Diazyme's 25-OH Vitamin D Assay for Clinical Chemistry Analyzers new

Chemistry Analyzers for Diazyme's 25-OH Vitamin D Assay for Clinical Chemistry Assay include those listed below but are not limited to:

Alfa Wassermann

Dimension Vista*

Pentra 400

Konelab 30*
Indiko Plus*

Cobas Integra 400/800*
Cobas Mira
Modular P


*Parameters Proposed

Diazyme's 25-OH Vitamin D Assay for Clinical Chemistry Analyzers

Assay Principle:

Diazyme's Enzyme-Immunoassay FemtoQuant™ 25-Hydroxy Vitamin D test is based on the principle of α-complementation of the enzyme β-galactosidase and the competition between an enzyme donor-25-OH Vitamin D conjugate, an anti-Vitamin D antibody and the 25-OH Vitamin D content of a serum sample. Samples with higher 25-OH Vitamin D concentrations produce higher β-galactosidase activities and vice versa. A nitrophenyl-ß- galactoside derivative (NPG) is used as the enzyme substrate. The reaction's product has maximum absorbance at 415 nm. The 25-OH Vitamin D concentration of a sample is proportional to the measured β-galactosidase activity.

Diazyme 25-OH Vitamin D for Clinical Chemistry Analyzers Kit Configuration:

Diazyme's Vitamin D assay kit contains 1 sample diluent and 3 liquid stable reagents and calibrator set. The intended use is for the quantitative determination of 25-(OH) D levels in serum or plasma, on automated chemistry analyzers, and for the assessment of Vitamin D sufficiency.

Assay Features:

  • Multiple instrument options available
  • Reagent kit, calibrator and control sets offered separately
  • Liquid Stable format
  • Minimal sample of only 20 μL needed
  • 15-19 minutes to first result
  • Report total 25-OH Vitamin D (D2+D3)
  • No off-line sample pretreatment needed
  • Excellent Correlations to LC-MS/MS and leading 25-OH Vitamin D Immunoassays
  • Cost effective

Assay Procedure:

The assay procedure for the Roche Modular P chemistry analyzer is shown below: Specimen calibrator, control and samples are first diluted onboard: 20 μL of serum which is then diluted with 155 μL of diluent. Once diluted an additional 20 μL of the diluted specimen is then used for analysis.

Assay Accuracy:

The performance of this assay was compared to the performance of a legally marketed 25-OH Vitamin D enzyme immunoassay. The results for 98 serum samples are shown in the table below:

Deming Regression Analysis95% Confidence Interval
Slope1.005 (0.969 to 1.041)
Intercept-0.21 (-2.15 to 1.73)
Correlation Coefficient0.984 (0.976 to 0.989)

Assay Linearity:

Eleven levels of linearity were prepared by diluting a high serum sample with Vita-min D-depleted serum. Linearity levels were prepared according to the CLSI EP6-A guideline. Measurements were done in triplicates. The assay was found to be linear between 7.6 and 147.8 ng/mL.

The assay demonstrated excellent correlations with results determined by LC-MS/MS and DiaSorin CLIA methods with R2 values of >0.95 and 0.96.

Assay Sensitivity:

The LOB, LOD, and LOQ of Diazyme's 25-OH Vitamin D Assay for Clinical Chemistry were determined according to CLSI (formerly NCCLS) EP17-A guidelines. The assay's LOB = 2.0 ng/mL; LOD = 3.5 ng/mL; and LOQ = 7.6 ng/mL.