LDL-C LDL-C holesterol assay kit(Direct method)

In vitrote st for the quantitative determination of LDL-Cholesterol (LDL-C) concentration in serum and plasma on photometric systems. LDL-Cholesterol is directly related to the risk of developing coronary heart disease. A low HDL/LDL-Cholesterol ratio is directly related to the risk of developing coronary artery disease. Elevated LDL-Cholesterol is the primary target of cholesterol lowering therapy.

Principle

The System monitors the change in absorbance at 546nm. This change in absorbance is directly proportional to the concentration of cholesterol in the sample and is used by the System to calculate and express the LDL-cholesterol concentration.

Storage and stability

Up to expiration date indicated on the label, when stored unopened at 2-8℃ and protected from light.

Once opened, the reagents are stable for 28 days when refrigerated on the analyzer or refrigerator.

Contamination of the reagents must be avoided. 

Do not freeze the reagents.

Once dissolved, the calibrator are stable for 7 days at 2–8℃, the control are stable for 7 days at 2–8℃ , do not freeze.

Reagents preparation

Sample requirements

Serum is suitable for samples. EDTA plasma, whole blood, hemolysis and urine are not recommended for use as a sample. Freshly drawn serum is preferred specimen.

Applicable instrument

Hitachi 7180/7170/7060/7600 automatic biochemical analyzer, Di Rui CS-400B, Abbott c16000, OLYMPUS AU640 automatic biochemical analyzer.

Method

1. Reagent preparation ：Liquid reagent can be used when opened

2. Measurement：

Main wavelength 546nm

Sub wavelength 700nm

Temperature 37℃

Type 2-Endpoint

Calibration Preparation

Carefully open the bottle, avoiding the loss of lyophilizate, and pipette in exactly 1.0 mL of distilled/deionized water. Carefully close the bottle and dissolve the contents completely by occasional gentle swirling within 30 minutes. Avoid the formation of foam. The dissolved calibrator can be used without any other Pretreatment.

Calibration

It is recommended to use the Calibrator from Hyasen and distilled/deionized water for two-point calibration.

Calibration frequency:

After reagent lot changed. 

As required following quality control procedures.

Steps

△A=[（A2-A1）sample / calibrator]-[（A2-A1） blank]

Reference intervals [1,2]

Each laboratory should establish its own reference intervals based upon its patient population. The reference intervals measured at 37 ℃ listed below were taken from literature:0~4. 11 mmol/L

Quality control

At least two levels of control material should be analyzed with each batch of samples. Each laboratory should establish its own internal quality control scheme and procedures for corrective action if controls do not recover within the acceptable tolerances.

Interferences/specificity

The following substances were tested for interference with this methodology. Criterion: Recovery within ±10 % of initial value.

Reagent blank absorbance

The absorbance of reagent blank at 546nm should be <0.03.

Sensitivity/detection limit

When testing 1.00mmol/L LDL cholesterol, the absolute value of absorbance difference should not be less than 0.04.

Precision

Within-run : CV≤3%

Between-run: CV≤5%

Linearity range

1. Within the interval of 0. 15 ～ 15.00mmol/L, the correlation coefficient r should not be less than 0.990;
2. Within the interval of [0. 15 ～ 2.00]mmol/L, the absolute deviation between the measured concentration and the estimated value should not exceed ± 0.20mmol/L; In the interval of (2.50 ～15.00 In the interval of]mmol/L, the relative deviation between the measured concentration and the estimated value should not exceed ±10%.

Warnings and precautions

1. For in vitro diagnostic use.

2. Take the necessary precautions for the use of laboratory reagents.

3. Preservative contained. Do not swallow. Avoid contact with skin and mucous membranes.

4. Disposal of all waste material should be in accordance with local guidelines.

References

[1] National Committee for Clinical Laboratory Standards, How to Define, Determine, and Utilize Reference Intervals in the Clinical Laboratory, Approved Guideline, CLSI publication C28-A, Villanova, PA(1995).

[2] Tietz, N. W., ed., Fundamentals of Clinical Chemistry, 3rd Edition, W.B. Saunders, Philadelphia, PA (1987).

[3] CLSI. Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline-Second Edition. CLSI document EP5-A2 [ISBN 1-56238-542-9. CLSI, 940 West Valley Road, Suite 1400, Wayne, PA19087 USA, 2008.963-968.