离子色谱法测定海产品中磷酸盐、焦磷酸盐、偏磷酸盐和总磷

建立了离子色谱法测定海产品中磷酸盐、焦磷酸盐、偏磷酸盐和总磷的分析方法。样品经100 mmol/L NaOH溶液浸提,固相萃取柱去除有机物、阳离子、中和OH~后用于海产品中磷酸盐、焦磷酸盐和偏磷酸盐的测定;样品经干灰化法消化,固相萃取柱净化后用于总磷测定。考察了提取溶液的pH、有机物和共存离子对测定结果的影响。该方法的线性范围为0.3～60 mg/L,检出限为2.1～2.3 mg/kg,相对标准偏差为1.6%～2.6%。海鱼和虾仁样品中目标物的加标回收率为81.8%～100.0%。该方法选择性好,灵敏度高,用于实际样品测定结果令人满意。     

Determination of scandium in sea-water by atomic-absorption spectroscopy

A method for the determination of scandium in sea-water at the sub-microgram level has been developed. Scandium is coprecipitated with iron(III) hydroxide at pH 8-9, and then separated from the iron by ion-exchange. The final concentration is achieved by extracting the scandium into a solution of oxine in butanol. A nitrous oxide-acetylene flame is used for the determination by atomic-absorption spectroscopy. Recoveries of 99-100% are obtained. The storage of the solutions before analysis has been investigated by radiometric techniques with (46)Sc. The scandium concentration in surface waters of the South China Sea was found to be 0.01 +/- 0.005 microg/l .     

Determination of total phosphorus in detergents by atomic absorption spectroscopy

Summary A method is described for the determination of phosphorus in solid detergents. Nitric acid plus perchloric acid followed by treatment of the residue with hydrofluoric acid serves admirably to dissolve detergents in aqueous solutions. The phosphorus is determined by atomic absorption spectroscopy using a phosphorus hollow cathode tube. The method of additions is utilized to overcome matrix interference. The values obtained for phosphorus are in good agreement with a standard colorimetric method. No loss occurred by volatilization.

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Zusammenfassung Eine Methode zur Bestimmung von Phosphor in festen Detergenzien wurde beschrieben. Salpetersäure, Perchlorsäure und nachfolgende Behandlung des Rückstandes mit Flußsäure eignen sich hervorragend, um Detergenzien in wäßrige Lösung zu bringen. Der Phosphor wird durch Atomarabsorption bestimmt, wobei eine Phosphor-Hohlkathodenröhre verwendet wird. Durch Zusätze umgeht man Störungen seitens der Matrix. Die erhaltenen Resultate stimmen gut mit denen der kolorimetrischen Standardmethode überein. Durch Verflüchtigung entstehen keine Verluste.

     

Determination of total chromium in phosphate rocks by ion chromatography

Chromium(VI) is one of seven elements which is classified in the fertilizer industry as being harmful to plants and biological systems. Phosphate rocks represent the raw material for complex fertilizer production in the world. This paper investigates for the first time the determination of total chromium in phosphate rocks by ion chromatography. The developed analytical method involves the digestion of phosphate rocks with nitric acid followed by sample treatment of the resulting solution. The digestion solution obtained was treated with an oxidising agent (potassium peroxosulphate) to convert all chromium to the hexavalent state. The analytical method developed utilizes anion-exchange ion chromatography to achieve the separation and spectrophotometric post-column reaction for detection with diphenylcarbazide. The relative standard of deviation from analytical data comparison of six different phosphate rocks with atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry techniques, and cross-analysis data against an internationally certified phosphate rock standard were between 0.58 and 1.45%. Calibration curve between 0.2 and 0.9 μg/ml was excellent, and the method has a detection limit for Cr(VI) of 0.05 ng. The developed method offers a fast, a reliable and an alternative procedure for the determination of total chromium in phosphate rock deposits by ion chromatography.     

Determination of potassium in sea-water by capillary isotachophoresis

Summary A new analytical procedure for the determination of potassium in sea-water was developed using capillary isotachophoresis and ion-exchange. After the sea-water sample was passed through the column packed with an ammonium form cation-exchange resin, sodium ion was removed with 2×10^–2 mol/l ammonium chloride solution and then potassium ion was eluted with 3×10^–1 mol/l ammonium chloride solution. Simultaneous determination of potassium and sodium ions was performed with a newly developed electrolyte system; the leading electrolyte was 5 mmol/l cesium hydroxide containing 2 mmol/l 18-crown-6, 0.01% hydroxypropyl methylcellulose (HPMC) and 70% methanol; the terminating electrolyte was 5 mmol/l tetrabutylammonium bromide containing 0.01% HPMC and 70% methanol. A large amount of ammonium in the eluate did not interfere with the isotachophoretic measurement of potassium and sodium ions. A linear working curve was obtained for artificial sea-water samples containing up to 700 mg/l potassium ion. The proposed method was applied to the determination of potassium in surface and bottom sea-water samples.

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Kaliumbestimmung in Meereswasser durch Capillar-Isotachophorese

     

Determination of nitrite in sea-water by ion-exchanger colorimetry

Summary A microdetermination method (at theg/l level for nitrite) has been developed, based on ion-exchanger colorimetry. The nitrite is reacted with sulphanilamide andN-(1-naphthyl)ethylenediamine to form an azo dye which is then sorbed on Dowex 50W-X2. The resin phase absorbance at 550 and 800 nm is measured directly. The relative detection limit is 0.27g/l and the distribution ratio is 2.6×10⁴. The method has been applied to determination of nitrite in 500-ml sea-water samples and compared with a conventional technique.

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Bestimmung von Nitrit in Meerwasser durch Ionenaustausch-Kolorimetrie

Zusammenfassung Eine Mikromethode zur Bestimmung von Mikrogramm Nitrit/Liter mit Hilfe der lonenaustausch-Kolorimetrie wurde ausgearbeitet. Zu diesem Zweck wird Nitrit mit Sulfanilamid und N-(1-Naphthyl)ethylendiamin zu einem Azofarbstoff umgesetzt, der an Dowex 50W-X2 adsorbiert wird. Die Absorbanz der Harzphase wird unmittelbar bei 550 und 800 nm gemessen. Die relative Nachweisgrenze beträgt 0,27g/l, das Verteilungsverhältnis 2,6×10⁴. Das Verfahren wurde zur Bestimmung von Nitrit in 500-ml-Proben Meerwasser verwendet und mit konventionellen Methoden verglichen.

     

Automatic method for the determination of ortho-phosphate and total dissolved phosphorus in the marine environment

Summary An automatic method for the determination of ortho-phosphate in seawater is described. It is based on the original molybdenum blue method and is very sensitive because of the very small dilution of samples by reagents. An all-glass reaction manifold is proposed, the use of plastic material should be avoided as far as possible. The described method may also be used in a slightly modified version for the determination of total dissolved phosphorus, when samples are first digested with peroxidisulfate. Orthophosphate and total dissolved phosphorus can be determined exactly in the concentration range from 0.01–5 g at P/l with a sampling frequency of 30 h^–1.

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Automatische Methode zur Bestimmung von ortho-Phosphat und gelöstem Gesamt-Phosphor in Meerwasser

Zusammenfassung Für die Bestimmung von ortho-Phosphat in Seewasser wird eine automatische Methode beschrieben, die auf der üblichen Molybdänblaumethode basiert und sehr empfindlich ist, weil die Proben mit einer sehr geringen Menge Reagenz verdünnt werden. Für die Reaktionseinheit wird ein Allglassystem vorgeschlagen, der Einsatz von Plastikmaterial sollte weitgehend vermieden werden. Die beschriebene Methode ist in leicht modifizierter Form auch für die Bestimmung von gelöstem Gesamt-Phosphor geeignet, wenn die Proben zuvor mit Peroxodisulfat aufgeschlossen werden. Die Methode liefert bei einer Probenfrequenz von 30 h^–1 für ortho-Phosphat und gelösten Gesamt-Phosphor genaue Ergebnisse im Bereich von 0,01–5 g at P/1.

     

Determination of chromium(III) and total chromium in marine waters

The development of an analytical technique is described which may be used to determine chromium, chromium(III) and chromium(VI) in estuarine and coastal waters. The method is based on selective micro-solvent extraction with subsequent GFAAS. The technique has been applied in a major North Sea estuary. The results obtained confirm that thermodynamic factors alone cannot be relied upon to describe the form of chromium in estuaries. Kinetic factors appear to have a strong influence over speciation and lead to the persistence of Cr(III) species in environments where Cr(VI) would be expected to be present.     

Determination of zinc in sea-water by anodic stripping voltammetry

The horizontal distribution of zinc in surface waters from Guanabara Bay has been studied by use of optimized voltammetric techniques and ultraclean working procedures. The non-linearity observed between the peak current for zinc and the electrolysis time, as well as the appearance of a peak at −1.16 V, are discussed. The values found for total zinc in the samples range between 0.3 and 22 μg/l.     

Determination of chromium(III) and total chromium in marine waters

The development of an analytical technique is described which may be used to determine chromium, chromium(III) and chromium(VI) in estuarine and coastal waters. The method is based on selective micro-solvent extraction with subsequent GFAAS. The technique has been applied in a major North Sea estuary. The results obtained confirm that thermodynamic factors alone cannot be relied upon to describe the form of chromium in estuaries. Kinetic factors appear to have a strong influence over speciation and lead to the persistence of Cr(III) species in environments where Cr(VI) would be expected to be present.     

Determination of ammonium ion in sea-water by capillary isotachophoresis

A new procedure for determination of ammonium ion in sea-water by means of capillary isotachophoresis and a gas-liquid separator with a tubular microporous polytetrafluoroethylene membrane for preliminary enrichment has been developed. Ammonia generated by adding sodium hydroxide solution to the sea-water samples is allowed to permeate through the membrane and then dissolve in sulphuric acid. A linear calibration graph has been obtained with artificial sea-water samples containing up to 300 mug/1. ammonium ion. The method has been applied to the determination of ammonium ion in surface and bottom sea-water samples.     

Determination of total phosphorus in water by photochemical decomposition with ultraviolet irradiation

A simple and convenient photochemical decomposition method has been developed for the determination of total phosphorus in natural and sewage water. Organic phosphorus compounds and inorganic polyphosphates may be completely converted into orthophosphate in the presence of 0.3M sulphuric acid and 0.12% potassium persulphate with 50 min irradiation. The relative standard deviations found for analysis of natural water (P 35 microg/l.) and sewage (P 2.4 mg/l.) were 5.7% and 1.0% respectively. The method gives results comparable to those obtained by digestion with persulphate.     

Solvent extraction-spectrophotometric determination of phosphate with molybdate and malachite green in river water and sea-water

Molybdophosphate, formed between orthophosphate and molybdate in sulphuric acid solution, is extracted into a mixture of toluene and 4-methylpentan-2-one (1:3 v v ) with Malachite Green as counter-ion. A single extraction with equal phase volumes gives an apparent molar absorptivity for phosphate of 2.3 x 10(5) l.mole(-1).cm(-1) at 630 nm; the absorbance of the reagent blank is 0.03. With an organic to aqueous phase-volume ratio of 1:10, the molar absorptivity is 2.5 x 10(5) l.mole(-1).cm(-1) and the absorbance of the reagent blank 0.08. By the proposed method, ng ml levels of phosphorus can be determined, and the detection limit is about 0.1 ng ml . The standard deviation and relative standard deviation for the determination of phosphorus in tap water (4.3 ng ml ) are 0.05 ng ml and 1.1%, respectively. The method can also be applied to the determination of phosphorus in river water and sea-water.     

Determination of Ag, Cd, Pb, Zn and Pd in sea-water by thermal-ionization isotope-dilution mass spectrometry

The concentrations of Ag, Cd, Pb, Zn and Pd in sea-water have been determined by thermal-ionization isotope-dilution mass spectrometry. The concentrations found, in ng/kg, were 0.6 +/- 0.4 Ag, 1.9 +/- 0.4 Cd, 18 +/- 8 Pb, 30 +/- 8 Zn and < 4 Pd. These levels are lower than some reported previously. Determination of Pd in sea-water is reported for the first time.     

The storage of sea-water samples for the determination of dissolved inorganic phosphate

A study has been made of methods of preservation of sea-water samples to be analysed for inorganic phosphate. It is recommended that the filtered samples be treated with 0.7 ml of chloroform per 100 ml of water and stored in the dark in glass bottles. Polyethylene bottles should not be used for water storage since they strongly adsorb phosphate ion.     

Determination of tin and triorganotin compounds in sea-water by graphite-furnace atomic-absorption spectrophotometry

An analytical method based on graphite-furnace atomic-absorption spectrophotometry employing a suitable signal-enhancing medium for determination of inorganic tin and two of its trisubstituted organic derivatives in sea-water has been established. This method allows determination of triphenyltin and tributyltin compounds down to 2 x 10(-12) and 2.8 x 10(-12)M respectively by means of enrichment by collection on graphitized carbon black (enrichment factor up to 8 x 10(4)) and a separation on a small silica-gel column. Inorganic tin, which is not adsorbed on the graphitized carbon black, is isolated from the matrix by liquid-liquid extraction of its pyrrolidinedithiocarbamate complex into dichloromethane. The method gives good recovery (95%) and precision ( less, similar5%) at the ng/l. level.     

A compact portable flow analysis system for the rapid determination of total phosphorus in estuarine and marine waters

The development and evaluation of a portable flow analysis system for the in situ determination of total phosphorus is described. The system has been designed with rapid underway monitoring in mind. The system employs an ultra-violet photo-reactor and thermal heating for peroxodisulfate digestion of total phosphorus to orthophosphate, followed by spectrophotometric detection with a multi-reflective flow cell and low-power light emitting diode using the molybdenum blue method. Reagents are stored under gas pressure and delivered using software controlled miniature solenoid valves. The fully automated system has a throughput of 115 measurements per hour, a detection limit of 1 μg P L⁻¹, and gives a linear response over the calibration range of 0-200 μg P L⁻¹ (r² = 0.9998), with a precision of 4.6% RSD at 100 μg P L⁻¹ (n = 10). Field validation of the instrument and method was performed in Port Philip and Western Port Bays in Victoria, SE Australia, where 2499 analyses were performed over a 25 h period, over a cruise path of 285 km. Good agreement was observed between determinations of samples taken manually and analysed in the laboratory and those measured in situ with the flow analysis system.     

Determination of total phosphorus in soya food samples by capillary isotachophoresis (cITP)

Capillary isotachophoresis (cITP) was applied for the determination of total phosphorus in soya food. The leading electrolyte was 8 mM HCl adjusted with β-alanine to pH=3.55 plus 3 mM bis-tris-propane and 0.2% hydroxyethylcellulose, whereas the terminating electrolyte 5 mM citric acid. Obtained results were compared with the spectrophotometric method. The correlation coefficients were 0.9996 for cITP and 0.9986 for standard method indicating the satisfactory precision of the calibration curves. The separation of anions was achieved within 25 min. Accuracy was determined using standard reference material (non-fat milk powder) and recovery assay based on standard additions method. Obtained results were discussed in respect to the accuracy and statistical parameters. Satisfactory values of recovery ranged between 99.22 and 99.85%, whereas R.S.D.<1% what demonstrate the advantage of cITP method in the routine analyses of phosphorus content in food samples.