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Measurement of citrate in urine using liquid chromatography tandem mass spectrometry: comparison with an enzymatic method.
Ann Clin Biochem. 2005 Sep; 42(Pt 5):357-63.AC

Abstract

BACKGROUND

Measurement of urine citrate is used to assess the risk of further urinary stone formation and to assess the benefit of treatment in affected individuals. We wanted to develop a simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of urinary citrate and to compare it with our current enzymatic assay.

METHODS

For the LC-MS/MS assay, samples were prepared in a deep-well block by adding 10 microL of urine and 20 microL of internal standard to 400 microL of water. After mixing, 3 microL of the diluted sample was injected into the LC-MS/MS system. An LC system was used to isocratically elute a C18 column (50 x 2.1 mm) with 0.4 mL/min water containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid. A step gradient of 100% methanol containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid was used to wash the column. The retention times were 1.4 min for citrate and 1.4 min for d4-citrate. Cycle time was 4.0 min, injection to injection. The analytes were monitored using a tandem mass spectrometer operated in multiple reaction monitoring mode using the following transitions, citrate m/z 191.0>111.0 and d4-citrate m/z 195.0>113.0.

RESULTS

Within and between-batch coefficients of variation were <3% over the range 480-3800 micromol/L. The lower limit of quantification was 24.0 micromol/L. Regression analysis showed LC-MS/MS = 0.8781 (enzymatic assay) + 102.5, r = 0.964, n = 73.

CONCLUSIONS

We have developed a simple LC-MS/MS method for urinary citrate measurement that shows acceptable performance.

Authors+Show Affiliations

Keevil BG
Department of Clinical Biochemistry, Wythenshawe Hospital, South Manchester University Hospitals NHS Trust, Southmoor Road, Manchester M23 9LT, UK. bkeevil@smuht.nwest.nhs.uk
Owen L
No affiliation info available
Thornton S
No affiliation info available
Kavanagh J
No affiliation info available

MeSH

Chromatography, High Pressure LiquidCitric AcidHumansKidney CalculiReference StandardsReproducibility of ResultsSensitivity and SpecificitySpectrometry, Mass, Electrospray Ionization

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

16168191

Citation

Keevil, B G., et al. "Measurement of Citrate in Urine Using Liquid Chromatography Tandem Mass Spectrometry: Comparison With an Enzymatic Method." Annals of Clinical Biochemistry, vol. 42, no. Pt 5, 2005, pp. 357-63.
Keevil BG, Owen L, Thornton S, et al. Measurement of citrate in urine using liquid chromatography tandem mass spectrometry: comparison with an enzymatic method. Ann Clin Biochem. 2005;42(Pt 5):357-63.
Keevil, B. G., Owen, L., Thornton, S., & Kavanagh, J. (2005). Measurement of citrate in urine using liquid chromatography tandem mass spectrometry: comparison with an enzymatic method. Annals of Clinical Biochemistry, 42(Pt 5), 357-63.
Keevil BG, et al. Measurement of Citrate in Urine Using Liquid Chromatography Tandem Mass Spectrometry: Comparison With an Enzymatic Method. Ann Clin Biochem. 2005;42(Pt 5):357-63. PubMed PMID: 16168191.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Measurement of citrate in urine using liquid chromatography tandem mass spectrometry: comparison with an enzymatic method. AU - Keevil,B G, AU - Owen,L, AU - Thornton,S, AU - Kavanagh,J, PY - 2005/9/20/pubmed PY - 2005/11/8/medline PY - 2005/9/20/entrez SP - 357 EP - 63 JF - Annals of clinical biochemistry JO - Ann Clin Biochem VL - 42 IS - Pt 5 N2 - BACKGROUND: Measurement of urine citrate is used to assess the risk of further urinary stone formation and to assess the benefit of treatment in affected individuals. We wanted to develop a simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of urinary citrate and to compare it with our current enzymatic assay. METHODS: For the LC-MS/MS assay, samples were prepared in a deep-well block by adding 10 microL of urine and 20 microL of internal standard to 400 microL of water. After mixing, 3 microL of the diluted sample was injected into the LC-MS/MS system. An LC system was used to isocratically elute a C18 column (50 x 2.1 mm) with 0.4 mL/min water containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid. A step gradient of 100% methanol containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid was used to wash the column. The retention times were 1.4 min for citrate and 1.4 min for d4-citrate. Cycle time was 4.0 min, injection to injection. The analytes were monitored using a tandem mass spectrometer operated in multiple reaction monitoring mode using the following transitions, citrate m/z 191.0>111.0 and d4-citrate m/z 195.0>113.0. RESULTS: Within and between-batch coefficients of variation were <3% over the range 480-3800 micromol/L. The lower limit of quantification was 24.0 micromol/L. Regression analysis showed LC-MS/MS = 0.8781 (enzymatic assay) + 102.5, r = 0.964, n = 73. CONCLUSIONS: We have developed a simple LC-MS/MS method for urinary citrate measurement that shows acceptable performance. SN - 0004-5632 UR - https://www.unboundmedicine.com/medline/citation/16168191/Measurement_of_citrate_in_urine_using_liquid_chromatography_tandem_mass_spectrometry:_comparison_with_an_enzymatic_method_ DB - PRIME DP - Unbound Medicine ER -