Determination of thiram residues in fresh water using flow injection diperiodatonickelate(IV)-quinine chemiluminescence detection.

This study developed a simple flow injection (FI) method based on diperiodatonickelate(IV)-sulfuric acid reaction using chemiluminescence (CL) detection for the determination of thiram (THI) fungicide in fresh water using quinine as the sensitizer. The possible mechanism of the CL reaction was described using UV-Vis. absorption and CL spectra. Experimental variables were optimized by applying a univariate approach, and a linear calibration curve was obtained in the range of 1.0 × 10-3 -2.0 mg L-1 (R2 = 0.9994, n = 9) with a limit of detection of 5.0 × 10-4  mg L-1 (S/N = 3) and an injection throughput of 200 h-1 . This approach was successfully applied to determine THI in fresh water by using solid-phase extraction and achieved a good recovery rate of 94%-110% with a relative standard deviation of 1.9%-3.7% (n = 4). The results obtained were compared with the reported FI-CL and high-performance liquid chromatography-ultraviolet methods, and the three methods did not differ significantly at the 95% confidence limit.

Flow-injection determination of manganese (II) using surfactant enhanced diperiodatonickelate (IV)-rhodamine 6G chemiluminescence.

Chemiluminescence (CL) of the rhodamine 6-G-diperiodatonickelate (IV) (Rh6-G-Ni(IV) complex) in the presence of Brij-35 was examined in an alkaline medium and implemented using flow-injection analysis to analyze Mn(II) in natural waters. Brij-35 was identified as the surfactant of choice that enhanced CL intensity by about 62% of the reaction. The calibration curves were linear in the range 1.7 × 10-3 - 0.2 (0.9990, n = 7) and 8.0 × 10-4 - 0.1 µg ml-1 (0.9990, n = 7) with limits of detection (LODs) (S:N = 3) of 5.0 × 10-4 and 2.4 × 10-4 µg ml-1 without and with using an in-line 8-hydroxyquinoline (8-HQ) resin mini-column, respectively. The sample throughput and relative standard deviation were 200 h-1 and 1.7-2.2% in the range studied respectively. Mn(II) concentrations in certified reference materials and natural water samples was successfully determined. A brief discussion about the possible CL reaction mechanism is also given. In addition, analysis of V(III), Cr(III) and Fe(II) was also performed without and with using an in-line 8-HQ column and selective elution of each metal ion was achieved by adjusting the pH of the sample carrier stream with aqueous HCl solution.

Fate, distribution, and bioconcentration of pesticides impact on the organic farms of Cameron Highlands, Malaysia.

Occurrence and distribution of organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), and pyrethroid pesticides (PYRs) residues in the leafy vegetables were analyzed together with the soil samples using gas chromatography-electron capture detector. Edible tissues of vegetables showed detectable residues of these compounds indicating the influence of the conventional farms and nearby organic farms. In the vegetables, the OCPs concentrations were recorded as nd-133.3 ng/g, OPPs as nd-200 ng/g, and PYRs as nd-33.3 ng/g. In the soil, the OCPs concentrations were recorded as nd-30.6 ng/g, OPPs as nd-26.6 ng/g, and for PYRs as nd-6.7 ng/g. Bioconcentration factor (BCF) was higher for the OPPs (0.3) than the OCPs and PYRs (1.1). The OCPs concentration in the vegetables decreased in the following order: spinach > celery > broccoli > cauliflower > cabbage > lettuce > mustard. For OPPs, the concentration decreased in the following order: cauliflower > spinach > celery > cabbage > broccoli > lettuce > mustard and for PYRs as spinach > celery > lettuce > cabbage > broccoli. Principal component analysis indicates that the sources of these pesticides are not the same, and the pesticide application on the vegetables depends on the type of crop. There is a significant positive correlation between OPPs and the soil (r = 0.65) as compared to OCPs and PYRs (r = 0.1) as the vegetables accumulated OPPs more efficiently than OCPs and PYRs.

Flow Injection-Chemiluminescence Method for Determination of Hyoscine Butylbromide Using Silver(III) as Oxidizing Agent.

Diperiodatoargentate(III) (DPA)/silver(III) complex, [Ag(HIO6)2]5-, in sulfuric acid medium has been used to determine hyoscine butylbromide (HBB) by flow injection (FI) coupled with chemiluminescence (CL) detector. A linear standard curve between the CL intensity and concentration range from 0.005 to 20 mg L-1 was obtained. The determination coefficient (R2), limit of detection (3s × blank), relative standard deviation (RSD) for 0.5 mg L-1 HBB and analytical throughput were 0.9992 (n = 8), 5 × 10-4 mg L-1, 1.5% (n = 10) and 160 injections h-1, respectively. The developed method was applied for the determination of HBB in pharmaceutical formulations with recoveries from 92 ± 4 to 108 ± 3%. For comparison, a spectrophotometric method was used and the results obtained by both methods were in good agreement at a 95% confidence level. The effect of key chemical and physical variables (reagent concentration, flow rate, sample volume, PMT voltage) and interfering species (pharmaceutical excipients and inorganic ions) on the determination of HBB was examined. The possible CL mechanism of HBB on silver(III) complex in sulfuric acid medium was also discussed in brief.

Flow-Injection Determination of Thiabendazole Fungicide in Water Samples Using a Diperiodatocuprate(III)-Sulfuric Acid-Chemiluminescence System.

Chemiluminescence (CL) with a flow-injection method is reported for the determination of thiabendazole (TBZ) fungicide based on its enhancement effect on diperiodatocuprate(III) (DPC)-sulfuric acid-CL system. The calibration graph was linear in the concentration range of 1 - 2000 µg L(-1) (R(2) = 0.9999, n = 8) with a limit of detection (S/N = 3) of 0.3 µg L(-1). The injection throughput was 160 h(-1) with relative standard deviations (RSD, n = 4) of 1.1 - 2.9% in the concentration range studied. The experimental variables e.g., reagents concentrations, flow rates, sample volume, and PMT voltage were optimized, and the potential interferences were investigated individually. The method was successfully applied to the determination of TBZ in water samples showing good agreement and recovery in the range of 92 ± 2.2 - 108 ± 3% (n = 3) using dispersive liquid-liquid micro-extraction (DLLME). The possible CL reaction mechanism for DPC-sulfuric acid-TBZ is also discussed.