Wet Ash Method for Ca, Mg and K Using Nitric Acid and 30% Hydrogen Peroxide.
- Weigh +/- 200mg dried (60C) and ground (20 or 40 mesh) plant tissue into
a digestion tube (20x150mm test tube - lignin tubes). Note: for K, use only
100mg of the NIST apple standard due to it's high K value.
- Add 4ml of concentrated nitric acid (HNO3). Let it
- Place tubes in the dry-block and heat at 120C for one hour. Remove and allow
- Add 3ml 30% hydrogen peroxide (H2O2)
and place tubes back in the dry-block. Repeat the additions of 30% hydrogen
peroxide until the digest is colorless.
- Remove from dry-block and allow to cool.
- Pour each tube into a 50ml volumetric flask, rinsing the tube with DI water.
Bring to volume with DI water and mix thoroughly.
- For analysis on the ICP in EM-1, the solution needs to be filtered to at least 0.45µm..
Plant Analysis Handbook; Jones, Wolf and Mills 1991
Micro-Macro Publishing, Athens Georgia ISBN 1-878148-001
In Falcon Library at QK 865,J66
Laboratory Guide for Conducting Soil Tests and Plant Analysis
J. Benton Jones, Jr., CRC Press 2001 ISBN 0-8493-0206-4