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Analytical and Bioanalytical Chemistry (v.357, #4)
The ultra-clean chemical laboratory (UCCL) at the Institute for Reference Materials and Measurements (IRMM) by A. Lamberty; J. R. Moody; E. Van Duffel; P. De Bièvre; J. Broothaerts; P. Taylor; C. Lathen (pp. 359-363).
An Ultra-Clean Chemical Laboratory (UCCL) has been built at IRMM to allow reliable, contamination-free chemical treatment of samples prior to inorganic elemental or isotopic analysis. The concept is intended to guarantee a dust-free environment as well as resistance to corrosion even if hot concentrated mixtures of acids are continuously used, thus establishing not a clean or dust-free room but a clean laboratory. The excellent air quality is demonstrated both by particle measurements and the analysis of acids purified by subboiling distillation in the UCCL.
The ultra-clean chemical laboratory (UCCL) at the Institute for Reference Materials and Measurements (IRMM) by A. Lamberty; J. R. Moody; E. Van Duffel; P. De Bièvre; J. Broothaerts; Ph. Taylor; C. Lathen (pp. 359-363).
An Ultra-Clean Chemical Laboratory (UCCL) has been built at IRMM to allow reliable, contamination-free chemical treatment of samples prior to inorganic elemental or isotopic analysis. The concept is intended to guarantee a dust-free environment as well as resistance to corrosion even if hot concentrated mixtures of acids are continuously used, thus establishing not a clean or dust-free room but a clean laboratory. The excellent air quality is demonstrated both by particle measurements and the analysis of acids purified by subboiling distillation in the UCCL.
Preparation and properties of a new chelating resin containing imidazolyl azo groups by P. Chattopadhyay; C. Sinha; D. K. Pal (pp. 368-372).
A new chelating resin incorporating imidazolyl azo groups into a matrix of polystyrene divinylbenzene has been prepared. The exchange capacity of the resin for the ions mercury(II), silver(I) and lead(II) as a function of pH has been determined. The resin exhibits no affinity to alkali, or alkaline earth metals. It is highly selective for only mercury(II) and silver(I). In column operation it has been observed that mercury(II) in trace quantities is very effectively removed from river water spiked with mercury(II) at the usual pH of natural waters.
Preparation and properties of a new chelating resin containing imidazolyl azo groups by P. Chattopadhyay; C. Sinha; D. K. Pal (pp. 368-372).
A new chelating resin incorporating imidazolyl azo groups into a matrix of polystyrene divinylbenzene has been prepared. The exchange capacity of the resin for the ions mercury (II), silver(I) and lead(II) as a function of pH has been determined. The resin exhibits no affinity to alkali, or alkaline earth metals. It is highly selective for only mercury(II) and silver(I). In column operation it has been observed that mercury(II) in trace quantities is very effectively removed from river water spiked with mercury(II) at the usual pH of natural waters.
Certification of morphine-3-β-D-glucuronide in a human urine standard reference material by S. S.-C. Tai; Richard G. Christensen; Lane C. Sander; Michael J. Welch (pp. 373-378).
The U.S. National Institute of Standards and Technology (NIST) has developed and certified a standard reference material, SRM 2382, for use in testing for bias in the determination of morphine present as a glucuronide in human urine. This SRM consists of three levels of morphine-3-β-D-glucuronide (M-3-G) in lyophilized urine. Two independent hydrolysis procedures, enzymatic and acidic, for quantitative release of morphine were investigated. The results of hydrolysis efficiency from these two procedures agreed well. These two hydrolysis procedures along with two analytical methods developed previously for measurement of free morphine [1] were used to certify M-3-G in SRM 2382. Enzymatic hydrolysis was used with the GC/MS method and acidic hydrolysis was used with LC/MS. The results from these two pairs of methods were in good agreement, and were statistically combined to yield certified values of 209±20, 437±21, and 853±39 ng/mL for morphine, as the free base. Round-robin studies on this material among ten military laboratories demonstrated the suitability of the SRM for its intended purpose.
Certification of morphine-3-β-D-glucuronide in a human urine standard reference material by Susan S. -C. Tai; Richard G. Christensen; Lane C. Sander; Michael J. Welch (pp. 373-378).
The U.S. National Institute of Standards and Technology (NIST) has developed and certified a standard reference material, SRM 2382, for use in testing for bias in the determination of morphine present as a glucuronide in human urine. This SRM consists of three levels of morphine-3-β-D-glucuronide (M-3-G) in lyophilized urine. Two independent hydrolysis procedures, enzymatic and acidic, for quantitative release of morphine were investigated. The results of hydrolysis efficiency from these two procedures agreed well. These two hydrolysis procedures along with two analytical methods developed previously for measurement of free morphine [1] were used to certify M-3-G in SRM 2382. Enzymatic hydrolysis was used with the GC/MS method and acidic hydrolysis was used with LC/MS. The results from these two pairs of methods were in good agreement, and were statistically combined to yield certified values of 209 ± 20, 437 ± 21, and 853 ± 39 ng/mL for morphine, as the free base. Round-robin studies on this material among ten military laboratories demonstrated the suitability of the SRM for its intended purpose.
Novel surface acoustic wave-interdigitated array electrode gas sensor for dissolved ammonia by Kang Chen; Yuanjin Xu; Hong Zhang; Lihua Nie; S. Yao (pp. 379-383).
A novel surface acoustic wave-interdigitated array electrode (SAW-IDA) ammonia gas sensor is proposed. A gas-permeable membrane is employed to separate the buffer solution in the inner cell of the gas-sensing probe from the sample solution in the detection cell. The response of the IDA conductive electrodes is based on the impedance change of the buffer solution during ammonia adsorption. Therefore, this gas sensor overcomes the influence of water vapour in the conventional film-coated SAW gas sensor and can be used for the detection of gases in aqueous solutions. The ammonia sensor exhibits a favourable frequency response to 5×10-7–1×10-3 mol/l ammonia. The optimal buffer composition and probe parameters have been determined. Dynamic range, response time, selectivity, and temperature drift are discussed. The ammonia sensor was also applied to the determination of serum ammonia. Results were in good agreement with those from the conventional enzymatic-spectrophotometric method.
Novel surface acoustic wave-interdigitated array electrode gas sensor for dissolved ammonia by Kang Chen; Yuanjin Xu; Hong Zhang; Lihua Nie; Shouzhuo Yao (pp. 379-383).
A novel surface acoustic wave-interdigitated array electrode (SAW-IDA) ammonia gas sensor is proposed. A gas-permeable membrane is employed to separate the buffer solution in the inner cell of the gas-sensing probe from the sample solution in the detection cell. The response of the IDA conductive electrodes is based on the impedance change of the buffer solution during ammonia adsorption. Therefore, this gas sensor overcomes the influence of water vapour in the conventional film-coated SAW gas sensor and can be used for the detection of gases in aqueous solutions. The ammonia sensor exhibits a favourable frequency response to 5 × 10−7−1 × 10−3 mol/1 ammonia. The optimal buffer composition and probe parameters have been determined. Dynamic range, response time, selectivity, and temperature drift are discussed. The ammonia sensor was also applied to the determination of serum ammonia. Results were in good agreement with those from the conventional enzymatic-spectro-photometric method.
Use of microwave plasma torch atomic emission spectrometry for the determination of silicon by Feng Liang; Hanqi Zhang; Q. Jin; Daxin Zhang; Y. Lei (pp. 384-388).
A method for the elimination of matrix effects was developed for the determination of trace amounts of silicon by microwave plasma torch atomic emission spectrometry (MPT-AES). The sample solution was introduced into the MPT with a pneumatic nebulizer (PN). When Ar was used as both carrier and support gas, a detection limit of 10.8 ng/ml was obtained. The precision was 4.2% (RSD). The characteristics of the emission spectrum of silicon in MPT was studied in detail. The interference of some concomitant cations with the silicon emission was eliminated by incorporation of a cation-exchange column into the flow injection system. The method has been applied to analyze some practical samples and the results obtained are satisfactory.
Use of microwave plasma torch atomic emission spectrometry for the determination of silicon by Feng Liang; Hanqi Zhang; Qun Jin; Daxin Zhang; Yahu Lei; Qinhan Jin (pp. 384-388).
A method for the elimination of matrix effects was developed for the determination of trace amounts of silicon by microwave plasma torch atomic emission spectrometry (MPT-AES). The sample solution was introduced into the MPT with a pneumatic nebulizer (PN). When Ar was used as both carrier and support gas, a detection limit of 10.8 ng/ml was obtained. The precision was 4.2% (RSD). The characteristics of the emission spectrum of silicon in MPT was studied in detail. The interference of some concomitant cations with the silicon emission was eliminated by incorporation of a cation-exchange column into the flow injection system. The method has been applied to analyze some practical samples and the results obtained are satisfactory.
Sensitive and selective determination of mercury by differential pulse stripping voltammetry after accumulation of mercury vapour on a gold plated graphite electrode by Mieczysław Korolczuk (pp. 389-391).
A selective and sensitive method is proposed for the determination of mercury by anodic stripping voltammetry after its preconcentration from the gas phase. Mercury from the sample solution is reduced to elemental Hg by SnCl2 and volatilized by the bubbles of a carrier gas. The gas containing mercury vapour is dried and passed through a capillary onto a gold coated graphite electrode. An anodic stripping voltammogram is recorded from 0.1 mol/l HClO4+3×10-3 mol/l HCl solution. The calibration curve is linear from 1×10-9 to 4×10-8 mol/l Hg(NO3)2. The absolute detection limit is 0.46 ng Hg. The relative standard deviations for 4×10-9 mol/l and 2×10-8 mol/l Hg(NO3)2 are 9.8% and 6.1%, respectively (n=5).
Sensitive and selective determination of mercury by differential pulse stripping voltammetry after accumulation of mercury vapour on a gold plated graphite electrode by Mieczysław Korolczuk (pp. 389-391).
A selective and sensitive method is proposed for the determination of mercury by anodic stripping voltammetry after its preconcentration from the gas phase. Mercury from the sample solution is reduced to elemental Hg by SnCl2 and volatilized by the bubbles of a carrier gas. The gas containing mercury vapour is dried and passed through a capillary onto a gold coated graphite electrode. An anodic stripping voltam-mogram is recorded from 0.1 mol/1 HClO4 + 3 × 10−3 mol/1 HCl solution. The calibration curve is linear from 1 × 10−9 to 4 × 10−8 mol/1 Hg(NO3)2. The absolute detection limit is 0.46 ng Hg. The relative standard deviations for 4 × 10−9 mol/1 and 2 × 10−8 mol/1 Hg(NO3)2 are 9.8% and 6.1%, respectively n = 5).
Flow injection analysis with amperometric detection for measurements of proton activities in solutions of strong acids and strong bases by Anastas Dimitrov Dakashev (pp. 392-396).
Flow injection and reversed flow injection analysis with amperometric detection were used for the determination of the concentrations of strong acids and strong bases and the pH of the solutions. The amperometric detection was based on the reduction current of hydrogen ion or water molecules. A platinum indicator electrode cathodically polarized at a constant potential was employed, choosing the potential in the rising part of the current/potential curve. On the basis of the experimental data an equation was developed for the calculation of the concentrations of the strong acids and strong bases and the pH by a non-linear regression computer program.
Flow injection analysis with amperometric detection for measurements of proton activities in solutions of strong acids and strong bases by Anastas Dimitrov Dakashev (pp. 392-396).
Flow injection and reversed flow injection analysis with amperometric detection were used for the determination of the concentrations of strong acids and strong bases and the pH of the solutions. The amperometric detection was based on the reduction current of hydrogen ion or water molecules. A platinum indicator electrode cathodically polarized at a constant potential was employed, choosing the potential in the rising part of the current/potential curve. On the basis of the experimental data an equation was developed for the calculation of the concentrations of the strong acids and strong bases and the pH by a non-linear regression computer program.
Identification of reaction products of mild oxidation of H2S in solution and in solid state by UV-VIS spectroscopy by J. Melsheimer; R. Schlögl (pp. 397-400).
UV-VIS spectroscopic investigations were carried out on several sulphur-compounds to attribute the absorption bands (290, 302, 330 nm) observed by in-situ reflectance spectroscopy to particular SxO2- y and S2- x species. It was possible to assign the absorption bands to S2O2- 3, S2- 2 and S2O2- 4. These species are relevant in the catalytic oxidation of H2S over alumina.
Identification of reaction products of mild oxidation of H2S in solution and in solid state by UV-VIS spectroscopy by J. Melsheimer; R. Schlögl (pp. 397-400).
UV-VIS spectroscopic investigations were carried out on several sulphur-compounds to attribute the absorption bands (290, 302, 330 nm) observed by in-situ reflectance spectroscopy to particular SxO y 2− and S x 2− species. It was possible to assign the absorption bands to S2O 3 2− , S 2 2− and S2O 4 2− . These species are relevant in the catalytic oxidation of H2S over alumina.
Simultaneous separation and microdetermination of cobalt(II), nickel(II) and copper(II) by M. A. Kabil; S. E. Ghazy; A. A. El-Asmy; Y. E. Sherif (pp. 401-404).
A sensitive and selective flotation procedure for the separation of microamounts of Co(II), Ni(II) and Cu(II) separately or in admixture is described. The maximum separation rate (∼1) for 0.1 mmol/L of each analyte is achieved using 1 mmol/L of both oleic acid (HOL) surfactant and 4-phenylthiosemicarbazide (HPTS) as a collector in the pH range 6–7. A method for the simultaneous separation and microdetermination of the analytes is elaborated, based on adding excess HPTS and floating the species with HOL at pH ∼6. The filtrate (which is clear brownish-yellow) obtained from the scum is used for the spectrophotometric determination of Co(II) at 350 nm. The formation constants of 1:1 and 1:2 [Co(II):HPTS] species are 6.9×105 and 1.22×1010 L mol-1, respectively. Beer’s law is obeyed up to 9 μg/mL of Co(II) with a molar absorptivity of 1.15×104 L mol-1 cm-1. The precipitate in the scum layer is quantitatively collected, dissolved in aqua regia and aspirated directly into the flame for the (AAS) determination of Ni and Cu. The procedure is successfully applied to some natural water samples. A mechanism for the separation of the analytes is proposed.
Simultaneous separation and microdetermination of cobalt(II), nickel(II) and copper(II) by M. A. Kabil; S. E. Ghazy; A. A. El-Asmy; Y. E. Sherif (pp. 401-404).
A sensitive and selective flotation procedure for the separation of microamounts of Co(II), Ni(II) and Cu(II) separately or in admixture is described. The maximum separation rate (∼ 1) for 0.1 mmol/L of each analyte is achieved using 1 mmol/L of both oleic acid (HOL) surfactant and 4-phenylthiosemicarbazide (HPTS) as a collector in the pH range 6–7. A method for the simultaneous separation and microdetermination of the analytes is elaborated, based on adding excess HPTS and floating the species with HOL at pH ∼6. The filtrate (which is clear brownish-yellow) obtained from the scum is used for the spectrophotometric determination of Co(II) at 350 nm. The formation constants of 1:1 and 1:2 [Co(II):HPTS] species are 6.9 × 105 and 1.22 × 1010 L mol−1, respectively. Beer’s law is obeyed up to 9 μg/mL of Co(II) with a molar absorptivity of 1.15 × 104 L mol−1 cm−1. The precipitate in the scum layer is quantitatively collected, dissolved in aqua regia and aspirated directly into the flame for the (AAS) determination of Ni and Cu. The procedure is successfully applied to some natural water samples. A mechanism for the separation of the analytes is proposed.
The analysis of chromium, cobalt, iron, nickel, niobium, tantalum, titanium and zinc in cemented tungsten carbides with cobalt as a binder by inductively coupled plasma atomic emission spectrometry by T. Piippanen; Jouko Jaatinen; Jouni Tummavuori (pp. 405-410).
Inductively coupled plasma atomic emission spectrometry (ICP-AES) was applied as a rapid routine method for the analysis of cemented tungsten carbides. Chromium, cobalt, iron, nickel, niobium, tantalum, titanium and zinc were selected as major, minor and trace constituents in the material investigated. In the first step, the sample was treated with hydrochloric and orthophosphoric acid. The second step consisted of the simultaneous addition of hydrofluoric and nitric acids. Cemented tungsten carbides dissolved completely, leaving only minor quantities of carbon in the solution. Multiple linear regression proved to be very effective in the search for interfering elements. Using simple acid based standards, all the elements investigated could be determined individually from the complicated matrix using an appropriate method of calculation. The method described was successfully applied to real type commercial samples. The advantages of the ICP-AES method in comparison with the XRF-method are discussed.
The analysis of chromium, cobalt, iron, nickel, niobium, tantalum, titanium and zinc in cemented tungsten carbides with cobalt as a binder by inductively coupled plasma atomic emission spectrometry by Tero Piippanen; Jouko Jaatinen; Jouni Tummavuori (pp. 405-410).
Inductively coupled plasma atomic emission spectrometry (ICP-AES) was applied as a rapid routine method for the analysis of cemented tungsten carbides. Chromium, cobalt, iron, nickel, niobium, tantalum, titanium and zinc were selected as major, minor and trace constituents in the material investigated. In the first step, the sample was treated with hydrochloric and orthophosphoric acid. The second step consisted of the simultaneous addition of hydrofluoric and nitric acids. Cemented tungsten carbides dissolved completely, leaving only minor quantities of carbon in the solution. Multiple linear regression proved to be very effective in the search for interfering elements. Using simple acid based standards, all the elements investigated could be determined individually from the complicated matrix using an appropriate method of calculation. The method described was successfully applied to real type commercial samples. The advantages of the ICP-AES method in comparison with the XRF-method are discussed.
Isolation and determination of dissolved organic sulphur compounds – development of the organic group parameter DOS by F. Binde; H.-H. Rüttinger (pp. 411-415).
A procedure has been worked out for the determination of organic sulphur compounds (OSCs) in aqueous solution. They are isolated from water by solid phase extraction on macroporous resins and reversed-phase sorbents. The total sulphur content of the extracts is determined via a process of thermal cracking and hydrogenation (pyrohydrogenolysis) of small amounts of extract in a heated quartz tube (1100° C) flushed with hydrogen. Sulphur is detected at a wavelength of 394 nm in the hydrogen flame of a flame photometer. The flame photometric detector (FPD) is calibrated with a coulometric H2S-generator. The procedure of solid phase extraction and subsequent pyrohydrogenolysis/flame photometry of the extracts can be used to determine the organic group parameter DOS (Dissolved Organic Sulphur) in the range of 20– 1000 μg/l.
Isolation and determination of dissolved organic sulphur compounds — development of the organic group parameter DOS by F. Binde; H. -H. Rüttinger (pp. 411-415).
A procedure has been worked out for the determination of organic sulphur compounds (OSCs) in aqueous solution. They are isolated from water by solid phase extraction on macroporous resins and reversed-phase sorbents. The total sulphur content of the extracts is determined via a process of thermal cracking and hydrogenation (pyrohydrogenolysis) of small amounts of extract in a heated quartz tube (1100°C) flushed with hydrogen. Sulphur is detected at a wavelength of 394 nm in the hydrogen flame of a flame photometer. The flame photometric detector (FPD) is calibrated with a coulometric H2S-generator. The procedure of solid phase extraction and subsequent pyrohydrogenolysis/flame photometry of the extracts can be used to determine the organic group parameter DOS (Dissolved Organic Sulphur) in the range of 20–1000 μg/1.
Two-step solvent extraction flow injection system for the determination of anionic surfactants by spectrophotometry by Shihua Fan; Z. Fang (pp. 416-419).
An automated flow injection procedure for the determination of anionic surfactants with two-step extraction was developed, based on the official methylene blue method. A washing step was used for on-line treatment of the extracted products with methylene blue to eliminate interferences. An improved gravitational phase separator was used to overcome the limitations of the membrane separator, and an effective separation of the two phases was performed by gravity separation in a conical cavity constructed of PTFE and stainless steel. Use of PTFE pump tubing allowed reliable and reproducible withdrawal and propulsion of organic extractant at low flow-rates. The calibration graphs were linear up to 6.0 mg/l of sodium dodecyl sulfonate in aqueous solution when 100 μl of sample was injected, a relative standard deviation of 4.6% (n=7) was achieved. The recoveries of the procedure were in the range of 89–107%. The results obtained for anionic surfactants in waste water samples agreed well with those obtained by the standard methylene blue batch method.
Two-step solvent extraction flow injection system for the determination of anionic surfactants by spectrophotometry by Shihua Fan; Zhaolun Fang (pp. 416-419).
An automated flow injection procedure for the determination of anionic surfactants with two-step extraction was developed, based on the official methylene blue method. A washing step was used for on-line treatment of the extracted products with methylene blue to eliminate interferences. An improved gravitational phase separator was used to overcome the limitations of the membrane separator, and an effective separation of the two phases was performed by gravity separation in a conical cavity constructed of PTFE and stainless steel. Use of PTFE pump tubing allowed reliable and reproducible withdrawal and propulsion of organic extractant at low flow-rates. The calibration graphs were linear up to 6.0 mg/l of sodium dodecyl sulfonate in aqueous solution when 100 μl of sample was injected, a relative standard deviation of 4.6% (n = 7) was achieved. The recoveries of the procedure were in the range of 89–107%. The results obtained for anionic surfactants in waste water samples agreed well with those obtained by the standard methylene blue batch method.
Species analysis of automotive carbon particles: Application of XPS for integral analysis of filter samples by U. Wild; N. Pfa¨nder; R. Schlo¨gl (pp. 420-428).
In the discussion of possible toxic effects of carbon particle emissions from automotive sources the question about the origin of the material is of relevance. Besides the emissions of Diesel soot (DS) a second source of debris from tire abrasion (TD) has the potential to contribute significantly to the carbon particle emissions. The discrimination between these chemically different species is complicated by the unavoidable presence of molecular carbon species from general sources, from fuel components and from polycyclic aromatic hydrocarbons (PAH) on the filter surface deposits from imission tests. Based on the different surface reactivity of DS and TD, a quantitative data analysis procedure using the X-ray photoelectron spectroscopy (XPS) carbon 1s profile is suggested, which gives an estimate of the fraction of DS in the total carbon present. The difference to 100% is the sum of TD and molecular carbon which constitutes its dominant contribution. The method agrees semi-quantitatively with traditional chemical analysis of the elemental carbon fraction on the filters. Several independent chemical tests are provided for the internal consistency of the analysis method which is based upon the use of reference spectra from pure TD. The application of a simplified analytical equipment for large numbers of samples is discussed.
Species analysis of automotive carbon particles: Application of XPS for integral analysis of filter samples by U. Wild; N. Pfänder; R. Schlögl (pp. 420-428).
In the discussion of possible toxic effects of carbon particle emissions from automotive sources the question about the origin of the material is of relevance. Besides the emissions of Diesel soot (DS) a second source of debris from tire abrasion (TD) has the potential to contribute significantly to the carbon particle emissions. The discrimination between these chemically different species is complicated by the unavoidable presence of molecular carbon species from general sources, from fuel components and from polycyclic aromatic hydrocarbons (PAH) on the filter surface deposits from imission tests. Based on the different surface reactivity of DS and TD, a quantitative data analysis procedure using the X-ray photoelectron spectroscopy (XPS) carbon 1s profile is suggested, which gives an estimate of the fraction of DS in the total carbon present. The difference to 100% is the sum of TD and molecular carbon which constitutes its dominant contribution. The method agrees semi-quantitatively with traditional chemical analysis of the elemental carbon fraction on the filters. Several independent chemical tests are provided for the internal consistency of the analysis method which is based upon the use of reference spectra from pure TD. The application of a simplified analytical equipment for large numbers of samples is discussed.
Simultaneous voltammetric determination of molybdenum and copper in biological samples by Stella T. Giroussi; A. N. Voulgaropoulos; Aristomenis Ayiannidis (pp. 429-432).
A selective, sensitive and reliable voltammetric method for the simultaneous determination of Cu and Mo is developed. Both metals form complexes with 8-hydroxyquinoline (oxine). Mo gives two reduction peaks with oxine in acidic chloride media at −0.52 V and −0.58 V, while copper exhibits only one at −0.14 V. Common heavy metals do not interfere at all. The limit of detection is 0.29 ng/ml for Mo and 0.14 ng/ml for Cu after preconcentration on the hanging mercury drop electrode for 30 s at −0.2 V. The R.S.D. at a concentration level of 10 ng/ml is 3.8% for Cu and 5.3% for Mo. The method is applied to different biological samples.
Simultaneous voltammetric determination of molybdenum and copper in biological samples by Stella T. Giroussi; Anastasios N. Voulgaropoulos; Aristomenis Ayiannidis (pp. 429-432).
A selective, sensitive and reliable voltammetric method for the simultaneous determination of Cu and Mo is developed. Both metals form complexes with 8-hydroxyquinoline (oxine). Mo gives two reduction peaks with oxine in acidic chloride media at −0.52 V and −0.58 V, while copper exhibits only one at −0.14 V. Common heavy metals do not interfere at all. The limit of detection is 0.29 ng/ml for Mo and 0.14 ng/ml for Cu after preconcentration on the hanging mercury drop electrode for 30 s at −0.2 V. The R.S.D. at a concentration level of 10 ng/ml is 3.8% for Cu and 5.3% for Mo. The method is applied to different biological samples.
Spectrophotometric determination of nitrite in natural waters using diazotization-coupling method with column preconcentration on naphthalene supported with ion-pair of tetradecyldimethylbenzyl-ammonium and iodide by M. Satake; Gen-Feng Wang (pp. 433-438).
A column preconcentration method has been established for the spectrophotometric determination of traces of nitrite using diazotization and coupling on an naphthalene-tetradecyldimethylbenzylammonium (TDBA)-iodide (I) adsorbent. Nitrite ion reacts with sulfanilic acid (SA) in the pH range 1.8–3.0 for the SA-1-naphthol system and in the pH range 2.3–3.2 for the SA-1-naphthylamine-4-sulfonate system (SA-NAS system) in hydrochloric acid medium to form water-soluble colourless diazonium cations. These cations were coupled with 1-naphthol in the pH range 1.6–4.6 and with NAS in the pH range 2.6–5.0 to be retained on naphthalene-TDBA-I packed in a column. The solid mass was dissolved from the column with 5 mL of dimethylformamide (DMF) and the absorbance measured at 418 nm for the SA-1-naphthol system and at 485 nm for the SA-NAS system. The calibration curve was linear over the concentration range 0.02–0.87 mg/L for SA-1-naphthol and 0.02–0.80 mg/L in the sample for SA-NAS. The molar absorptivity was calculated to be 1.70×104 L mol-1 cm-1 for SA-1-naphthol and 1.66×104 L mol-1 cm-1 for SA-NAS. The detection limits were found to be 0.014 and 0.016 mg/L for SA-1-naphthol and SA-NAS, respectively. The preconcentration factors were 8 and 6 for SA-1-naphthol and SA-NAS, respectively. Replicate determinations of seven sample solutions containing 6.6 μg of nitrite for SA-1-naphthol and 5.3 μg of nitrite for SA-NAS gave mean absorbances of 0.486 and 0.382 with relative standard deviations of 0.49 and 0.58%, respectively. Interferences due to various foreign ions have been studied and the method has been applied to the determination of 27–65 μg/L levels of nitrite in natural waters. The recovery and relative standard deviation for water samples were 98–102% and 0.49–0.58% for both systems.
Spectrophotometric determination of nitrite in natural waters using diazotization-coupling method with column preconcentration on naphthalene supported with ion-pair of tetradecyldimethylbenzyl-ammonium and iodide by Masatada Satake; Gen-Feng Wang (pp. 433-438).
A column preconcentration method has been established for the spectrophotometric determination of traces of nitrite using diazotization and coupling on an naphthalene-tetradecyldimethylbenzylammonium (TDBA)-iodide (I) adsorbent. Nitrite ion reacts with sulfanilic acid (SA) in the pH range 1.8–3.0 for the SA-1-naphthol system and in the pH range 2.3–3.2 for the SA-1-naphthylamine-4-sulfonate system (SA-NAS system) in hydrochloric acid medium to form water-soluble colourless diazonium cations. These cations were coupled with 1-naphthol in the pH range 1.6–4.6 and with NAS in the pH range 2.6–5.0 to be retained on naphthalene-TDBA-I packed in a column. The solid mass was dissolved from the column with 5 mL of dimethylformamide (DMF) and the absorbance measured at 418 nm for the SA-1-naphthol system and at 485 nm for the SA-NAS system. The calibration curve was linear over the concentration range 0.02–0.87 mg/L for SA-1-naphthol and 0.02–0.80 mg/L in the sample for SA-NAS. The molar absorptivity was calculated to be 1.70 × l04 Lmol−1 cm−1 for SA-1-naphthol and 1.66 × l04 L mol−1 cm−1 for SA-NAS. The detection limits were found to be 0.014 and 0.016 mg/L for SA-1-naphthol and SA-NAS, respectively. The preconcentration factors were 8 and 6 for SA-1-naphthol and SA-NAS, respectively. Replicate determinations of seven sample solutions containing 6.6 ug of nitrite for SA-1-naphthol and 5.3 ug of nitrite for SA-NAS gave mean absorbances of 0.486 and 0.382 with relative standard deviations of 0.49 and 0.58%, respectively. Interferences due to various foreign ions have been studied and the method has been applied to the determination of 27–65 μg/L levels of nitrite in natural waters. The recovery and relative standard deviation for water samples were 98–102% and 0.49–0.58% for both systems.
Distillation, on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS as a new combination for the determination of methylmercury in sediments and fish tissue by Ralf Eiden; Falf Falter; Barbara Augustin-Castro; Heinz Friedrich Scho¨ler (pp. 439-441).
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high performance liquid chromatography – ultra violet – post column oxidation – cold vapour atomic absorption spectrometry) for the determination of methylmercury at background levels in sediments, soils and fish tissue. To prove the accuracy of this method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.
Distillation, on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS as a new combination for the determination of methylmercury in sediments and fish tissue by Ralf Eiden; Ralf Falter; Barbara Augustin-Castro; Heinz Friedrich Schöler (pp. 439-441).
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high performance liquid chromatography — ultra violet — post column oxidation — cold vapour atomic absorption spectrometry) for the determination of methylmercury at back-ground levels in sediments, soils and fish tissue. To prove the accuracy of this method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.
Chlorobiphenyl (PCB) composition of extracts of subsurface soil, superficial dust and air from a contaminated landfill by L. G. Hansen; D. Green; J. Cochran; S. Vermette; B. Bush (pp. 442-448).
Samples of 3 matrices (air, superficial dust and subsurface soil) from an aged PCB-containing landfill were extracted and the extracts refined for bioassay. Acetone:hexane extraction was modestly selected for non-planar compounds. Coplanar PCBs and PCDFs were enriched about 2-fold in the subsequent benzene:methylene chloride extracts of the soil. Extract refinement with Florisil slurry and alumina column chromatography did not appreciably change the composition of the extracts. CB 28 (2,4,4′-triCB) dominated in all extracts. The congener composition of soil and air were surprisingly similar, being enriched in tri- and tetraCBs while dust retained higher proportions of congeners with 4 and 5 chlorines. It is postulated that anaerobic dechlorination in the moist subsurface soil depleted the higher chlorinated congeners; more volatile congeners escaped into the atmosphere while moderately chlorinated congeners were trapped in the superficial dust and debris. The refined extracts represent distinct compositions of environmental PCB mixtures suitable for bioassay.
Chlorobiphenyl (PCB) composition of extracts of subsurface soil, superficial dust and air from a contaminated landfill by L. G. Hansen; D. Green; J. Cochran; S. Vermette; B. Bush (pp. 442-448).
Samples of 3 matrices (air, superficial dust and subsurface soil) from an aged PCB-containing landfill were extracted and the extracts refined for bioassay. Acetone: hexane extraction was modestly selected for non-planar compounds. Coplanar PCBs and PCDFs were enriched about 2-fold in the subsequent benzene:methylene chloride extracts of the soil. Extract refinement with Florisil slurry and alumina column chromatography did not appreciably change the composition of the extracts. CB 28 (2,4,4′-triCB) dominated in all extracts. The congener composition of soil and air were surprisingly similar, being enriched in tri- and tetraCBs while dust retained higher proportions of congeners with 4 and 5 chlorines. It is postulated that anaerobic dechlorination in the moist subsurface soil depleted the higher chlorinated congeners; more volatile congeners escaped into the atmosphere while moderately chlorinated congeners were trapped in the superficial dust and debris. The refined extracts represent distinct compositions of environmental PCB mixtures suitable for bioassay.
Simultaneous determination of drugs in concentration ratios above 40 : 1 by application of multivariate calibration to absorbance and derivative spectrophotometric signals by R. D. Bautista; A. I. Jiménez; F. Jiménez; J. J. Arias (pp. 449-456).
The performance of two multivariate calibration methods, multiple linear regression (MULTI3) and partial least-square regression (PLS-2), for the resolution of the ternary mixtures of acetylsalicylic acid-caffeine-codeine and acetaminophen-caffeine-codeine is compared. The methodologies were checked by applying them to the analysis of two sets of laboratory-prepared mixtures over the concentration ranges 13.0–19.0, 1.00–3.00 and 0.20–1.00 μg · ml–1 for acetylsalicylic acid-caffeine-codeine and 12.0–22.0, 0.40–2.00 and 0.20–1.00 μg · ml–1 for acetamimophen-caffeine-codeine, respectively. While the results provided by MULTI3 were unacceptable in the majority of the cases, those obtained by PLS-2 were quite good with considerably diminished errors, as a result of calibration and/or checking with MULTI3, taking no account of potential interactions between analytes. It was shown that it is possible by using PLS-2 to resolve complex mixtures of analytes in a highly disparate proportion, even when they have overlapping signals. The proposed method was successfully demonstrated for pharmaceutical tablets.
Simultaneous determination of drugs in concentration ratios above 40:1 by application of multivariate calibration to absorbance and derivative spectrophotometric signals by R. D. Bautista; A. I. Jiménez; F. Jiménez; J. J. Arias (pp. 449-456).
The performance of two multivariate calibration methods, multiple linear regression (MULTI3) and partial least-square regression (PLS-2), for the resolution of the ternary mixtures of acetylsalicylic acid-caffeine-codeine and acetaminophen-caffeine-codeine is compared. The methodologies were checked by applying them to the analysis of two sets of laboratory-prepared mixtures over the concentration ranges 13.0–19.0, 1.00–3.00 and 0.20–1.00 μg · ml−1 for acetylsalicylic acid-caffeine-codeine and 12.0–22.0, 0.40–2.00 and 0.20–1.00 μg · ml−1 for acetamimophen-caffeine-codeine, respectively. While the results provided by MULTI3 were unacceptable in the majority of the cases, those obtained by PLS-2 were quite good with considerably diminished errors, as a result of calibration and/or checking with MULTI3, taking no account of potential interactions between analytes. It was shown that it is possible by using PLS-2 to resolve complex mixtures of analytes in a highly disparate proportion, even when they have overlapping signals. The proposed method was successfully demonstrated for pharmaceutical tablets.
Direct copper determination in whole milk, non-fat milk and whey milk by electrothermal atomic absorption spectrometry by P. Bermejo Barrera; R. Domínguez González; A. Bermejo Barrera (pp. 457-461).
A method for the direct determination of copper in samples of whole milk, non-fat milk and whey milk by electrothermal atomic spectrometry (ETAAS) was studied. The fat separation by centrifugation at 3200 rpm and the separation of casein mycelles to obtain the whey milk by ultracentrifugation at 31 000 g were investigated. In all cases Mg(NO3)2 was used as chemical modifier and Triton X-100 (0.2% w/v) as emulsifying agent. The optimum pyrolysis temperature was 1500° C. The detection limit was 0.4 μg/l of copper. The precision was studied for the whole milk and the coefficients of variation (CV) were 5.7, 4.0, 2.4 and 2.8% for 0, 5, 10 and 20 μg/l of copper added. The accuracy was determined by using the Reference Material Milk A-11 (IAEA) with a certified content of 378.4 ± 24 ng Cu/g; 359 ± 16 ng/g were found. The method was applied to ten cow milk samples, the levels of copper being determined for whole milk, non-fat milk and whey milk. A statistical study was applied and it was concluded that the majority of copper is in the non-fat milk.
Direct copper determination in whole milk, non-fat milk and whey milk by electrothermal atomic absorption spectrometry by P. Bermejo Barrera; R. Domínguez González; A. Bermejo Barrera (pp. 457-461).
A method for the direct determination of copper in samples of whole milk, non-fat milk and whey milk by electrothermal atomic spectrometry (ETAAS) was studied. The fat separation by centrifugation at 3200 rpm and the separation of casein mycelles to obtain the whey milk by ultracentrifugation at 31000 g were investigated. In all cases Mg(NO3)2 was used as chemical modifier and Triton X-100 (0.2% w/v) as emulsifying agent. The optimum pyrolysis temperature was 1500°C. The detection limit was 0.4 μg/1 of copper. The precision was studied for the whole milk and the coefficients of variation (CV) were 5.7, 4.0, 2.4 and 2.8% for 0, 5, 10 and 20 μg/1 of copper added. The accuracy was determined by using the Reference Material Milk A-11 (IAEA) with a certified content of 378.4 ± 24 ng Cu/g; 359 ± 16 ng/g were found. The method was applied to ten cow milk samples, the levels of copper being determined for whole milk, non-fat milk and whey milk. A statistical study was applied and it was concluded that the majority of copper is in the non-fat milk.
Extraction and separation of scandium salicylate with triphenylphosphine oxide by N. G. Bhilare; V. M. Shinde (pp. 462-463).
Scandium can be extracted from 5.0 × 10–2 mol/l sodium salicylate solution, adjusted to pH 4.0–5.0 with 0.5% triphenylphosphine oxide dissolved in toluene as an extractant. After stripping from the organic phase with 0.5 mol/l HCl it can be subsequently determined spectrophotometrically with Alizarin Red S. The method permits a separation of Sc(III) from Ti(IV), V(V), Cr(VI), Fe(III), Y(III), La(III), Ce(III), Nd(III) and Sm(III) in synthetic mixtures. The method is fast, simple and selective.
Extraction and separation of scandium salicylate with triphenylphosphine oxide by N. G. Bhilare; V. M. Shinde (pp. 462-463).
Scandium can be extracted from 5.0 × 10−2 mol/1 sodium salicylate solution, adjusted to pH 4.0–5.0 with 0.5% triphenylphosphine oxide dissolved in toluene as an extractant. After stripping from the organic phase with 0.5 mol/1 HCl it can be subsequently determined spectrophotometrically with Alizarin Red S. The method permits a separation of Sc(III) from Ti(IV), V(V), Cr(VI), Fe(III), Y(III), La(III), Ce(III), Nd(III) and Sm(III) in synthetic mixtures. The method is fast, simple and selective.
Simultaneous determination of chromium (III) and copper (II) by using derivative spectrophotometry with MEDTA by H. Seco-Lago; J. Pérez-Iglesias; J. M. Fernández-Solís; J. M. Castro-Romero; V. González-Rodríguez (pp. 464-466).
The application of derivative spectrophotometry to the simultaneous determination of chromium (III) and copper (II) with MEDTA is described. The procedure is suitable for concentrations of 0.40–2.60 mg ml–1 of chromium (III) and 0.15–0.60 mg ml–1 of copper (II). The main interferences, both anionic and cationic, are easily eliminated. The method was applied to different aqueous matrices. It was compared with an atomic absorption method and good results were obtained.
Simultaneous determination of chromium (III) and copper (II) by using derivative spectrophotometry with MEDTA by H. Seco-Lago; J. Pérez-Iglesias; J. M. Fernández-Solís; J. M. Castro-Romero; V. González-Rodríguez (pp. 464-466).
The application of derivative spectrophotometry to the simultaneous determination of chromium (III) and copper (II) with MEDTA is described. The procedure is suitable for concentrations of 0.40–2.60 mg ml−1 of chromium (III) and 0.15–0.60 mg ml−1 of copper (II). The main interferences, both anionic and cationic, are easily eliminated. The method was applied to different aqueous matrices. It was compared with an atomic absorption method and good results were obtained.
Application of microcolumn ion chromatography using octadecylsilica immobilized with bovine serum albumin as stationary phase for the determination of inorganic anions by Rahmiana Zein; Edison Munaf; T. Takeuchi; Tomoo Miwa (pp. 466-468).
Microcolumn ion chromatography of inorganic anions has been studied using octadecylsilica immobilized with bovine serum albumin as a stationary phase. The analytes were monitored with a conductivity detector. The detection limits for chloride, nitrate and thiocyanate at S/N = 3 were 0.8, 1.0 and 3.0 μmol L–1, respectively. The present system was applied to the determination of inorganic anions in tap water and serum samples.
Application of microcolumnion chromatography using octadecylsilica immobilized with bovine serum albumin as stationary phase for the determination of inorganic anions by Rahmiana Zein; Edison Munaf; Toyohide Takeuchi; Tomoo Miwa (pp. 466-468).
Microcolumn ion chromatography of inorganic anions has been studied using octadecylsilica immobilized with bovine serum albumin as a stationary phase. The analytes were monitored with a conductivity detector. The detection limits for chloride, nitrate and thiocyanate at S/N = 3 were 0.8, 1.0 and 3.0 μmol L−1, respectively. The present system was applied to the determination of inorganic anions in tap water and serum samples.