Quantitative Analysis of Vitamin D Metabolite Using Triple Quadrupole LC/MS/MS

Significance of the topic

Vitamin D is a fat-soluble secosteroid hormone essential for calcium metabolism and bone health. It also modulates immune response, maintains muscle strength, and may offer protective effects against autoimmune diseases, hypertension, and certain cancers. Accurate quantification of its circulating metabolites, 25-hydroxyvitamin D2 and D3, in human serum is critical for clinical diagnostics and research exploring these physiological roles.

Objectives and overview of the study

The study aims to develop and validate a robust LC/MS/MS method using Shimadzu’s triple quadrupole LCMS-8050 coupled with Nexera X2 for precise quantification of 25-OH vitamin D2 and D3 in human serum. The approach incorporates supported liquid extraction (ISOLUTE® SLE+) to enhance extraction efficiency relative to conventional protein precipitation.

Methodology and sample preparation

Sample processing employed a four-step protocol:

1. Pre-treatment: 100 µL serum mixed with 150 µL water, 150 µL isopropanol, and internal standard; vortex for 10 s.
2. Load: Apply 400 µL to ISOLUTE® SLE+ plate under positive pressure, then allow gravity flow for five minutes.
3. Elution: Perform two 700 µL heptane elutions, collect in deep-well plate, then apply pressure to recover residual volume.
4. Post-extraction: Evaporate eluates at 40 °C and reconstitute in 100 µL mobile phase (33 % A, 67 % B).

Used Instrumentation

• LC System: Shimadzu Nexera X2 with YMC Triart C18 column (50 × 2 mm, 1.9 µm) at 40 °C.
• Mobile Phases: A: Water/Methanol/Formic acid (50/50/0.025); B: Methanol. Gradient: 67 % B (0–1 min) to 95 % B (3–4 min) and back to 67 % B (6 min); flow rate 0.5 mL/min; injection 10 µL.
• MS: Shimadzu LCMS-8050 triple quadrupole; ESI positive; interface 180 °C; DL 150 °C; block heater 400 °C; nebulizing gas 3 L/min; drying and heating gas 10 L/min.

Main results and discussion

Calibration curves spanned 2.4–150 ng/mL for both metabolites, exhibiting r² > 0.998. Comparison with protein precipitation demonstrated:

• Higher recovery and lower matrix effects using ISOLUTE® SLE+ (average recovery ~82 % for both D2 and D3; RSD < 10 %).
• Enhanced signal-to-noise ratio and sharper MRM chromatograms, indicating cleaner extracts and improved quantitation reliability.

Benefits and practical applications

This validated method delivers high-throughput, accurate measurement of 25-OH vitamin D2/D3 in clinical and research settings. The SLE-based extraction minimizes matrix interferences and improves precision, supporting diagnostic laboratories and large-scale epidemiological studies.

Future trends and possibilities for application

Advances in microextraction and automation could further streamline sample processing. Emerging high-resolution mass spectrometry may enable simultaneous profiling of additional vitamin D metabolites. Integration with laboratory information systems will support real-time data analysis and personalized medicine approaches.

Conclusion

This study establishes a reliable LC/MS/MS protocol leveraging ISOLUTE® SLE+ for quantitative analysis of 25-hydroxy vitamin D metabolites. The approach enhances extraction efficiency, reduces matrix effects, and provides robust calibration, offering a valuable tool for clinical diagnostics and research into vitamin D’s broader physiological roles.

References

• Shimadzu Corporation. Application Note LAAN-A-LM-E078, Quantitative Analysis of Vitamin D Metabolite Using Triple Quadrupole LC/MS/MS. First Edition, May 2015.