Determination of Blood Folate Using Acid Extraction and Internally Standardized Gas Chromatography–Mass Spectrometry Detection

Dueker, Stephen R.; Lin, Yumei; Jones, A. Daniel; Mercer, Roger S.; Fabbro, Elisabetta; Miller, Joshua W.; Green, Ralph; Clifford, Andrew J.

doi:10.1006/abio.2000.4660

Cited by 34 publications

(34 citation statements)

References 33 publications

(25 reference statements)

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“…On average, 1-2 g of total RNA was isolated from five 5-m tissue sections. For each sample, 200 ng of total RNA was converted to cDNA and processed in the DASL assay as described previously (11,13 ). Oligonucleotides targeting 502 cancer-related genes were used in these experiments, at a density of three nonoverlapping probes per gene, giving a 1506-plex measurement for each sample.…”

Section: Distribution Of Results For Metanephrinementioning

confidence: 99%

“…Oligonucleotides targeting 502 cancer-related genes were used in these experiments, at a density of three nonoverlapping probes per gene, giving a 1506-plex measurement for each sample. Our previous study showed that three probes per gene lend the assay sufficient sensitivity and reproducibility for quantitative detection of differential expression in FFPE tissues (13 ). Mean signal values were computed for each gene by determining the mean signal for the three representative probes (11 ).…”

Section: Distribution Of Results For Metanephrinementioning

confidence: 99%

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Nonparametric Determination of Reference Intervals for Plasma Metanephrine and Normetanephrine

2004

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Section: Distribution Of Results For Metanephrinementioning

confidence: 99%

Section: Distribution Of Results For Metanephrinementioning

confidence: 99%

Nonparametric Determination of Reference Intervals for Plasma Metanephrine and Normetanephrine

2004

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“…Between-day imprecision was measured by assaying the same samples on 20 different days over a 3-week period. (27 ). Fig.…”

Section: Recovery and Imprecisionmentioning

confidence: 99%

Measurement of Folate in Fresh and Archival Serum Samples as p-Aminobenzoylglutamate Equivalents

2008

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Background: The development of accurate and precise folate assays has been difficult, mainly because of folate instability. Large interassay and interlaboratory differences have been reported. We therefore developed a serum folate assay that measures folate and putative degradation products as p-aminobenzoylglutamate (pABG) equivalents following oxidation and acid hydrolysis. Methods: Serum was deproteinized with acid in the presence of 2 internal calibrators ([13C2]pABG and [13C5]5-methyltetrahydrofolate). 5-Methyltetrahydrofolate and other folate species in serum were converted to pABG by oxidation and mild acid hydrolysis. pABG and its internal calibrators were quantified by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Results: The limit of quantification was 0.25 nmol/L, and the assay was linear in the range 0.25–96 nmol/L, which includes the 99.75 percentile for serum folate concentrations in healthy blood donors. Within- and between-day imprecision was ≤5%. We detected no residual folate in serum samples after sample preparation. Folate concentrations in fresh serum samples obtained with the pABG assay and with a microbiologic assay showed good agreement (r = 0.96). In stored samples containing low folate concentrations due to folate degradation, the pABG assay yielded substantially higher folate concentrations than the microbiologic assay. Conclusions: The pABG assay combines automated sample preparation with LC-MS/MS analysis. It allows measurement of folate not only in fresh samples of serum/plasma but also in stored samples in which the folate has become oxidized and degraded to an extent that it cannot be assayed with traditional folate assays.

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“…Gas chromatography/mass spectrometry used to analyze WBF after cleavage of folates to p-aminobenzoic acid showed greater sensitivity than previous chromatographic methods and used for the first time an isotopelabeled internal standard (IS). The method, however, requires a complex and lengthy multistep sample preparation including chemical derivatization (11,(13)(14)(15). We describe here the first automated 96-well plate stableisotope-dilution liquid chromatography-tandem mass spectrometry (LC/MS/MS) method that measures intact folate monoglutamates in conventionally prepared whole blood (WB) lysates and serum.…”

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Measurement of Folates in Serum and Conventionally Prepared Whole Blood Lysates: Application of an Automated 96-Well Plate Isotope-Dilution Tandem Mass Spectrometry Method

Fazili

Pfeiffer

2004

Clinical Chemistry

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Determination of Blood Folate Using Acid Extraction and Internally Standardized Gas Chromatography–Mass Spectrometry Detection

Cited by 34 publications

References 33 publications

Nonparametric Determination of Reference Intervals for Plasma Metanephrine and Normetanephrine

Nonparametric Determination of Reference Intervals for Plasma Metanephrine and Normetanephrine

Measurement of Folate in Fresh and Archival Serum Samples as p-Aminobenzoylglutamate Equivalents

Measurement of Folates in Serum and Conventionally Prepared Whole Blood Lysates: Application of an Automated 96-Well Plate Isotope-Dilution Tandem Mass Spectrometry Method

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