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Technical Briefs |
1
Centers for Disease Control and Prevention, Newborn Screening Quality Assurance Program, MS-19, 4770 Buford Hwy., Atlanta, GA 30341-3724;
2
NeoGen Screening, Inc., 110 Roessler Rd., Pittsburgh, PA 15220;
3
Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands;
a author
for correspondence: fax 770-488-4831, e-mail bwa1@cdc.gov
Dried blood spots (DBSs) are used to screen newborns for phenylketonuria and other aminoacidopathies. The calibrators for this testing are usually DBSs with values for Phe. Two DBS reference materials have been prepared, the European Working Standard for Phe (EWS-Phe-01) (1) and the amino acid reference material (AARM) from the CDC (2). The two reference materials are not interchangeable because they differ in blood hematocrit, blood-spot size, and filter paper, each of which (3)(4)(5)(6) affects analyte recovery. We measured quantitatively the effects of these differences on analyte recovery from DBSs and used results from our measurements to predict expected Phe recoveries from tandem analyses of the two sets of materials.
In EWS-Phe-01 (1)(7), human blood with a 50.5% hematocrit and intact red cells was divided into five portions for enrichment with 0, 20, 40, 80, and 120 mg Phe/L blood (0, 120, 240, 480, and 720 µmol/L blood). The liquid added during enrichment (7) was sufficient to reduce the hematocrit to 50.1%. The Phe-enriched blood portions were dispensed in 35-µL aliquots (7) onto Schleicher & Schuell (S&S) Grade 2992 (lot no. 121576) filter paper (1).
The AARM was prepared (2) by dividing human blood with a
57% hematocrit and intact red cells into six portions for enrichment
with pure amino acids to cover the usual analytic ranges of Phe, Tyr,
Leu, Met, and Val. The Phe enrichments were 0, 40, 80, 120,
160, and 200 mg Phe/L blood (0, 240, 480, 720, 960, and 1200 µmol/L
blood). The liquid added during enrichment was sufficient to reduce the
hematocrit to 53%. The whole-blood pools were dispensed in 100-µL
portions onto S&S Grade 903 (lot no. W941) filter
References
The following articles in journals at HighWire Press have cited this article:
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  D. H. Chace, T. A. Kalas, and E. W. Naylor Use of Tandem Mass Spectrometry for Multianalyte Screening of Dried Blood Specimens from Newborns Clin. Chem., November 1, 2003; 49(11): 1797 - 1817. [Abstract] [Full Text] [PDF]
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 T. W. McDade and B. Shell-Duncan Whole Blood Collected on Filter Paper Provides a Minimally Invasive Method for Assessing Human Transferrin Receptor Level J. Nutr., December 1, 2002; 132(12): 3760 - 3763. [Abstract] [Full Text] [PDF]
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D. H. Chace, J. C. DiPerna, T. A. Kalas, R. W. Johnson, and E. W. Naylor Rapid Diagnosis of Methylmalonic and Propionic Acidemias: Quantitative Tandem Mass Spectrometric Analysis of Propionylcarnitine in Filter-Paper Blood Specimens Obtained from Newborns Clin. Chem., November 1, 2001; 47(11): 2040 - 2044. [Full Text] [PDF]
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D. H. Chace, J. C. DiPerna, B. L. Mitchell, B. Sgroi, L. F. Hofman, and E. W. Naylor Electrospray Tandem Mass Spectrometry for Analysis of Acylcarnitines in Dried Postmortem Blood Specimens Collected at Autopsy from Infants with Unexplained Cause of Death Clin. Chem., July 1, 2001; 47(7): 1166 - 1182. [Abstract] [Full Text] [PDF]
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J. V. Mei, J. R. Alexander, B. W. Adam, and W. H. Hannon Use of Filter Paper for the Collection and Analysis of Human Whole Blood Specimens J. Nutr., May 1, 2001; 131(5): 1631S - 1636. [Abstract] [Full Text]
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D. H. Chace, J. C. DiPerna, B. W. Adam, and W. H. Hannon Errors Caused by the Use of D,L-Octanoylcarnitine for Blood-Spot Calibrators Clin. Chem., April 1, 2001; 47(4): 758 - 760. [Full Text] [PDF]
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