Establishment of a quantitative, qualitative, and high-throughput analysis of sulfatides from small amounts of sera by matrix-assisted laser desorption ionization–time of flight mass spectrometry

Based on our previous measurements of sulfatides, we further developed a quantitative, qualitative, and high-throughput analytical method for serum sulfatides as forms of lysosulfatides by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Using 0.1 N NaOH in 90% MeOH for saponification instead of absolute MeOH, as previously used, we succeeded in eliminating the formation of lysosulfatide artifacts, facilitating much more sensitive detection. The use of MonoTip C18 allowed quantitation of serum sulfatides from 100 50-μl serum specimens within 1 working day. Purification of lysosulfatides with MonoTip C18 also gave rise to clear MALDI-TOF MS spectra, allowing overall analysis of sphingoid molecular species of sulfatides in serum. The composition was as follows: d18:1 (61.3 ± 2.8%), d18:2 (13.3 ± 1.7%), t18:0 (11.8 ± 1.5%), d18:0 (7.6 ± 0.8%), d20:0 (3.0 ± 1.2%), t20:0 (2.3 ± 0.8%), and d20:1 (1.6 ± 0.5%). This is also the first detailed report on sphingoid molecular species of sulfatides in human serum. We believe that this method is suitable for daily clinical analysis of sulfatides in various clinical samples such as blood, urine, cerebrospinal fluid, and specimens from biopsies.