José A. Salonia

Determination of lead in tap water by ICP-AES with flow-injection on-line adsorption preconcentration using a knotted reactor and ultrasonic nebulization

An on-line lead preconcentration and determination system implemented with inductively coupled plasma atomic emission spectrometry (ICP-AES) combined with a flow injection (FI) method with ultrasonic nebulization (USN) was studied. The lead was retained as the lead-diethyldithiocarbamate complex at pH 9.5. The lead complex was eluted from the knotted reactor (KR) with 4.0 mol l –1 hydrochloric acid. A total enhancement factor of 140 was obtained with respect to ICP-AES using pneumatic nebulization ( 14.8 for USN and 9.5 for KR). The detection limit for the preconcentration of 10 ml of aqueous solution was 0.2 ng ml –1 . The precision for ten replicate determinations at the 20 µg l –1 lead level was 2.7% relative standard deviation, calculated with the peak heights obtained. The calibration graph using the preconcentration system for lead was linear with a correlation coefficient of 0.9993 at levels near the detection limits up to at least 100 ng ml –1 . The method was successfully applied to the determination of lead in tap water samples.

Determination of vanadium (V) in drinking water by flow injection and pre-concentration in a knotted reactor by inductively coupled plasma optical emission spectrometry with ultrasonic nebulization

Abstract An on-line vanadium pre-concentration and determination system implemented with inductively coupled plasma optical emission spectrometry (ICP-OES) associated with a flow injection (FI) method with ultrasonic nebulization (USN) system was studied. The vanadium was retained as vanadium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol V(V)-(5-Br-PADAP) complex, at pH 3.2. The vanadium complex was removed from the knotted reactor (KR) with 30% v/v nitric acid. A sensitivity enhancement factor of 180 was obtained with respect to ICP-OES using pneumatic nebulization (15 for USN and 12 for KR). The value of detection limit for the pre-concentration of 10 ml of aqueous solution was 19 ng l −1 . The precision for 10 replicate determinations at the 5 μg l −1 V(V) level was 2.6% relative standard deviation (R.S.D.), calculated with the peak heights obtained. The calibration graph using the pre-concentration system for vanadium was linear with a correlation coefficient of 0.9995 at levels near the detection limits up to at least 100 μg l −1 . The method was successfully applied to the determination of vanadium in drinking water samples.

Factorial design for multivariate optimization of an on-line preconcentration system for platinum determination by ultrasonic nebulization coupled to inductively coupled plasma optical emission spectrometry

A system for on-line preconcentration and determination of platinum by ultrasonic nebulization (USN) coupled to inductively coupled plasma optical emission spectrometry (ICP-OES) was studied. It is based on the chemical sorption of platinum on a column packed with polyurethane foam loaded with thiocyanate reagent. The optimization step was carried out using two level full factorial design. Three variables (pH, loading flow rate (LFR) and eluent concentration) were regarded as factors in the optimization. Results of the two level factorial design 2(3) with three replicates of the central point for platinum preconcentration, based on the variance analysis (ANOVA), demonstrated that the factors and their interactions are not statistically significant. The proposed procedure allowed the determination of platinum with a detection limit of 0.28mugl(-1). The precision for 10 replicate determinations at 10.0mugl(-1) Pt level was 3.8% relative standard deviation (R.S.D.), calculated from the peak heights obtained. A total enhancement factor of 100 was obtained with respect to ICP-OES using pneumatic nebulization (10 for USN and 10 for preconcentration). A sampling frequency of 50 samples per hour was obtained. The effect of other ions in concentrations agreeing with water samples was studied. The addition/recovery experiments in the samples analyzed demonstrated the accuracy and applicability of the system developed for platinum determination in spiked water samples.

Determination of scandium in river water by ICP-OES with flow-injection on-line preconcentration using knotted reactor and ultrasonic nebulization

An on-line scandium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry (ICP-OES) associated with flow injection (FI) with an ultrasonic nebulization system (USN) was studied. The scandium was retained as the scandium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, Sc-(5-Br-PADAP), complex, at pH 9.5. The 5-Br-PADAP solution concentration was 1 × 10−4 mol l−1 and it was dissolved in a 17% (v/v) ethanol–water solution. The scandium complex was removed from the knotted reactor (KR) with 30% (v/v) nitric acid. A total enhancement factor of 1120 was obtained with respect to ICP-OES using pneumatic nebulization –Meinhard, Pneumatic Nebulizer– (25 for USN and 45 for KR) with a preconcentration time of 300 s. The value of the detection limit for the preconcentration of 30 ml of sample solution was 0.45 ng l−1. The precision for 10 replicate determinations at 10 ng l−1 Sc level was 3.5% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for scandium was linear with a correlation coefficient of 0.9996 at levels near the detection limits up to at least 50 µg l−1. The method was successfully applied to the determination of scandium in river water samples.

Inductively Coupled Plasma Optical Emission Spectrometric Determination of Gadolinium in Urine Using Flow Injection On‐Line Sorption Preconcentration in a Knotted Reactor

Abstract An on‐line gadolinium preconcentration and determination system, implemented with ultrasonic nebulization coupled to inductively coupled plasma optical emission spectrometry (ICP‐OES), associated with flow injection (FI) was studied. Gadolinium was retained as Gd‐2‐(5‐bromo‐2‐pyridilazo)‐5‐diethylaminophenol complex (Gd‐5‐Br‐PADAP) at pH 9.0, on the inner walls of the knotted reactor (KR). The collected analyte complexes were quantitatively eluted from the 200 cm KR with 30% (v/v) nitric acid. An enhancement factor of 255‐fold was obtained (17 for KR and 15 for USN). The detection limit (DL) value for the preconcentration of 15 mL of sample was 4.0 ng L−1. The relative standard deviation (RSD) was 3.5%, calculated from the peak heights obtained. The calibration graph using the preconcentration system for gadolinium was linear, with a correlation coefficient of 0.9996 at levels near the detection limit up to at least 200 µg L−1. The method was successfully applied to the determination of gadolinium in urine samples.

On‐Line Preconcentration and Analysis of Zinc in Water by Flow Injection‐Knotted Reactor: Application to Geological and Environmental Exploration

Abstract A preconcentration on‐line system composed of flow injection (FI) and a knotted reactor (KR), associated with inductively coupled plasma atomic emission spectrometry (ICP‐AES) has been used to determine Zn concentrations in river water. The zinc was retained as Zn‐2(5‐bromo‐2‐pyridilazo)5‐diethylaminofenol precipitated complex on the knotted reactor (KR). The limit of detection (0.09 µg L−1 of Zn) of this method makes it particularly suitable for hydrochemical exploration in geological and environmental projects. This application has been validated in the volcanogenic gold (copper, zinc, lead) deposit of La Carolina in the province of San Luis, Argentina. The Carolina Stream and the Grande River have been sampled for water downstream this deposit. The regional background in river water is 2 µg L−1. Six times this concentration has been observed at more than 6.5 km from the source, La Carolina mine.