PRINCIPLE OF THE METHOD
Direct method for determining inorganic phosphate.
Inorganic phosphate reacts in acid medium with ammonium molybdate to
form a phosphomolybdate complex with yellow color.
The intensity of the color formed is proportional to the inorganic
phosphorus concentration in the sample1,2.
CLINICAL SIGNIFICANCE
Phosphorus is an essential mineral for tissue bone formation and is
required by every cell in the body for normal function. Approximately 85%
of the body phosphorus is found in bone and in teeth.
Low levels of phosphorus, can be caused by hypervitaminosis D, primary
hyperparathyroidism, renal tubular disorders, antacids or malabsortion.
High levels of phosphorus can be caused by diet, bone metastases, liver
disease, alcohol ingestion, diarrhea and vomiting1,5,6.
Clinical diagnosis should not be made on a single test result; it should
integrate clinical and other laboratory data.
PRECAUTIONS
R: H314-Causes severe skin burns and eye damage.
Follow the precautionary statements given in MSDS and label of the
product.
PREPARATION
Reagent and Standard are ready to use.
STORAGE AND STABILITY
All the components of the kit are stable until the expiration date on the
label when stored tightly closed at 2-8ºC, protected from light and
contaminations prevented during their use.
Do not use reagents over the expiration date.
Signs of reagent deterioration:
- Presence of particles and turbidity.
- Blank absorbance (A) at 340 nm 0,54.
ADDITIONAL EQUIPMENT
- Spectrophotometer or colorimeter measuring at 340 nm.
- Matched cuvettes 1,0 cm light path.
- General laboratory equipment (Note 2).
SAMPLES
- Serum or plasma1,5:
Free of haemolysis. Serum or plasma should be removed from the
clot as quickly as possible to avoid elevation of serum phosphorus
from hydrolysis or leakage of phosphate present in erythrocytes.
Stability: 7 days at 2-8ºC.
- Urine1,2 (24 h):
Collect the specimen into a bottle containing 10 mL of 10% v/v
hydrochloric acid (HCl) to avoid phosphate precipitations. Adjust to
pH 2. Dilute the sample 1/10 with distilled water. Mix. Multiply the
result by 10 (dilution factor). Stability: 10 days at 2-8ºC.
INTERFERENCES
Hemolyzed specimens are unacceptable because erythrocytes contain high
concentrations of organic phosphate esters, which can be hydrolyzed to inorganic
phosphate during storage. Inorganic phosphate increases by 4 to 5 mg/dL per
day5
. A list of drugs and other interfering substances with phosphorus
determination has been reported by Young et. al3,4.
NOTES
1. PHOSPHORUS CAL: Proceed carefully with this product because due its
nature it can get contaminated easily.
2. Most of the detergents and water softening products used in the laboratories
contain chelating agents and phosphates. It is recommended to rinse
glassware in diluted nitric acid and water before using.
3. Calibration with the aqueous standard may cause a systematic error in
automatic procedures. In these cases, it is recommended to use a serum
Calibrator.
4. Use clean disposable pipette tips for its dispensation.
5. SPINREACT has instruction sheets for several automatic analyzers.
Instructions for many of them are available on request.
