An automatic method for the determination of ammonia in sea water

A method is described for the determination of ammonia in sea and estuarine water employing an autoanalyzer. The manifold design allows for the determination of ammonia concentration in the range of 0.2–20 μg at NH₄-N/l over a salinity range of 35-10‰ with negligible interference from amino acids.     

An automated procedure for the determination of phosphorus

Procedures for the determination of dissolved orthophosphate and total phosphorus in surface fresh waters (e.g. rivers. lakes and reservoirs) and organic wastes (e.g. domestic sewage. creamery effluents and the like) (particulate or dissolved) are described. Total phosphorus compounds are converted to orthophosphate by acid persulphate digestion. The digestion time is 3 h which goes to completion without any supervision. The method allows for a maximum of 36 samples. 2 blanks and 2 standards to be processed simultaneously. There is no pH adjustment required. Interference from silica and iron(III) up to 20 mg l⁻¹ is absent. Detection limits for the automated step involving orthophosphate are 1 μg 1⁻¹. Recovery and effectiveness of proposed procedures are excellent.     

An improved hydrazine reduction method for the automated determination of low nitrate levels in freshwater

An automated nitrate determination is described in which nitrate is reduced to nitrite with hydrazine sulphate under alkaline conditions in the presence of Cu²⁺ and Zn²⁺. Interferances encountered in natural water samples were eliminated by the addition of Zn²⁺ to the Cu²⁺ catalyst solution.The method is suitable for the determination of low NO₃−N concentrations and compares favourably with the manual copperised cadmium technique for freshwater samples containing 10–800 mg m⁻³ NO₃−N. The method is also linear at nitrate concentrations below 10 mg N m⁻³. The standard deviations (S.D.) of blanks and of samples containing 2 mg NO₃−N m⁻³ were 0.013 and 0.06 mg N m⁻³ respectively at an analysis rate of 30 samples h⁻¹.     

An automated procedure for the determination of total Kjeldahl nitrogen

A procedure for the determination of total Kjeldahl nitrogen in surface fresh waters and organic wastes is described. Organic nitrogen compounds are converted to ammonium sulphate by a catalytic (red mercuric oxide) acid-sulphate digestion. The digest time is 3 h and allows for a maximum of 36 samples, 2 blanks and 2 standards to be processed simultaneously. There is no pH adjustment required following the digestion. Calibration curves covering the ranges (i) 0.5–100 μg NH₃---Nl⁻¹ and (ii) 10–1000 μg NH₃---Nl⁻¹ were linear within ±2%. The detection limit of the method is 0.5 μg TKNl⁻¹. The concentration range of TKN for which the method is suitable is 0.5 μg Nl⁻¹–40 mg Nl⁻¹. The method displayed a high tolerance to interferences from copper, iron, mercury and hardness. Digest procedure gave a high recovery and reproductibility over a wide range of nitrogen compounds tested.     

An automated system for the determination of chemical oxygen demand

Measured volumes of sample, mercuric sulphate and potassium dichromate/ sulphuric acid digestant are metered into a mixing pot. The mixed solution is pumped through a 40 ft length of glass coil suspended in a fluidized sand bath heated to 160°C. After cooling, the solution is passed through a colorimeter which measures the change in optical density due to the reduction in dichromate concentration and records it as a peak on a strip chart recorder. The chemical oxygen demand (COD) of samples is computed by reference to the peak heights given by known standards. A base or wash solution is automatically added between samples to separate the individual peaks and re-establish the base line. A new system designed to eliminate the use of a peristaltic pump is described. This has eliminated stoppage of the system due to failure of the pump tubing. This was previously the most frequent cause of breakdown.     

Sorption-photometric method for determination of sodium dodecyl sulfate with methylene blue in the presence of non-ionic surfactant

The extraction of sodium dodecyl sulfate with methylene blue by polyurethane foam in the presence and absence of non-ionic surfactant additives was investigated using diffuse reflectance spectrophotometry method. The sorption-photometric method for determining sodium dodecyl sulfate in water of various types was developed. The linearity of calibration curve with the test sample volume being 25 cm³ was kept within the range of 0.04–6.0 mg/dm³.     

Validation of an automated fluorescein method for determining bromide in water

Surface, atmospheric precipitation and deionized water samples were spiked with μg l^?1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0.015 to 0.5 mg l^?1 of bromide. The correlation coefficient for the same sets of paired data is 0.9987. Recovery data, except for the surface water samples to which 0.005 mg l^?1 of bromide was added, range from 89 to 112%. There appears to be no loss of bromide from solution in either type of container.     

Colorimetric method for the determination of arsenic in potable water

A colorimetric method for the determination of arsenic in potable water was developed with a limit of detection of 0.0005 mg l⁻¹. Arsenic(V) reacts quantitatively with potassium iodide in the presence of sulphuric acid and releases an equivalent amount of iodine, which imparts a pink colour to a carbon tetrachloride extract, this colour being measured at a predetermined wavelength of 515 nm. The method was used to differentiate between arsenic(V) and arsenic(III) and to analyse water samples from rivers, wells and lakes. No interference from arsenic(III), iron(III), chromium(VI) or lead(IV) was observed.     

Adsorption of non-ionic surfactants on activated carbon and mineral clay

A series of non-ionic surfactants of nonyl-phenol ethoxylates, with n = 4?23;0 ethylene oxide groups and dinonyl-phenol ethoxylate were studied in dilute aqueous solution. Their removal efficiencies and mechanisms by adsorption on powdered and granular activated carbon and on Na-montmorillonite clay were investigated. The powdered activated carbon proved to be the most efficient with 94–100% non-ionic surfactants removal by addition of 40–80 mg activated carbon.Various models of adsorption isotherms such as Langmuir, BET and S-type were used to determine Q⁴, the limiting adsorption capacity. The relationships between Q^o and parameters affecting the adsorption of non-ionic surfactants such as n, HLB and CMC were determined. The cross-sectional area σ₀ occupied by surfactant molecules on the adsorbent was calculated. Adsorption has been proven to be a potential advanced physicochemical treatment method for the effective removal of non-ionic surfactants present in effluents intended for reuse.     

A low level spectrophotometric method for the determination of sulfite in water

A method for determining low levels of sulfite in water is described based on the liberation of sulfur dioxide from an acidified water sample by purging with nitrogen gas and re-absorbing it in a solution containing ferric ion and 1,10-phenanthroliné. The ferric ion is reduced to ferrous ion by the sulfur dioxide and the orange Tris-(1,10-phenanthroline)iron(II) complex is formed. After removing the excess ferric ion with ammonium bifluoride to stop further color development, the stable complex is measured colorimetrically at 510 nm. The detection limit is 0.01 mg l⁻¹ SO²⁻₃. The effect of and removal of interferences and the effect of temperature are discussed.     

The determination of non-ionic detergents in sewage works samples

An air stripping technique is described for the transfer of non-ionic detergent from aqueous samples into benzene. The non-ionic detergent trapped in the benzene phase is quantitatively determined by an extension of the Brown and Hayes cobaltithiocyanate method. This extension involves measuring the thiocyanate content of the nonionic/cobaltithiocyanate complex after extraction into the aqueous phase. This gives a direct reading of the nonionic detergent content from a prepared calibration graph.     

An improved method for the determination of adenosinetriphosphate in environmental samples

An improved method has been developed for the analysis of the adenosinetriphosphate (ATP) content of environmental samples with the luciferin-luciferase assay. Factors affecting the recovery and stability of the ATP as well as the enzymatic reaction were optimized. The most versitile method utilizes procedure which can be used for natural waters, sediments and sludges. This involves homogenization at room temperature in 10⁻² M trisodium phosphate, pH 11.7, containing 23% chloroform. This method is more effective than other methods tested and results in minimal interference with the enzymatic reaction. It also provides improved ATP recovery and long term stability of extracted ATP. Another method that can be used on natural waters and sludges is by boiling for 5 min in 10⁻² M glycine buffer, 5 × 10⁻³ M Mg-EDTA, pH 10, which resulted in complete extraction and no hydrolytic loss of ATP. However, it is not satisfactory for sediments containing high humic acid substances as well as high metal loadings.In addition to the direct comparison of endogenous ATP extraction by various methods, actual recoveries of spiked radioactive ATP was measured. ATP adsorption, hydrolysis and recoveries in each method were determined by the use of [8-¹⁴C] ATP and [γ-³²P] ATP.     

Determination of non-ionic surfactants and their biotransformation by-products adsorbed on alive activated sludge

A procedure has been developed for the determination of non-ionic surfactants (NS) adsorbed on particles of alive and dead activated sludge. The procedure also enables the determination of adsorption of major biodegradation by-products: short-chained ethoxylates, long- and short-chained PEG. The basis of measurement is the determination of NS concentration in a slurry of activated sludge and in a solution phase. The difference between these two concentrations represents the NS adsorbed on activated sludge. Separation of NS and their biotransformation by-products from samples and then on narrower fractions was performed by a sequential liquid-liquid extraction and precipitation with modified Dragendorff reagent. The indirect tensammetric technique (ITT) was applied for the final determination. The developed method was checked using the example of the treatment of the surfactant C12E10 (oxyethylated fatty alcohol) (C12E10) in the continuous flow activated sludge facility. No statistically significant accumulation of C12E10 on the alive activated sludge was detected, probably because of faster C12E10 fission than its adsorption. However, significant adsorption of the short-chained ethoxylates (including free alcohol) on the alive activated sludge was found, as well as statistically significant adsorption of long- and short-chained PEG. The adsorption of surfactant C12E10 and its biodegradation by-products on dead activated sludge was found to be higher than the species adsorption on alive activated sludge.     

An automated and semi-continuous method for the analysis of water-soluble constituents in PM(2.5)

An automated and semi-continuous method for measuring water-soluble constituents in PM(2.5) was developed. The system consists of a multi-tube diffusion scrubber (MTDS), a low temperature particle impactor (LTPI), an inertial air/liquid separator, and two ion chromatography systems. The MTDS acts as an interfering gas removal system and also as a humidifier for growing particles. Since the MTDS operates at 40 degrees C, the loss of volatile compounds and hydrological conversion of nitrogen oxides to nitrite were not of significant concern. The condensation of water vapor, dissolution of soluble constituents, and capture of insoluble particles occurred in the LTPI. The condensed liquid containing the dissolved species and the insoluble particles was separated from the airflow using an inertial air/liquid separator. The analysis of cations and anions in the effluent liquid was performed using two ion chromatography systems. The collection efficiency, including the inlet loss, of the system was 96.6+/-7.1% at an air flow rate of 1.0 SLPM. The limits of detection ranged from 12 to 57 ng/m(3) for major ionic constituents without any pre-concentration procedure. This method was tested in the field and the average data capture was over 90%, demonstrating the reliability of the system.     

仪器法测定水环境高锰酸盐指数的应用

提高水环境检测数据质量和检测效率,传统手工容量法检测的弊端日益显现,因此依循环境监测标准设计的自动化检验分析设备,提高环境监测实验室检测水平尤为重要。本文对水质高锰酸盐指数全自动分析仪方法的准确度和精密度进行了测定分析,并与国标容量法的操作过程和数据分析进行对比探讨,仪器法在测定水质高锰酸盐指数中的数据更可靠,效率更高。     

Effect of surfactants on the determination of fluoride in waters

Eleven surfactants representing pure cationic anionic and nonionic detergents, four commercial detergents, sodium pyrophosphate, sodium tripolyphosphate, a soap and nitrilotriacetic acid were investigated for their effect on the spectrophotometric and specific ion electrode determinations of fluoride in water. Cationic, anionic and nonionic detergents at concentrations up to 50, 400 and 1000 mg l⁻¹, respectively, gave 5% error or less in the determination of fluoride. Sodium tripolyphosphate interfered badly above 1.5 mg l⁻¹, and therefore the interference by formulated detergents containing tripolyphosphate was large. The fluoride ion activity electrode method is the most suitable procedure for the determination of fluoride in polluted waters containing surfactants.     

Effect of surfactants on the determination of aluminium in waters

Eleven surfactants representing pure cationic, anionic and nonionic detergents, four commercial detergents, sodium pyrophosphate, sodium tripolyphosphate, a soap and nitrilotriacetic acid (NTA) were investigated for their effect on the determination of aluminium in water using the eriochrome cyanine R, ferron-orthophenanthroline and chrome azurol S methods. Cationic, anionic and nonionic detergents at concentrations up to 2, 100 and 1000 mg l⁻¹, respectively, did not interfere. Sodium tripolyphosphate interfered badly above 1.0 mg l⁻¹, and therefore the interference by formulated detergents containing tripolyphosphate was serious. Concentrations of NTA, soap and sodium pyrophosphate had to be below 0.5, 10 and 20 mg l⁻¹, respectively, to limit the error to 5%.     

Effect of surfactants on the determination of sulphate in waters

The effects of pure cationic, anionic and non-ionic detergents, industrially prepared detergents, sodium tripolyphosphate, sodium pyrophosphate, soap and NTA, in quantities up to 1000 mg l⁻¹, on the analysis of soluble iron in water using the phenanthroline, tripyridine and biquinoline methods were investigated. The tripyridine method is superior to the other two methods for the determination of iron in the presence of up to 1000 mg l⁻¹ of various surfactants but not for up to 100 mg l⁻¹ of non-ionic detergents. The phenanthroline method can be used to determine iron in the presence of up to 1000 mg l⁻¹ of cationic, anionic and non-ionic detergents, but sodium tripolyphosphate interfered above 2 mg l⁻¹. The biquinoline method can be used for the determination of iron in the presence of up to 1000 mg l⁻¹ of cationic, 100 mg l⁻¹ of anionic and 70 mg l⁻¹ of non-ionic detergents, and 50 mg l⁻¹ of sodium tripolyphosphate.     

An ignition method for determination of total phosphorus in lake sediments

A method is described for determination of total phosphorus in lake sediments or biogenic material. The organic matter is destructed by ignition. Material remaining after ignition is boiled in 1 N HCl and orthophosphate determined after dilution. The method generally gave lower results than the perchloric acid digestion method (97·7, 98·7, 94·4, 100·5 and 97·3%) for four sediment samples and one sample of dried leaves. The reproducibility of the ignition method was slightly less than that observed with the perchloric acid method. Recovery after addition of known amounts of hydroxylapatite to the sediment samples was 98·5–102·6%.     

变水头法测定渗透系数试验方法分析及探讨

指出渗透系数是土的一项重要的力学指标,通过介绍变水头法测定粉土及黏性土渗透系数的方法,分析了影响变水头法测定土渗透系数的因素,为提高变水头试验测定渗透系数的成功率及准确性提供了依据。