Improvement on the modified Lowry method against interference of divalent cations in soluble protein measurement

摘要: This paper systematically investigated the interference of calcium and magnesium in protein measurement with a modified Lowry method first proposed by Frolund et al. (Appl Microbiol Biotechnol 43:755–761, 1995). has past been largely ignored resulting variable unreliable results when applied to natural water matrices. We discovered significant formation precipitates that lead decline light absorbance at 750 nm during determination. Underestimation concentration (sometimes even yielding negative concentrations) low experiment reproducibility were demonstrated high concentrations divalent cations (e.g., [Ca2+] over 1 mmol L−1). To eliminate from magnesium, two pretreatment strategies established based on cation exchange dialysis. These pretreatments convenient found be highly effective removing samples. By using these pretreatments, proteins standard solutions wastewater samples successfully quantified good reliability reproducibility. In addition, we simultaneous quantification humic substances was not affected pretreatments. approaches are expected applicable substance determination different research fields, cases where is sensitive concentrations.