Gibberellin Levels Are Not a Suitable Indicator for Properly Cold-treated Tulip Bulbs

To find a suitable indicator for properly cold-treated tulip bulbs (Tulipa gesneriana L. cv. Apeldoorn), the content of the endogenous free gibberellins (GAs) GA1, GA4, GA9, GA24, and GA34 was investigated. GA levels were measured in the shoots and basal plates at the start and at the end of a complete cold treatment of 12 weeks at 5 °C by combined gas chromatography–mass spectrometry using deuterated internal standards. Bulbs stored at 17 °C for 12 weeks served as controls and the experiment was repeated three times. Before the cold treatment, GA1 and GA4 were the major occurring GAs in the shoots. After 12 weeks, GA4 was the main GA component and the levels of GA1 were low in precooled and nonprecooled bulb shoots. The levels of GA4, GA9, GA24, and GA34 in precooled and nonprecooled bulb shoots and basal plates were similar. Hence, no direct correlation between cold-stimulated growth and a change in the endogenous GA status in shoots or basal plates was determined during the cold treatment. The free GA content in shoots or basal plates at the end of bulb storage cannot be used as a marker in a test for properly cold-treated `Apeldoorn' tulip bulbs.

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Determination of 3-methoxy-4-hydroxyphenylpyruvic acid, 3,4-dihydroxyphenylethylene glycol, and 3,4-dihydroxyphenylmandelic acid in urine by mass fragmentography, with use of deuterium-labeled internal standards.

Clinical Chemistry ◽

10.1093/clinchem/24.11.2001 ◽

1978 ◽

Vol 24 (11) ◽

pp. 2001-2008 ◽

Cited By ~ 14

Author(s):

F A Muskiet ◽

D C Fremouw-Ottevangers ◽

G T Nagel ◽

B G Wolthers ◽

J A de Vries

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Gas Chromatography Mass Spectrometry ◽

Mass Fragmentography ◽

Decarboxylase Inhibitor ◽

Purification Method ◽

Internal Standards ◽

Chromatography Mass Spectrometry ◽

Catecholamine Metabolites

Abstract We report the determination of 3-methoxy-4-hydroxyphenylpyruvic acid, 3,4-dihydroxyphenylmandelic acid, and 3,4-dihydroxyphenylethylene glycol in urine, by use of gas chromatography/mass spectrometry in combination with a simple purification method and deuterium-labeled internal standards. Normal excretion values in terms of creatinine, expressed as a function of age, are given, together with results obtained for patients with neuroblastoma, pheochromocytoma, or parkinsonism treated with L-DOPA + peripheral decarboxylase inhibitor, and for a patient receiving dopamine. We were unable to identify 3, 4-dihydroxyphenyllactic acid in urine. The results obtained and their relation to other catecholamine metabolites and catecholamine-precursor metabolites in urine are discussed.

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Rapid Analysis of Metanephrine and Normetanephrine in Urine by Gas Chromatography-Mass Spectrometry

Clinical Chemistry ◽

10.1093/clinchem/48.2.332 ◽

2002 ◽

Vol 48 (2) ◽

pp. 332-337 ◽

Cited By ~ 18

Author(s):

David K Crockett ◽

Elizabeth L Frank ◽

William L Roberts

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Solid Phase ◽

Correlation Coefficients ◽

Hplc Method ◽

Gas Chromatography Mass Spectrometry ◽

Internal Standards ◽

Rapid Decomposition ◽

Chromatography Mass Spectrometry ◽

Deming Regression

Abstract Background: Widely used HPLC methods for quantification of metanephrine and normetanephrine in urine often have long analysis times and are frequently plagued by drug interferences. We describe a gas chromatography-mass spectrometry method designed to overcome these limitations. Methods: Metanephrine and normetanephrine conjugates were converted to unconjugated metanephrine and normetanephrine by acid hydrolysis. To avoid the rapid decomposition of the deuterated internal standards (metanephrine-d3 and normetanephrine-d3) under hydrolysis conditions, the internal standards were added after hydrolysis. Solid-phase extraction was used to isolate the hydrolyzed metanephrines from urine. Samples were concentrated by evaporation, then derivatized simultaneously with N-methyl-N-(trimethylsilyl)trifluoroacetamide and N-methyl-bis-heptafluoro-butryamide at room temperature. Results: The assay was linear from 25 to 7000 μg/L. The intraassay CVs were <5% and the interassay CVs <12%. Comparison with a routine HPLC method (n = 192) by Deming regression yielded a slope of 1.00 ± 0.02 μg/L, an intercept of −5.8 ± 7.8 μg/L, and Sy|x = 50.6 μg/L for metanephrine and a slope of 0.94 ± 0.03, intercept of 19 ± 11 μg/L, and Sy|x = 60 μg/L for normetanephrine. The correlation coefficients (r) were calculated after log transformation of the data and gave r = 0.97 for metanephrine and r = 0.97 for normetanephrine. Interference from common medications or drug metabolites was seen in <1% of samples. The time between sequential injections was <7 min. Conclusions: This new gas chromatography-mass spectrometry assay for total fractionated metanephrines is rapid, compares well with a standard HPLC assay, and avoids most drug interferences that commonly affect HPLC assays for urine metanephrines.

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