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We describe a new and specific method for measurement of lecithin palmitic acid in amniotic fluid. Dipalmitoyl lecithin, the major alveolar surfactant, has previously been estimated by measuring the lecithin-sphingomyelin ratio, total lecithin, total phospholipid phosphorus, and (or) total palmitic acid. Our method is more specific for estimation of dipalmitoyl lecithin, because nonphospholipid sources of palmitic acid are removed by solvent extraction. Using a hexane/2-propanol/sulfuric acid system, we obviated the major interferences from triglycerides and free fatty acids. The palmitic acid derived from the phospholipid fraction is measured by gas-liquid chromatography of its methyl ester. No contribution appears to be made by sphingomyelin palmitic acid--probably owing to the mild hydrolysis conditions. The measured palmitic acid therefore appears to be derived from lecithins, principally dipalmitoyl lecithin. The value for palmitic acid determined by this method correlates well with the lecithin-sphingomyelin ratio and total phospholipid phosphorus. Infants are unlikely to develop respiratory distress syndrome when the measured palmitic acid in amniotic fluid exceeds 8.0 mg/liter, which corresponds to an lecithin-sphingomyelin ratio of 2.0.
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
March 1980,
Clinica chimica acta; international journal of clinical chemistry,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
January 1974,
British medical journal,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
January 1977,
Clinica chimica acta; international journal of clinical chemistry,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
January 1980,
Clinical and experimental obstetrics & gynecology,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
November 1976,
Scandinavian journal of clinical and laboratory investigation,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
November 1974,
Clinical chemistry,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
April 1973,
American journal of obstetrics and gynecology,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
January 1972,
Archives francaises de pediatrie,
M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
October 1977,
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M P Ip, and
T F Draisey, and
R J Thibert, and
G L Gagneja, and
G M Jasey
July 1982,
Medical laboratory sciences,
