Editing Phospholipid (section)

== Characterization ==
Phospholipids are optically highly [[birefringent]], i.e. their refractive index is different along their axis as opposed to perpendicular to it. Measurement of [[birefringence]] can be achieved using cross polarisers in a microscope to obtain an image of e.g. [[Vesicle (biology)|vesicle]] walls or using techniques such as [[dual polarisation interferometry]] to quantify lipid order or disruption in supported bilayers.{{citation needed|date=September 2022}}

=== Analysis ===
There are no simple methods available for analysis of phospholipids, since the close range of polarity between different phospholipid species makes detection difficult. Oil chemists often use spectroscopy to determine total phosphorus abundance and then calculate approximate mass of phospholipids based on molecular weight of expected fatty acid species. Modern lipid profiling employs more absolute methods of analysis, with [[NMR spectroscopy]], particularly [[Phosphorus-31 nuclear magnetic resonance|<sup>31</sup>P-NMR]],<ref>{{cite journal | url =  http://www.jlr.org/content/29/5/679 | title =  High resolution 31P NMR of extracted phospholipids |author1=N. Culeddu  |author2=M. Bosco  |author3=R. Toffanin  |author4=P. Pollesello | year = 1998 | journal = Magnetic Resonance in Chemistry | volume = 36 | issue =  12 | pages = 907–912 | doi=10.1002/(sici)1097-458x(199812)36:12<907::aid-omr394>3.0.co;2-5| s2cid = 85602251 }}</ref><ref>{{cite journal | doi = 10.1007/s12154-012-0090-1 | title = The lipidome and proteome of oil bodies from Helianthus annuus (common sunflower) | year = 2013 | last1 = Furse | first1 = Samuel | last2 = Liddell | first2 = Susan | last3 = Ortori | first3 = Catharine A. | last4 = Williams | first4 = Huw | last5 = Neylon | first5 = D. Cameron | last6 = Scott | first6 = David J. | last7 = Barrett | first7 = David A. | last8 = Gray | first8 = David A. | journal = Journal of Chemical Biology | volume = 6 | issue = 2 | pages = 63–76 | pmid = 23532185 | pmc = 3606697}}</ref> while [[High-performance liquid chromatography|HPLC]]-[[Evaporative light scattering detector|ELSD]]<ref>{{cite journal | title = HPLC analysis of phospholipids in crude oil for evaluation of soybean deterioration  |author1=T.&nbsp;L. Mounts |author2=A.&nbsp;M. Nash | journal = Journal of the American Oil Chemists' Society | year = 1990 | volume =67 | issue =11 | pages = 757–760 | doi = 10.1007/BF02540486|s2cid=84380025 | url =https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=24329&content=PDF }}</ref> provides relative values.