Method For Determination Of Sulfide Research Articles

Determination of sulfide at screen-printed electrode modified with ferricyanide-doped partially quaternized poly (4-vinylpyridine)

The indirect voltammetric method for determination of sulfide using the screen-printed electrode modified with ferricyanide-doped partially quaternized poly (4-vinylpyridine) in pH 7 phosphate buffer solution is reported. The electrode is prepared by adsorbing ferricyanide onto the screen-printed electrode coated with partially quaternized poly (4-vinylpyridine) anion-exchange polymer and finally sealing with sol-gel. The modified screen-printed electrode showed a highly stable and sensitive for sulfide analysis. The indirect electrochemical oxidation signal of sulfide appears at 0.2 V versus Ag/AgCl in pH 7 phosphate buffer solution. The calibration curve showed good linearity with a slope of 23.7 nA/μM at 0.4–100 μM sulfide. The detection limit (S/N = 3) was 0.12 μM. This method was applied to the determination of sulfide in cigarette smoke sample.

Interference Elimination of Sulfide Determination by Iodometry

As a classical method for sulfide determination in wastewater, iodimetry is adopted by many countries. But the existing of high concentration of reducing materials such as thiosulfate, sulfite and dissolved organic, which cant be eliminated by the pretreatment of zinc acetate-precipitation filtration, have an important influence on determination. The study on elimination method is carried out in this paper. It is indicated that the interference of S2O32-and SO32-can be eliminated by washing sedimentation with KOH solution of 10%. Iodometric titration with the pretreatment of zinc acetate-precipitation filtration and washing precipitate with 10% KOH is an accurate method to determine the sulfide content.

A novel gel‐based technique for the high resolution, two‐dimensional determination of iron (II) and sulfide in sediment

Many coastal marine sediments display highly heterogeneous biogeochemistry due to complex biological and chemical interactions. Existing measurement techniques are limited in their ability to characterize the distributions of reduced species at high resolution in two dimensions. To obtain more detailed information than existing methods, a novel technique for the simultaneous high‐resolution (1 mm), two‐dimensional determination of porewater iron (II), and sulfide using a gel‐based diffusive sampler was developed. A diffusive equilibration in a thin‐film (DET) hydrogel was colorized by Ferrozine reagent, imaged electronically, and analyzed using computer imaging densitometry. With the selected gel parameters, the method detection limit for iron (II) was 0.6 µmol L−1, with an upper calibration limit of 500 µmol L−1 and relative standard deviations below 10% across the calibration range. This method was integrated into the existing diffusive gradient in a thin film (DGT) method for sulfide determination. Field deployments of a prototype probe, which measured an area of 170 × 80 mm, in estuarine sediment revealed complex, fine‐scale, interlocking zones of iron (II) and sulfide. This confirms the need to assess more than a single dimension, at appropriately high resolution, to obtain an accurate representation of sediment geochemistry. Advantages of the technique include its high spatial resolution, minimal sample handling, flexible probe size, simultaneous measurement of two analytes at exactly the same location in the sediment, and the rapid production of data without requiring expensive analytical instrumentation.

Development of a new method for sulfide determination by vapor generator–inductively coupled plasma–mass spectrometry

A new sensitive methodology for the determination of total reduced sulfur species in natural waters and acid volatile sulfides in sediments at low levels (μg L − 1 ) is described. Reduced sulfur species were separated from the water matrix in the form of H 2S after reaction with hydrochloric acid in a commercial vapor generator coupled to an inductively coupled plasma quadrupole mass spectrometer (VG–ICP–QMS) equipped with a reaction cell. The method avoided the effect of polyatomic isobaric interferences at m/z 32 caused by 16O 16O + and 14N 18O + through the elimination of the aqueous matrix, a source of oxygen. By introducing a mixture of helium and hydrogen gases into the octopole reaction cell, a series of ion-molecule reactions were induced to reduce the interfering polyatomic species. Operating conditions of the octopole reaction cell system and the analyzer were optimized to get the best signal to background ratio for 32S; a full factorial 2 3 experimental design was developed in order to evaluate which variables had a significant effect and a simplex methodology was applied to find the optimum conditions for the variables. The new method was evaluated by comparison to the standard potentiometric method. The analytical methodology developed was applied to the analysis of reduced sulfur species in natural waters and acid volatile sulfides in sea sediments.

Direct rapid determination of traces of sulfide in environment samples

An improved ethylene blue method for determination of sulfide is developed. It has been adapted to a direct determination of sulfide by both common spectrophotometric method and total differential spectrophotometric method. In common spectrophotometric method, the calibration curve is A=1.69ρ+0.006 and the correlation coefficient is 0.9994. The apparent molar absorptivity is 5.42 × 104 L·mol−1·cm−1 and calibration curve is liner when ρ is in the range of 0–0.9 mg·L−1. In total differential spectrophotometric method, the calibration curve is A=9.25ρ + 0.004 and the correlation coefficient is 0.9996. The apparent molar absorptivity is 2.96 × 105 L·mol−1 L·mol−1·cm−1 and calibration curve is liner when ρ is in the range of 0–0.10 mg·L−1. The sensitivity of this method is increased significantly compared with the former ethylene blue method. The speed of reaction is also faster than the former one. The limit of detection is found to be 1.0 ng·mL−1 by both common spectrophotometric method and total differential spectrophotometric method. Ten replicate analyses of a sample solution containing 100 ng·mL−1 sulfide give a relative standard deviation of 1.8%. The effects of various cations and anions on the determination of sulfide are studied and procedures for removal of interference is described. The method is used for the determination of sulfide in environment samples with satisfactory results.

A simple, optimized method for the determination of sulphide in whole blood by GC–MS as a marker of bowel fermentation processes

Hydrogen sulphide is produced in human large intestine by anaerobic fermentation and may play a pathogenic role. An analytical method for determination of sulphide in whole blood using an extractive alkylation technique was optimised and validated for this purpose. The sample was mixed with organic phase containing pentafluorobenzyl bromide as an alkylating agent. The benzalkonium chloride was used as a phase-transfer catalyst. The quantitative determination was performed using GC–MS technique in selected ion monitoring mode. The blood levels of sulphide of healthy controls were measured (35–80 μ M/l). The method is versatile, reproducible (RSD=2.7%) and suitable for research of anaerobic fermentation in vivo.

Determination of elemental sulphur, sulphide and their mixtures in electrolyte solutions by a.c. voltammetry

The electrochemical behaviour of elemental sulphur, sulphide and their mixtures on a mercury electrode in 0.5 mol dm −3 NaCl-NaOH supporting electrolyte at pH 10 with and without the addition of 10% (v/v) methanol and 1 × 10 −5 mol dm −3 toluene was studied. Investigations were carried out over a wide concentration range (from 1 × 10 −8 to 1 × 10 −3 mol dm −3) of sulphur species in solution by a.c. voltammetry. Differences in the electrochemical behaviour during the formation of HgS at the electrode surface were observed between the two investigated species under different experimental conditions such as accumulation at different potential and voltammetric scan directions. Based on these differences, a method for the determination of sulphide, elemental sulphur and their mixtures in the aqueous solution is proposed. The solubility of elemental sulphur in aqueous medium at room temperature was determined as 1.7 × 10 −6 mol dm −3. The usefulness of the proposed method for the direct determination of sulphide and elemental sulphur in natural waters is discussed.

Determination of sulfide with chloranilic acid by biamperometric and automatic potentiometric end-point detection with a lead chloranilate selective electrode

A titrimetric method for determination of sulfide and of sulphur in steels with chloranilic acid by biamperometric and automatic potentiometric end-point detection is described. The construction of the sensor for potentiometric indication is also described. The results obtained agree with those of the iodine—thiosulfate method and with the certified values for the steels.

Spectrophotometric method for determination of sulfide with iron(III) and nitrilotriacetic acid by flow injection

A manual colorimetric method for determination of sulfide has been adapted to flow injection, systematically optimized, and more fully characterized. Its intended application is for measurement of sodium sulfide reagent strength in pulp process streams, and sulfide contamination in effluent from Kraft pulp mills. In the flow-injection method developed, a sample solution containing sulfide is reacted with a mixture of iron(III) and nitrilotriacetic acid under ammoniacal conditions. The absorbance of the intensely-colored green product of this reaction is measured at 636 nm. Excess sulfite is present as a color stabilizer. A linear dynamic range of 20–100 ppm sulfide is readily achieved; the relative standard deviation is less than 1.2% ( n = 10) throughout this range, and 0.37% ( n = 10) midrange at 60 ppm. The usable dynamic range is 8–250 ppm sulfide. Long-term stability of the method is ensured by periodically performing an automatic cleaning cycle using a hydrochloric acid wash solution. This prevents tube discoloration and removes any precipitates which are formed under strongly alkaline conditions. The sample throuhput rate is at least 30/hr, given alternate acid wash cycles.

Sulfide determination by N,N-dimethyl-p-phenylenediamine immobilization in cationic exchange resin using an optical fiber system

A new method for sulfide determination is described in which its reaction with N,N-dimethyl-p-phenylenediamine immobilized on a solid support yields methylene blue. The reaction takes place on the cationic exchange resin Dowex 50-X8, and light reflected from the sample is focused through an optical fiber system. Because of the irreversibility of the process, an optical cell rather than a sensor was chosen to monitor the methylene blue concentration. Up to 0.06 ppm sulfide, a linear calibration graph is obtained, although strict adherence to conditions is required to attain reproducible results.