Abstract
Dep. of Agronomy and Range Science, Univ. of California at Davis, Davis, CA 95616.
* Corresponding author.
Sodium, K, Mg, and Ca in plant tissue were measured by single column ion chromatography (SCIC) as an alternative to traditional methods such as atomic absorption spectrophotometry (AAS) or inductively coupled plasma-atomic emission spectrophotometry (ICPAES). Interference of the NH 4 peak on the Na peak in SCIC was eliminated by removal of NH 4 ions by drying the nitric-perchloric acid plant digest at 350 °C. Cations were separated using an IC-Pack CM/D column with 0.1 m M EDTA + 3 m M HNO 3 as eluent. Inclusion of 10% (v/v, = 1.89 M ) acetonitrile in the eluent shortened the retention time of divalent cations by 22% compared with the time without acetonitrile. The Na, K, Mg, and Ca content of plant samples analyzed with this technique agreed closely with certified values provided by the National Institute of Standards and Technology (NIST). The lower limit of detection of SCIC for Na, K, Mg, and Ca were 0.05, 0.2, 0.025, and 0.05 mg L –1 , respectively, using a 100-µL sample. The response of peak areas as a function of solute concentration was linear up to 10 mg L –1 of each cation. The SCIC method was cheaper than AAS or ICP, and faster than AAS, mainly due to simultaneous analyses of all four cations. SCIC did not generate hazardous and toxic waste and thus did not require special disposal procedures.
Received for publication October 27, 1992.