Lipidomix mass spec standard solution

Deuterium-labeled ceramide LIPIDOMIX^® Mass Spec Standard Solution, EquiSPLASH™ LIPIDOMIX^® Mass Spec Standard Solution, and N-palmitoyl-d31-D-erythro-sphingosine (d31-Cer16:0, MW 569.1) were purchased from Avanti Polar Lipids (Alabaster, AL, USA). Deuterated cholesterol-2,2,3,4,4,6-d6 (d6-CH MW 392), deuterated cholesterol sulfate sodium salt (d7-CHS, MW 495), and hexadecanoic-9,9,10,10,11,11,12,12,13,13,14,14,15,15,16,16,16-d17 acid (d17-PA, MW 273), glyceryl trihexadecanoate-d98 (d98TG 48:0, MW 906), and n-hexadecyl-1,1,2,2-d4 hexadecanoate-16,16,16-d3 (d7WE, MW 488) were purchased from CDN Isotopes Inc. (Pointe-Claire, Quebec, Canada). Details on the internal standards used are reported in Table S1. HPLCMS-grade ethyl acetate, acetone, and chloroform were purchased from Carlo Erba (Milan, Italy). HPLCMS-grade acetonitrile, isopropanol, and methanol were purchased from Biosolve (Chimie SARL, Dieuze, France; BV, Valkenswaard, Netherlands). Ultra-HPLCMS-grade water was purchased from LiChrosolv by Merck (Darmstadt, Germany). Butylated hydroxytoluene (BHT) and the mobile-phase modifiers ammonium formate (NH₄COOH) and ammonium fluoride (NH₄F) were purchased from Sigma Aldrich (Milan, Italy). The mass calibration solution was prepared from Agilent Technologies Tuning mix (HP0321 solution, Agilent Technologies, Santa Clara, CA, USA) upon dilution in acetonitrile.

N-palmitoyl-D-erythro-sphingosine (Cer16:0), N-stearoyl-D-erythro-sphingosine (Cer18:0), N-lignoceroyl-D-erythro-sphingosine (Cer24:0) and N-nervonoyl-D-erythro-sphingosine (Cer24:1) were obtained from Avanti Polar Lipids, Inc., Alabaster, AL, while their respective isotope-labeled standards used as an internal standard (IS) were purchased as a mixture (LIPIDOMIX^® Mass Spec Standard solution) from Avanti Polar Lipids, Inc., Alabaster, AL, USA.