Monitoring of Inorganic and Organic Cations Using On-Line Ion Chromatography

Phosphorus (P) containing compounds, depending on their origin, can enter freshwater systems in variety of forms. Utilization of bioavailable P, a key nutrient in living organisms, is a crucial factor in biological productivity in aquatic environment¹. An increase in the P concentration in water, resulting from both natural and anthropogenic processes, can lead to eutrophication and an excessive growth of vegetative biomass. Determination of organic and inorganic P species in ground, surface and waster is an important part of water quality control and monitoring². Analytical determination of P compounds, quantification, identification (Chapter 2) and P speciation process can be problematic due to P adsorption on storage containers, sulfate interference, presence of acid hydrolysable P species and colloidal matter, association of both inorganic and organic phosphates with iron, manganese and aluminum, biological uptake of P. Such processes have to be considered when designing an analytical procedure for analysis of P species. Analytical P compound separation by ion chromatography with mass spectrometry/Orbitrap technology for compound detection (Chapter 3) is a powerful technology with highly sensitive and selective properties capable of performing P speciation in one analytical run. Selectivity of the Orbitrap detector also allows for utilization of isotope dilution technique which can compensate for loss of P compounds during storage and transportation and thus increase accuracy of measurements and holding time of sample matrices. Analytical techniques used in the past were able to determine broad P-fractions, such as total P, total P or functional groups of inorganic and organic P compounds. Identification of variety of specific P-containing compounds of inorganic and organic origin by the methodology used in this thesis in combination with multivariate statistical analysis can be used to explain the large sets of intercorrelated analytical variables with a smaller set of independent variables (Chapter 4) and help in source identification in water pollution studies³.

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Estimating Diphenylamine in Gunshot Residues from a New Tool for Identifying both Inorganic and Organic Residues in the Same Sample

Separations ◽

10.3390/separations6010016 ◽

2019 ◽

Vol 6 (1) ◽

pp. 16 ◽

Cited By ~ 4

Author(s):

Ana Argente-García ◽

Lusine Hakobyan ◽

Carmen Guillem ◽

Pilar Campíns-Falcó

Keyword(s):

Limit Of Detection ◽

Solid Phase ◽

High Sensitivity ◽

Capillary Liquid Chromatography ◽

Organic Residues ◽

Cotton Swab ◽

Gunshot Residues ◽

Relative Standard ◽

On Line ◽

Inorganic And Organic

A method involving the collection and determination of organic and inorganic gunshot residues on hands using on-line in-tube solid-phase microextraction (IT-SPME) coupled to miniaturized capillary liquid chromatography with diode array detection (CapLC-DAD) and scanning electron microscopy coupled to energy dispersion X-ray (SEM-EDX), respectively, for quantifying both residues was developed. The best extraction efficiency for diphenylamine (DPA) as the main target among organic residues was achieved by using a dry cotton swab followed by vortex-assisted extraction with water, which permits preservation of inorganic residues. Factors such as the nature and length of the IT-SPME extractive phase and volume of the sample processed were investigated and optimized to achieve high sensitivity: 90 cm of TRB-35 (35% diphenyl, 65% polydimethylsiloxane) capillary column and 1.8 mL of the processed sample were selected for the IT-SPME. Satisfactory limit of detection of the method for analysis of DPA deposited on shooters’ hands (0.3 ng) and precision (intra-day relative standard deviation, 9%) were obtained. The utility of the described approach was tested by analyzing several samples of shooters’ hands. Diphenylamine was found in 81% of the samples analyzed. Inorganic gunshot residues analyzed by SEM-EDX were also studied in cotton swab and lift tape kit samplers. Optical microscopy was used to see the inorganic gunshot residues in the cotton swab samplers. The lift tape kits provided lesser sensitivity for DPA than dry cotton swabs—around fourteen times. The possibility of environmental and occupational sources could be eliminated when DPA was found together with inorganic residues. Then, the presence of inorganic and organic residues in a given sample could be used as evidence in judicial proceedings in the forensic field.

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