Enzymic colorimetric determination of phosphatidylglycerol in amniotic fluid.

Abstract

We describe a procedure for the enzymic, colorimetric determination of phosphatidylglycerol in amniotic fluid. After extraction into chloroform:methanol (2:1 by vol) and evaporation, the phospholipid-containing residue is redissolved in a non-ionic detergent, which thus provides an aqueous sample. The subsequent enzymic reaction sequence involves phospholipase-catalyzed hydrolysis of glycerol from its phospholipid. Subsequent enzyme-catalyzed reactions phosphorylate this glycerol and oxidize the resulting glycerol phosphate to produce hydrogen peroxide, which is reacted to produce an intense red chromogen in the peroxidase-catalyzed coupling of 4-aminoantipyrine and 2-hydroxy-3,5-dichlorobenzenesulfonate. When used in conjunction with previously reported enzymic techniques for determination of lecithin and sphingomyelin, this procedure may provide an accurate and precise "lung profile" for assessment of fetal lung maturity.

Ultraviolet and light absorption spectrometry

“…Phosphatidylglycerol in amniotic fluid was determined by addition of a lipase enzyme to produce glycerol, phosphorylation, and oxidation giving hydrogen peroxide, and measurement of the intense red chromogen of the peroxidasecatalyzed coupling of 4-aminoantipyrene with 2-hydroxy-3,5-dichlorobenzenesulfonate (18). Serum triglycerides have been determined by measuring the absorbance of the product of complicated coupled-reaction schemes, the final step of which is reaction between titanium(II) chloride and 4-(2pyridylazo)resorcinol (508 nm) (327), 4-aminoantipyrine and iV,iV-diethyl-m-toluidine (540 nm) (498), and 4-aminoantipyrine AyV-dimethyl-m-toluidine and potassium ferrocyanide (545 nm) (499).…”