Dipalmitoylphosphatidylcholine in amniotic fluid quantified by fast-atom-bombardment mass spectrometry.

Abstract

Dipalmitoylphosphatidylcholine (DPC) is quantified by taking advantage of stable-isotope-labeled d9-DPC as internal standard. Use of a mass spectrometer to measure the ratio of d9/d0 makes this procedure a quantitative one. d9-DPC was synthesized by refluxing dipalmitoylethanolamine with d3-methyl iodide in methanol in the presence of sodium bicarbonate for 26 h. The yield of d9-phosphatidylcholine (d9-lecithin) was 89% after column-chromatographic purification. Fast atom bombardment was used to desorb the preformed phosphatidylcholine ions in a mass spectrometer of Nier-Johnson geometry. In our assessment of accuracy and precision of this technique, we found a correlation coefficient of 0.9994 between signal and sample concentration. The method was less precise when the total d0- plus d9-DPC was less than 0.2 micrograms or when the ratio of d0- to d9-lecithin exceeded 100. The within-run CV was about 1.0%. The amount of DPC in amniotic fluid samples assessed by mass spectrometry was compared with results for total phosphatidylcholine quantified by thin-layer chromatography. The fate of DPC in various laboratory manipulations was also studied.

Lipidomic profiling of amniotic fluid and its application in fetal lung maturity prediction

“…Nowadays, this testing method was much less commonly used in clinical laboratories due to the technical barriers of TLC that is often inaccurate, time‐consuming, and labor intensive . Alternatively, there had been some studies about the measurement of the L/S ratio by fast atomic bombardment mass spectrometry . Later, Kwak and his colleagues established new methods to measure the L/S ratio on liquid chromatography‐tandem mass spectrometry (LC–MS/MS) and matrix‐assisted laser desorption and ionization time of flight mass spectrometry (MALDI‐TOF MS).…”

Proteomics: A Novel Methodology to Complement Prenatal Diagnosis of Chromosomal Abnormalities and Inherited Human Diseases

“…97 The first attempts to apply MS for prenatal diagnosis of inherited metabolic diseases originated in the early 1980s. [98][99][100] By taking advantage of several MS methods, investigators sought to identify and quantify several metabolic products to assess fetal lung maturity in utero by the identification of dipalmitoylphosphatidylcholine, 98 or to diagnose prenatal genetic disorders such as carnitine deficiency 99 or isovaleric acidemia. 100 These preliminary experiments were an important prerequisite for modern molecular research and diagnosis of human genetic disorders by proteomics.…”

Phospholipid Profile of Amniotic Fluid in Ovine Model of Congenital Diaphragmatic Hernia (CDH): The Effect of Fetal Tracheal Occlusion

“…9,10 However, the most frequently used FLM test is based on a nonspecific analysis, as in the case of lecithin determination, which does not specifically measure the predominant surfactant dipalmitoyl-PC species but includes all of the disaturated phosphatidylcholines. 11 In this regard, new perspectives are opening up by exploiting the AF metabolic/lipidic profile, 12 although, to our knowledge, none or very few studies combine the metabolomics/lipidomics approach with the investigation of CDH.…”

“…Among PC molecular species, dipalmitoyl-PC [PC(16:0/16:0), DPPC] has a major role in lowering surface tension at the alveolar air–water interface. , However, the most frequently used FLM test is based on a nonspecific analysis, as in the case of lecithin determination, which does not specifically measure the predominant surfactant dipalmitoyl-PC species but includes all of the disaturated phosphatidylcholines …”