d6 24 25 epoxycholesterol  (Croda International Plc)

Journal: Analytica Chimica Acta

Article Title: Deep mining of oxysterols and cholestenoic acids in human plasma and cerebrospinal fluid: Quantification using isotope dilution mass spectrometry

doi: 10.1016/j.aca.2021.338259

Figure Lengend Snippet: LC-MS separation of GP-derivatised monohydroxycholesterols (HC). (A) Upper panel, RIC of the [M] + ions of monohydroxycholesterols (539.4368 ± 5 ppm) found in plasma. Lower panel, MRM 539.4 → 455.4→353.3 characteristic of 24R/S-HC. The red dashed line indicates the coincidence of 24S-HC in the upper and lower panels and the black dashed lines indicates where 24R–HC partially overlaps (in time, but not in MRM) with (25R)26-HC. (B) Upper panel, RICs for [ 2 H 7 ]-labelled monohydroxycholesterols (546.4807 ± 5 ppm). The green arrow indicated the distortion in the [ 2 H 7 ]24R–HC chromatographic peak as a consequence of the co-eluting and mass spectrometrically-unresolved [M+1] + ion of [ 2 H 6 ](25R)26-HC ( m/z 546.4777). Lower panel, MRM 546.5 → 462.4→353.3 characteristic of [ 2 H 7 ]24R/S-HC. Note the fragment ion at m/z 353.3 is also evident in MS 3 spectra of [ 2 H 7 ]22R/S–HCO. Coloured dashed lines indicate the coincidence of peaks of the same oxysterol. (C) Upper panel, RICs for [ 2 H 6 ]-labelled monohydroxycholesterols (545.4744 ± 5 ppm). Lower panel total ion chromatogram (TIC) 545.5 → 461.4→ for [ 2 H 6 ]-labelled monohydroxycholesterols. (D) RIC for monohydroxycholesterols in plasma (upper panel) and [ 2 H 7 ]-labelled standards (lower panel) recorded on a shorter chromatographic time scale. (E) RIC for monohydroxycholestenones in plasma (534.4054 ± 5 ppm) and [ 2 H 7 ]-labelled standards (541.4493 ± 5 ppm). Note in all chromatograms the deuterium labelled oxysterols elute slightly earlier than their non-labelled analogues. Relevant MS 3 spectra are presented in Supplemental Figs. S3 and S5 . (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Article Snippet: Additional quantitative isotope labelled standards provided in methanol in exact quantities from Avanti Polar Lipids were [26,26,26,27,27,27- 2 H 6 ]24R/S-HC (51.95 μg/mL, LM-4110), [ 2 H 7 ]7α-HC (48.74 μg/mL, LM-4103), [ 2 H 7 ]7-OC (51.42 μg/mL, LM-4107) and [25,26,26,26,27,27,27- 2 H 7 ]cholesterol (526.01 μg/mL, LM-4100).

Techniques: Liquid Chromatography with Mass Spectroscopy

Journal: Analytica Chimica Acta

Article Title: Deep mining of oxysterols and cholestenoic acids in human plasma and cerebrospinal fluid: Quantification using isotope dilution mass spectrometry

doi: 10.1016/j.aca.2021.338259

Figure Lengend Snippet: LC-MS separation of GP-derivatised cholestenoic acids, and mono- and dihydroxycholesterols in CSF. (A) RIC for the [M] + ions of (upper panel) 7αH,3O-CA(25R/S) (564.3796 ± 5 ppm) found in CSF, and (lower panel) [ 2 H 3 ]7αH,3O-CA(25R/S) (567.3984 ± 5 ppm). (B) RIC for the [M] + ions of (upper panel) 7αH,3O-CA(25R/S) + 3β,7α-diHCA(25R/S) (569.4110 ± 5 ppm) found in CSF, and (lower panel) [ 2 H 3 ]7αH,3O-CA(25R/S) (572.4298 ± 5 ppm). In (A) the derivatisation agent was [ 2 H 0 ]GP and in (B) [ 2 H 5 ]GP. (C) RIC for the [M] + ions of diH,3O-CA isomers (585.4059 ± 5 ppm) found in CSF (upper panel), note the triHCA equivalents are absent. TIC for the MS 3 fragmentation (585.4 → 501.3→) for diH,3O-CA isomers (2nd panel). MRM (585.4 → 501.3→427.3) targeting 7α,24-diH,3O-CA (3rd panel), and MRM (585.4 → 501.3→455.3) targeting 7α,25-diH,3O-CA (bottom panel). See Supplemental Figures S4P & S4Q for relevant fragmentation schemes. Chromatograms in (A–C) are from non-hydrolysed CSF. (D) RIC of the [M] + ions of monohydroxycholesterols (539.4368 ± 3 ppm) found in CSF (upper panel). RIC (546.4807 ± 3 ppm) for [ 2 H 7 ]24R/S-HC, [ 2 H 7 ]7β-HC, [ 2 H 7 ]7α-HC and dehydrated [ 2 H 7 ]5α,6β-diHC (central panel). RIC (545.4744 ± 3 ppm) for [ 2 H 6 ]25-HC and [ 2 H 6 ](25R)26-HC (lower panel). (E) TIC for the MS 3 fragmentations (555.4 → 471.4→) of 7α,25-diHC and 7α,(25R/S)26-diHC found in CSF (upper panel) and for the fragmentations (561.5 → 477.4→) of [ 2 H 6 ]7α,25-diHC and [ 2 H 6 ]7α,(25R/S)26-diHC. Chromatograms (D & E) are for hydrolysed CSF. Coloured dashed lines indicate the coincidence of peaks of the same oxysterol. All chromatograms were recorded over a 17 min gradient.

Article Snippet: Additional quantitative isotope labelled standards provided in methanol in exact quantities from Avanti Polar Lipids were [26,26,26,27,27,27- 2 H 6 ]24R/S-HC (51.95 μg/mL, LM-4110), [ 2 H 7 ]7α-HC (48.74 μg/mL, LM-4103), [ 2 H 7 ]7-OC (51.42 μg/mL, LM-4107) and [25,26,26,26,27,27,27- 2 H 7 ]cholesterol (526.01 μg/mL, LM-4100).

Techniques: Liquid Chromatography with Mass Spectroscopy

Journal: Analytica Chimica Acta

Article Title: Deep mining of oxysterols and cholestenoic acids in human plasma and cerebrospinal fluid: Quantification using isotope dilution mass spectrometry

doi: 10.1016/j.aca.2021.338259

Figure Lengend Snippet: LC-MS separation of GP-derivatised cholestenoic acids, monohydroxycholesterols and monohydroxycholestenones in plasma samples representative of the inborn errors of cholesterol metabolism ACOX2 deficiency and CTX. (A) RIC (564.3796 ± 5 ppm) for [M] + ions corresponding to 7αH,3O-CA(25R/S) in NIST SRM 1950 plasma (upper panel), from a patient suffering from ACOX2 deficiency (central panel), and the RIC (567.3984 ± 5 ppm) corresponding to the [M] + ion of [ 2 H 3 ]7αH,3O-CA(25R/S) (lower panel). (B) RIC (569.4110 ± 5 ppm) for [M] + ions corresponding to 3β,7α-diHCA(25R/S) + 7αH,3O-CA(25R/S) in NIST SRM 1950 plasma (upper panel), from a patient suffering from ACOX2 deficiency (central panel), and the RIC (572.4298 ± 5 ppm) corresponding to the [M] + ion of [ 2 H 3 ]7αH,3O-CA(25R/S) (lower panel). Samples in (A) have been treated with [ 2 H 0 ]GP and those in (B) with [ 2 H 5 ]GP. (C) RIC (539.4368 ± 5 ppm) for [M] + ions corresponding to monohydroxycholesterols and monohydroxycholestenones in NIST SRM 1950 plasma (upper panel), from a sample from a patient suffering from CTX (central panel), and the RIC (546.4807 ± 5 ppm) corresponding to the [M] + ion of [ 2 H 7 ]24R/S-HC (lower panel). (D) RIC (564.3796 ± 5 ppm) for [M] + ions corresponding to 7αH,3O-CA(25R/S) in NIST SRM 1950 plasma (upper panel), from a sample from a patient suffering from CTX (central panel), and the RIC (567.3984 ± 5 ppm) corresponding to the [M] + ion of [ 2 H 3 ]7αH,3O-CA(25R/S) (lower panel). Coloured dashed lines indicate the coincidence of oxysterols between chromatograms.

Article Snippet: Additional quantitative isotope labelled standards provided in methanol in exact quantities from Avanti Polar Lipids were [26,26,26,27,27,27- 2 H 6 ]24R/S-HC (51.95 μg/mL, LM-4110), [ 2 H 7 ]7α-HC (48.74 μg/mL, LM-4103), [ 2 H 7 ]7-OC (51.42 μg/mL, LM-4107) and [25,26,26,26,27,27,27- 2 H 7 ]cholesterol (526.01 μg/mL, LM-4100).

Techniques: Liquid Chromatography with Mass Spectroscopy