Analysis of plant hormones by microemulsion electrokinetic capillary chromatography coupled with on-line large volume sample stacking

Abstract

A novel method of microemulsion electrokinetic capillary chromatography (MEEKC) coupled with on-line large volume sample stacking was developed for the analysis of six plant hormones including indole-3-acetic acid, indole-3-butyric acid, indole-3-propionic acid, 1-naphthaleneacetic acid, abscisic acid and salicylic acid. Baseline separation of six plant hormones was achieved within 10 min by using the microemulsion background electrolyte containing a 97.2% (w/w) 10 mM borate buffer at pH 9.2, 1.0% (w/w) ethyl acetate as oil droplets, 0.6% (w/w) sodium dodecyl sulphate as surfactant and 1.2% (w/w) 1-butanol as cosurfactant. In addition, an on-line concentration method based on a large volume sample stacking technique and multiple wavelength detection was adopted for improving the detection sensitivity in order to determine trace level hormones in a real sample. The optimal method provided about 50-100 fold increase in detection sensitivity compared with a single MEEKC method, and the detection limits (S/N = 3) were between 0.005 and 0.02 μg mL(-1). The proposed method was simple, rapid and sensitive and could be applied to the determination of six plant hormones in spiked water samples, tobacco leaves and 1-naphthylacetic acid in leaf fertilizer. The recoveries ranged from 76.0% to 119.1%, and good reproducibilities were obtained with relative standard deviations (RSDs) less than 6.6%.

Rapid simultaneous determination of four indole compounds in dietary supplements by micellar electrokinetic chromatography with a dilute and shoot step

“…At pH 8.00, the peaks for I3A and IAA were not baseline separated (top electropherogram, Fig. 26,31 IAA is a weak acid with a pK a of 4.75, 20 and is thus fully ionized in the pH range of the buffer (8.00-9.50). Generally in CE, the lower the pH the smaller the EOF velocity but this is not the case in MEKC.…”

“…13 Thus, the development of a simple, rapid and reliable analytical method for the determination of I3C, DIM and related indole compounds in dietary supplements for quality control is needed, especially when there are a large number of samples for analysis. 3,19,20 The dilute and shoot method is promising to incorporate into sample preparation since there is only a simple dilution of the aliquot of the sample before the direct measurement of the compounds. 18 MEKC has been applied to the determination of some indole compounds in plants, broccoli and plant tissues with multi-step sample-pretreatment, such as liquid-liquid extraction and solid-phase extraction prior to the chromatography.…”

Water-compatible dummy molecularly imprinted resin prepared in aqueous solution for green miniaturized solid-phase extraction of plant growth regulators

“…First, the calibration curves were constructed with the areas of chromatographic peaks measured at nine spiked levels over the range of 5-250 ng mL −1 , and good linearity of MIR-mini-SPE-HPLC method was observed throughout this concentration range for IAA, IPA, IBA, and NAA with correlation coefficient (r) ≥0.9998 as shown in Table 2. LODs and LOQs were 0.4-1.2 ng mL −1 and 1.2-4.1 ng mL −1 based on the signal-to-noise ratios of 3 and 10 respectively, which were lower than the LODs and LOQs of previous reported methods [32][33][34]. Second, recovery experiment was conducted with three different spiked levels of coconut samples, and the recovery of MIR-mini-SPE-HPLC method was in the range of 87.6-100.0% for coconut juice with RSDs of ≤8.1%, as shown in Table 3.…”

Twenty‐one years of microemulsion electrokinetic chromatography (1991–2012): A powerful analytical tool

“…After sample injected, the temporary reverse of polarity could pump out the sample matrix. More recently, a novel MEEKC method coupled with on‐column LVSS technique was proposed for analysis of trace plant hormones in 10 min . The sample matrix was pushed out of capillary by reversing the polarity.…”