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High-performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS2) with a triple quadrupole is proposed for determining the synthetic phosphodiesterase-5 inhibitors, sildenafil, tadalafil and vardenafil, and the active metabolite N-desmethyl sildenafil. The method was successfully applied to the analysis of waters of different origins and human urine samples. Dispersive liquid-liquid microextraction (DLLME) was applied in the classical way for water analysis, whereas a previous extraction into an organic solvent was necessary for urine samples, the acetonitrile extract being used as dispersant solvent in the DLLME step. The analytes were determined by LC-ESI-MS2 in the multiple reaction monitoring mode. Detection limits were in the 5-50 and 15-250ngL-1 ranges for water and urine samples, respectively. The repeatability was calculated using the relative standard deviation, obtaining values of between 3.6% and 10.1%. The enrichment factors were between 75 and 81. Accuracy of the procedure was calculated through recovery assays and average recoveries ± SD (n = 48) of 93.6 ± 3.5 and 91.1 ± 3.5 were obtained for water and urine samples, respectively. None of the samples analyzed contained the target compounds, at least above the corresponding detection limits.

A magnetic dispersive micro-solid phase extraction procedure for the determination of the thallium content in waters is presented. The incorporation in the sample (10 mL) of a small amount of graphene-Fe3O4 composite (3.6 mg) in the presence of 10−4 mol L−1 Aliquat 336 at pH 2 results in the complete retention of both thallium(I) and thallium(III). After separation with a magnet, the micro-solid phase recovered is treated with 0.05 mL of a 0.1 mol L−1 sodium ethylenediaminetetracetate solution at pH 9, and the supernatant obtained after application of the magnet is introduced in the electrothermal atomizer of an atomic absorption spectrometer to obtain the signal corresponding to the total thallium content. For speciation, the trivalent form in a second sample aliquot is separated by means of a liquid-liquid extraction stage with chloroform and methyl trioctyl ammonium in the presence of bromide, and the signal corresponding to the monovalent form is obtained, the concentration of thallium(III) being obtained by difference. The enrichment factor is 185, which permits a detection limit as low as 0.01 μg L−1 of the analyte to be achieved. The relative standard deviation for five measurements at the 0.1 μg L−1 thallium level is below 5%. The reliability of the procedure is verified by analysing five certified reference samples for which speciation data are also given.

A micro-solid phase extraction procedure for the separation and preconcentration of antimony based in the use of magnetic particles covered with silver nanoparticles functionalized with the sodium salt of 2-mercaptoethane-sulphonate (MESNa) is discussed. After separation by means of a magnetic field, the solid phase is directly introduced into an electrothermal atomizer for antimony determination. Alternatively, the solid can be slurried and then injected into the atomizer. In all cases, palladium nitrate is used as a chemical modifier. The preconcentration factors are close to 205 and 325, with detection limits of 0.02 and 0.03µgL-1 antimony, for the slurry and solid sampling procedures, respectively. Speciation of Sb(III) and Sb(V) is achieved by means of two extractions carried out at different acidity. The results for total antimony are verified using certified reference materials. Water samples are analyzed for antimony speciation.

Freshly in situ prepared ferrite particles were used for the micro-solid phase extraction of arsenic species. When the separation was carried out at pH 8, inorganic arsenic (As(III) + As(V)) and monomethylarsonic acid (MMA) were retained in the magnetic material. A second aliquot was treated with 2,3 dimercapto propanol, leading to the retention of As(V)+MMA, while a third aliquot was first treated with sodium thiosulphate, in which case only inorganic arsenic passed to the solid phase. In all cases, the solid residue collected by a magnet was suspended in a dilute nitric acid solution containing Triton X-100 and introduced into the electrothermal atomizer to obtain the analytical signal of arsenic. The use of palladium as a chemical modifier allowed calibration to be carried out with aqueous standards. The detection limit was 0.02 µg L−1 arsenic for a 10 mL sample volume. The procedure was applied to waters and herbal infusions, and its reliability was evaluated by analyzing eleven certified reference materials for which speciation data are provided.

A graphene oxide (GO) suspension was used to retain chromium (III) species in a neutral solution. The addition of Triton X-45 followed by heating resulted in a coacervate, to which the GO nanoparticles containing the analyte retained were transferred. Chromium was determined directly in the surfactant-rich phase by electrothermal atomic absorption spectrometry. The procedure was repeated using a second aliquot of sample to which sodium hydrogen sulphite was added to reduce chromium (VI) to chromium (III). By again obtaining the analytical signal of chromium in the condensed phase, the concentration of the hexavalent form was calculated by difference. Using 10mL for the sample volume and 0.01% for the Triton X-45 concentration, the enrichment factor was 140, and the detection limit was 5ngL-1. The repeatability for five consecutive measurements at the 100ngL-1 level was close to 5%. The reliability of the procedure was verified by analysing seven water samples with certified contents of total chromium. Speciation data are given for these standard materials and for seven potable waters and one seawater sample.

The dispersive liquid–liquid microextraction of edible oils with a low volume of an acidic solution in the presence of isopropyl alcohol allows cadmium and lead to be completely separated into the aqueous phase. After centrifugation, the metals are determined by electrothermal atomization atomic absorption spectrometry using a palladium salt for chemical modification in the heating cycle. Using a 10 g oil sample, the enrichment factor is 140, which permits detection limits of 0.6 and 10 ng kg −1 for cadmium and lead, respectively. The results agree with those obtained after sample mineralization. Data for the cadmium and lead levels for 15 samples of different characteristics are given.

A simple and rapid method was developed using reversed-phase liquid chromatography (LC) with both diode array (DAD) and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of the vitamins ergocalciferol (D2), cholecalciferol (D3), phylloquinone (K1), menaquinone-4 (K2) and a synthetic form of vitamin K, menadione (K3). The Taguchi experimental method, an orthogonal array design (OAD), was used to optimize an efficient and clean preconcentration step based on dispersive liquid-liquid microextraction (DLLME). A factorial design was applied with six factors and three levels for each factor, namely, carbon tetrachloride volume, methanol volume, aqueous sample volume, pH of sample, sodium chloride concentration and time of the centrifugation step. The DLLME optimized procedure consisted of rapidly injecting 3 mL of acetonitrile (disperser solvent) containing 150 µL carbon tetrachloride (extraction solvent) into the aqueous sample, thereby forming a cloudy solution. Phase separation was performed by centrifugation, and the sedimented phase was evaporated with nitrogen, reconstituted with 50 µL of acetonitrile, and injected. The LC analyses were carried out using a mobile phase composed of acetonitrile, 2-propanol and water, under gradient elution. Quantification was carried out by the standard additions method. The APCI-MS spectra, in combination with UV spectra, permitted the correct identification of compounds in the food samples. The method was validated according to international guidelines and using a certified reference material. The validated method was applied for the analysis of vitamins D and K in infant foods and several green vegetables. There was little variability in the forms of vitamin K present in vegetables, with the most abundant vitamer in all the samples being phylloquinone, while menadione could not be detected. Conversely, cholecalciferol, which is present in food of animal origin, was the main form in infant foods, while ergocalciferol was not detected.

A microextraction procedure for the speciation of very low concentrations (0.005–0.2 µg L−1) of chromium is discussed. To the aqueous sample (10 mL), diluted hydrochloric acid, sodium chloride and a small amount of tributylphosphate (80 µL) are incorporated, and the mixture is submitted to ultrasounds for 10 min. The organic phase recovered after centrifuging is injected into the electrothermal atomizer, and the signal due to hexavalent chromium obtained. The repetition of the procedure using another aliquot in which all the chromium present is oxidized to Cr (VI) allows the Cr(III) content to be obtained by difference. The enrichment factor is 240 and the detection limit 0.002 µg L−1 chromium. The relative standard deviation for ten consecutive microextractions of a 0.1 µg L−1 chromium solution is close to 8%. The procedure is applied to waters and to the leachates obtained from low cost toys made of plastic materials.

A procedure for the determination of ultratrace levels of lead and cadmium using dispersive liquid–liquid microextraction followed by electrothermal atomic absorption spectrometry (ETAAS) has been developed. The ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C8MIm][NTf2]), is formed in situ and used to extract the lead and cadmium complexes with ammonium pyrrolidinedithiocarbamate. The very fine droplets of ([C8MIm][NTf2]) allow effective dispersion without the need for organic solvents. After centrifugation, the concentrations of lead and cadmium in the sedimented phase can be determined by ETAAS. Using a 10 mL aqueous sample, the enrichment factor of the procedure was 280 and detection limits of 0.2 and 3 ng L−1 were obtained for cadmium and lead, respectively. The relative standard deviations for 10 replicates at the 10 ng L−1 cadmium and 0.2 μg L−1 lead levels were 6.5 and 7.3%, respectively. The method was successfully applied to the analysis of waters as well as to lixiviates obtained from toys made of plastic materials.

This study describes a method for coupling dispersive liquid–liquid microextraction (DLLME) and normal-phase liquid chromatography (NP-LC) with fluorescence detection for vitamin A determination with the view to developing a new green sample preparation technique. Parameters affecting DLLME, including the nature and volume of both extractant and disperser solvents, salt addition and time and speed of the centrifugation step, were optimized. The sample was saponified according to European Standards to convert all forms of vitamin A to retinol. For microextraction, 8 mL water were placed in a glass tube with conical bottom and the saponified sample consisting of 2 mL of the methanolic extract containing 100 μL tetrachloroethane was rapidly injected by syringe, thereby forming a cloudy solution. Phase separation was performed by centrifugation, and a volume of 20 μL of the sedimented phase was analyzed by NP-LC. The enrichment factor, calculated as the ratio between the slopes of DLLME-LC and direct LC, was 50±3. The matrix effect was evaluated for different juice samples, and it was concluded that sample quantification can be carried out by aqueous calibration when the standards are also submitted to saponification. The proposed method was applied for determining both cis- and trans- retinol isomers in commercial juices of different types. The intraday and interday precisions were lower than 6% in terms of relative standard deviation. The method was validated using two certified reference materials.

A procedure for the determination of inorganic arsenic (III, V) and antimony (III, V) in water samples by using a miniaturized solid-phase extraction with carbon nanotubes followed by electrothermal atomic absorption measurement is proposed. The trivalent species are first complexed with ammonium pyrrolidinedithiocarbamate, next retained in a mini-column containing nanotubes and then eluted by means of a plug of an ammonia solution. The atomizer is impregnated with a tungsten salt which acts as an effective chemical modifier during the heating cycle. Total inorganic arsenic and antimony are determined after the reduction of the pentavalent forms with an ammonium iodide solution. Pentavalent arsenic and antimony are calculated by difference. When using 50 mL sample solutions, the limits of detection are 0.02 and 0.05 μg L−1 for As and Sb, respectively, and the enrichment factor is 250. The relative standard deviations calculated for five determinations at the 1 μg L−1 level are below 4%.

A new method for the electrothermal atomic absorption spectrometric determination of vanadium in milk and infant formulas using suspensions to avoid the need for previous dissolution of samples is described. Sensitivity is improved by a procedure based on preconcentration and removal of the matrix, using ion-exchange (Dowex 1X8-100). Suspensions of 15% (m/v) infant formula samples were prepared in a medium containing 0.05 M sodium citrate (pH 7.2) and passed through the ion exchange column. Vanadium was eluted from the column using 1 M hydrochloric acid and injected in the graphite furnace using a mixture of hydrofluoric acid plus magnesium nitrate as chemical modifiers. Calibration was carried out using multiple injection and aqueous standards prepared in the same medium. Detection limits were 0.2 ng g−1 for infant formulas and 0.02 μg L−1 for cow milk samples. The reliability of the procedure was checked by comparing the results obtained with those found using a previous mineralization stage and by analyzing five certified reference materials.

A reversed-phase high performance liquid chromatographic (RP-HPLC) method for determination of econazole nitrate, preservatives (methylparaben and propylparaben) and its main impurities (4-chlorobenzyl alcohol and alpha-(2,4-dichlorophenyl)-1 H -imidazole-1-ethanol) in cream formulations, has been developed and validated. Separation was achieved on a column Bondclone ® C18 (300 mm × 3.9 mm i.d., 10 μm) using a gradient method with mobile phase composed of methanol and water. The flow rate was 1.4 mL min −1 , temperature of the column was 25 °C and the detection was made at 220 nm. Miconazole nitrate was used as an internal standard. The total run time was less than 15 min. The analytical curves presented coefficient of correlation upper to 0.99 and detection and quantitation limits were calculated for all molecules. Excellent accuracy and precision were obtained for econazole nitrate. Recoveries varied from 97.9 to 102.3% and intra- and inter-day precisions, calculated as relative standard deviation (R.S.D.), were lower than 2.2%. Specificity, robustness and assay for econazole nitrate were also determined. The method allowed the quantitative determination of econazole nitrate, its impurities and preservatives and could be applied as a stability-indicating method for econazole nitrate in cream formulations.

A gas chromatography method with atomic emission detection (GC-AED) for the determination of dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and inorganic arsenic was optimized. The analytes were derivatized in the sample solutions with methyl thioglycolate (TGM) and the products were extracted into cyclohexane before an aliquot of this organic phase was directly injected into the chromatograph. The procedure was applied to the analysis of seawaters, wines, beers and infant foods, the last requiring an additional enzymatic reaction prior to analyte derivatization. Detection limits in seawaters and beverages were 0.05, 0.15 and 0.8 ng mL −1 for DMA, MMA and inorganic arsenic, respectively. In infant foods the detection limits were 1, 10 and 25 ng g −1 for DMA, MMA and inorganic arsenic, respectively. Inorganic arsenic was detected in some of the seawater samples and three of the wines analyzed at concentration levels in the range 1–40 ng mL −1 , and DMA in several of the infant foods in the range 20–80 ng g −1 . The method was validated by analyzing a certified reference material and by recovery studies. All the samples were also analyzed by hydride generation and atomic fluorescence spectrometry (HG-AFS), which provided data for the total arsenic content.

A computer-controlled manifold allowing the automatic generation of concentration profiles is described. For this purpose, the sample or standard solution is placed inside a semi-closed loop to which diluent is incorporated at a given flow rate, while the solution is removed at the same flow rate and directed towards the detector. The flow manifold, which works in a similar way to the tank model, includes a membrane micropump to recirculate the solution in the semi-closed loop. For simplicity purposes in the assessment of the system, a flame atomic absorption spectrometer is used for both withdrawing liquid and detection, although the basic idea can easily be extended to other detectors. The experimental data, verified by measuring the calcium, magnesium, sodium and potassium contents of some soft drinks demonstrate that the approach is reliable and may be a basis for developing portable instruments of reduced-size.

Atomic fluorescence spectrometry was used as an element-specific detector in hybridation with liquid chromatography (LC) and hydride generation for the speciation of Sb(III), Sb(V) and trimethylantimony dichloride (TMSbCl2). The three species were poorly resolved in a single chromatogram but good results were obtained by anion-exchange chromatography, using a mobile phase with 20 mM EDTA and 8 mM hydrogenphthalate to separate Sb(III) and Sb(V) and 1 mM carbonate at pH 10 to separate Sb(V) and TMSbCl2. Calibration graphs were linear between 2 and 100 μg l−1. Detection limits were 0.9, 0.5 and 0.7 μg l−1 for Sb(III), Sb(V) and TMSbCl2, respectively. The method was applied to the speciation of antimony in environmental samples.

Two manifolds allowing the automation of the standard additions method in flame atomic absorption spectrometry by using two computer-controlled variable-speed peristaltic pumps operating in a programmed way are presented in this article. One of the pumps increases and the other decreases its turning speed linearly with time, so that the flow-rate supplied to the nebulizer is constant. In the first manifold, one pump moves the sample solution, while the other pump propels a standard solution, so that a continuously changing on-line mixture of both the solutions is obtained. In the second manifold, both pumps, one of which also pumps a standard solution, while the other pumps a diluent solution, propel the sample solution. This second manifold that exactly reproduces the standard additions method, is automatic and allows releaser solutions to be used. Both the procedures present the additional advantage over the conventional batch procedure of the very high number of data that can be acquired by the computer. The theoretical background of both manifolds is presented and their correct operation is experimentally verified.

The cloud point extraction (CPE) of silver nanoparticles (AgNPs) by Triton X-114 allows chromium (III) ions to be transferred to the surfactant-rich phase, where they can be measured by electrothermal atomic absorption spectrometry. Using 20 mL sample and 50 μL Triton X-114 (30% w/v), the enrichment factor was 1150, and calibration graphs were obtained in the 5-100 ng L(-1) chromium range in the presence of 5 µg L(-1) AgNPs. Speciation of trivalent and hexavalent chromium was achieved by carrying out two CPE experiments, one of them in the presence of ethylenediaminetetraacetate. While in the first experiment, in absence of the complexing agent, the concentration of total chromium was obtained, the analytical signal measured in the presence of this chemical allowed the chromium (VI) concentration to be measured, being that of chromium (III) calculated by difference. The reliability of the procedure was verified by using three standard reference materials before applying to water, beer and wine samples.

A procedure is described for the rapid determination of calcium, magnesium and zinc in honey with no previous mineralization stage. The samples are dissolved in a solution containing dilute hydrochloric acid and a lanthanum salt, and then directly introduced into the flame atomic absorption spectrometer by means of a simple continuous-flow manifold. The computer-controlled system performs an automatic on-line dilution of the solutions, in this way decreasing matrix effects due to the organic matter content and allowing analytical signals within the linear response range to be obtained. Calibration is carried out against aqueous standards. Reproducibilities for calcium and magnesium measurements in the honey samples are close to +/-3%. The detection limit for zinc is 0.2 mug g(-1), the reproducibility obtained for a honey sample containing 1.7 mug g(-1) zinc being +/-5.2%. The results agree with those obtained by means of a lengthy mineralization-based procedure, the main advantages of the non-conventional methodology reported being automation, saving of time and a decrease in the contamination risk.

Pressurized liquid extraction (PLE) and dispersive liquid-liquid microextraction (DLLME) were used to isolate and preconcentrate tocopherols and tocotrienols from plant foods. The Taguchi experimental method was used to optimize the six factors (three levels for each factor), affecting DLLME, namely: carbon tetrachloride volume, methanol volume, aqueous sample volume, pH of sample, sodium chloride concentration and time of the centrifugation step. The influencing parameters selected were 2 mL of methanol:isopropanol (1:1) (disperser solvent), 150 µL carbon tetrachloride (extraction solvent) and 10 mL aqueous solution. The organic phase was injected into reversed-phase liquid chromatography (LC) with an isocratic mobile phase composed of an 85:15 (v/v) methanol:water mixture and a pentafluorophenyl stationary phase. Detection was carried out using both fluorescence and atmospheric pressure chemical ionization mass spectrometry (APCI-MS) in negative ion mode. Quantification was carried out by the standard addition method. Detection limits were in the range 0.2-0.3 ng mL(-1) for the vitamers with base-line resolution. The recoveries obtained using the optimized DLLME were in the 90-108% range, with RSDs lower than 6.7%. The APCI-MS spectra, in combination with fluorescence spectra, permitted the correct identification of compounds in the vegetable and fruit samples. The method was validated according to international guidelines and using two certified reference materials.

Nine volatile halogenated organic compounds (VHOCs), including four trihalomethanes (THMs), were determined in soils by capillary gas chromatography with microwave induced-plasma atomic emission spectrometry (GC-AED), using a purge-and-trap system (PT) for sample preconcentration. Analytes were previously extracted from the soil sample in methanol and the extract was preconcentrated before being chromatographed. Element-specific detection and quantification were carried out monitoring two wavelength emission lines, corresponding to chlorine (479nm) and bromine (478nm). Each chromatographic run took 21min, including the purge step. The method showed a precision of 1.1-7.2% (R.S.D.) depending on the compound. Detection limits ranged from 0.05 to 0.55ngml(-1), for chloroform and dichloromethane, respectively, corresponding to 3.3 and 36.0ngg(-1) in the soil samples. The chromatographic profiles obtained showed no interference from co-extracted compounds. Low levels of dichloromethane and chloroform ranging from 0.04 to 1.13mugg(-1) were found in samples obtained from small gardens irrigated with tap water. The method is reliable and can be used for routine monitoring in soil samples.

Fast-heating programmes for determining titanium and tin in soils, sediments and sludges using electrothermal atomic absorption spectrometry (ETAAS) with slurry sampling are developed. For titanium determination, suspensions are prepared by weighing 5-40mg of sample and adding 25ml of a solution containing 50% (v/v) concentrated hydrofluoric acid. For tin determination, suspensions are prepared by weighing up to 300mg of sample and then adding 1ml of a solution containing 25% (v/v) concentrated hydrofluoric acid. Palladium (30mug) and ammonium dihydrogen phosphate (7% w/v) are used as matrix modifiers for titanium and tin, respectively. Prior mild heating in a microwave oven is recommended for titanium determination. Calibration is carried out using aqueous standards. The tin and titanium contents of a number of samples obtained by using the slurry approach agree with those obtained by means of a procedure based on the total dissolution of the samples using microwave oven digestion. The reliability of the procedures is also confirmed by analysing several certified reference materials.

Rapid and direct procedures for the determination of molybdenum, chromium and aluminium in human urine samples are developed. Fast-programme methodology is used to simplify the heating cycles. Hydrogen peroxide, nitric acid and Triton X-100 are added to the urine samples which are directly introduced into the furnace. For molybdenum, two successive injection steps are required due to the low level of this element in the samples analyzed. Calibration is carried out using aqueous standards for aluminium and the standard additions method for both molybdenum and chromium. The reliability of the procedures is checked by analyzing two certified reference materials.

Infant formula and powdered milk samples were suspended in a medium containing 20% ethanol, 0.65% nitric acid, 6% hydrogen peroxide and 0.1% ammonium dihydrogenphosphate and directly introduced in the electrothermal atomizer. Liquid milk samples were diluted with this suspension solution. The build-up of carbonaceous residues inside the atomizer was avoided by using a combination of hydrogen peroxide and nitric acid. Fast programs were used to simplify the heating cycles. Calibration was carried out using aqueous standards and the detection limits for copper and zinc were found to be 70 and 15 pg, respectively. The metal contents of several milk samples obtained by direct introduction of the samples agree with those obtained by means of a conventional procedure based on the total dissolution of the samples. The reliability of the methods was also confirmed by analyzing three certified reference materials. The free and protein binding fractions were measured by ultrafiltration membrane permeability of the milk samples.

A study on the use of slurries in flame atomic absorption spectrometry is reported. Samples with a very high silica content are ground and then slurried in a solution containing 2% hydrochloric and 3% v/v hydrofluoric acids. The suspensions are prepared in the 0.01–1% m/v range and introduced into the flame by means of a simple flow injection manifold. Relative standard deviations for the measurements of iron, calcium and magnesium in diatomaceous earth samples are in the 1.5–2.8, 2.2–5.3 and 2.8–5.0% ranges, respectively. To avoid the use of suspensions prepared with a very low percentage of solid sample and to improve the reproducibility, an on-line dilution manifold is tried. The use of an easy-to-construct variable volume dilution chamber allows the on-line dilution of the slurries, thus permitting the determination of calcium and magnesium over a wide range of concentrations. Calibration is performed using aqueous standards. The experimental conditions, optimized for the determination of iron, calcium and magnesium in diatomaceous earth samples, can also be applied to other silica-based materials, as is shown by the analysis of several standard reference materials.

A rapid procedure for the determination of lead in commercial paprika samples is described. The samples are first calcined at 350°, then suspensions are prepared in water containing 0.1% v/v Triton X-100 and 0.1% w/v ammonium phosphate and injected into the electrothermal atomiser. The use of platform atomisation with a preatomisation cooling step allows for simple calibration with aqueous standards. When using 0.4% suspensions the detection limit is 0.2 ug/g. The results for seven paprika samples agree with those obtained by an alternative method involving calcination and dissolution in acid.

A sensitive and rapid spectrophotometric method for the determination of cadmium is described, based on the formation of a blue complex at pH 4 between the anionic iodide complex of cadmium(II) and Malachite Green; the colour is stabilized with poly(vinyl alcohol). The calibration graph for measurement at 685 nm is linear over the range 1-50 mug of cadmium per 25 ml of final solution, with a relative standard deviation of +/-1.7% for 1 mug/ml cadmium. The molar absorptivity is 6.1 x 10(4) 1.mole(-1).cm(-1). The method can be successfully adapted for FIA, the peak height being proportional to the cadmium concentration over the range 0.1-3 mug/ml; a two-channel manifold is used and an improvement in selectivity is obtained. The use of a gradient tube is demonstrated to give a good calibration for Cd(II) over the range 2 x 10(-2) -2 x 10(-6)M.

Sensitive spectrophotometric and spectrofluorimetric procedures for the determination of palladium have been developed, based on solvent-extraction of the ion-pair formed between Rhodamine B and the anionic complex of Pd(II) with thiocyanate. With an organic to aqueous phase-volume ratio of 1:5, the molar absorptivity is 9.0 × 10 4 l·mole −1 .cm −1 and the absorbance of the reagent blank is 0.026. Spectrophotometrically, palladium can be determined in the range 0.1–8.8 μg. Spectrofluorimetrically, it can be determined over the range 0.04–1.5 μg. The spectrophotometric procedure has been applied to the determination of palladium in dental alloys, organopalladium compounds and hydrogenation catalysts.