Selective and simultaneous determination of phosphate and silicate ions in leaching process waters for ceramics glaze raw materials of narutal origin by ion-exclusion chromatography coupled with UV-detection after postcolumn derivatization.

The selective and simultaneous ion-exclusion chromatography (IEC) with UV-detection on a weakly acidic cation-exchange resin column in the H+ -form (TSKgel Super IC-A/C) was developed and applied for the simultaneous determination of phosphate and silicate ions as the water quality parameters required for optimizing the water-leaching process for ceramics glaze raw materials of natural origin including feldspar, woods-ash, and straw-ash. Phosphate and silicate ions in these water-leaching process water samples were separated selectively from the coexisting anions such as sulfate, chloride, nitrate and carbonate ions, based on the ion-exclusion separation mechanism. They were detected selectively and simultaneously by a postcolumn derivatization with molybdenum-yellow using the UV-detector. Under the optimized separation and detection conditions (eluent, 0-1 mM sulfuric acid; reactant, 10 mM sodium molybdate-25 mM sulfuric acid; detector, UV at 370 nm; temperature, 45 degrees C), the linearity of calibration was in the range 0.1 - 10 ppm for both phosphate and silicate ions, and the detection limits at S/N = 3 were 2.58 ppb for silicate ions and 4.75 ppb for phosphate ions. The effectiveness of this method was demonstrated in practical applications to the water-leaching process for some ceramics glaze raw materials.     

A new tool for inorganic nitrogen speciation study: simultaneous determination of ammonium ion, nitrite and nitrate by ion chromatography with post-column ammonium derivatization by Nessler reagent and diode-array detection in rain water samples

The paper presents a new method for a simultaneous determination of inorganic nitrogen species in the oxidized (NO₂⁻, NO₃⁻) and reduced (NH₄⁺) form in rain water samples. The method is based on a system of nitrogen species separation employing ion exchange and diode-array detection. The ions are separated in a strong ion-exchanger, nitrites and nitrates are determined directly at 208 and 205 nm, respectively, while the ammonium ions are determined in the column hold-up time after a post-column derivatization by the Nessler reagent, at 425 nm. The use of a diode-array detector permits a simultaneous identification of the inorganic nitrogen species in 8 min. The detection limits obtained are: NO₂⁻, 0.1 mg L⁻¹; NO₃⁻, 0.05 mg L⁻¹; NH₄⁺, 1 mg L⁻¹. The method proposed has been successfully used for speciation analysis of inorganic nitrogen in precipitation.     

Determination of octylphenol and nonylphenol in aqueous sample using simultaneous derivatization and dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry

A simple and fast sample preparation method for the determination of nonylphenol (NP) and octylphenol (OP) in aqueous samples by simultaneous derivatization and dispersive liquid–liquid microextraction (DLLME) was investigated using gas chromatography–mass spectrometry (GC/MS). In this method, a combined dispersant/derivatization catalyst (methanol/pyridine mixture) was firstly added to an aqueous sample, following which a derivatization reagent/extraction solvent (methyl chloroformate/chloroform) was rapidly injected to combine in situ derivatization and extraction in a single step. After centrifuging, the sedimented phase containing the analytes was injected into the GC port by autosampler for analysis. Several parameters, such as extraction solvent, dispersant solvent, amount of derivatization reagent, derivatization and extraction time, pH, and ionic strength were optimized to obtain higher sensitivity for the detection of NP and OP. Under the optimized conditions, good linearity was observed in the range of 0.1–1000 μg L⁻¹ and 0.01–100 μg L⁻¹ with the limits of detection (LOD) of 0.03 μg L⁻¹ and 0.002 μg L⁻¹ for NP and OP, respectively. Water samples collected from the Pearl River were analyzed with the proposed method, the concentrations of NP and OP were found to be 2.40 ± 0.16 μg L⁻¹ and 0.037 ± 0.001 μg L⁻¹, respectively. The relative recoveries of the water samples spiked with different concentrations of NP and OP were in the range of 88.3–106.7%. Compared with SPME and SPE, the proposed method can be successfully applied to the rapid and convenient determination of NP and OP in aqueous samples.     

Determination of melamine and related triazine by-products ammeline, ammelide, and cyanuric acid by micellar electrokinetic chromatography

In this study, micellar electrokinetic chromatographic (MEKC) methods were developed for the detection of traces of melamine and its related by-products (ammeline, ammelide, and cyanuric acid). Two on-line sample concentration steps namely reversed electrode polarity stacking mode (REPSM) and cation-selective injection (CSI) were used for improving the detection sensitivity. For REPSM, a borate-NaOH buffer (pH 10, 35 mM) composed of 60 mM SDS and 10% (v/v) methanol, was used as carrier electrolyte, and samples were prepared in an aqueous solution of 10 mM NaOH. In CSI, a phosphate buffer (pH 2, 50 mM) containing 41 mM SDS was used as the carrier electrolyte, and samples were prepared with an aqueous solution of 10 mM NaOH and a phosphate buffer (pH 2.0, 25 mM) in a volume ratio of 1:9. The results indicated that REPSM enhanced all analyte signals except for melamine, which could be concentrated only by the CSI. The detection limit was reduced from 1.7 mg L⁻¹ to 2.8 μg L⁻¹ for melamine by the optimal CSI step, and from 0.23-1.2 mg L⁻¹ to 2.4-5.0 μg L⁻¹ for the other three analytes by the optimal REPSM step. Tableware made of melamine and samples of flour were used as test samples, and the results indicated that the proposed MEKC methods can successfully determine contaminations from melamine. The study also indicated that when the plastic made of melamine was exposed only once to an acidic solution (acetic or phosphoric acid) at 80 °C for 30 min, melamine continuously leached out from the test sample even without any further treatment with an acidic solution.     

A novel capillary electrophoretic method for determining methylglyoxal and glyoxal in urine and water samples

Two non-electroactive biomarkers methylglyoxal (MGo) and glyoxal (Go) in urine and environmental water samples were determined for the first time by capillary electrophoresis with amperometric detection (CE-AD) after derivatizing with an electroactive compound 2-thiobarbituric acid. Experimental conditions of derivatization and CE-AD detection were optimized. Highly linear response was obtained for these two biomarkers over three orders of magnitude with good correlation (r² > 0.999). The limits of detection (LODs) and limits of quantitation (LOQs) of MGo and Go were 0.2 μg L⁻¹ and 1.0 μg L⁻¹, 0.5 μg L⁻¹ and 2.0 μg L⁻¹, respectively. The average recovery and relative standard deviation (RSD) were within the range of 90.9–101.3% and 0.7–2.2%, respectively. The proposed CE-AD method provides a reliable and sensitive quantitative evaluation of MGo and Go in real sample matrices by employing relatively simple and inexpensive instrument.     

Liquid chromatographic determination of microcystins in water samples following pre-column excimer fluorescence derivatization with 4-(1-pyrene)butanoic acid hydrazide

A method to measure the concentrations of microcystins (MCs) in water samples has been developed by incorporating pre-column fluorescence derivatization and liquid chromatography (LC). A solid-phase extraction for pretreatment was used to extract the MCs in water samples. The MCs were derivatized with excimer-forming 4-(1-pyrene)butanoic acid hydrazide (PBH). The MCs could then be detected by fluorescence after separation with a pentafluorophenyl (PFP)-modified superficially porous (core shell) particle LC column. The derivatization reactions of MCs with PBH proceeded easily in the presence of 4,6-dimethoxy-1,3,5-triazin-2-yl-4-methylmorpholinium (DMT-MM) as a condensation reagent, and the resulting derivatives could be easily separated on the PFP column. The derivatives were selectively detected at excimer fluorescence wavelengths (440–540 nm). The instrument detection limit and the instrument quantification limit of the MCs standards were 0.4–1.2 μg L⁻¹ and 1.4–3.9 μg L⁻¹, respectively. The method was validated at 0.1 and 1.0 μg L⁻¹ levels in tap and pond water samples, and the recovery of MCs was between 67 and 101% with a relative standard deviation of 11%. The proposed method can be used to quantify trace amounts of MCs in water samples.     

Confirmation of vanadium complex formation using electrospray mass spectrometry and determination of vanadium speciation by sample stacking capillary electrophoresis

Capillary zone electrophoresis (CZE) with UV detection was used to determine vanadium species. Nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylene glycol-bis(2-aminoethylether)-tetraacetic acid (EGTA) and 2,6-pyridinedicarboxylic acid (PDCA) were investigated to determine whether these ligands formed stable anionic complexes with vanadium. Of all the ligands studied HEDTA was the most suitable ligand because it gave the largest UV response with reasonable migration time. Electrospray mass spectrometry (ES-MS) was used to confirm the formation of [VO₂(HEDTA)]²⁻ and [VO(HEDTA)]¹⁻ in solution. An electrolyte containing 25 mM phosphate, 0.25 mM tetradecyltrimethylammonium bromide (TTAB) at pH 5.5 was optimum for the separation of these anionic vanadium complexes. Sample stacking techniques, including large-volume sample stacking (LVSS) and field-amplified sample injection (FASI), were tested to improve the sensitivity. Best sensitivity was obtained using FASI, with detection limits of 0.001 μM, equivalent to 0.4 μg L⁻¹, for [VO₂(HEDTA)]²⁻ and 0.01 μM, equivalent to 3.4 μg L⁻¹ for [VO(HEDTA)]¹⁻. The utility of the method for the speciation of V(IV) and V(V) was demonstrated using ground water samples.     

Sequential injection anodic stripping voltammetry with monosegmented flow and in-line UV digestion for determination of Zn(II), Cd(II), Pb(II) and Cu(II) in water samples

A cost-effective sequential injection system incorporating with an in-line UV digestion for breakdown of organic matter prior to voltammetric determination of Zn(II), Cd(II), Pb(II) and Cu(II) by anodic stripping voltammetry (ASV) on a hanging mercury drop electrode (HMDE) of a small scale voltammetric cell was developed. A low-cost small scale voltammetric cell was fabricated from disposable pipet tip and microcentrifuge tube with volume of about 3 mL for conveniently incorporated with the SI system. A home-made UV digestion unit was fabricated employing a small size and low wattage UV lamps and flow reactor made from PTFE tubing coiled around the UV lamp. An in-line single standard calibration or a standard addition procedure was developed employing a monosegmented flow technique. Performance of the proposed system was tested for in-line digestion of model water samples containing metal ions and some organic ligands such as strong organic ligand (EDTA) or intermediate organic ligand (humic acid). The wet acid digestion method (USEPA 3010a) was used as a standard digestion method for comparison. Under the optimum conditions, with deposition time of 180 s, linear calibration graphs in range of 10-300 μg L⁻¹ Zn(II), 5-200 μg L⁻¹ Cd(II), 10-200 μg L⁻¹ Pb(II), 20-400 μg L⁻¹ Cu(II) were obtained with detection limit of 3.6, 0.1, 0.7 and 4.3 μg L⁻¹, respectively. Relative standard deviation were 4.2, 2.6, 3.1 and 4.7% for seven replicate analyses of 27 μg L⁻¹ Zn(II), 13 μg L⁻¹ Cd(II), 13 μg L⁻¹ Pb(II) and 27 μg L⁻¹ Cu(II), respectively. The system was validated by certified reference material of trace metals in natural water (SRM 1640 NIST). The developed system was successfully applied for speciation of Cd(II) Pb(II) and Cu(II) in ground water samples collected from nearby zinc mining area.     

One-step extraction and derivatization liquid-phase microextraction for the determination of chlorophenols by gas chromatography–mass spectrometry

A sample pretreatment method for the determination of 18 chlorophenols (CPs) in aqueous samples by derivatization liquid-phase microextraction (LPME) was investigated using gas chromatography–mass spectrometry. Derivatization reagent was spiked into the extraction solvent to combine derivatization and extraction into one step. High sensitivity of 18 CPs derivatives could be achieved after optimization of several parameters such as extraction solvent, percentage of derivatization reagent, extraction time, pH, and ionic strength. The results from the optimal method showed that calibration ranging from 0.5 to 500 μg L⁻¹ could be achieved with the RSDs between 1.75% and 9.39%, and the limits of detection (LOD) are ranging from 0.01 to 0.12 μg L⁻¹ for the CPs. Moreover, the proposed LPME method was compared with solid-phase microextraction (SPME) coupled with on-fiber derivatization technique. The results suggested that using both methods are quite agreeable. Furthermore, the recoveries of LPME evaluated by spiked environmental samples ranged from 87.9% (3,5-DCP) to 114.7% (2,3,5,6-TeCP), and environmental water samples collected from the Pearl River were analyzed with the optimized LPME method, the concentrations of 18 CPs ranged from 0.0237 μg L⁻¹ (3,5-DCP) to 0.3623 μg L⁻¹ (2,3,6-TCP).     

Sensitive determination of hydrazine in water by gas chromatography–mass spectrometry after derivatization with ortho-phthalaldehyde

A gas chromatography–mass spectrometric (GC–MS) method has been established for the determination of hydrazine in drinking water and surface water. This method is based on the derivatization of hydrazine with ortho-phthalaldehyde (OPA) in water. The following optimum reaction conditions were established: reagent dosage, 40 mg mL⁻¹ of OPA; pH 2; reaction for 20 min at 70 °C. The organic derivative was extracted with methylene chloride and then measured by GC–MS. Under the established condition, the detection and the quantification limits were 0.002 μg L⁻¹ and 0.007 μg L⁻¹ by using 5.0-mL of surface water or drinking water, respectively. The calibration curve showed good linearity with r² = 0.9991 (for working range of 0.05–100 μg L⁻¹) and the accuracy was in a range of 95–106%, and the precision of the assay was less than 13% in water. Hydrazine was detected in a concentration range of 0.05–0.14 μg L⁻¹ in 2 samples of 10 raw drinking water samples and in a concentration range of 0.09–0.55 μg L⁻¹ in 4 samples of 10 treated drinking water samples.     

Continuous flow method for the simultaneous determination of phosphate/arsenate based on their different kinetic characteristics

This paper proposes a new automated spectrophotometric method for the simultaneous determination of phosphate and arsenate without pre-treatment, which is faster, simpler, less expensive and hazardous than other well-known methods used with water samples. Such method is based on the different kinetic characteristics of complex formation of phosphate and arsenate with ammonium molybdate. A flow system was used in order to achieve good mixing and to provide precise time control. All the measurements were performed at the isosbestic point wavelength (885 nm). Chemical variables were optimized by factorial design (ammonium molybdate 0.015 mol L⁻¹, potassium antimony tartrate 1 × 10⁻⁴ mol L⁻¹, and sulphuric acid 0.7 mol L⁻¹). An appropriate linear range for both analytes (0.50-8.00 μmol L⁻¹), good inter-day reproducibility (4.9% [P] and 3.3% [P + As]) and a sample throughput of 6 h⁻¹ were obtained. The detection limits are 0.4 μmol L⁻¹ P and 0.19 μmol L⁻¹ [P + As] (3.3 Sy/x). The method was validated.     

Liquid chromatography on an amide stationary phase with post-column derivatization and fluorimetric detection for the determination of streptomycin and dihydrostreptomycin in foods

The separation of streptomycin and its derivative dihydrostreptomycin using ion-pair liquid chromatography is proposed. The method is based on the use of a new stationary phase based on a ligand with amide groups and the endcapping of trimethylsilyl which avoids the appearance of tailed peaks. The isocratic mobile phase consisted of a 6:94 (v/v) acetonitrile/10 mM pentanesulfonic acid (pH 3.3) mixture at a flow-rate of 1 mL min⁻¹ and fluorescence detection involved a post-column derivatization reaction using β-naphthoquinone-4-sulfonate. Linearity, precision, recovery and sensitivity were satisfactory. The procedure was applied to the analysis of the aminoglycoside antibiotics in different types of foods, as honey, milk, egg and liver. Extraction was carried out by acidic hydrolysis to release protein-bound antibiotics. Detection limits in the food samples are 7.5 and 15 μg kg⁻¹ for streptomycin and dihydrostreptomycin, respectively.     

Evaluation of on-line preconcentration and flow-injection amperometry for phosphate determination in fresh and marine waters

Dissolved reactive phosphorus (DRP) was determined as orthophosphate (PO₄-P) in fresh and saline water samples by flow-injection (FI) amperometry, without and with in-valve column preconcentration. Detection is based on reduction of the product formed from the reaction of DRP with acidic molybdate at a glassy carbon working electrode (GCE) at 220 mV versus the Ag/AgCl reference electrode. A 0.1 M potassium chloride solution was used as both supporting electrolyte and eluent in the preconcentration system. For the FI configuration without preconcentration, a detection limit of 3.4 μg P l⁻¹ and sample throughput of 70 samples h⁻¹ were achieved. The relative standard deviations for 50 and 500 μg P l⁻¹ orthophosphate standards were 5.2 and 5.9%, respectively. By incorporating an ion exchange preconcentration column, a detection limit of 0.18 μg P l⁻¹ was obtained for a 2-min preconcentration time (R.S.D.s for 0.1 and 1 μg P l⁻¹ standards were 22 and 1.0%, respectively). Potential interference from silicate, sulfide, organic phosphates and sodium chloride were investigated. Both the systems were applied to the analysis of certified reference materials and water samples.     

Determination of flavonoids and saponins in Gynostemma pentaphyllum (Thunb.) Makino by liquid chromatography-mass spectrometry

Gynostemma pentaphyllum (Thunb.) Makino, a traditional Chinese herb possessing antitumor and antioxidant activities, has been shown to contain several functional components like saponins and flavonoids. However, their identities remain uncertain. The objectives of this study were to develop an appropriate extraction, purification and HPLC-MS method to determine saponins and flavonoids in G. pentaphyllum. Both flavonoids and saponins were extracted with methanol, followed by purification with a C18 cartridge to elute the former with 50% methanol and the latter with 100% methanol. A total of 34 saponins were separated within 40 min by a Gemini C18 column and a gradient mobile phase of acetonitrile and 0.1% formic acid in water, in which 18 saponins were identified by LC-MS with ESI mode and Q-TOF (LC/MS/MS). Similarly, a total of eight flavonoids were separated within 45 min by the same column and a gradient solvent system of methanol and 0.1% formic acid in water, with identification being carried out by a post-column derivatization method and LC-MS with ESI mode. The amounts of flavonoids in G. pentaphyllum ranged from 170.7 to 2416.5 μg g⁻¹, whereas saponins were from 491.0 to 89,888.9 μg g⁻¹.     

Determination of the steroid hormone levels in water samples by dispersive liquid-liquid microextraction with solidification of a floating organic drop followed by high-performance liquid chromatography

In this study, the steroid hormone levels in river and tap water samples were determined by using a novel dispersive liquid-liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO). Several parameters were optimized, including the type and volume of the extraction and dispersive solvents, extraction time, and salt effect. DLLME-SFO is a fast, cheap, and easy-to-use method for detecting trace levels of samples. Most importantly, this method uses less-toxic solvent. The correlation coefficient of the calibration curve was higher than 0.9991. The linear range was from 5 to 1000 μg L⁻¹. The spiked environmental water samples were analyzed using DLLME-SFO. The relative recoveries ranged from 87% to 116% for river water (which was spiked with 4 μg L⁻¹ for E1, 3 μg L⁻¹ for E2, 4 μg L⁻¹ for EE2 and 9 μg L⁻¹ for E3) and 89% to 102% for tap water (which was spiked with 6 μg L⁻¹ for E1, 5 μg L⁻¹ for E2, 6 μg L⁻¹ for EE2 and 10 μg L⁻¹ for E3). The detection limits of the method ranged from 0.8 to 2.7 μg L⁻¹ for spiked river water and 1.4 to 3.1 μg L⁻¹ for spiked tap water. The methods precision ranged from 8% to 14% for spiked river water and 7% to 14% for spiked tap water.     

Ultra-sensitive determination of cyanide in surface water by gas chromatography–tandem mass spectrometry after derivatization with 2-(dimethylamino)ethanethiol

A gas chromatography–tandem mass spectrometric (GC–MS/MS) method has been established for the determination of cyanide in surface water. This method is based on the derivatization of cyanide with 2-(dimethylamino)ethanethiol in surface water. The following optimum reaction conditions were established: reagent dosage, 0.7 g L⁻¹ of 2-(dimethylamino)ethanethiol; pH 6; reaction carried out for 20 min at 60 °C. The organic derivative was extracted with 3 mL of ethyl acetate, and then measured by using GC–MS/MS. Under the established conditions, the detection and quantification limits were 0.02 μg L⁻¹ and 0.07 μg L⁻¹ in 10-mL of surface water, respectively. The calibration curve had a linear relationship relationship with y = 0.7140x + 0.1997 and r² = 0.9963 (for a working range of 0.07–10 μg L⁻¹) and the accuracy was in a range of 98–102%; the precision of the assay was less than 7% in surface water. The common ions Cl⁻, F⁻, Br⁻, NO₃⁻, SO₄²⁻, PO₄³⁻, K⁺, Na⁺, NH₄⁺, Ca²⁺, Mg²⁺, Ba²⁺, Mn⁴⁺, Mn²⁺, Fe³⁺, Fe²⁺ and sea water did not interfere in cyanide detection, even when present in 1000-fold excess over the species. Cyanide was detected in a concentration range of 0.07–0.11 μg L⁻¹ in 6 of 10 surface water samples.     

Fabrication of electrolytic cell for online post-column electrochemical derivatization in ion chromatography

An electrolytic cell (EC), composed of two ruthenium-plated titanium electrodes separated by cation-exchange membranes, was fabricated and evaluated for online postcolumn derivatization in ion chromatography (IC). Folic acid (FA) and methotrexate (MTX) were preliminarily used as prototype analytes to test the performance of EC. After separation by an anion exchange column, FA and MTX, which emit very weak fluorescence when excited, were electrochemically oxidized online in the anode chamber of the EC. The compounds with strong fluorescence, which are oxidation products, were detected by the fluorescence detector. The phosphate buffer solution (100 mM KH₂PO₄) served as an optimal eluent for anion exchange chromatographic separation and a suitable supporting electrolyte for electro-oxidation, leading to ideal compatibility between IC separation and the postcolumn electrochemical derivatization. For the presently proposed method, the linear ranges were from 0.01 mg L⁻¹ to 5 mg L⁻¹ for both FA and MTX. The detection limits of FA and MTX were 1.8 and 2.1 μg L⁻¹, and the relative standard deviations (RSD, n = 7) were 2.9% and 3.6%, respectively. The method was applied for the simultaneous determination of FA and MTX in the plasma of patients being treated for rheumatoid arthritis. The determination of MTX in the urine of the patients of diffuse large B cell lymphoma was also demonstrated.     

Determination of bisphenol A and naphthols in river water samples by capillary zone electrophoresis after cloud point extraction

As a first attempt, cloud point extraction (CPE) was developed to preconcentrate bisphenol A (BPA), α-naphthol and β-naphthol prior to performing capillary zone electrophoresis (CZE) analysis. The parameters influencing the CPE efficiency, such as Triton X-114 concentrations, pH value, extraction time and temperature were systematically evaluated.After diluting with acetonitrile, the surfactant-rich phase of CPE can be injected directly into the CE instrument. The CZE baseline separation was achieved with running buffer (pH 9.5) composed of 50 mM sodium tetraborate in 30% (v/v) methanol, and an applied voltage of 25 kV. Under the optimized CPE and CZE conditions, an preconcentration factor of 50 times could be obtained and the limit of quantification for the three analytes were found to be 1.67 μg L⁻¹, 0.80 μg L⁻¹ and 0.67 μg L⁻¹ for BPA, α-naphthol and β-naphthol, respectively. The proposed methods have shown to be a green, rapid and effective approach for determination of three analytes present in river water samples.     

Zwitterionic hydrophilic interaction chromatography coupled with post-column derivatization for the analysis of glutathione in wine samples

In this study the development, validation and application of a new chromatographic method for the determination of glutathione (GSH) in wine samples is presented. The separation of the GSH was carried out using a sulfobetaine-based hydrophilic interaction chromatography (HILIC) analytical column whereas its detection was carried out spectrofluorimetrically (λ_ext/λ_em = 340/455 nm) after post-column derivatization with o-phthalaldehyde. GSH was separated efficiently from matrix endogenous compounds of wines by using a mobile phase of 15 mmol L⁻¹ CH₃COONH₄ (pH = 2.5)/CH₃CN, 35/65% (v/v). The parameters of the post-column reaction (pH, amount concentration of the reagent and buffer solution, flow rate, length of the reaction coil) were investigated. The linear determination range for GSH was 0.25–5.0 μmol L⁻¹ and the LOD was 19 nmol L⁻¹. No matrix effect was observed, while the accuracy was evaluated with recovery experiments and was ranged between 89% and 108%.     

A fast screening method for the presence of atrazine and other triazines in water using flow injection with chemiluminescent detection

Atrazine is a triazine herbicide which contains two secondary aliphatic amine groups. Previous studies have shown that aliphatic amines react with tris(2,2′-bipyridyl)ruthenium(III) to produce chemiluminescence. This paper describes the application of tris(2,2′-bipyridyl)ruthenium(III) to the detection of atrazine and related triazine herbicides in water by flow injection chemiluminescence analysis. The optimised experimental conditions were determined to be: sample and carrier flow rates of 4.6 mL min⁻¹, sample at pH 9 buffered with 50 mM borax, and reagent concentration of 1 mM tris(2,2′-bipyridyl)ruthenium(III) in 20 mM H₂SO₄ (pH 1). Under these conditions, the logarithm of the chemiluminescence intensity versus concentration was linear in the range of 2.15-2150 μg L⁻¹ for samples in MilliQ water, and the limit of detection of atrazine in water was determined to be 1.3 ± 0.1 μg L⁻¹. Validation of the method was performed using direct injection HPLC. The presence of natural organic matter (NOM) significantly increased the chemiluminescence, masking the signal generated by atrazine. Isolating the target analyte via solid phase extraction (SPE) prior to analysis removed this interference and concentrated the samples, resulting in a greatly improved sensitivity with a detection limit of 14 ± 2 ng L⁻¹.