ABSTRACT
The European Union Water Framework Directive (2013/39/EU) sets very restrictive environmental quality standards for 45 priority substances and other pollutants, including organotin compounds (OTCs). Therefore, it is necessary to develop analytical methods in compliance with the environmental quality standard (EQSs) proposed to protect the aquatic environment and humans. The proposed method (HS-SPME-GC-QqQ-MS/MS) allows the determination of OTCs, i.e. monobutyltin (MBT), dibutyltin (DBT) and TBT in water in the range of few ng L(-1). The method is nearly full automated, sensitive and simple; it involves less reagents, reduces waste, and is less-time consuming than traditional methods for OTCs. As such, the procedure connects with the principles of green analytical chemistry. Additionally, good precision (RSD<20%), a very low method quantification limit (MQL) (0.76 ng L(-1) for TBT by using only 10 mL of sample) and excellent linearity (range MQL-20 ng L(-1)) are achieved. Under these conditions, the very restrictive limits for the environmental quality standards (EQS) fixed by the 2013/39/EU Directive are achieved.
Subject(s)
Environmental Monitoring/methods , Gas Chromatography-Mass Spectrometry , Organotin Compounds/analysis , Solid Phase Microextraction , Water Pollutants, Chemical/analysis , Water/chemistry , European UnionABSTRACT
A pressurised liquid extraction (PLE) procedure, by using methanol/water mixture, was developed for extracting arsenical species from marine biological material (mussel and fish) and standard reference materials (CRMs). A Plackett-Burman 2(8)x3/64 designs (PBD) was used as a multivariate strategy for the evaluation of the effects of several variables (MeOH/H(2)O solvent mixture, temperature, static time, extraction steps, pressure, mean particle size and diatomaceous earth (DE) mass/sample mass ratio) on the extracting procedure. Electrothermal atomic absorption spectrometry (ETAAS) was used to determine the total As concentration on the methanolic extracts. The accuracy of the optimised extraction procedure was verified by analysing several CRMs (GBW-08751, BCR-278R and DORM-2). The precision obtained (between 4.5 and 6.2%) was adequate. The extracted arsenic species (mainly arsenobetaine (AsB)) were analysed by high performance liquid chromatography coupled to ultraviolet cracking and hydride generation-atomic fluorescence spectrometry (HPLC-UV-HG-AFS). The analytical performances obtained were adequate for the arsenic speciation in marine biological samples; LOD between 10 and 35ng g(-1). The accuracy was verified for AsB using DORM-2. Finally, the proposed method (PLE followed by HPLC-UV-HG-AFS) was applied to mussel and fish samples.
ABSTRACT
Continuous flow hydride generation procedures for As(III), total inorganic As, Cd, total inorganic Sb, Se(IV) and total inorganic Se from sea and hot-spring water samples were optimised by experimental designs. Ir-coated graphite tubes were used as preconcentration and atomisation medium of the hydrides generated. Several factors affecting the hydride generation efficiency were studied. Results obtained from Plackett-Burman designs suggest that sodium borohydride flow rate and reduction coil length, are significant factors for total inorganic arsenic hydride generation. For cadmium hydride generation the significant factors are hydrochloric acid concentration, hydrochloric acid and sodium borohydride flow rates and reduction coil length. For total inorganic antimony hydride generation the factors affecting the hydride generation procedure are hydrochloric acid and potassium iodide concentrations and reduction coil length; finally, pre-reduction coil length and oven temperature for the pre-reduction step are statistically significant factors for total inorganic selenium hydride generation. In addition, the factors studied for the arsenic and selenium hydride generation from As(III) and Se(IV) are not significant. From these studies, the significant variables were optimised by central composite designs. Validation carried out analysis on three reference materials: SLRS-4 (Riverie water), CASS-3 (seawater) and NIST-1643d.
ABSTRACT
Fifteen metallic species, silver (Ag), aluminum (Al), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), strontium (Sr) and zinc (Zn), were determined in 46 cocaine samples confiscated by the Spanish police in Galicia (northwest Spain). Classification of these cocaine samples according to their geographic origin (Colombia and Venezuela) was achieved by the application of pattern recognition techniques to the metallic content data. Cocaine samples, around 0.5 g, were directly dissolved in 2 mL of 35.0% (v/v) HNO3, diluted to 10 mL with ultrapure water. The metals were quantified by means of electrothermal atomic absorption spectrometry (Ag, Al, Cd, Cr, Cu, Mn, Ni, Pb and Sr), flame atomic absorption spectrometry (Ca, Fe, Mg and Zn), and flame atomic emission spectrometry (K and Na). Results show that two geographic origins can be established through the presence of trace and major elements.
Subject(s)
Cocaine/classification , Drug Contamination , Illicit Drugs/chemistry , Metals/analysis , Substance Abuse Detection/methods , Cocaine/chemistry , Humans , Spectrophotometry, Atomic/methods , TemperatureABSTRACT
Methods for the direct determination of Ni in sea water samples by ETAAS were developed using Zeeman effect background correction system (ZEBC) and a multi-injection technique. A mass of palladium nitrate of 2.5 mug (for an injection volume of 100 mul) was used as chemical modifier. The optimum pyrolysis and atomization temperatures were 1700 and 2100 degrees C, respectively. The characteristic mass (m(0)) and characteristic concentration (C(0)), precision and accuracy were studied for different injection volumes (20, 100 and 200 mul). For an injection volume of 100 mul (five 20 mul aliquot) of sample the accuracy analysis of different certified materials (saline and non saline water) was agreeable. The total time of the proposed procedure is 6 min. A m(0) and C(0) of 34.5 pg and 0.3 mug l(-1), respectively were obtained for this injection volume (100 mul). Finally, interferences from major and minor components of sea water was studied.
ABSTRACT
Methods for the determination of aluminium and manganese in human scalp hair samples by electrothermal atomic absorption spectrometry using the slurry sampling technique were developed. Palladium and magnesium nitrate were used as chemical modifiers. Hair samples were pulverized using a zirconia vibrational mill ball, and were prepared as aqueous slurries. Determinations can be performed in the linear ranges of 1.9-150 mug l(-1) Al(3+) and 0.03-10.0 mug l(-1) Mn(2+). Limits of detection of 0.9 mg kg(-1) and 27.6 mug kg(-1) were obtained for aluminium and manganese, respectively. The analytical recoveries were between 99.6 and 101.8% for aluminium and in the 98.3-101.3% range for manganese. The repeatability of the methods (n=11), slurry preparation procedure and ETAAS measurement, was 16.0 and 7.9% for aluminium and manganese, respectively. The methods were finally applied to the aluminium and manganese determination in 25 scalp hair samples from healthy adults. The levels for aluminium were between 8.21 and 74.08 mg kg(-1), while concentrations between 0.03 and 1.20 mg kg(-1) were found for manganese.
ABSTRACT
Methods for the direct determination of silver and manganese in cocaine and heroin by electrothermal atomic absorption spectrometry using palladium as chemical modifier have been developed. Cocaine samples, 0.5 g, were dissolved in 2 ml of 35.0% (m/v), HNO(3) diluting to 10 ml with ultrapure water. A comparative study of palladium, magnesium nitrate, palladium-magnesium nitrate and nitric acid used as chemical modifiers was carried out, and it was found that palladium alone is adequate to stabilize silver and manganese at charring temperatures of 1000 and 1300 degrees C respectively. A study was made on the insertion of a cooling step before the atomization step, and this approach was not advantageous. Limits of detection of 2.3 and 6.9 microg kg(-1) were obtained for silver and manganese respectively. The analytical recovery oscillated between 95.9 and 103.6% for silver and between 99.7 and 103.0% for manganese. Finally, a study of some interferences and a study of the precision and analytical recovery of the amount of sample were also carried out.
ABSTRACT
A method for the determination of lead in human hair slurries by electrothermal atomic absorption spectrometry was optimized. Particle size reduction was achieved with a vibrational mill ball equipped with zirconia cups, 20 min being sufficient grinding time to achieve an adequate particle diameter (<1 mum). The use of different thickening agents, namely glycerol, Triton X-100 and Viscalex HV30, was studied and glycerol was found to be the best. The use of Pd and Mg(NO(3))(2) at optimum concentrations of 20 and 25 mg l(-1) respectively was found to be satisfactory for stabilizing lead at 1100 degrees C. A limit of detection of 0.21 mg kg(-1) was obtained. The limit of detection can be reduced to 0.05 mg kg(-1) without loss of analytical performance by increasing four-fold the amount of hair sample. Accuracy was studied by analysis of a CRM 397 human hair reference material with a certified lead content of 33.0 +/- 1.2 mg Pb kg(-1). The standard addition method was used for the determination of lead in hair samples from healthy people, the levels being between 2.3 and 35.5 mg kg(-1).
ABSTRACT
A comparative study of different chemical modifiers for the direct determination of arsenic in real and in synthetic sea water samples of high (72.8 per thousand ) and low (34.2 per thousand ) salinity was carried out. The use of lanthanum chloride and magnesium nitrate (LOD=3.0 microg l(-1)) offers good recoveries for low salinities, while for high salinities an enhancement higher than 200% was obtained, rendering this method unsuitable for sea water samples. The use of silver nitrate (LOD=2.0 microg l(-1)) produces unfavourable analytical recoveries, around 150 and 300% for synthetic sea water of low and high salinity. Zirconium oxychloride (LOD=1.8 microg l(-1)) and palladium nitrate alone or combined with magnesium nitrate and reducing agents (LOD=1.1-1.3 microg l(-1)) produce analytical recoveries close to 100% for all arsenic concentration tried over all salinities; thus, a single calibration curve using aqueous standard solutions may be applied to the analysis of sea water samples over all salinities. Finally, the addition of reducing agents and magnesium nitrate to palladium does not improve the sensitivity.
ABSTRACT
A method for the determination of total chromium in cocaine and heroin by flameless atomic absorption spectrometry is presented. Cocaine samples were dissolved in 2 ml of HNO(3) 35.0% (v/v) and diluted to 10 ml with ultrapure water; heroin samples were dissolved in ultrapure water, adding 0.4 ml of HNO(3) 35.0% (v/v) to dissolve inert species, and also diluted to 10 ml. Mg(NO(3))(2) and HNO(3), as chemical modifiers, were compared in terms of sensitivity, precision and accuracy, a lower detection limit being obtained for the use of Mg(NO(3))(2), 5.77 mug kg(-1) (7.23 mukg(-1) for HNO(3)). Within-batch precision was found to be 6.19% and 1.48% for drug solution spiked with 0 and 10 mug l(-1) of Cr(3+), respectively, when using Mg(NO(3))(2), and 7.45 and 1.19% for the same respective concentration levels when using HNO(3). Similar results on analytical recovery were obtained for both Mg(NO(3))(2) and HNO(3). Mg(NO(3))(2) was selected as the more adequate of the two chemical modifiers. A study of the introduction of a cooling-down step of 50 degrees C was carried out and compared in terms of sensitivity to the programme without a cooling-down step, but no advantage was observed. Studies on the variation in precision and analytical recovery with the amount of sample, and interferent effects of different species on chromium determination were developed. Finally, chromium concentrations obtained in cocaine samples varied between 0.02 and 0.14 mg kg(-1), the levels in the heroin samples being in the 0.05-0.59 mg kg(-1) range.
