Determination of phosphorus in waste water by EDXRF

Summary In a method developed for the determination of phosphorus in aqueous solutions, phosphorus was changed to the phosphate form, coprecipitated with hydrated iron(III) oxide, bound with activated charcoal and measured by EDXRF. The detection limit was 0.89 mg P/g activated charcoal. The method was used to determine the total phosphorus content of a waste water sample from a paper mill. Investigation of two sample destruction methods, dry ashing/HCl digestion and persulphate oxidation, showed the former to be more suitable for our purpose.     

分光光度法测定水中氟离子的优化

氟离子在弱酸性缓冲介质中与显色剂反应生成蓝色三元络合物,络合物在620 nm波长处的吸光度与氟离子浓度成正比,据此建立检测水中氟化物含量的分光光度法.研究了缓冲液和显色剂加入量、络合物稳定剂、稳定时间对测定结果的影响,并确定了最佳分析条件:向适量水样中加入1 mL缓冲液、1 mL显色剂、1 mL乙醇,静置20 min,...     

Determination of total dissolved phosphorus in water samples by axial inductively coupled plasma atomic emission spectrometry

A procedure was developed to determine total dissolved phosphorus in groundwater-like samples using axial ICP-AES. Severe and peculiar matrix effects (strongly positive at lower and leveling off at higher matrix concentrations) in the presence of Na and Ca were observed. To reduce these matrix effects, a double approach was utilized consisting of a so-called minimum matrix in combination with an internal standard (Ga in this case). The ‘minimum matrix’ (small amounts of K, Mg and Na) was only added to the standard solution(s) used for the calibration. The detection limit for the whole procedure was 12 μg/L using the P213 nm line. Residual matrix effects were less than 3% (P213 nm line). Received: 21 February 1997 / Revised: 5 June 1997 / Accepted: 6 June 1997     

Determination of total dissolved phosphorus in water samples by axial inductively coupled plasma atomic emission spectrometry

A procedure was developed to determine total dissolved phosphorus in groundwater-like samples using axial ICP-AES. Severe and peculiar matrix effects (strongly positive at lower and leveling off at higher matrix concentrations) in the presence of Na and Ca were observed. To reduce these matrix effects, a double approach was utilized consisting of a so-called minimum matrix in combination with an internal standard (Ga in this case). The ‘minimum matrix’ (small amounts of K, Mg and Na) was only added to the standard solution(s) used for the calibration. The detection limit for the whole procedure was 12 μg/L using the P213 nm line. Residual matrix effects were less than 3% (P213 nm line). Received: 21 February 1997 / Revised: 5 June 1997 / Accepted: 6 June 1997     

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 mercury and methylmercury in biological samples by photochemical vapor generation

Cold vapor atomic absorption spectrometry (CV-AAS) based on photochemical reduction by exposure to UV radiation is described for the determination of methylmercury and total mercury in biological samples. Two approaches were investigated: (a) tissues were digested in either formic acid or tetramethylammonium hydroxide (TMAH), and total mercury was determined following reduction of both species by exposure of the solution to UV irradiation; (b) tissues were solubilized in TMAH, diluted to a final concentration of 0.125% m/v TMAH by addition of 10% v/v acetic acid and CH₃Hg⁺ was selectively quantitated, or the initial digests were diluted to 0.125% m/v TMAH by addition of deionized water, adjusted to pH 0.3 by addition of HCl and CH₃Hg⁺ was selectively quantitated. For each case, the optimum conditions for photochemical vapor generation (photo-CVG) were investigated. The photochemical reduction efficiency was estimated to be ∼95% by comparing the response with traditional SnCl₂ chemical reduction. The method was validated by analysis of several biological Certified Reference Materials, DORM-1, DORM-2, DOLT-2 and DOLT-3, using calibration against aqueous solutions of Hg²⁺; results showed good agreement with the certified values for total and methylmercury in all cases. Limits of detection of 6 ng/g for total mercury using formic acid, 8 ng/g for total mercury and 10 ng/g for methylmercury using TMAH were obtained. The proposed methodology is sensitive, simple and inexpensive, and promotes “green” chemistry. The potential for application to other sample types and analytes is evident.     

Determination of soluble phosphate,and total phosphorus in sea-water and of total phosphorus in marine muds

Summary The use ofp-methylaminophenol sulphate (metol) at 100 for the reduction of phosphomolybdic acid in the determination of phosphate in sea-water has a number of advantages over stannous chloride. The molybdenum blue colour once formed, is stable for several hours, and the calibration curve is not dependent upon the batches of reagent used; Beer's law is obeyed up to concentrations of at least 1 mg PO₄-P/l. The salt error is very small and the method has approximately 30% greater sensitivity in sea-water than has the stannous chloride method. Arsenic does not interfere at concentrations five times greater than its sea-water concentration. Iron and copper in moderate amounts do not interfere.Evaporation to dryness with a mixture of concentrated nitric and perchloric acids, followed by colorimetric determination of inorganic phosphate, is employed for the determination of total phosphorus in sea-water and marine muds. The method shows a coefficient of variation of ca. 2% with sea-water containing 60g P/l.

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Zusammenfassung Die Anwendung von p-Methylaminophenolsulfat (Metol) bei 100 für die Reduktion von PhosphomolybdÄnsÄure bei der Bestimmung der Phosphate in Meerwasser hat gegenüber Zinn(II)chlorid eine Reihe von Vorteilen. Das einmal gebildete MolybdÄnblau ist für einige Stunden stabil und die Eichkurve nicht von der angewendeten Menge Reagens abhÄngig; das Beersche Gesetz ist für Konzentrationen bis zu 1 mg Phosphat-Phosphor/l gültig. Der Salzfehler ist sehr klein und die Methode für Meerwasser etwa um 30% empfindlicher als die Zinn(II)chloridmethode. Arsen stört bei Konzentrationen, die fünfmal größer sind als in Meerwasser, nicht. Eisen und Kupfer in mÄßigen Mengen stören gleichfalls nicht.Für die Bestimmung des Gesamtphosphors in Meerwasser und Seeschlamm wird mit einer Mischung von konz. SalpetersÄure und PerchlorsÄure zur Trockne verdampft und das anorganische Phosphat kolorimetrisch gemessen. Die Methode zeigt eine Schwankungsbreite von etwa 2% für Meerwasser mit 60g P/l.

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Résumé L'emploi du sulfate de p-méthylaminophenol (métol) à 100 pour la réduction de l'acide phosphomolybdique lors du dosage des phosphates contenus dans l'eau de mer présente de multiples avantages sur celui du chlorure stanneux. Après sa formation, le bleu de molybdène reste stable pendant plusieurs heures et la courbe d'étalonnage ne varie pas avec le lot de réactif employé; la loi deBeer est applicable jusqu'à des concentrations au moins égales à 1 mg de phosphore phosphorique par litre. L'erreur de sel est très faible et la sensibilité de la méthode appliquée à l'eau de mer est environ 30% plus élevée que la méthode au chlorure stanneux. L'arsenic ne gÊne pas mÊme pour des concentrations cinq fois supérieures à celle qu'il atteint dans l'eau de mer. Des teneurs modérées de fer et de cuivre n'apportent pas de perturbation. On évapore à siecité en présence d'un mélange d'acides nitrique et perchlorique concentrés puis on effectue une détermination colorimétrique des phosphates minéraux pour doser le phosphore total de l'eau de mer et des boues marines. La méthode est sujette à des variations d'environ 2% pour leau de mer contenant 60 g de phosphore par litre.

     

Determination of organic peroxides by liquid chromatography with on-line post-column ultraviolet irradiation and peroxyoxalate chemiluminescence detection

A combination of the electrophoretically mediated microanalysis methodology with a partial filling technique was applied for the inhibition study of bovine liver rhodanese by 2-oxoglutarate. In this set-up, part of the capillary is filled with the best buffer for the enzymatic reaction, while the rest of the capillary is filled with the optimal background electrolyte for separation of substrates and products. The estimated value of K_I for 2-oxoglutarate was 3.62·10⁻⁴±1.43·10⁻⁴ M with respect to cyanide and 1.40·10⁻³±1.60·10⁻⁴ M with respect to thiosulfate. In addition, the type of inhibition was also evaluated. The findings of 2-oxoglutarate as the competitive inhibitor with respect to cyanide and as the uncompetitive inhibitor with respect to thiosulfate are in accordance with previous literature data.     

气相色谱-质谱法测定水体中5种典型有机紫外防晒剂

建立了水体中5种典型有机紫外防晒剂甲氧基肉桂酸乙基己酯（ethylhexyl methoxycinnamate,EHMC）、二苯酮-3（benzophenone-3,BP-3）、4-甲基苄亚基樟脑（4-methylbenzylidene camphor,4-MBC）、奥克立林（octocrylene,OC）和胡莫柳酯（homosalate,HMS）的气相色谱-质谱检测方法。对HMS、BP-3衍生化条件进行了系统的优化。以100 μL双（三甲基硅烷基）三氟乙酰胺（N,O-bis（trimethylsilyl） trifluoroacetamide,BSTFA）为衍生化试剂,在100 ℃下反应100 min。水样固相萃取选用Oasis HLB萃取柱（0.5 g）,洗脱溶剂为乙酸乙酯-二氯甲烷（1：1,v/v）,水样pH 3~5。该方法对5种化合物的检出限范围为0.5~1.2 ng/L,定量限范围为1.4~4.0 ng/L。最佳实验条件下,加标水样回收率为87.85%~102.34%,相对标准偏差（n=3）均小于5%。该方法成功地应用于昆明市第一污水厂进出口水样中目标物质的分析。     

K2S2O8-离子色谱法测定水中总氮量

在不锈钢蒸汽消毒器中用K2S2O8将水中含氮物质中的N氧化为NO3-,用离子色谱测定,从而测定水中总氮量。实验对K2S2O8氧化液用量及反应时间等进行探讨,并对长江水中总氮量进行了测定。实验结果表明测定最佳条件是氧化时间10 min以上、氧化剂用量为理论用量的5倍;长江水(武汉段)总氮量为2.09 mg/L,测得的总氮量与文献报道的基本吻合。     

Determination of total phosphorus in waters with amperometric detection by coupling of flow-injection analysis with continuous microwave oven digestion

For the determination of total phosphorus in waters by flow-injection analysis, a continuous microwave oven decomposition with subsequent amperometric detection of orthophosphate is proposed. The percentage digestion was examined for two different decomposition reagents and by varying the pH of the carrier and the length and diameter of the digestion coil. With potassium peroxodisulphate decomposition the recoveries of phosphorus vary from 91 to 100% for organic phosphorus compounds, and with perchloric acid decomposition the recoveries vary from 60 to 70% for inorganic polyphosphates. Calibration graphs are linear for up to 30 mg P l^?1, the determination limit is 0.1 mg P l^?1 and the precision of the method is 3% (relative standard deviation) (n = 5) at 5 mg P l^?1. The sampling rate is 20 h^?1. Good recoveries of phosphorus after addition to domestic waste water sample are obtained.     

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.     

Tyrosine formation from phenylalanine by ultraviolet irradiation

When phenylalanine was irradiated at ultraviolet (UV) light, p-tyrosine, m-tyrosine and o-tyrosine were identified as hydroxylated products. From p-tyrosine and m-tyrosine, the formation of L-3,4-dihydroxyphenylalanine (DOPA) was observed. The hydroxylation of phenylalanine was prevented by radical scavengers, e.g., catalase, superoxide dismutase, sodium thiocyanate, mannitol, potassium iodide and thiourea. Replacement of air with nitrogen gas prevented the hydroxylation, but did not depress it completely. The addition of H2O2 increased significantly the hydroxylation of phenylalanine. These results suggest that the hydroxylation of phenylalanine by UV irradiation may be caused by .OH formed during the decomposition of H2O.     

Oscillatory photochemical decomposition of tetrathionate ion

When subject to illumination, tetrathionate ion decomposes in an oscillatory fashion with a period of about 1 h to yield products identified as colloidal sulfur and trithionate ion. This system represents the first experimental example of a stirred, batch photochemical oscillator. A simple model consisting of four reaction steps and four adjustable rate parameters gives good agreement with the observed oscillatory behavior.     

紫外光引发甲基丙烯酸甲酯乳液聚合

以60W高压汞灯为光源,以偶氮二异丁氰(AIBN)为主要光引发剂,以甲基丙烯酸甲酯(MMA)为单体进行乳液聚合,考察了光照时间、单体浓度、光引发剂浓度等因素对单体转化率的影响;采用透射电镜观察了乳胶粒的形态,并测定了其尺寸.结果表明,转化率随光照时间和单体浓度的增加而上升;当光引发剂质量分数为3%时单体转化率最高.     

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 total tin in river water by hydride generation-atomic absorption spectrometry

Summary The total tin in river water was determined by hydride generation-atomic absorption spectrometry in sulphuric acid medium. The water was concentrated with nitric and sulphuric acids. Interference from copper and iron was eliminated by extracting copper with a carbon tetrachloride solution of zinc dibenzyldithiocarbamate and by complexing iron with 1,10-phenanthroline in solution. The acidities of the sample solutions were checked by weighing the residue in the flasks during the acid digestion so that the acidities of the sample solutions became approximately equal to those of the calibration solutions. When a 1,000 mg/l tin(IV) solution was diluted with water, the hydrolysed tin could not be determined entirely as the total tin by acidification with sulphuric acid, but it could be recovered completely by digestion even after 5 days. Thus digestion is essential when determining the total tin in water.     

Determination of total copper in haemodialysis water by differential-pulse anodic stripping voltammetry

An anodic stripping voltammetric method was developed in order to determine copper in the water used to prepare haemodialysis solutions. The interference from organic matter was overcome by high-pressure bomb mineralization. The electrochemical results were compared with those obtained by using graphite furnace atomic absorption spectrometry and the correlation was excellent (r = 0.983, p < 0.001). The detection limit was 0.2 μg l^?1 copper.