Related Experiment Videos
Sodium oxalate corrects calcium interference in Lowry protein assay
1Department of Surgery, Oregon Health Science University, Portland 97201.
The Journal of Surgical Research
|September 1, 1989
Summary
Physiologic calcium levels significantly impact protein quantification using the Lowry assay. Pre-treating samples with sodium oxalate can reduce these errors by up to 95%, ensuring more accurate protein measurements.
Area of Science:
- Biochemistry
- Analytical Chemistry
Background:
- The Lowry assay is a common method for protein determination.
- Calcium is a ubiquitous ion in biological systems.
- High calcium concentrations are known to interfere with the Lowry assay.
Purpose of the Study:
- To investigate the interference of physiologic calcium levels with the Lowry assay.
- To determine the efficacy of sodium oxalate in mitigating calcium interference.
Main Methods:
- Bovine serum albumin standards were tested using the Lowry assay.
- Calcium chloride was added at concentrations ranging from 0 to 5 mM.
- Sodium oxalate was used as a pretreatment for calcium-spiked samples.
Main Results:
- 1-2 mM calcium caused up to 384% error in low protein concentrations (12.5-50 µg/ml).
- 1-2 mM calcium caused up to 40% error in higher protein concentrations (100-400 µg/ml).
- Sodium oxalate pretreatment reduced errors by 70-95% across tested concentrations.
Conclusions:
- Physiologic calcium levels cause significant errors in Lowry assay protein estimations.
- Routine pretreatment with sodium oxalate improves accuracy in biological samples.
- Sodium oxalate is a simple and effective method to correct for calcium interference.