Analysis of Caffeine

Abstract

Caffeine has been recommended for the treatment of apnea in newborn children. Most of the current methods for measurement of caffeine in newborns have used high-performance liquid chromatography (HPLC) because analysis can be performed on as little as 50 microliter of serum, an important factor when obtaining multiple blood samples for routine drug monitoring in infants and children. We evaluated the manual Syva enzyme multiplied immunoassay technique (EMIT) caffeine procedure and compared the assay results with our HPLC caffeine method. The EMIT procedure was also automated, and these results were compared with those of the manual and HPLC procedures. The 7-micrograms/ml calibrator was analyzed 20 times to establish within-run precision for the manual procedure. The mean +/- SD was 6.97 +/- 0.33, and the coefficient of variation (CV) was 4.80%. Reproducibility was tested by multiple analysis of the 11-micrograms/ml control. The mean +/- SD (CV) for the manual system was 11.3 +/- 0.45 (4%), n = 17; for the HPLC system, 10.58 +/- 0.89 (8.4%), n = 10; and for the automated system, 10.4 +/- 0.78 (7.5%), n = 12. Samples from 32 patients were analyzed by each of the above procedures. There was a good correlation among all three procedures. The correlation coefficient (r) for HPLC vs. manual EMIT was 0.98; for HPLC vs. automated EMIT, 0.97; and for automated EMIT vs. manual EMIT, 0.96. We conclude that the new Syva EMIT caffeine method is reliable and reproducible and can be applied to automated analysis.(ABSTRACT TRUNCATED AT 250 WORDS)