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See detailDetermination of urinary metanephrine, normetanephrine and methoxymetanephrine by liquid chromatography-electrospray tandem mass spectrometry.
LE GOFF, Caroline ULg; PEETERS, Stéphanie ULg; NETCHACOVITCH, Matthieu ULg et al

in Biochimica Clinica (2013, May), 37(SS), 316

Background: The aim of this work was to develop and validate a method for the determination of metanephrine (M), normetanephrine (NM) and methoxymetanephrine (METHO) in urine by liquid chromatography ... [more ▼]

Background: The aim of this work was to develop and validate a method for the determination of metanephrine (M), normetanephrine (NM) and methoxymetanephrine (METHO) in urine by liquid chromatography-tandem mass spectrometry (LCMS-MS) on the Triple Quad TQ 5500 from AB SCIEX. In fact, the determination of M and NM concentrations is used in clinical diagnosis of pheochromocytoma, a rare but potentially fatal tumor arising primarily from the chromaffin cells of the adrenal medulla. Methods: The samples were made of 24 hours acidified urines after centrifugation. Sample preparation was performed by hydrolysing and purifying by extraction column. After that, labeled M, NM and METHO were added as internal standard. Samples were analysed by liquid chromatography-electrospray tandem mass spectrometry. We determined the repeatability, reproducibility, accuracy profile and recovery on pooling urines samples from 9 volunteers analysed in triple run. Results: The results of the precision evaluation are shown in table. The repeatability did not exceed 8.4 % for M, 6.8% for NM and 10.8% for METHO. The concentration range was 71-781 µg/24h, 71-853 µg/24h and 20-854µg/24h for the M, NM and METHO respectively. The total precision did not exceed 12.5%, 11.8% and 8.8% for M, NM and METHO. The limit of quantification (LOQ) were 33.77µg/24h, 14.49µg/24H and 19.81 µg/24H for M, NM and METHO respectively. The accuracy varied from 99.69 to 100.2% for a range of 71 to 781 µg/24h, from 93.32 to 100.2% for a range of 71-853 µg/24h and from 99.85 to 100.6% for the range 20-854µg/24h for M, NM and METHO respectively. The recovery were 99.96% (95% CI for the mean: 96.5-103.4), 99.75% (96.5-102.9) and 100.08 (95.97-104.2) for the M, NM and METHO respectively. Conclusions: We have successfully developed and validated an LCMS-MS method to determine urinary M, NM and METHO on the TQ 5500 from AB SCIEX. It represents a convincing alternative to the HPLC method for a faster and reliable measurement of urinary M, NM and METHO. [less ▲]

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See detailComparison between Perkin-Elmer and Chromsytem Vitamin D kit on TQ 5500 from AB SCIEX
LE GOFF, Caroline ULg; PEETERS, Stéphanie ULg; CRINE, Yannick ULg et al

in Biochimica Clinica (2013, May), 37(SS), 471

Background: Twenty-five hydroxy-vitamin D (25(OH) D) determination is now routinely prescribed in the Laboratory. Recently, different new methods have been available for this determination. Among them ... [more ▼]

Background: Twenty-five hydroxy-vitamin D (25(OH) D) determination is now routinely prescribed in the Laboratory. Recently, different new methods have been available for this determination. Among them, LCMS/MS methods have emerged in some laboratories. However these methods are generally “home-brewed” and an important variability between them can be seen on different external quality controls, mainly due to a lack of standardization. Recently, Perkin-Elmer (PE) (Turku, Finland) and Chromsystem (CS) (Grafelfing, Germany) launched a standardised method for 25(OH )D determination on LCMS/MS. The aim of our study was to compare these methods on the AB SCIEX TQ5500 (Framingham, Massachusetts, USA) LCMS/MS to measure 25(OH) D3. Methods All the samples were treated according to our preanalyitical procedure: after sampling, they were spun at +4°c at 3500G, aliquoted and kept frozen at -20°c until determination. A method comparison was assessed with CS and PE for the measurement of the 25(OH)D3. We selected 110 remnant samples with 25(OH)D3 levels ranging from 1.6 to 136.7 ng/ml with the PE method to cover the range of usually values Slope and intercept were calculated using Passing and Bablock linear regression and we compared the methods with the Bland and Altman plots. Results For CS, the method is linear up to 250 µg/L, the LOQ is 3.6 µg/L, the intra-assay CV is < 5% and the inter-assay is < 7%. For PE, the method is linear up to 314 µg/L, the LOQ is 3.4 µg/L, the intra-assay CV is < 7.8% and the inter-assay is < 8.5%. On the whole range of measure (n=110), the regression equation is PE = 0.8521+0.9226 (CS) (95%CI of the intercept: (-0.0048;1.37) and 95% CI of the slope (0.89;0.95). The Bland and Altman plot does not show any bias between the two methods (mean difference CS-PE= -2.5 ng/ml) and the standard deviation of the mean is 3,98 ng/ml Conclusion: The performances of these methods are comparable on our new TQ 5500 from AB SCIEX. For now, there is no consensus on a “reference” method for vitamin D quantification. We notice only that the values obtained by CS are systematically a little bit lower than PE’s values, especially for results below 20 ng/ml. However, we have no clear explanation for such behaviour. [less ▲]

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See detailEvaluation of the cross-reactivity of 25-hydroxyvitamin D2 on seven commercial immunoassays on native samples
LE GOFF, Caroline ULg; PEETERS, Stéphanie ULg; CRINE, Yannick ULg et al

in Clinical Chemistry & Laboratory Medicine (2012), 50(11), 2031-2

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See detailCross-reactivity of 25-hydroxyvitamin D2 in ADVIA Centaur Total Vitamin D
FORTUNATO, Antonio; LE GOFF, Caroline ULg; PEETERS, Stéphanie ULg et al

Poster (2012, May)

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