Normalization and reproducibility of mass profiles in the detection of individual differences from urine.

The mass profiles of urine samples and their reproducibility (coefficient of variation) obtained by field-ionization mass spectrometry (volcano source) depend upon the choice of normalization method. We compared six different normalization techniques in terms of improved reproducibility and sensitivity. Several simple procedures markedly improved reproducibility while preserving the high degree of sensitivity. Although these procedures gave similar and satisfactory results, others were clearly inferior and are not recommended for clinical profiling.