Dispersive liquid–liquid microextraction coupled with capillary electrophoresis for simultaneous determination of sulfonamides with the aid of experimental design

Abstract

The spatial distribution of ammonia-oxidizing Betaproteobacteria (βAOB) was investigated by FISH (fluorescence in situ hybridization) and DGGE (denaturing gradient gel electrophoresis) techniques in the sediment off the Changjiang River Estuary. Sediment samples were collected from eight stations in June before the formation of hypoxia zone in 2006. The abundance of βAOB ranged from 1.87×105 to 3.53×10 5 cells/g of sediment. βAOB abundance did not present a negative correlation with salinity, whereas salinity was implicated as the primary factor affecting nitrification rates. The DGGE profiles of PCR-amplified amoA gene fragments revealed that the βAOB community structure of sample S2 separated from other samples at the level of 40% similarity. The variations in composition of βAOB were significantly correlated with the salinity, temperature, absorption ability of sediments and TOC. The statistical analysis indicates that the βAOB abundance was a main factor to influence nitrification rates with an influence ratio of 87.7% at the level of 40% biodiversity similarity. Considering the good correlation between βAOB abundance and nitrification estimates, the abundance and diversity of βAOB community could be expected as an indirect index of nitrification activity at the study sea area in summer.

Recent Advances in Dispersive Liquid - Liquid Microextraction for Organic Compounds Analysis in Environmental Water: A Review

“…2) To expand the combination ranges of DLLME. The coupling with other analytical instruments, such as inductively coupled plasma-optical emission spectrometry (ICP-OES) and capillary electrophoresis (CE), need some progress, which has not been widely applied [100]. The conjunction with other pretreatment methods, such as solid-liquid extraction, SBSE and SPE, can provide high EF, consistent recovery values as well as highly selective extractions.…”

“…5) To fully utilize chemometrics for the optimization of influence factors of DLLME. The use of chemometrics, in particular, experimental design methodology, can enable to achieve the best extraction conditions quickly in a relatively small number of experiments [100]. 6) To motivate the automation and instrumentation of DLLME.…”

“…The linear ranges obtained for all analytes were 0.01-2.0 μg mL -1 with LODs ranged from 0.14 to 0.81 μg L -1 . Lately, the UA-DLLME was also further developed by Chen and co-workers [99,100]. Sixteen PAHs in seawater samples were excellently separated and determined by UA-DLLME combined with little solvent consumption by GC-MS [99], and five sulfonamides were successfully detected in several environmental water samples by UA-DLLME coupled with capillary electrophoresis (CE) with the aid of experimental design [100].…”

Salting-out assisted liquid–liquid extraction with the aid of experimental design for determination of benzimidazole fungicides in high salinity samples by high-performance liquid chromatography

“…The employed Box-Behnken design involved 15 experimental runs, similar to our previous work [19], and the low, medium and high levels of each variable were coded as À 1, 0 and þ1, respectively. The Box-Behnken design matrix, i.e., the extraction conditions for each of the 15 runs and the recovery values for four benzimidazole fungicides are listed in Table 1.…”

Determination of 16 polycyclic aromatic hydrocarbons in seawater using molecularly imprinted solid-phase extraction coupled with gas chromatography-mass spectrometry

“…By monitoring the temporal amount of PAHs in the solutions, the procedures of the dynamic adsorption test were performed as follows: 50 mg of MIPs were dissolved in 10 mL of seawater spiked with 2 mg L À 1 individual PAH standards, and then the mixture was continuously oscillated in a thermostatically controlled water bath at room temperature for 1-24 h; the polymers were removed centrifugally, and then the 5 mL of supernatant was extracted by using dispersive liquid-liquid microextraction (DLLME) procedure [9,33,34] into a 10 mL glass-centrifuge tube; and then the analytes were located in the bottom of the tube, 1 mL of which was sampled for GC-MS analysis. For each adsorbent, these experiments were repeated at least triplicates.…”