Stacking and determination of phenazine-1-carboxylic acid with low pKa in soil via moving reaction boundary formed by alkaline and double acidic buffers in capillary electrophoresis.
As shown herein, a normal moving reaction boundary (MRB) formed by an alkaline buffer and a single acidic buffer had poor stacking to the new important plant growth promoter of phenazine-1-carboxylic acid (PCA) in soil due to the leak induced by its low pK(a). To stack the PCA with low pK(a) efficiently, a novel stacking system of MRB was developed, which was formed by an alkaline buffer and double acidic buffers (viz., acidic sample and blank buffers). With the novel system, the PCA leaking into the blank buffer from the sample buffer could be well stacked by the prolonged MRB formed between the alkaline buffer and blank buffer. The relevant mechanism of stacking was discussed briefly. The stacking system, coupled with sample pretreatment, could achieve a 214-fold increase of PCA sensitivity under the optimal conditions (15 mM (pH 11.5) Gly-NaOH as the alkaline buffer, 15 mM (pH 3.0) Gly-HCl-acetonitrile (20%, v/v) as the acidic sample buffer, 15 mM (pH 3.0) Gly-HCl as the blank buffer, 3 min 13 mbar injection of double acidic buffers, benzoic acid as the internal standard, 75 μm i.d. × 53 cm (44 cm effective length) capillary, 25 kV and 248 nm). The limit of detection of PCA in soil was decreased to 17 ng/g, the intra-day and inter-day precision values (expressed as relative standard deviations) were 3.17-4.24% and 4.17-4.87%, respectively, and the recoveries of PCA at three concentration levels changed from 52.20% to 102.61%. The developed method could be used for the detection of PCA in soil at trace level.
Sun
Chong
C
Key Laboratory of Microbial Metabolism of Education Ministry, School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
Yang
Xiao-Di
XD
Fan
Liu-Yin
LY
Zhang
Wei
W
Xu
Yu-Quan
YQ
Cao
Cheng-Xi
CX
D000143:Acids / Q000737:chemistry; D000468:Alkalies / Q000737:chemistry; D002021:Buffers; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D007700:Kinetics; D010619:Phenazines / Q000737:chemistry; D010937:Plant Growth Regulators / Q000737:chemistry*; D012987:Soil / Q000032:analysis
D000143:Acids; D000468:Alkalies; D002021:Buffers; D010619:Phenazines; D010937:Plant Growth Regulators; D012987:Soil; C037165:1-phenazinecarboxylic acid