University of North Florida
Browse the Citations
-OR-

Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

View Stuart Chalk's profile on LinkedIn

Hair

Classification: Biological material -> hair

Citations 31

"Optimization Of Flame Atomic Absorption Spectrometry With Preconcentration By Flow Injection Online Sorbent Extraction Of Cadmium And Lead In Biological Materials"
Bol. Soc. Chilena Quim. 1999 Volume 44, Issue 3 Pages 321-335
BRUHN, CARLOS G., VILCHES, CAROLINA and CID, HERNAN J.

Abstract: A flow injection (FI) system with a minicolumn of bonded silica with octadecyl groups (C-18) to collect diethyldithiocarbamate complexes of Cd and Pb in reference solutions and in acid-digested hair and blood solutions was developed and evaluated by flame atomic absorption spectrometry (FAAS). The system was optimized by multivariate method, based on a factorial experimental design in two levels, selecting eight parameters that mostly affected the expected analytical signal. The detection limits (3s(BL)/slope, 60 s pre-concentration) were 0.7 and 5 µg/L for Cd and Pb, respectively and the sampling frequency was 40 samples/h. Effects of interfering ions are discussed. The methodology was validated by analysis of certified reference materials of hair and blood for Pb, and by recoveries of Cd and Pb spikes performed in hair and blood samples. Results for Pb agreed well with certified values and recoveries were satisfactory (103% in blood and 100% in hair). Also, the recovery of Cd in hair was fair (107%); however, in blood it was not quantitative (22%).
Cadmium Lead Spectrophotometry Preconcentration C18 Diethyldithiocarbamate Column Optimization Interferences

"Hair Analysis. 1. Differential Pulse Anodic Stripping Voltammetric Determination Of Lead, Cadmium, Zinc, Copper In Human Hair Samples Of Persons In Permanent Contact With A Polluted Workplace Environment"
Anal. Chim. Acta 1996 Volume 335, Issue 3 Pages 201-207
Wieslaw Wasiak*, Wanda Ciszewska and Aleksander Ciszewski

Abstract: Prior to determination of Pb, Cd, Zn and Cu by differential pulse anodic stripping voltammetry microwave digestion has been evaluated for the decomposition of human hair samples using a HNO3---H2O2 mixture. The efficiency of the decomposition, and the accuracy and precision of the proposed procedure was studied using a human hair standard. Hair samples were collected from the vertex of the scalps of donors who were employed in factories manufacturing lead-acid batteries, nickel-cadmium batteries and gas (petroleum) vending station workers. The results show that, in all cases, permanent contact with the polluted environment makes it possible to absorb very large amounts of lead or cadmium, simultaneously depressing zinc absorption. Results of a study on the content of the above elements in human hair of persons who had had no work place contact with these elements are also presented.
Lead Cadmium Zinc Copper Voltammetry

"Simultaneous Flow Injection Determination Of Iron(II) And Total Iron By Micelle Enhanced Luminol Chemiluminescence"
Anal. Chim. Acta 1998 Volume 376, Issue 2 Pages 247-254
Kumiko Saitoh, Takashi Hasebe, Norio Teshima, Makoto Kurihara and Takuji Kawashima*

Abstract: A flow injection method is proposed for the determination of Fe(II) and for the simultaneous determination of Fe(II) and total Fe based on the catalytic effect of Fe(II) on the oxidation of luminol with H2O2 in an alkaline medium. The activating effect for the catalysis of Fe(II) was extremely exhibited in the presence of citric acid, while citric acid acted as a masking agent for Fe(III). Also, the sensitivity of the method was enhanced by adding tetradecyltrimethylammonium bromide (TTAB) as a cationic surfactant together with citric acid. The Fe(III) in sample solution can be determined by passing through the Ag reductor column introduced in the FIA system to reduce Fe(III) to Fe(II), which allows total Fe determination Calibration graphs for Fe(II) and total Fe were linear over the range 5 x 10^-9-1 x 10^-6 mol L-1 at a rate of 18 samples h-1 (36 peaks h-1). The relative standard deviations (n = 10) for 4 x 10^-8 mol L-1 Fe(II) and 1 x 10^-7 mol L-1 total Fe were 3.0% and 1.5%, respectively. The proposed method was successfully applied to the determination of Fe in human hair (NIES, number 5) and natural waters.
Iron(2+) Iron Chemiluminescence Indirect Speciation Catalysis Micelle Surfactant Sensitivity Reference material

"Application Of Ion-exchange Resin Phase Spectrophotometry To Flow Injection Analysis System. 1. Determination Of Trace Zinc In Hair Of Children"
Talanta 1993 Volume 40, Issue 3 Pages 381-384
Ren-Min Liu, Dao-Jie Liu and Ai-LingSun

Abstract: The flow injection analysis system is based on ion-exchange resin phase spectrophotometry of Zn as the zincon complex. An anion-exchange resin is loaded with zincon and packed into the flow-through cell (5-mm path length, 1.5 mm diameter) of a spectrophotometer. A sample aliquot is injected into the carrier solution (H2O containing a boric acid - KCl - thiourea buffer solution at pH 9.0) of the flow injection analysis system and transported to the flow cell where the zincon complex is formed. The change in absorbance at 650 nm is measured. The complex is decomposed by injecting 1.0 mL of 0.20 M HCl. When the absorbance has returned to its baseline another sample can be injected. The calibration graph is rectilinear from 16 to 360 µg L-1 of Zn and the detection limit is 4.2 µg l-1. Of various metal ions investigated, only Cu(II) causes severe interference and must be masked by addition of thiourea to the carrier solution The procedure is applied to children's hair. The hair is washed to remove surface contamination and dry ashed in a muffle furnace at 450°C, and the residue is dissolved in HNO3. The results are tabulated and compared with those obtained by AAS.
Zinc Spectrophotometry Complexation Interferences Resin

"Electrothermal Atomic Absorption Spectrometric Determination Of Ultratrace Amounts Of Tin By In Situ Preconcentration In A Graphite Tube Using Flow Injection Hydride Generation With Online Ion-exchange Separation"
Talanta 1995 Volume 42, Issue 3 Pages 375-383
Guanhong Tao and Zhaolun Fang*

Abstract: Geological samples (0.5 g) were treated with 5 mL HNO3/HF (7:3) at 40°C. After boiling nearly to dryness a further 2 mL acid was added. After cooling, the digests were diluted to 50 mL and 1 mL was diluted further to 100 mL with 2 M HCl. Hair (0.2 g) or 1 mL serum was acid-treated as above and then the digests were diluted to 50 mL with 2 M HCl. Tap water samples were filtered and acidified to 2 M HCl with concentrated HCl. The samples were passed through a microcolumn (3 cm x 3 mm i.d.) packed with anion-exchanger D-201 (Shenyang Organic Chemicals Co.). The Sn was retained as its chlorostannate complex and subsequently eluted with water into the hydride generation system. The hydride and H2 evolved were separated from the liquid phase in a gas-liquid separator and transferred into a Pd-coated graphite tube pre-heated to 300°C to collect the analyte which was later atomized at 2300°C, followed by AAS. Tin was determined at a sampling frequency of 30/hr with a detection limit of 0.01 µg/l. RSD were ~1.5%.
Tin Sample preparation Spectrophotometry Phase separator Preconcentration Reference material Volatile generation Ultratrace Volatile generation

"Simultaneous Spectrofluorimetric Determination Of Selenium(IV) And (VI) By Flow Injection Analysis"
Analyst 1997 Volume 122, Issue 3 Pages 221-226
M. J. Ahmed, C. D. Stalikas, P. G. Veltsistas, S. M. Tzouwara-Karayanni and M. I. Karayannis

Abstract: A sample (100 µL) was injected into a carrier stream of 2 M H2SO4 at a flow rate of 0.1 ml/min and mixed with a reagent stream of 0.2 mM 2-(α-pyridyl)thioquinaldinamide in propan-2-ol at a flow rate of 0.3 ml/min. The fluorescence intensity due to Se(IV) was measured at 500 nm (excitation at 350 nm). A second portion (100 µL) was then injected into the carrier stream and passed through a coil (40 cm x 0.8 mm i.d.) where it was irradiated at 254 nm. The irradiated sample stream was then mixed with the reagent stream and the fluorescence intensity due to total Se was measured. Se(VI) was determined from the difference in the two fluorescence intensity values. The calibration graphs were linear from 0.01-2.2 and 0.1-2.4 µg/ml Se(IV) and Se(VI), respectively; corresponding detection limits were 1 and 10 ng/ml. RSD were 0.1-2% (n=5). The throughput was 25 samples/h. The method was applied to the analysis of alloys, hair, tap and lake water, sediments, soil, tea, flour and eggs. A simple, sensitive, highly selective, automatic spectrofluorimetric method for the simultaneous determination of selenium (IV) and (VI) as selenite-selenate by flow injection analysis (FIA) has been developed. The method is based on the selective oxidation of the non-fluorescent reagent 2-(α-pyridyl)thioquinaldinamide (PTQA) in acidic solution (1.5-3.0 M H2SO4) by Se(IV) to give an intensely fluorescent oxidation product (lambda ex =350 nm; lambda em = 500 nm). Selenium (VI) is reduced online to Se(IV), in a reduction coil installed in a photo- reactor, which is then treated with PTQA and the fluorescene due to the sum of Se(IV) and Se(VI) is measured; Se(Vi) is determined from the difference in fluorescence values. Various analytical parameters, such as effect of acidity, flow rate, sample size, dispersion coefficient, temperature, reagent concentration and interfering species were studied. The photo-reduction conditions were optimized, with an FIA procedure, for Se(VI) on the basis of its reduction efficiency. The calibration graphs were rectilinear for 0.1-2.4 µg mL-1 of Se(VI) and 10 ng mL-1 - 2.2 µg mL-1 of Se(IV), respectively. The method was applied to the determination of Se in several Standard Reference Materials (alloy, sediments and tea), as well as in some environmental waters (tap and surface water), food samples (flour and egg), a biological sample (human hair), soil sample and in synthetic mixtures. Up to 25 samples per hour can be analyzed with an RSD approximately 0.1-2%.
Selenium(IV) Selenium(VI) Fluorescence Speciation Photochemistry Selectivity Reference material Interferences

"Online Preconcentration And Determination Of Mercury In Biological Samples By Flow Injection Vapor Generation Inductively Coupled Plasma Atomic-emission Spectrometry"
Fresenius J. Anal. Chem. 1995 Volume 352, Issue 6 Pages 615-617
Pedro Cañada Rudner, José Manuel Cano Pavón, Amparo García de Torres and Fuensanta Sánchez Rojas

Abstract: Hair was digested with 65% nitric acid for 30 min followed by microwave digestion at 360 W for 4 min and 180 W for 10 min. After cooling for 14 min, the digests were concentrated by evaporation, neutralized with NaOH and diluted with water. Pig kidney and dogfish muscle were prepared by the method of Niazi et al. (Analyst, 1993, 118, 821). The extracts (1.4 ml/min) were mixed with 0.2 M HCl/0.2 M glycine buffer of pH 3.6 (0.4 ml/min) in a FIA system. The flow merged with a stream of 1,5-bis(di-2-pyridyl)methylene thiocarbonohydrazide in IBMK (0.5 ml/min) at a solvent segmentor. The stream passed through an extraction coil (200 cm x 0.5 mm i.d.) to a membrane phase separator and the aqueous phase went to waste. The organic phase filled a sample loop (500 mL volume) and the excess went to waste. The sample was injected into a carrier stream (3.3 ml/min) of IBMF/DMF (1:1) and merged with a reagent stream (0.5 ml/min) of SnCl2 in DMF. The resulting stream passed through a mixing coil (100 cm x 0.8 mm i.d.) for the generation of Hg vapor. The gas and solvent passed to a gas-liquid separator and to Hg vapor was swept to a ICP torch by Ar. The Hg was determined by ICP-AES (operating details tabulated). The calibration graph was linear for 10^-2500 ng/ml of Hg(II) with a detection limit of 4 ng/ml and RSD (n = 10) of 1% at 100 ng/ml. The effects of foreign ions are discussed.
Mercury Sample preparation Spectrophotometry Sample preparation Extraction Preconcentration Interferences Phase separator Volatile generation MIBK Volatile generation

"A New Pyrrolidinedithiocarbamate Screening Method For The Determination Of Methylmercury And Inorganic Mercury Relation In Hair Samples By HPLC-UV-PCO-CVAAS"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 4 Pages 492-493
R. Falter and H. F. Schöler

Abstract: A new analytical screening technique for the determination of methylmercury and inorganic mercury in hair samples by HPLC-PCO-CVAAS has been developed. It is based on the extraction of mercury compounds by a buffered sodium pyrrolidinedithiocarbamate solution, separation by reversed-phase HPLC, post column oxidation by UV-irradiation, reduction with alkaline sodium borohydride, and determination by cold vapor atomic absorption detection. The standard deviation was 7% and recoveries were 90% for both compounds. The limit of detection (S/N = 3) for both compounds was calculated to be about 4 ppb.
Mercury(II) Methylmercury ion HPLC Spectrophotometry Photochemistry UV reactor

"Determination Of Chromium(III) In Urine, Blood Serum, And Hair Using Flow Injection Chemiluminescence Analysis"
Fresenius J. Anal. Chem. 1998 Volume 361, Issue 5 Pages 509-511
R. Escobar, M. S. García-Domínguez, A. Guiraúm, F. F. de la Rosa

Abstract: A flow injection (FI) chemiluminescence method for the determination of Cr(III) in blood serum, urine, and hair samples is reported. It is based on the chromium-catalyzed light emission from the luminol oxidation by H2O2. The app. consists of an FI system with a flow cell formed by a coiled transparent tube suitable for chemiluminescence detection. The specificity of the method is achieved in presence of EDTA. The detection limit under optimum conditions is 0.01 µg/L of Cr(III). Precision and accuracy were evaluated by determining Cr(III) concentrations in urine standards from the National Institute of Standard and Technol. (NIST).
Chromium(III) Chemiluminescence Indirect EDTA Optimization Reference material

"Kinetic FIA Determination Of Mercury(II) Based On Its Catalytic Effect On The Reaction Between Safranin And Iodide"
Anal. Lett. 1996 Volume 29, Issue 5 Pages 807-819
Afsaneh Safavi; Mohammad Reza Baezzat

Abstract: A schematic diagram of the FIA manifold is given. Safranin-buffer solution of pH 5 (0.75 ml/min) was merged with iodide solution in a 1 m coil. The sample (300 µL) was injected into a carrier stream of water (0.75 ml/min) and merged with the safranin-buffer - iodide mixture in a 5 m coil at 10°C. The stream from the reaction coil was measured at 520 nm. The detection limit was 90 ng Hg(II). There was little chemical interference. The method was applied to the determination of Hg in contact lens cleaning solution and hair.
Mercury(II) Spectrophotometry Interferences Kinetic

"Development Of Transient Data-acquisition System For Hyphenated Techniques Coupled With Inductively Coupled Plasma Atomic-emission Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1753-1759
Xiaoru Wang*, Zhixia Zhuang, Chenglong Yang, Pengyuan Yang, Xiaomei Yan and Jianming Lin

Abstract: The apparatus described is suitable for use with FIA, HPLC, ET vaporization and laser ablation coupled with multielement ICP-AES. The internal computer of the spectrophotometer scans ten preselected photomultiplier channels at a maximum rate of 100 data points per s with a minimum integration time of 0.01 s per channel, and the data are transferred at 4800 baud through an RS-232C port to a Compaq 486 computer, which both collects and manipulates the data according to QuickBASIC routines. Good results are demonstrated for the determination of metals in serum by flow injection ICP-AES and in hair by ET-vaporization ICP-AES and for the speciation of metals in tea by HPLC-ICP-AES.
Metals Spectrophotometry HPLC Speciation Computer

"Continuous-flow Cold Vapor Procedure For Mercury Determination By Atomic Emission Using The Reverse-flow Injection Approach"
Spectrochim. Acta B 1994 Volume 49, Issue 8 Pages 787-795
João Carlos De Andrade* and Maria Izabel M. S. Bueno

Abstract: The sample solution is pumped at 4 ml/min and 40-50 µL of 2-3% SnCl2 solution in 1.5-4 M HCl is injected into it. After passage of the mixing zone through a reaction coil the Hg is swept from the solution in a stream of He (100 ml/min) to a PTFE membrane in a permeation cell, and the permeated He and Hg pass to a quartz tube containing 0.3 g of Au foil on which the Hg is concentrated. The Hg is released by resistive heating and determined at 253.7 nm in an 11 W He DC plasma. Diagrams of the apparatus are presented. The calibration graph is linear up to 50 ng/ml of Hg2+ and the detection limit is ~50 pg/ml. For 15 replicate injections into 50 ng/ml of Hg2+ the RSD was 1.6%. Only selenite, sulfide and iodide interfere seriously, but the interference from sulfide and iodide can be removed by preparing the sample solution in an oxidizing acid medium. The result for reference standard human hair ('NIES Certified Reference Material, Human Hair', National Institute for Environmental Studies, Japan Environment Agency, Tsukuba, Japan, 1985) was 4.2 ± 0.1 µg/g (cf. the certified value of 4.4 ± 0.4 µg/g).
Mercury Spectrophotometry Interferences Reference material Teflon membrane Reverse Volatile generation Volatile generation

"Establishment And Analytical Quality Control Of Laboratories For Hg Determination In Biological And Geological Samples In The Amazon, Brazil"
Cienc. Cult. 1998 Volume 50, Issue 4 Pages 255-260
WANDERLEY R. BASTOS, OLAF MALM, WOLFGANG C. PFEIFFER, DAVID CLEARY2

Abstract: During the past 20 yr significant amounts of Hg were released in the Amazonian environment due to gold mining activities. Several Brazilian and foreign research groups were studying the region, always facing difficulties regarding preservation and transfer of the collected samples from the field to the anal. labs. Aiming to solve these problems two high quality Hg anal. labs. were established in the region. One is located at Fundacao Esperanca (FE, Santarem, PA), a medical assistance foundation and the other at the Universidade Federal de Rondonia (UNIR), Porto Velho, RO. Their main equipment is: Atomic absorption spectrophotometers for Hg anal. (Flow Injection Mercury System-FIAS 400 with automatic samples-AS90-Perkin Elmer) and a microwave oven digestion system (MDS-2000-CEM). Technicians and researchers were trained in several aspects like environmental and human sampling, digestion methods and Hg anal. for biotic and abiotic materials. This training as well as the installation of the mentioned labs. were the responsibility of the Universidade Federal do Rio de Janeiro (UFRJ). Intercalibration exercises were performed between several labs.: Environmental Medicine of Odense University (Denmark), Center de Toxicologie du Quebec, Canada and Occupational Health Sciences (Health-Canada). In the last 18 mo the FE lab. joined the Hg urine anal. intercalibration program of the Lab. of the Center of Toxicol. in Quebec, Canada, reaching accurate results. To date both Amazonian labs. are able to analyze several different materials: Sediment, soil, fish, urine, hair and blood. The FE lab. is becoming more specialized in human samples such as urine, blood and hair, while UNIR lab. deals with environmental samples such as fish, sediment and soil.
Mercury Spectrophotometry Sample preparation FIAS-400 FIMS

"Trace Elements Determined Along Single Strands Of Hair By Inductively Coupled Plasma Mass Spectrometry"
Clin. Chem. 1993 Volume 39, Issue 8 Pages 1650-1655
Jun Yoshinaga, Yasuyuki Shibata, and Masatoshi Morita

Abstract: Flow injection inductively coupled plasma mass spectrometry has been evaluated for determining the distribution profile of trace elements along a single strand of hair. Hair was cut into several mm long sections from follicle to the distal end. Each section was solubilized in a capped 1.5 mL polypropylene tube with small volume of nitric acid (typically 50 µL) at room temperature. After dilution an aliquot (50 µL) was introduced into the mass spectrometer by flow injection. The limit of determination was typically 5-50 pg with 5-10% precision (CV), depending on the element examined; this corresponds to sub-microgram/g concentrations of these elements in hair segments. Recent exposure and intake history of individuals to thallium or mercury could be reconstructed by this system. Sections of hair strand (several mm in length) were incubated overnight at room temperature with 50 µL of HNO3. After addition of water, a 50 µL portion was subjected to ICP-MS by flow injection (six-way valve and PTFE tubing, 0.5 mm i.d.). The limits of determination were 0.1, 1.0, 0.1, 0.05, 0.05, 0.1, 0.01 and 0.05 µg/l of Cu, Zn, As, Cd, Sb, Hg, Tl and Pb, respectively. Calibration graphs were linear for 1.0 ppb of Pb, Cd or As. The RSD (n = 4-6) were 5-10%.
Trace elements Arsenic Lead Mercury Copper Zinc Thallium Antimony Spectrophotometry Mass spectrometry Clinical analysis

"Flow Injection Catalytic Spectrophotometric Determination Of Trace Selenium In The Presence Of Nonionic Surfactants. 1"
Fenxi Huaxue 1991 Volume 19, Issue 4 Pages 433-435
Qi, W.;Chen, X.G.

Abstract: Sample was dissolved in concentration. HNO3, the solution was treated with 1 to 2 mL of HNO3 - HClO4 (5:1) and evaporated to dryness. The residue was dissolved with water and acidified. The solution was passed through a cation-exchange column, the eluate was mixed with 2 mL of 5% hydroxylamine hydrochloride solution, and the mixture was concentrated and neutralized. The solution was analyzed by the cited method in a flow injection system (diagram given). Sample solution (250 µL) was injected into a carrier stream at 1.8 mL min-1 for reaction at pH 9.2 with 3.7 mM Fe3+, aqueous 0.5% triethanolamine, 5.4 mM EDTA, 11.3 mM Na2S, aqueous 2% Tween 80, aqueous 0.375% Na2SO3, 0.4 mM methylene blue and aqueous 10% formaldehyde in a 1-m reaction coil. The method was applied to hair; bivalent Cu and Fe3+ did not interfere. The calibration graph was rectilinear from 0.1 to 0.5 µg g-1 of Se and the detection limit was 8 ng g-1.
Selenium Spectrophotometry Catalysis Column EDTA Interferences Surfactant

"Determination Of Trace Arsenic, Selenium, Molybdenum, Sulfur And Chromium With Online Flow Injection Anion-exchange Preconcentration Inductively Coupled Plasma Atomic-emission Spectrometry"
Fenxi Huaxue 1993 Volume 21, Issue 3 Pages 328-330
Liu, E.;Chen, W.J.;Zhao, C.Y.

Abstract: A system for online flow injection anion-exchange pre-concentration. ICP-AES (diagram given) for determination of As, Se, Mo, S and Cr is described. Sample solution was passed through two parallel columns (8 cm x 2 mm) packed with D296 anion-exchange resin (40 mesh) at a flow rate of 1.23 mL min-1 for pre-concentration.; elution was effected with 0.5 M NH4Cl and 3 M NH3 (1.23 mL min-1) and exposure time was 40 s. The detection limits were 13, 25.2, 2.04, 6.19 and 3.64 ng mL-1 for As, Se, Mo, S and Cr, respectively. The method was used for the analysis of geological, hair and bovine liver standards. Results agreed with the certified values.
Arsenic Selenium Molybdenum Sulfur Chromium Spectrophotometry Sample preparation Ion pair extraction Reference material Preconcentration

"Spectrophotometric Determination Of Mercury With 2-hydroxy-3-carboxy-5-sulfobenzenediazoaminoazobenzene By Flow Injection Analysis"
Fenxi Huaxue 1996 Volume 24, Issue 4 Pages 459-462
Guo Zhongxian

Abstract: An appropriate amount of hair digest or pretreated water sample was mixed with 2 mL mixed masking reagent containing 1% NaF, 2% sodium sulfosalicylate, 2% ethylenediamine and 5% Na2CO3. A 18 µL portion of the solution was injected into a carrier stream of Na2B4O7/NaOH buffer of pH 10.3 (4.5 ml/min), which was mixed with a stream of 0.95 µM reagent stream, containing 0.15% OP, flowing at the same rate. The mixture was transferred to a reaction coil (50 cm) and the absorbance of the resulting complex was measured at 522 nm. The calibration graph was linear from 0.05-1 µg/ml of Hg and the detection limit was 0.016 µg/ml. Recoveries were 97.9-102.7% and RSD (n = 6) was 1.5%. The sample throughput was 100/h. Tolerance levels for thirty six foreign ion species on the determination of 0.8 mg/l of Hg are listed.
Mercury Spectrophotometry

"Flow Injection Micelle-sensitized Chemiluminescence Determination Of Trace Amounts Of Nickel And Cobalt In Hair With Microwave Digestion Of Sample"
Fenxi Huaxue 1996 Volume 24, Issue 6 Pages 743-743
Fang, G.Z.;Liu, L.

Abstract: Hair (0.1 g) was digested with HNO3 and H2O2 in a microwave oven and the digest was converted into a test solution. For the determination of total Ni and Co: portions of reagent solution (2.5 mL ethanolic 5 mM alizarin purple, 2 mL 25 mM cetyltrimethylammonium bromide and 10 mL 1 M KOH diluted to 25 mL with H2O) were injected into the chemiluminescence (CL) apparatus and mixed with sample solution containing 1 mL 30% H2O2 and 1 drop 0.5% p-nitrophenol solution, adjusted to pH neutral and diluted to 25 mL with 1 mM HCl and the CL intensity was measured. For the determination of Ni: a second portion of reagent solution (as above) was injected into the apparatus to react with a sample containing both Ni and Co as above but with 1.5 mL aqueous triethanolamine (1:1000) added to mask Co(II) before measuring the Cl intensity. The difference between the two readings was used for calculation of Co content. Calibration graphs were linear from 0.5-12 and 7-140 µg/l, respectively, for Co(II) and Ni(II) with detection limits reaching 0.1 µg/l. Co-existing ions did not interfere. Sampling frequency was 50 runs per h. Recoveries were 92.5-109% with RSD of 3.6-8.1%.
Cobalt Nickel Chemiluminescence Sample preparation Interferences Micelle

"Determination Of Traces Of Zinc By Flow Injection Spectrophotometry With 2-hydroxy-3-[(4-phenylazophenyl)triazeno]-5-sulfobenzoic Acid"
Fenxi Huaxue 1996 Volume 24, Issue 12 Pages 1472-1472
Guo, Z.X.;Zhang, S.Y.

Abstract: With 0.05 M Na2B4O7/NaOH buffer of pH 10.8 as the carrier stream (5.2 ml/min), ethanolic 0.68 mM reagent/aqueous 4% emulsifier OP (unspecified)/H2O (20:3:77) as the reagent stream (5.2 ml/min) and detection at 520 nm, the calibration graph was linear for 0.072-0.05 mg/l of Zn, with a detection limit of 0.036 mg/l. Masking with NaF/potassium sodium tartrate/sodium sulfosalicylate permitted the tolerated amounts of Al(III), Fe(III), Cd(II) and Hg(II) to be greatly increased. The method was used in the analysis of human hair, rice, flour and tap water, with recoveries of 70.9-100.5%. The results were compared with those obtained by dithizone-extraction spectrophotometry.
Zinc Spectrophotometry Sample preparation Dithizone Extraction

"Chemiluminescence Reaction Between Lucigenin And Iron(II) By Flow Injection Analysis With Micelle Sensitization"
Fenxi Huaxue 1998 Volume 26, Issue 8 Pages 1007-1010
Zhu, Z.;Lu, J.

Abstract: A new flow injection chemiluminescence method for the determination of iron is described. It is based upon the chemiluminescence reaction of iron(II)-lucigenin system with Jones reductor. The chemiluminescence signal-to-noise ratio can be improved apparently by the addition of cetyltrimethylammonium bromide and emulsor OP. The present method has a wide linear range of 1 x 10^-11 ~ 1 x 10^-5 g/mL for Fe(II). The detection limit is 2 x 10^-12 g/mL. The relative standard deviation is 2.0% ( 1 x 10^-8 g/mL Fe, n = 11). The method has been applied to the determination of iron in hair samples with satisfactory results. The mechanism of this reaction is also investigated in detail.
Iron(2+) Chemiluminescence Micelle Reduction column Linear dynamic range

"Determination Of Cobalt(II) With Alizarin Violet Chemiluminescence System By Flow Injection Analysis"
Fenxi Shiyanshi 1989 Volume 8, Issue 2 Pages 27-29
Zhang Wumin, Zhong Shiming, Hu Hejin and Gong Jianyi

Abstract: Cobalt was determined by mixing the sample with 0.2 M NaOH, 1.25 mM hexadecylammonium bromide and alizarin violet in a flow injection system (diagram given) with chemiluminescence detection. The calibration graph was rectilinear from 0.02 to 60 µg L-1 of Co and the detection limit was 3.2 ng l-1. The coefficient of variation at 10 µg L-1 was 0.27%. The method can be applied to the determination of Co in hair.
Cobalt Chemiluminescence Calibration Detection limit

"Catalytic Spectrophotometric Determination Of Trace Manganese(II) By Flow Injection Analysis"
Fenxi Shiyanshi 1993 Volume 12, Issue 5 Pages 53-54
Zhu, H.Y.;Peng, A.S.;Zhang, L.

Abstract: Sample (50 µL) was injected and carried (all streams at 1.5 ml/min) by 6 M H3PO4, mixed with 0.01% diantipyrinephenylenemethane in a tube (40 cm x 0.5 mm) then with 2 mM Cr(VI) in a reaction tube (100 cm x 0.5 mm) at 40°C before detection at 540 nm. Relationship between peak height and concentration. was linear for 0.03-5 ng/ml of Mn2+. Most foreign ions did not interfere. The method was applied to analysis of hair and well water with recoveries of 93-110% and RSD of 2.9-6.4%.
Manganese(II) Spectrophotometry Catalysis Interferences

"Study On The Determination Of Vanadium By Flow Injection Chemiluminescence Based On Coupled Reaction"
Fenxi Shiyanshi 1998 Volume 17, Issue 1 Pages 41-44
Li Weihua,Wang Zhanling,Li Jianzhong and Zhang Zhujun*

Abstract: A new method for determining V(IV) by flow injection chemiluminescence was developed. It is based on the oxidation of I- by K2Cr2O7 induced by V(IV), and the subsequent chemiluminescence reaction of luminol oxidized by I2. The CL intensity is linear to V (IV) concentration. over the range of 1 x 10^-5 ~ 1 x 10^-9 mol/L. The detection limit is 7 x 10^-10 g/mL, the relative standard deviation is 2.8% for 11 measurements of 8 x 10^-9 g/mL V(IV) standard solution The method was used to determine V in hair and water samples with satisfactory results.
Vanadium(IV) Chemiluminescence Indirect

"Determination Of Trace Mercury In Environmental And Biological Samples By Flow Injection Hydride-generation Graphite-furnace AAS"
Guangpuxue Yu Guangpu Fenxi 1993 Volume 13, Issue 5 Pages 107-110
Ma, Y.P.;Gulikezi;Fang, X.H.

Abstract: Pre-treated sample (500 µL) was injected and carried by a stream of water (6 ml/min) to react with streams of 5 M HCl and 0.3% KBH4 (both at 1 ml/min). After passing through a gas-liquid separator, the generated Hg was carried by Ar at 50-80 ml/min to a self-made Au-coated graphite-furnace for AAS, with pre-concentration and atomization temperature of 45-160°C and 500°C and 600°C, respectively. By standard-additions method, recovery was 98-101%; RSD were 5-10%. The calibration graph was linear with a detection limit of 20 pg of Hg. The method was applied to assay of human hair, urine, soil and peach leaf. No interference was observed from co-existing ions. Sampling rate was 50 runs per h.
Mercury Spectrophotometry Interferences Preconcentration Standard additions calibration

"Determination Of Trace Manganese(II) With Online Flow Injection Solvent-extraction Preconcentration Flame Atomic Absorption Spectrometry"
Guangpuxue Yu Guangpu Fenxi 1994 Volume 14, Issue 1 Pages 91-94
Chi, X.Z.;Zhou, J.

Abstract: Sample solution was prepared by mixing sample with acetic acid/sodium acetate buffer solution of pH 6 and ethanolic 1.2% ammonium pyrrolidinedithiocarbamate (I). A FIA system (diagram given) comprised of pumps to deliver sample solution (4 ml/min) and methyl isobutyl ketone (2 ml/min) to an extraction flask, the absorbance of the organic extract containing Mn-I complex was measured automatically by AAS with use of an AA-670 atomic absorption spectrophotometer with lamp current of 8 mA, acetylene flow rate of 2.5 l/min, air flow rate of 10 l/min, burner height of 3 mm and slit width of 0.19 nm. The calibration graph was linear from 0.5-5 µg/ml. The detection limit was 0.076 µg/ml. Recoveries ranged from 94-102%. The method was used to determine trace Mn in hair, surface water and traditional Chinese medicine.
Manganese(II) Spectrophotometry Sample preparation Solvent extraction Complexation Organic phase detection Preconcentration MIBK

"Automatic Determination Of Mercury In Samples Of Environmental Interest"
J. Autom. Methods Manag. Chem. 1996 Volume 18, Issue 6 Pages 193-198
MARIA CRISTINA CANELA, WILSON F. JARDIM, and JARBAS J. R. ROHWEDDER

Abstract: An automatic flow injection (FI) system for the determination of mercury was developed using a commercial Gold vapor atomic absorption spectrophotometer (CVAAS). Control and data acquisition in the FI system was done with an IBM-PC 286 XI compatible microcomputer and a home-made interface, using software written in QuickBasic 4.5. Mercury content was determined by: sampling using a combination of four electromechanical three-way poly(tetrafluoroethylene) valves; separation of the dissolved reduced mercury in a gas/liquid separation cell using nitrogen as carrier, followed by amalgamation of the stripped metal on a gold wire column; after stripping the metal, cleaning the separation cell using vacuum, which was controlled by a three-way electromechanical valve; heating the gold wire column automatically to release the amalgamated mercury using an external nichrome wire coil; storing the output signals automatically to calculate the final mercury concentration, using commercially available software. The optimized system presents a detection limit of 5.3 ng L-1 of mercury (30 pg absolute) using 5.7 mL (three injections of 1900 µl of the sample) with an analytical frequency of six samples per hour and reproducibility of 5%. The procedure was used to determine mercury in fish, hair and natural water samples. 30 References A solution which contained 0.01-100 ppb Hg(II) and a reductant solution of 10% SnCl2/5% HNO3 (2:3) were mixed (4.6 ml/min) in a sample introduction device (illustrated). The resultant Hg vapor was swept in N2 via a gas/liquid separator into a quartz tube (4 cm x 0.35 cm i.d.) packed with 200 mg of Au wire (0.21 mm diameter) protected with a pre-column packed with soda lime. The quartz tube was heated electrically to 320°C in 30 s and cooled in 75 s and the displaced Hg determined by cold vapor AAS. Calibration graphs were linear for 10^-75 ng/l Hg, with a detection limit of 5.3 ng/l Hg (30 pg absolute) for a 5.7 mL sample (3 x 1900 µL) and RSD of 5%. The procedure was used to determine Hg in fish, hair and water (details of sample preparation given).
Mercury Sample preparation Spectrophotometry Computer Column Amalgamation Phase separator Optimization

"Determination Of Lead In Hair Of Exposed Gas Station Workers And In Unexposed Adults By Microwave-aided Dissolution Of Samples And Flow Injection - Atomic Absorption Spectrometry"
J. Trace Elem. Electrolytes Health Dis. 1987 Volume 1, Issue 1 Pages 21-26
Burguera JL, Burguera M, Rondon CE, Rivas C, Burguera JA, Alarcon OM

Abstract: Samples of human hair were washed with ethanol, then air-dried and decomposed with HNO3 - HClO4 by heating in a microwave oven with an aspirator to remove acid fumes. The digest was diluted with water before analysis in a flow injection AAS system. The method was applied to hair from gasoline station workers, the Pb content of which was on average over twice that of unexposed persons. Samples of human hair were washed with ethanol, then air-dried and decomposed with HNO3 - HClO4 by heating in a microwave oven with an aspirator to remove acid fumes. The digest was diluted with water before analysis in a flow injection AAS system. The method was applied to hair from gasoline station workers, the Pb content of which was on average over twice that of unexposed persons. Lead content in head hair of 53 gas station workers together with an equal number of normal controls was determined. Samples of hair were washed with ethanol and water and microwave-aided wet digested prior to the determination of lead by flow injection/atomic absorption spectrometry. The lead content in hair of the gas station workers (48.7±17.5 µg/g) was significantly higher than that of the normal controls (17.2±8.1 µg/g). The effects of washing and sample digestion procedures, head sampling site, hair color, age, smoking habits and duration of exposure to the metal are discussed.
Lead Spectrophotometry Sample preparation

"Flow Injection Analysis - Kinetic Method For The Determination Of Traces Of Zinc With Meso-tetra-(4-sulfophenyl)porphyrin"
Lihua Jianyan, Huaxue Fence 1992 Volume 28, Issue 3 Pages 170-172
Peng, X.J.;Mao, Q.K.;Cheng, J.K.

Abstract: The cited method was based on the measurement of the absorbance due to the formation of Zn - meso-tetra-(4-sulfophenyl)porphyrin (I) complex using imidazole (II) as catalyst. The reagent solution was prepared by mixing 0.5 mL of 10.2 mM I, 2 mL of Na acetate - acetic acid buffer solution (pH 4.8) and 2 mL of 0.55% II. Portions (25 µL each) of the reagent solution and the sample solution containing 1 µg mL-1 of Zn were subjected to flow injection analysis (at 85°C) with redistilled water as carrier solution (2 mL min-1) and absorbance measured at 424.4 nm after stopping the flow for 60 s. Calibration graph was rectilinear for up to 2.5 µg mL-1 of Zn. The coefficient of variation (n = 16) was 0.8% for 1 µg mL-1 of Zn. Tolerance levels of 17 foreign ions were tabulated. The method was used to determine trace Zn in hair, tap water and peach leaves. Results agreed with those obtained by ICP-AES.
Zinc Spectrophotometry Kinetic Complexation Method comparison Catalysis Interferences Stopped-flow

"Flame Atomic Absorption Spectrometry With Flow Injection Sample Introduction For The Determination Of Heavy Metals In Biological Materials"
Wiss. Z. Univ. Halle 1987 Volume 36, Issue 1 Pages 3-15
Friese, K.;Matschiner, H.

Abstract: The cited method was applied in the determination of Mn in hair, Cr in biological tissues and Pb in blood. The coefficient of variation were 5.8, 8.1 and 1.7% for 1.9 ppm of Mn, 0.07 ppm of Cr and 4.6 µM-Pb, respectively.
Chromium Metals, heavy Lead Manganese Spectrophotometry Theory

"Determination Of Chromium And Manganese Traces In Biological Material By Flame AAS With Flow Injection Sample Introduction"
Zentralbl. Pharm., Pharmakother. Lab. Diagn. 1988 Volume 127, Issue 6 Pages 420-421
Friese, K.

Abstract: The combination of flow injection analysis and flame AAS is briefly discussed. For the cited application, samples were digested in closed PTFE vessels to give a final volume of 0.5 to 2 mL. Human hair samples (25 to 50 mg) were analyzed for Mn and gave day-to-day coefficient of variation of 20% (at 0.2 ppm) and 5% (at 2 ppm). Various biological tissues were analyzed for Cr. The accuracy of the procedure was demonstrated by analysis of four IAEA standard reference materials.
Chromium Manganese Spectrophotometry Reference material

"Time-based On-line Preconcentration Cold Vapour Generation Procedure For Ultra-trace Mercury Determination With Inductively Coupled Plasma Atomic Emission Spectrometry"
Anal. Bioanal. Chem. 2004 Volume 379, Issue 5-6 Pages 764-769
Aristidis N. Anthemidis, George A. Zachariadis, Christos E. Michos and John A. Stratis

Abstract: A time-based sequential dispensing on-line column pre-concentration procedure for mercury determination at trace levels by cold vapor generation inductively coupled plasma atomic emission spectrometry (CV-ICP-AES), by means of a unified module of a pre-concentration column and a gas-liquid separator (PCGLS) is described. The complex of mercury formed on-line with ammonium pyrrolidine dithiocarbamate (APDC) is retained on the surface of the hydrophobic poly(tetrafluoroethylene) (PTFE) turnings, which are packed into the lower compartment of the PCGLS. Subsequently, mercury vapor is generated directly on the PTFE turnings by reductant SnCl2 and separated from the liquid mixture via the PCGLS by argon purge gas. The outlet of the PCGLS is connected directly to the torch adapter of the plasma without the normal spray chamber and nebulizer. With 60-s pre-concentration time and 12.0 mL min-1 sample flow rate, the sampling frequency is 30 h-1. The calibration curve is linear over the concentration range 0.02-5.0 µg L-1, the detection limit (cL) is 0.01 µg L-1 and the relative standard deviation (sr) is 3.1% at the 1.0 µg L-1 level. The proposed method was evaluated by analysis of BCR CRM 278 (Mytilus Edulis) reference material and applied to the determination of total mercury in digested urine, blood and hair samples.
Mercury Spectrophotometry Solid phase extraction Reference material Phase separator Preconcentration Dithiocarbamate