Calcium (Ca) Assay Kit – Bulk Reagents


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Selling unit: per 100ml

Product Name

  1. Common name: Calcium (Ca) assaykit (azoarsine method)
  2. English name: Ca Reagent Kit (Arsenazo Method)

Reagent Ratio

Single reagent

Intended Use

Used to determine the amount of Ca in human serum, plasma or urine.

Increased Ca levels are seen in primary hyperthyroidism, tumor bone metastases, vitamin D excess and malignant tumors. decreased Ca levels are seen in hypothyroidism, pseudohypothyroidism, rickets, steatorrhea, calcium loss syndrome, vitamin D deficiency and renal disease.

Test Principle

Arsenazo III is a calcium-binding reagent with a specific affinity for Ca. Under weakly acidic conditions, it reacts with Ca to form a blue-violet complex with a maximum absorption peak at 660 (630-670) nm, and the absorbance A is proportional to the Ca concentration within a certain range. The chelation of arsenazo III with Ca is not affected by other cations normally present in serum and plasma.

Main Components

1 For the reagent components included in the product.

Calcium (Ca)Assay Kit & Bulk Reagents

*Components are not interchangeable in kits with different lot numbers.

*Reagent components not included in the product, but necessary for the test: outsourced normal and abnormal QCs and calibrators.

Storage Conditions And Expiration Date

The kit is stored at 18-25°C away from light and is valid for one year.

Reagents that have been opened are taken care not to be contaminated and the reagents are stabilized in the instrument compartment (18-25°C) for one month.

The reagents must not be frozen.

Applicable Instruments

Hitachi 7180/7600; Olympus AU680/2700; Toshiba TBA120; Myriad BS2000M/480; Siemens ADVIA 1800/2400 series automatic biochemical analyzers.

Sample Request

Serum or plasma specimens or urine specimens to avoid hemolysis. Plasma should only be anticoagulated with heparin, other anticoagulants such as citrate, oxalate and EDTA interfere with the assay and should be avoided. Samples are stable at room temperature (15-25°C) for 7 days, 2-8°C for 3 weeks and frozen (-20°C) for at least 8 months in the absence of microbial contamination.

Test Method

  1. Reagent preparation: liquid reagents are ready to use out of the bottle.
  2. test conditions that must be met: (different test instruments can be requested according to the different parameters on the machine)

Calcium (Ca)Assay Kit & Bulk Reagents

-Operating steps.

Calcium (Ca)Assay Kit & Bulk Reagents

*Reagents and sample volumes can be increased or decreased in proportion to the requirements of different biochemical analyzers.

  1. Calibration procedure.

Randox calibration sera are recommended, and the method of choice for Randox calibration sera is arsenazo III (ARIII).

  1. QC control procedures.

It is recommended that each laboratory establish its own quality control system and select appropriate quality control products for quality control. The measured values of QC products should be within the specified range. If outside the specified range, it is necessary to take appropriate measures or contact the manufacturer.

  1. Calculation.

Ca concentration in the sample (mmol/L) =(ΔAsample – ΔAblank ) × Cstandard / (ΔAstandard – ΔAblank )

Positive Judgment Value

Serum, plasma: 2.08 ~ 2.80 mmol/L

It is recommended that laboratories validate this reference range or establish their own range of reference values.


Interpretation Of Test Results

The assay of Ca in serum, plasma or urine is only one of the indicators used by the clinician to make a diagnosis of the patient. The clinician must also make a comprehensive judgment based on the patient’s physical symptoms, medical history and other diagnostic items and diagnostic tools.

Limitations Of The Test Method

Bilirubin ≤ 40 mg/dL and celiac ≤ 500 mg/dL did not interfere with the assay.

Product Performance Index

Absorbance of reagent blank: wavelength 660 nm, optical diameter 1.0 cm, temperature 37°C, A0  ≤ 1.2.

Analytical sensitivity: the kit tests 3 mmol /L of the test substance, the absorbance change value ΔA ≥ 0.01.

Linearity interval: test serum samples, reagent linearity 1.00 ~ 4.00 mmol/L interval, linear correlation coefficient|r| should not be less than 0.990; in the 1.00 ~ 2.0 mmol/L interval, the absolute deviation of linearity should not exceed 0.2 mmol/L; in the (2.0 ~ 4.00 mmol/L interval, the relative deviation of linearity should not exceed ±10% ;

Accuracy: Repeatability CV ≤ 3.0%; relative extreme difference between batches ≤ 5.0%.

Accuracy: Relative deviation ≤ 5.0%.


  1. 1. This product is for in vitro diagnosis only.
  2. 2. Avoid contamination when using the reagent, the container used must be clean, and please take necessary precautions, do not swallow, and avoid contact with skin and mucous membrane.
  3. 3. Please dispose of the measured samples and waste liquids in accordance with the relevant national and local laws and regulations.
  4. 4. When changing the reagent lot number, please recalibrate.
  5. 5. High-fat samples can cause falsely elevated results, which can be corrected by using a sample blank tube: add 20 μl of sample to 1.00 ml of saline. Zero the sample with saline at 660 nm, read the absorbance value of the sample blank tube, and subtract the absorbance value of the sample blank tube from the absorbance value of the sample tube.


  1. Leary NO, et al ClinChem (1992); 38:1342
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