Simultaneous determination of acetamiprid and 6-chloronicotinic acid in environmental samples by using ion chromatography hyphenated to online photoinduced fluorescence detector.

This study aims to introduce a simple, sensitive, and cost-effective method for the simultaneous determination of acetamiprid and its main metabolite 6-chloronicotinic acid in environmental samples by using a nonsuppressed ion chromatography hyphenated with an online postcolumn photoinduced fluorescence detection system. The fluorescence detector wavelengths λex /λem  = 257/382 nm was set for up to 6.0 min for acetamiprid, while λex /λem  = 231/370 nm programmed for 6-chloronicotinic acid for the rest of the analysis time. Both samples were treated by applying miniaturized quick, easy, cheap, effective, rugged, and safe method before the separation of analytes on an IonPac® AS11-HC column by pumping 40 mM NaOH having minuscule content of acetonitrile (5%, v/v) as an eluent. Both intrinsically nonfluorescent analytes were turned-on by online postcolumn photoinduced derivatization, avoiding the need for complex chemical derivatization or addition of a postcolumn extra pump. The developed method was appraised for the analysis of environmental samples, exhibiting excellent linearity (0.050-10 µg/mL) with a correlation coefficient greater than 0.9993 for both analytes. Whereas, obtained limit of detection (0.025-0.0072 µg/mL), recoveries (98.02-116.00%), and inter- and intraday precision (≤3.02 %) were satisfactory for both compounds in environmental samples.

Determination of nitenpyram and 6-chloronicotinic acid in environmental samples by ion chromatography coupled with online photochemically induced fluorescence detector.

A simple, cost-effective, sensitive, and quick method for the determination of nitenpyram and its metabolite 6-chloronicotinic acid in environmental samples was developed by coupling an ion chromatograph with a fluorescence detector and a post-column photochemical reactor. This developed analytical method involved a rapid sample extraction by modified and miniaturized quick, easy, cheap, effective, rugged, and safe method followed by isocratic ion chromatographic separation of nitenpyram and 6-chloronicotinic acid into an IonPac™ AS11-HC column protected by IonPac™ AG11A guard column by running 30 mM NaOH + 10% acetonitrile mobile phase. A homemade post-column photochemical reactor was also integrated with the ion chromatographic system for online transformation of both analytes into their respective highly fluorescent photoproduct in basic media without using an extra pump. The developed method was validated by following SANTE/11945/2015 guidelines on analytical quality control and validation procedures. The method showed a good linear response (r > 0.999), improved limit of detection (0.101-0.132 µg/L), minimum or no matrix effect, excellent recoveries (90.2-100.10%) and relative standard deviations were found to be ≤6.50%.

Simultaneous determination of peroxydisulfate and conventional inorganic anions by ion chromatography with the column-switching technique.

The application of ion chromatography with the column-switching technique for the simultaneous analysis of peroxydisulfate and conventional inorganic anions in a single run is described. With this method, conventional inorganic anions were separated by consecutive elution through both the guard column and separation column, but peroxydisulfate that only passed through the guard column had a good peak shape and short retention time. A series of standard solutions consisting of target anions of various concentrations from 0.01 to 75 mg/L were analyzed, with a correlation coefficient (r) ≥ 0.9990. The limits of detection were in the range of 0.49-9.84 µg/L based on the S/N of 3 and a 25 µL injection volume. RSDs for retention time, peak area, and peak height were all <1.77%. A spiking study was performed with satisfactory recoveries between 97.6 and 103.4% for all anions. The quantitative determination of peroxydisulfate and conventional inorganic anions in surface waters was accomplished within 18 min by this column-switching technique.

Determination of anions using monolithic capillary column ion chromatography with end-to-end differential contactless conductometric detectors under resonance approach.

An end-to-end differential measurement approach with capacitively coupled contactless conductivity detection (C(4)D) was applied to anion-exchange monolithic capillary column ion chromatography. The column was prepared by thermally initiated radical polymerization of poly(glycidyl methacrylate) in a fused-silica capillary of 320 µm i.d. and modified by quaternary ammonium latex surface coating. Two C(4)Ds were placed near both ends of the capillary column and the output difference between them was measured. With 15 mM potassium hydrogen phthalate used as the eluent, good separation of a mixture of inorganic anions (F(-), Cl(-), NO(2)(-), NO(3)(-)) was achieved. The detection limits of conventional C(4)D are 1.6, 0.28, 0.53, and 0.47 mg L(-1) for F(-), Cl(-), NO(2)(-), and NO(3)(-), respectively. To further enhance the sensitivity, the capacitive impedance from C(4)D was neutralized by an inductive impedance from a piezoelectric resonator. An increase in sensitivity by a factor of 7-8 was achieved in the resonating C(4)D in comparison with the conventional C(4)D. The detection limits of the resonating C(4)D are 0.23, 0.041, 0.065, and 0.059 mg L(-1) for F(-), Cl(-), NO(2)(-), and NO(3)(-), respectively. The response of the resonating C(4)D was analyzed based on an equivalent circuit model.

Online clean-up setup for the determination of non-fluorescent acidic pharmaceutical drugs in complex biological samples.

Analysis of acidic pharmaceuticals in complex biological samples is a challenging and formidable task due to the existence of interfering constituents within the sample matrices. Therefore, in order to avoid analytical column clogging and suppression/enhancement of signals of the analyte of interest, herein a simple, cost-effective and quick online ion chromatography based clean-up setup was introduced. This system was further coupled with a cost-effective homemade photochemically induced fluorimetric (PIF) setup for direct online conversion of non-fluorescent acidic pharmaceutical drugs into their respective fluorescent species. This advantageous system was favorably applied for the determination of four non-fluorescent acidic compounds in two complex biological samples (human serum and oral fluid) with minimum labor and organic solvent consumption. At optimized conditions, the developed method has shown good sensitivity, selectivity, satisfactory recoveries (88.68-102.14%) and low limits of detection (0.35-8.10 µg/L) with minimum or zero matrix effect.

Simultaneous determination of two plant growth regulators in ten food samples using ion chromatography combined with QuEChERS extraction method (IC-QuEChERS) and coupled with fluorescence detector.

A new simple, isocratic, selective and highly sensitive method has been developed for the simultaneous separation and determination of two plant growth regulators (PGRs): 2-(1-Naphthyl)acetic acid (NAA) and 2-(Naphthalen-1-yl)acetamide (NAD). Both PGRs were extracted by modified and miniaturized ion chromatography-Quick, Easy, Cheap, Effective, Rugged and Safe (IC-QuEChERS) method from ten food samples. The separation and sensitive determination were carried out by using ion chromatography coupled with fluorescence and ultraviolet (IC-FLD/UV) detector. The proposed analytical and extraction methods were validated by using blank samples, fortified with a standard solution of these two PGRs at three concentration levels 5, 15 and 25µg/kg. The method showed good linearity (r2≥0.980), satisfactory recoveries (76.3-112) with tolerable precision having relative standard deviations less than 15.4% (RSDs, n=3). The limit of detection and limit of quantification were also in the range of 0.08-6.6ng/kg and 2.2-20ng/kg, respectively.

Porous SnO2 nanoparticles based ion chromatographic determination of non-fluorescent antibiotic (chloramphenicol) in complex samples.

Nowadays, there are rising concerns about the extensive use of the antibiotics such as chloramphenicol (CAP), has threatened the human life in the form of various vicious diseases. The limited selectivity and sensitivity of confirmatory techniques (UV and electrochemical) and non-fluorescence property of CAP make its determination a challenging task in the modern pharmaceutical analysis. In order to redeem the selective, sensitive and cost-effective fluorescence methodology, here by the dual role of synthesized porous SnO2 nanoparticles were exploited; (i) a porous sorbent in a µ-QuEChERS based sample preparation and as (ii) a stimulant for the transformation of non-fluorescent analytes namely CAP and p-nitrophenol (p-NP) into their respective fluorescent product. We report a green, simple, selective and cost effective ion chromatographic method for CAP sensitive determination in three complex matrices including milk, human urine and serum. The synthesized sorbent not only selectively adsorbed and degraded the matrix/interferences but also selectively reduced the non-fluorescent antibiotic CAP into a fluorescent species. This developed ion chromatographic method exhibited good selectivity, linearity (r2 ≥ 0.996) and limit of detection (LOD) was in the range 0.0201-0.0280 µg/kg. The inter- and intraday precisions were also satisfactory having a relative standard deviation (RSDs) less than 14.96% and excellent recoveries of CAP in the range of 78.3-100.2% were retrieved in various complex samples.

Comprehensive two-dimensional ion chromatography (2D-IC) coupled to a post-column photochemical fluorescence detection system for determination of neonicotinoids (imidacloprid and clothianidin) in food samples.

There are increasing concerns about the dietary risks of neonicotinoids (NNIs); therefore their sensitive and accurate determination in dietary products is indispensable. However, the complex composition of agricultural food matrixes makes their extraction and quantitative determination a challenging task. Realizing this need, we herein report a simple, cost-effective, selective and sensitive fluorescence analytical workflow for analyses of two non-fluorescent neonicotinoids imidacloprid (IMI) and clothianidin (CLT) in six complex food samples (honey, ginger, durian, apple, tomato, cucumber) by online clean-up of sample extracts using two-dimensional ion chromatography (2D-IC) and a subsequent online post column UV induced fluorescence detection system. This online clean-up setup has proven advantageous to improve the limit of detection, potentially diminish matrix effects, and reduce analysis time and labor. The developed method showed excellent analytical figures of merit including linearity, selectivity, repeatability, recovery, and resolution for analysis of IMI and CLT in food samples.

Application of a simple column-switching ion chromatography technique for removal of matrix interferences and sensitive fluorescence determination of acidic compounds (pharmaceutical drugs) in complex samples.

This work illustrates the introduction of a simple, rugged and flexible column-switching ion chromatography (IC) technique for an automated on-line QuEChERS extracted samples extracts washing followed by sensitive fluorescence (FLD) determination of five acidic pharmaceutical drugs namely; clofibric acid (CLO), ibuprofen (IBU), aspirin (ASP), naproxen (NAP) and flurobrofen (FLU) in three complex samples (spinach, apple and hospital sewage sludge). An old anion exchange column IonPac® AS11-HC was utilized as a pre-treatment column for on-line washing of inorganic and organic interferences followed by isocratic separation of five acidic drugs with another anion exchange IonPac® AS12A analytical column by exploiting the column-switching technique. This novel method exhibited good linearity with correlation coefficients (r2) for all drugs were in the range 0.976-0.996. The limit of detection and quantification of all five acidic drugs were in the range 0.024µg/kg to 8.70µg/kg and 0.082µg/kg to 0.029mg/kg, respectively, and better recoveries in the range 81.17-112.5% with percentage relative standard deviations (RSDs) less than 17.8% were obtained. This on-line sample pre-treatment method showed minimum matrix effect in the range of 0.87-1.25 except for aspirin. This simple rugged and flexible column-switching system required only 28min for maximum elimination of matrices and interferences in three complex samples extracts, isocratic separation of five acidic drugs and for the continuous regeneration of pre-treatment column prior to every subsequent analysis. Finally, this simple automated IC system was appeared so rugged and flexible, which can eliminate and wash out most of interference, impurities and matrices in complex samples, simply by adjusting the NaOH and acetonitrile concentration in washing mobile phase with maximum recoveries of acidic analytes of interest.

A single pump cycling-column-switching technique coupled with homemade high exchange capacity columns for the determination of iodate in iodized edible salt by ion chromatography with UV detection.

A single pump cycling-column-switching technique has been developed for the iodate analysis in edible salt. Homemade high exchange capacity columns were adopted for the separation of iodate and chloride. Iodate could be retained and concentrated in a homemade concentrator column after eluents passing through the suppressor. With UV detection, iodate exhibited satisfactory linearity in the range of 0.1-10.0 mg/L with a correlation coefficient of 0.9996. The detection limit (LOD) was 45.53 µg/L, based on the signal-to-noise ratio of 3 (S/N=3) and a 100 µL injection volume. Relative standard deviations (RSDs) for retention time, peak area and peak height were all less than 2.1%. Recoveries of added iodate were in the range of 98.4-101.6% for the spiked samples. The quantitative determination of iodate in edible salt was accomplished by this column-switching technique, without any pretreatment and interference. The results on six samples were statistically compared with results determined by conventional titrimetric method.

Simultaneous determination of imidacloprid and carbendazim in water samples by ion chromatography with fluorescence detector and post-column photochemical reactor.

A new analytical method has been developed and validated for the simultaneous determination of pesticides from different classes using ion chromatography-online photochemical derivatisation-fluorescence detector (IC-hv-FD). Fluorimetric detection was performed at λex/λem=332 nm/367 nm for imidacloprid and then detector was set at λex/λem=247 nm/470 nm for carbendazim. The two pesticides imidacloprid and carbendazim were successfully separated isocratically on an IonPac(®) AS11 (250 mm × 4 mm i.d; 13 µm particle size, Dionex) anion-exchange column using 40 mM KOH with 10% (v/v) acetonitrile and pumped at a flow rate of 1.0 mL min(-1). Under the optimized conditions, the limit of detection (LOD, S/N=3) of imidacloprid and carbendazim were 7.8 µg L(-1) and 67 µg L(-1), respectively. The experimental results showed that there was good linearity with a correlation coefficient (r)≥0.9966 over the range of 0.05-10 mg L(-1) for imidacloprid and 0.2-15 mg L(-1) for carbendazim. Good reproducibility with a relative standard deviation (RSD, n=7) less than 4.5%. Finally, the proposed method was applied with satisfactory results to the analysis of these pesticides in ground water, lake water and river water without any pre-treatment of samples. The average spiked recoveries were in the range of 90-104%.

Simultaneous determination of glucose, D-gluconic, 2-keto-D-gluconic and 5-keto-D-gluconic acids by ion chromatography-pulsed amperometric detection with column-switching technique.

A simple ion chromatographic (IC) method for simultaneous determination of glucose, D-gluconic acid (DGA), 2-keto-D-gluconic acid (2-KDG) and 5-keto D-gluconic acid (5-KDG) was proposed, with pulsed amperometric detection (PAD) and column-switching technique. Using this technique, the four compounds were detected simultaneously in a short time with strongly retained compounds (2-KDG and 5-KDG) eluted out prior to weakly retained compounds (glucose and DGA). Under the optimized conditions, the method showed good linearity in the range of 0.01-20 mg L(-1) with determination coefficients (R(2))≥ 99.84%. Low detection limits (LODs) in the range of 0.87-2.59 µg L(-1) and good repeatability (RSD<3%, n=6) were obtained. The proposed method has been successfully applied to the analysis of the four compounds in the fermentation broth, in which Gluconobacter oxydans was used to produce gluconic acids from glucose.

Ion chromatography combined with online electrochemical derivatization and fluorescence detection for the determination of carbamazepine in human plasma.

This paper describes the determination of carbamazepine (CBZ) in human plasma using ion chromatography combined with online electrochemical derivatization and fluorescence detection. Separation of CBZ with anion exchange column was demonstrated to be feasible using either basic (10 mM NaOH) or acidic (0.1 M H(3)PO(4)) reagent with a small amount of acetonitrile (ACN) added as eluent. Electrochemical derivatization of CBZ into a strongly fluorescent product, which could be carried out only under the acidic condition, was investigated via the previously reported electrolytic cell (EC), as well as two modes of acidification. The linear range of CBZ for human plasma was between 10-2000 µg L(-1) under the optimized experimental conditions. The limit of detection (LOD, S/N=3) was 1.3 µg L(-1) and the relative standard deviation (RSD, n=7) was 2.6%. Better sensitivity and selectivity of the present method were demonstrated in comparison with ion chromatography with ultraviolet detection (IC-UV). The spiked recoveries of CBZ in 2 human plasma samples were 78.5 and 114%, respectively.

Simultaneous determination of iodide and iodate in povidone iodine solution by ion chromatography with homemade and exchange capacity controllable columns and column-switching technique.

A simple ion chromatographic method for simultaneous detection of iodide and iodate in a single running was proposed, with columns packed with homemade functionalized polystyrene-divinylbenzene (PS-DVB) resins and column-switching technique. Homemade resins were functionalized with controllable amounts of quaternary ammonium groups. The low-capacity anion-exchange column and high-capacity anion-exchange column were prepared, due to the resins having different exchange capacities. With this method, iodide and iodate in povidone iodine solution were detected simultaneously in a short time with iodide being eluted off first. A series of standard solutions consisting of target anions of various concentrations from 0.01 mg/L to 100 mg/L were analyzed. Each anion exhibited satisfactory linearity, with correlation coefficient r ≥ 0.9990. The detection limits (LODs) for iodide and iodate obtained by injecting 100 µL of sample were 5.66 and 14.83 µg/L (S/N=3), respectively. A spiking study was performed with satisfactory recoveries between 101.2% and 100.6% for iodide and iodate.