Determination of low molecular weight organic acids in soil, plants, and water by capillary zone electrophoresis

Abstract

Determination of low molecular weight organic acids in soils and plants by capillary zone electrophoresis was accomplished using a phthalate buffer and indirect UV detection mode. The influence of some crucial parameters, such as pH, buffer concentration and surfactant were investigated. A good separation of seven organic acids was achieved within 5 min using an electrolyte containing 15 mmol L(-1) potassium hydrogen phthalate, 0.5 mmol L(-1) myristyltrimethylammonium bromide (MTAB), and 5% methanol (MeOH) (v/v) at pH 5.60, separation voltage -20 kV, and temperature 25 degrees C. The relative standard deviation (n=5) of the method was found to be in range 0.18-0.56% for migration time and 3.2-4.8% for peak area. The limit of detection ranged between 0.5 micro mol L(-1) to 6 micro mol L(-1) at a signal-to-noise ratio of 3. The recovery of standard organic acids added to real samples ranged from 87 to 119%. This method was simple, rapid and reproducible, and could be applied to the simultaneous determination of organic acids in environmental samples.

Comparison of a rhizosphere-based method with other one-step extraction methods for assessing the bioavailability of soil metals to wheat

“…In our separate study (Li et al, 2003) the concentrations of acetic, lactic, malic and formic acids in rhizosphere soil and plant roots were determined, which ranged from below the detection limits of capillary zone electrophoresis to several mM. Other studies have also reported that the most abundant monocarboxylic acids (such as formic, acetic and propionic acids) were up to 1 mM in soil solutions (Jones, 1998;Strobel, 2001).…”

A comparison of the rhizosphere-based method with DTPA, EDTA, CaCl2, and NaNO3 extraction methods for prediction of bioavailability of metals in soil to barley

“…The total concentration of LMOWAs and their ratio were chosen based on their abundance in the rhizosphere zone. Acetic and lactic acids are the highest concentrations of all five LMWOAs because these two organic acids are more likely to originate from rhizosphere bacteria (Jones, 1998) and are the most abundant carboxylic acids in soil solution (Strobel, 2001;Li et al, 2003). Bioavailability of soil metals is the result of a combination effect of rootesoilemicrobe interaction occurring in the rhizosphere soil zone, in which LMWOAs are the primary factor involved in the metal adsorption by roots (Wang et al, 2004b;Han et al, 2005).…”

“…In our previous study it was demonstrated that acetic, lactic, malic and formic acids were dominant in plant roots and in the rhizosphere soil, ranging from several mM to several hundreds of mM, respectively (Li et al, 2003;Han et al, 2005). In order to simulate the content gradient of LMWOAs from root surface to soil solution (Cies´lin´ski et al, 1998;Fox and Comerford, 1990) and to use a short-term extraction for simulation of longterm reaction in the rhizosphere environment, the use of a mixture of total 10 mM of acetic, lactic, citric, malic, and formic acids at the molar ratio of 4:2:1:1:1 as an extractant was proposed as reasonable.…”

“…In our previous study the total concentrations of acetic, lactic, malic and formic acids in rhizosphere soil and plant roots were found on average at sub-millimolar (Li et al, 2003). The effects of organic acids on metal release from soil and on the uptake of metals by plants have been studied (Shan et al, 2003b).…”

Relationship between the extractable metals from soils and metals taken up by maize roots and shoots

“…The first two steps of BCR method and a single extraction procedure were adopted in this study. Among the reported LMWOAs, acetic acid, formic acid, citric acid and malic acids were frequently found to be the abundant organic acids (Jones, 1998;Li et al, 2003). The detailed extraction conditions are listed in Table 2.…”