Effect of impurities on the matrix-assisted laser desorption mass spectra of single-stranded oligodeoxynucleotides.
The effect of impurities on the analysis of single-stranded DNA oligomers by the technique of matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry has been studied using the matrix 3-hydroxypicolinic acid and 355-nm pulsed light. By mixing the DNA oligomers with different concentrations of impurities and recording mass spectra, limits are set on the tolerable level of a given impurity in a sample. The tolerance limits for sodium chloride, potassium chloride, sodium acetate, sodium fluoride, sodium dodecyl sulfate (SDS), and manganese(II) chloride were found to be approximately 10(-2) M. It was found that magnesium salts degraded the mass spectrum at much lower levels of 10(-4) M. The organic compounds tris(hydroxymethyl)aminomethane (Tris), urea, dithiothreitol (DTT), glycerol, and ethylenediaminetetraacetic acid (EDTA), when present as its ammonium salt, were tolerable at concentrations into the range of 0.25-0.5 M, while the organic polyamine compound spermine substantially degraded the mass spectrum at concentrations above 10(-2) M. When comparing these results for DNA analysis with previously reported limits for protein analysis, large differences are seen for some of the impurities tested.
Shaler
T A
TA
Molecular Physics Laboratory, SRI International, Menlo Park, California 94025, USA.
Wickham
J N
JN
Sannes
K A
KA
Wu
K J
KJ
Becker
C H
CH
D001483:Base Sequence; D004277:DNA, Single-Stranded / Q000032:analysis; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D004277:DNA, Single-Stranded; D009841:Oligonucleotides