
Chapter 3 Preparing Samples
3-10 PerSeptive Biosystems
3
THAP
Use THAP for small oligonucleotides <3,500 Da, acidic
carbohydrates, acidic glycopeptides, acid sensitive
compounds. THAP provides a more even response than
3-HPA.
Matrix concentration • Oligonucleotides—10 mg/ml
• Acidic carbohydrates—2 mg/ml
Additive concentration 50 mg/ml diammonium citrate in deionized water
Final sample concentration 1–10 pmol/µl
Solvents 50 percent acetonitrile and deionized water
NOTE: HPLC-grade water may vary in salt
concentration. Do not use for oligonucleotide
analysis.
Preparation
1
Follow the procedure in “Preparing matrix” on
page 3-5 and:
Small oligonucleotides:
Combine 8:1 THAP:diammonium citrate. Air dry
sample plate after loading sample and matrix.
Acidic carbohydrates and glycopeptides:
Combine 20:1 THAP:diammonium citrate. Dry
sample plate under vacuum after loading
sample and matrix. Wait a few minutes after
drying until the sample absorbs ambient
humidity and turns faint white.
Crystals Larger than sinapinic, overlapping shingles,
non-uniform shape (see Figure 3-2 on page 3-35)
Stability Prepare weekly.
1. Other special sample preparation techniques are described in Papac, D.I., A. Wong, A.J.S. Jones,
Anal. Chem.,
1996, 68, 3215–3223.
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