PEP determination of serum bicarbonate

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PEP is called phosphoenolpyruvate tricyclohexylammonium salt (cyclohexylamine salt), which can be used for the determination of carbon dioxide in blood gas analysis and the determination of serum bicarbonate, usually at the same time as pH measurement, for metabolic and respiratory Diagnosis of acidosis.

Phosphoenolpyruvate tricyclohexylammonium salt PEP

Principle of PEP Determination of Bicarbonate

Phosphoenolpyruvate is an important substance in the photosynthesis of plant chloroplasts. It reacts with carbon dioxide to fix carbon and finally generates sugars and releases oxygen. Its reaction with carbon dioxide is extremely sensitive, so its ammonium salt is used to detect trace amounts of carbon dioxide or bicarbonate in serum (carbon dioxide is dissolved in water to generate bicarbonate). PEP and bicarbonate generate oxaloacetic acid and dihydrogen phosphate under the catalysis of PEPC and magnesium ions, and then under the catalysis of MDH, oxaloacetic acid reacts with NADH+H+ to generate malic acid and NAD+, and then the absorbance change at 405nm is detected. The bicarbonate content can be analyzed.


PEP test reagent for determination of bicarbonate

Blood sampling: The subjects will be fasted for 12 hours, and blood samples will be collected after 24 hours without drinking. The pregnant women should be in normal conditions for two weeks before the blood sampling. The pregnant women should be tested after delivery or 3 months after the termination of breastfeeding. Whether there are any drugs that affect the taking and the blood sampling season are recorded. . Except for bedridden patients, try to take blood from the sitting position. After 5 minutes of sitting still, use the elbow vein and the tourniquet for no more than 1 minute. The puncture should be released immediately.


Blood sample: Plasma uses heparin (or dipotassium EDTA) as anticoagulant. Serum or plasma is centrifuged at room temperature for 30-45 minutes, and the test is completed within 2 hours. Otherwise, the centrifuge tube sample should be covered and stored at 2-8 degrees Celsius.

Buffer: Tris buffer with pH=6.5, 25mmol/L is used.

Substrate: phosphoenolpyruvate PEP 6.3mmol/L, NADH (reduced coenzyme I, nicotinamide adenine dinucleotide) 0.45mmol/L

Enzyme preparation: phosphoenolpyruvate carboxylase PEPC 200U/L+magnesium ion reagent 8.0mmol/L, malate dehydrogenase MDH at least 600U/L.


Using PEP to determine serum bicarbonate can refer to the sensitivity: when the carbon dioxide concentration is 25mmol/L, the absorbance is 1.3625~1.4750; the result reference value is 20.0~29.0mmol/L. Desheng is a manufacturer of in vitro diagnostic reagent raw materials, which can produce and supply PEP and enzyme preparations, buffers or other types of substrates. You can purchase reagents for testing or directly use a complete set of carbon dioxide kits for testing.