Determining methemoglobin in blood by zero-crossing-point first-derivative spectrophotometry.
We determined methemoglobin in blood by zero-crossing-point first-derivative spectrophotometry. After lysis of erythrocytes, hemoglobin was converted into oxyhemoglobin and the first derivative spectrum was recorded between 405 and 425 nm. At the exact point where the first-derivative spectrum of oxyhemoglobin was zero ("zero-crossing point"), the first-derivative value of oxyhemoglobin and methemoglobin mixture was proportional to the methemoglobin concentration. The standard curve was linear for all proportions of methemoglobin. Within-assay precision (CV) was 3.4% for a 20% methemoglobin content. Correlation with results by the Evelyn and Malloy method was very good for high proportions of methemoglobin (greater than 10%), but the proposed technique was far better for low methemoglobin percentages because of its linearity, its high sensitivity, and its low detection limit.
Taulier
A
A
Laboratoire Central de Biochimie, Centre Hospitalier de Bicetre, Kremlin-Bicetre, France.
Levillain
P
P
Lemonnier
A
A
D006801:Humans; D008706:Methemoglobin / Q000032:analysis*; D010108:Oxyhemoglobins / Q000032:analysis; D013053:Spectrophotometry / Q000379:methods
D010108:Oxyhemoglobins; D008706:Methemoglobin