Trace Levels In Environmental Samples Research Articles

Determination of naphthalenesulfonic acid isomers by large-volume on-line derivatization and gas chromatography–mass spectrometry

This work presents a modified method to analyze polar and water-soluble naphthalene monosulfonic acid (NS) isomers in industrial effluents and river water samples. The method involves extraction of samples by a styrene–divinylbenzene copolymer solid-phase extraction cartridge, and on-line derivatization in the GC injection port using a large-volume (10 μl) sample injection with tetrabutylammonium salts. The analytes were then identified and quantitatively determined by GC–MS. The large-volume injection-port derivatization technique provides sensitivity, fast and reproducible results for NS isomers, to quantitation at 0.05 μg/l in 200 ml of water sample. Enhanced extracted mass chromatograms of molecular ion and [M−56] + ion of butylated NS isomers by electron impact ionization MS allows us to determine residues at trace levels in environmental samples. Recoveries of the NS isomers in spiked water samples ranged from 70 to 82% with RSDs around 10%. Naphthalene-2-sulfonic acid was found as a major pollutant and propagated in surface water and industrial effluents.

Applications of solid-phase microextraction (SPME) in the determination of residues of certain herbicides at trace levels in environmental samples.

A new analytical procedure based on solid-phase microextraction (SPME) has been developed for the determination of residues of eight selected herbicides: trifluralin, butachlor, pretilachlor, metolachlor, atrazine, acetochlor, alachlor, and fluroxypyr-meptyl, in ground water samples. Carbowax divinylbenzene was used for SPME of the herbicides. Quantification was done at equilibrium. Various parameters, such as, effect of pH, ionic strength, humic acid content and exposure time of fiber, were investigated to find the extraction efficiency. The linearity was determined. The method was found suitable for the determination of residues of herbicides at concentration levels from 5 to 20 ng L-1. The relative standard deviation of the detection limits were calculated. The humic acid content was found to interfere more significantly in the determination of residues. An ionic chloride strength, in terms of sodium chloride, of up to 10% did not have any significant impact on the determination. Furthermore, there was an enhanced sensitivity of detection up to pH 3.0. The method was applied to the analysis of the residue contents of the pesticides under investigation in real ground water samples collected from susceptible places. The results when compared with the standard methods published in the literature showed no significant deviation in their quantification and the values were comparable.

Analysis of linear alkylbenzenesulfonates in water samples by large-volume injection-port derivatization and gas chromatography–mass spectrometry

This work presents a modified method to analyze linear alkylbenzenesulfonates (LASs) in water samples. The method involves extraction of samples by a graphitized carbon black (GCB) cartridge, and direct derivatization in the GC injection port using a large-volume (10–20 μl) direct sample introduction (DSI) device with tetraalkylammonium (TAA) salts. The analytes were then identified and quantitated by ion-trap GC–MS. The large-volume DSI injection-port derivatization technique provides sensitivity, fast and reproducible results for LAS residues, to quantitation at 0.1 μg/l in 200 ml of water samples. The retention effect of TAA salts in the injection port was not detected. Enhanced selected mass chromatograms of [M−55] + ions of butylated C 10–C 13 LASs by electron impact ionization MS allows one to determine LAS residues at trace levels in environmental samples. Recovery of total LASs in spiked variety water samples ranged from 89 to 112% while RSDs ranged from 2 to 13%.

The effect of six reaction media on the determination of bismuth at trace levels in environmental samples by hydride generation and inductively coupled plasma-atomic emission spectrometry

An investigation was carried out to explore the effect of hydrochloric, tartaric, citric, oxalic, acetic and sulfosalicylic acids on the hydride generation of Bi at trace levels in a continuous flow system in conjunction with inductively coupled plasma atomic emission spectrometric detection. The operating conditions (chemical and physical parameters) and the concentrations of the acids studied were evaluated for the efficient generation of BiH3 (bismuthine). Kinetic information about the decomposition process of BiH3 was also obtained. Analytical figures of merit including detection limits, precision and linear dynamic ranges are given for the six acids employed. The detection limits for Bi ranged between 0.3 and 0.7 µg l–1 depending on the acid used to generate BiH3. Compared with conventional continuous nebulization, the present coupling gives a sensitivity increase of approximately two orders of magnitude. The interfering effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Ni, Zn), other hydride-forming elements (As, Ge, Pb, Sb, Se, Sn, Te) and Hg on the Bi signal using the different acids studied was evaluated. Tartaric acid is the most suitable reaction medium, in terms of efficiency in the hydride generation process and in the control of interferences. The proposed method was applied to the determination of Bi in certified reference materials (fresh water, silicate) and real environmental samples (iron ore and coal fly ash).

Alpha-spectrometry measurement of Am and Cm at trace levels in environmental samples using extraction chromatography

Various anthropogenic sources contribute to the presence of americium and curium isotopes in environmental samples. Incomplete radiochemical separations led to electrodeposited sources containing stable element impurities increasing auto-absorption effects. Other radioactive elements, such as 227Ac and its daughters, interfered with 241Am and 243,244Cm emissions. These impurities are now completely eliminated using a Tru-Spec® column. Very low levels of 241Am and 243,244Cm in environmental samples (i.e. algae, mussels, sediment, etc.) from the Channel and the Rhône river, including its estuary, were investigated using a routine radiochemical process and measurement at levels as low as achievable with state of the art measuring technology.

Spectrophotometric determination of zinc at trace level in environmental samples

Zinc is selectively extracted with N-hydroxy-N,N′-diphenylbenzamidine and spectrophotometrically determined with 4-(2-pyridylazo)resorcinol. The molar absorptivity is 9.4×104l·mol−1 cm−1. Relative standard deviation is ±1.5%.

Microwave-induced plasma as an element-specific detector for speciation studies at the trace level. Invited lecture

The microwave-induced plasma (MIP) is a promising excitation source for atomic spectrometry. In 1976 a major breakthrough was made by Beenakker, who introduced a cylindrical TM010 cavity capable of operating at atmospheric pressure for argon and helium plasmas. The helium-sustained MIP is particularly attractive because both non-metals and metals can be detected with good sensitivity. The characteristics of the MIP as an atomization and excitation source are briefly discussed and some advantages (multi-element detection of non-metals and metals) and limitations (only small amounts of sample can be tolerated) are highlighted. The MIP is efficient in the excitation of elements but the limited thermal energy available leads to difficulties with sample desolvation and atomization. In order to overcome the problems several techniques have been investigated to introduce volatilized samples into the MIP. Coupling with gas chromatography (GC), electrothermal vaporization, chemical vapour generation and other techniques is also discussed. The primary focus of work in this area has dealt with the utilization of the MIP as an element-specific detector for GC. With MIP atomic emission spectrometry it is possible to investigate chromatographic processes and to determine empirical molecular formulae of materials eluted from a GC column. Combination of the MIP with separation techniques for speciation of organic and organometallic compounds even at trace concentrations is the most important application for many disciplines, such as medicine and toxicology. Some of the useful features of MIP detection are exemplified by the determination of specific organomercury compounds at trace levels in environmental samples.

Determination of borate at trace levels in environmental samples by ion-exclusion chromatography

Dosage des ions borates dans diverses matrices (sediment, sol, eau) provenant de sites de l'environnement contamines