The Centers for Disease Control and Prevention and its partners have been operating the Newborn Screening Quality Assurance Program for >20 y. The program helps participating laboratories to evaluate and improve the quality of their newborn-screening testing efforts by providing quality control dried blood spot materials and proficiency-testing materials for the external evaluation of screening programs. The Newborn Screening Quality Assurance Program provides an independent evaluation of filter papers approved by the Food and Drug Administration for the collection of blood for clinical tests. These activities have created a mechanism for the validation of the filter paper blood collection device and the standardization of materials and methods for the analysis of dried blood spots.

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Background: Advances in technology and the earlier release of newborns from hospitals have pressed the demand for accurate calibration and improved interlaboratory performance for newborn screening tests. As a first step toward standardization of newborn screening aminoacidopathy tests, we have produced six-pool sets of multianalyte dried-blood-spot amino acid reference materials (AARMs) containing predetermined quantities of five amino acids. We describe here the production of the AARMs, validation of their amino acid contents, and characterization of their homogeneity and their stability in storage. Methods: To each of six portions of a pool of washed erythrocytes suspended in serum we added Phe (0–200 mg/L), Leu (0–200 mg/L), Met (0–125 mg/L), Tyr (0–125 mg/L), and Val (0–125 mg/L). Six-pool sets (1300) were prepared, dried, and packaged. We used isotope-dilution mass spectrometry to estimate the endogenous amino acid concentrations of the AARMs and validate their final amino acid concentrations. We used additional tandem mass spectrometry analyses to examine the homogeneity of amino acid distribution in each AARM, and HPLC analyses to evaluate the stability of the amino acid contents of the AARMs. Results: The absolute mean biases across the analytic range for five amino acids were 2.8–9.4%. One-way ANOVAs of the homogeneity results predicted no statistically significant differences in amino acid concentrations within the blood spots or within the pools (P >0.05). Regression slopes (0 ± 0.01) for amino acid concentrations vs storage times and their P values (>0.05) showed no evidence of amino acid degradation at ambient temperatures, 4 °C, or −20 °C during the intervals tested. Conclusion: The validation, homogeneity, and stability of these blood spots support their use as a candidate national reference material for calibration of assays that measure amino acids in dried-blood spots.

Hair nicotine and cotinine have been proposed as longer-term markers of exposure to secondhand smoke. In this study, we evaluated the rate and extent of nicotine and cotinine deposition into beard hair among six male nonsmokers following a single exposure to 4 mg of nicotine in Nicorette(®) (nicotine polacrilex) gum. We collected beard hair samples daily for 12 days following exposure and urine samples for 6 days after exposure. Using liquid chromatographic-tandem mass spectrometric analysis, we found that both nicotine and cotinine could be detected in beard samples within 24 h of the exposure and reached a maximum of about 71 pg nicotine and 47 pg cotinine/mg hair, respectively, within 1-2 days, followed by a gradual decline. Compared to beard hair concentrations, nicotine, cotinine, and hydroxycotinine were excreted in urine at much higher levels and also peaked on the day after exposure (mean ± SD urine cotinine = 300 ± 183 ng/mL). Our results confirmed that both nicotine and cotinine can be measured in beard hair samples following a single dose of nicotine. However, both the time-course and extent of deposition of these analytes in beard hair in this study differed from the results reported previously from a similar evaluation.