on over two days in duplicate, a total of 160 results annually for the certification programme.

The VDSCP Certification performance acceptance criteria are that the overall mean bias and precision calculated using CLSI EP9-A2 methods for total Vitamin D are within the limits of ± 5.0% and ≤ 10.0%, respectively. The MassTrak™ Vitamin D assay achieved a Mean bias of 0.6% from the VDSCP reference values and a mean imprecision of 4.9%, therefore meeting the certification performance criteria.

MassTrak™ Vitamin D Assay Performance Characteristics

The MassTrak™ Vitamin D precision study was based on CLSI EP05-A3. Single site precision was determined using four serum panels (Panel A-D) and two MassTrak™ Vitamin D quality controls. Precision performance for 25(OH)D2, 25(OH)D3 and Total 25(OH)D, total precision CVs ≤ 9.0% and repeatability within run CVs ≤ 8.1% for 4 patient pools and Quality Controls across the 20 days (n =80).

Precision was verified in a multi-site precision evaluation conducted at three sites according to CLSI EP05-A3, providing a total imprecision of ≤ 6.8 %CV for 25(OH)D2 and 25(OH)D3 and total 25(OH)D.

Sensitivity testing was conducted in accordance with CLSI EP 17-A2. 25(OH)D3 Limit of Detection and Limit of Quantification were 2.7 nmol/L and 7.3nmol/L respectively. 25(OH)D2 Limit of Detection and Limit of Quantification were 2.7 nmol/L and 5.7nmol/L respectively.

The carryover of the assay was determined to be 0.87 nmol/L for 25(OH)D2, 0.37 nmol/L for 25(OH)D3 and 1.24 nmol/L for Total 25(OH)D, which is significantly lower than the Limit of Quantitation of the assay for the analytes.

Linearity was assessed using CLSI EP6-A. The analytes 25(OH)D2 and 25(OH)D3 were demonstrated to be linear from 10 nmol/L to 375 nmol/L, within a range of ± 10% in this interval. Total 25(OH)D method was demonstrated to be linear from 20 nmol/L to 750 nmol/L, within ± 10% in that interval.

Interference testing was conducted according to the procedures described in CLSI EP7-A. Compounds tested included endogenous compounds: 5-Cholesten-3B-ol-7-one, 7-Dehydrocholesterol, Albumin, Bilirubin, Billirubin conjugate, Cholesterol, Creatinine, gc-globulin, Hemoglobin, Triglycerides, Uric Acid, Vitamin B12, Vitamin D2, and Vitamin D3. Exogenous compounds tested were: Amphotericin B, Atorvastatin, Cefaclor, Dextran 40, Epoetin Alfa, Erythromycin, Folic Acid, Gentaminicin, Glipizide, Glyburide, Insulin, Intralipid, Itraconazole, Kanamycin A, Kanamycin B, Ketoconazole, Lovastatin, Methicillin (Methicillin Sodium), Misoprostol, Morphine Sulfate, Methotrexate, Nifedipine, Omeprazole, Piperacillin, Prazosin (hydrochloride), Prednisolone, Prednisone, Rifampin, Tobramycin, Vancomycin and Verapamil, Potassium-EDTA, Sodium Citrate, Sodium Heparin and Lithium Heparin and Metabolites tested included: 1-alpha-(OH)Vitamin D3, 1-alpha-(OH)Vitamin D2, 1,25di(OH)Vitamin D2, 1,25di(OH)Vitamin D3, 3-epi-25(OH)Vitamin D2, 3-epi-25(OH)Vitamin D3, 23R,25di(OH)Vitamin D3, 24R,25di(OH)Vitamin D3, 24S,25di(OH)Vitamin D3. All compounds with the exception of 3-epi-25(OH)D2 and 3-epi-25(OH)D3 demonstrated a mean recovery of between 85% - 115%. There was significant interference from 3-epi-25(OH)D2 for 25(OH)D2 and 3-epi-25(OH)D3, for 25(OH)D3 which co-elute with the analytes of interest but no significant interference from 24,25di(OH)D3 which has been shown to be present in serum at equivalent or higher concentrations than the 3-epimer according to the literature.

Conclusion

The MassTrak™ Vitamin D kit calibrator materials are traceable to NIST SRM2972 via a documented unbroken chain of calibrations. The accuracy of this traceability to NIST SRM2972 has been verified through participation of the Vitamin D Standardisation Certification Program (VDSCP) in which the MassTrak™ Vitamin D Assay achieved a mean % bias of 0.6 % from the VDSCP reference values and an imprecision of 4.9%.


References & Acknowledgements:


Financial Disclosure

DescriptionY/NSource
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SalaryyesWaters Technologies Ireland Ltd
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Stockno
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IP Royalty: no

Planning to mention or discuss specific products or technology of the company(ies) listed above:

yes