Recipient Stream Research Articles

Comparison of a Piezoelectric Impedance Sensor-Based Flow-Injection System and a N,N,N,N-Tetrakis-2-hydroxylethyl Ethylenediamine-Coated Quartz Crystal Microbalance for Determination of CO2 in Wine and Beer.

A novel FIA system for CO2 was constructed and compared with a N,N,N’,N’-tetrakis-2-hydroxylethyl ethylenediamine(THEED)-coated quartz crystal microbalance (QCM) for the determination of CO2 in wine and beer samples. This FIA method is based on the use of a gas-permeable membrane to separate CO2 from a carrier stream of 0.5 mol/l phosphate buffer (pH 6.0) into a recipient stream of 10 mmol/l tris(hydroxymethylamino)methane (Tris) containing 1.0 mmol/l KCl and a piezoelectric impedance sensor to follow the conductance change occurring in the acceptor solution. Although the results for real samples obtained by the FIA, the QCM and the conventional titrimetric methods, respectively, agree well with each other, the FIA method offers the best precision. The FIA method is also characterized by its high throughput, promising sensitivity, excellent selectivity, low cost and easy manipulation, etc. The influence of some experimental parameters on the FIA’s performance is discussed in detail.

Determination of iron(III) in pharmaceutical samples using dialysis in a sequential injection analysis system

The use of membranes for on-line separations in flow-through dialysers as part of flow systems is extremely useful for automated sample preparation. Iron(III) was separated from a sample matrix by dialysis in a sequential injection system. The dialysed iron was complexed with tiron and the resulting complex was monitored spectrophotometrically at 667 nm. The influence of various parameters, including pump speed for both the donor and recipient streams, sample volume, reagent volume, dialysis time and the effect of multiple flow reversals, on dialysis efficiency was studied. The system proved to be feasible for the determination of iron in pharmaceutical samples which are usually turbid and contain undissolved organic particles. The system is fully computerised and is able to monitor iron(III) in samples at a frequency of 8 samples per hour with a relative standard deviation (RSD) of <1.50% in the linear calibration range (100–1000 mg l −1). The 3 σ detection limit is 45.0 mg l −1. Although the sample frequency of the proposed sequential injection system is much lower than that of conventional flow injection systems, the volume of sample used is much smaller and the consumption of reagents is much lower, which is more cost effective. Using the feature of multiple flow reversals, the percentage dialysis can be improved to up to 4.5%, which compares well with the 4% obtained with conventional flow injection analysis.

Study of mass transfer in on-line analytical parallel-plate dialysers in series in flow injection systems

Mass transfer of an analyte in passive dialysis was studied for two single membrane on-line dialysers in a tandem mode in series as well as a double membrane on-line dialyser in a flow injection system. The establishment of a suitable concentration gradient between the different channels was an important factor in mass transfer efficiency. A fast linear increase in copper(II) concentration occurred for the first 200 min in the first recipient streams of both dialysis systems due to the relatively large concentration gradient during this period whereafter the increase tended to slow down. The second recipient streams of both systems showed a very slow gradual increase in copper(II) concentration for the first 20 min, whereafter the increase speeded up owing to the development of a suitable concentration gradient. Comparison of concentration differences between the first recipient as well as the second recipient streams of the two different dialysis-flow injection systems revealed a faster increase in dialysis rate and mass transfer efficiency initially for a certain period for the single membrane on-line dialysers in series than for the double membrane on-line dialyser. They subsequently became equal whereafter the situation was reversed. It became evident that passive dialysis in flow injection systems is suitable for controllable dilution on-line.

The determination of sugars in beverages and medicines using on-line dialysis for sample preparation

A method is described for the analysis of sugars in beverages and medicines using on-line dialysis for sample preparation. The design, construction and method development for the on-line dialysis is described. The dialysis is carried out using a novel polypropylene membrane treated for wettability (Celgard 3401) which is mechanically strong and solvent resistant when compared to traditional cellulose acetate membranes. Counter-current dialysis was used at a flow rate of 0.8 ml min −1, with a recipient stream of water and the dialysate was then analysed by high-performance liquid chromatography. Fructose, glucose, lactose, maltose and sucrose were determined in a range of samples. The % RSD of the method was shown to be below 5% and the recoveries above 90% for all samples.

Flow‐through pH‐ISFET as detector in automated determinations

AbstractThe implementation of a pH‐ISFET (ion‐selective field effect transistor) planar chip in a flow‐injection system by means of a specially designed flow cell and the application of the sensor to the analysis of volatile compounds is described. Ammonia and sulfur dioxide are determined by exploiting the advantages of the flow techniques combined with continuous gas diffusion. Initial species are converted to gaseous compounds, which diffuse through a microporous hydrophobic membrane into an ammonium chloride or hydrogen sulfite recipient stream, producing a pH variation that is monitored by the semiconductor detector. The linear working range extends from 1 × 10−2 to 1 × 10−4 M for the ammonium system and from 4 × 10−3 to 7 × 10−5 for the sulfur dioxide system, with relative standard deviation of about 1 and 0.5%, respectively.

Electrophoretic comparison of the reproductive success of naturally spawning transplanted and wild steelhead trout through the returning adult stage

A previous electrophoretic assessment of the natural reproductive success of sympatric transplanted hatchery and wild summer-run steelhead trout Oncorhynchus mykiss (formerly Salmo gairdneri) populations was extended to include returns to the adult life history stage. The mean percentage of offspring from naturally spawning hatchery steelhead decreased at successive life history stages from a potential of 85–87% at the egg stage to 42% at the adult stage. In addition, reproductive success of naturally spawning hatchery steelhead compared to wild steelhead decreased from 0.750–0.788 at the subyearling stage to 0.108–0.129 at the adult stage. In freshwater, the period of greatest differential mortality for offspring of hatchery and wild steelhead occurred from the subyearling to smolt stage, suggesting that influences such as predation and competition affected survival of hatchery offspring to a greater extent than did environmental and ecological effects directly associated with differences in parental spawning time. Differential mortality of hatchery offspring also occurred during the smolt to adult phase, and was of a magnitude similar to that for the egg to subyearling phase. Poorer survival for naturally produced offspring of hatchery fish could have been due to long-term artificial and domestication selection in the hatchery population, as well as maladaptation of the transplanted hatchery stock in the recipient stream.

Flow-through pH-ISFET as detector in the determination of ammonia

A simple flow-injection metod for the determination of ammonium ions in water, based on a flow-through pH-ISFET, is described. Ammonium is converted to ammonia, which diffuses through a microporous hydrophic membrane into an ammonium chloride recipient stream, forming a pH buffer which is monitored by the semiconductor detector. The linear working range extends from 0.1 to 10 mmol l−1 with a relative standard deviation of ca. 1% at the 0.7 mmol l−1 level.

Investigation of a Chemiluminescent System for the Determination of Ammonia by Flow-Injection Analysis

Abstract A novel system for the determination of ammonia based on the chemiluminescent reaction between hypochlorite and luminol is presented. The technique of flow injection analysis was employed to automate the system. Ammonia reacts with hypochlorite to form monochloramine in basic solution which decreases the observed chemiluminescence intensity. Several interferents are identified, and the reasons why they interfere are discussed. The effects of interferents are Minimized through the use of a double-tube dialyzer where the ammonia is diffused across the dialyzer membrane into a recipient stream of hydrochloric acid.

Effect of membrane potential on dialysis of calcium in a continuous flow system

It has been found that the estimation of calcium by continuous flow analysis using a 12 inch dialyser leads to discrepant results if acidified aqueous calcium standards are used as the means of primary calibration. We have examined the effects of hydrogen ion concentration on the dialysis of 45 Ca and compared the rates of dialysis with dialyser membrane potentials. The amount of calcium dialysed increased from 5% to 12% when the concentration of acid was increased on the recipient stream of the dialyser. This corresponded to a change in potential of 0 mV to + 24 mV of the donor stream with respect to the recipient stream. Further experiments including protein on either side of the dialyser show that the Donnan effect does not explain the differences in rate of dialysis between protein and aqueous samples and that the migration of H + does explain most of these differences.

Electrical potentials generated in continuous flow dialyzers during autoanalysis

An electrical potential develops across the membrane when the moving streams in a continuous flow dialyzer module are electrolytes of different composition. The steady-state value for a pair of solutions and flow rates is little affected by introducing air bubbles into the flowing streams. The potential largely depends on the relative mobilities of the ions through the membrane, and these can be often qualitatively assessed from mobilities in water. In automated analysis of ionic metabolites, electrolyte composition of diluent and recipient stream reagents has an effect on sensitivity which can be predicted from these electrical potentials.

Use of Co-Current Dialysis in an Improved Estimation of Free Thyroxine in Serum

Abstract A new method is described for measuring free thyroxine in serum, in which co-current dialysis is used to simplify and speed the determination. The patient's serum is mixed with 125I-labeled thyroxine and buffer (28 ml of serum per deciliter) and co-currently dialyzed for 15 min against a mixture of pooled serum (8 ml/dl) in buffer. After dialysis, the free thyroxine of the patient's serum, which is now bound to the protein of the recipient stream (pooled serum), is precipitated with trichloroacetic acid. The radioactivity of this precipitate and of an undialyzed serum aliquot is measured, to obtain the total count. Use of pooled serum and trichloroacetic acid eliminates the need for the amounts of carrier thyroxine required in most other methods. The procedure is both simple and rapid (3 to 4 samples/unit/h). The values for free thyroxine correlate well with those obtained by the method of Lee and Pileggi [Clin. Chem. 17, 166 (1971)] and by others participating in the proficiency program of the College of American Pathologists.

A Generalized Approach to Content Uniformity Assays

In anticipation of the Content Uniformity requirements for USP XVIII and NF XIII, we developed a general procedure for the assay of intact capsules containing a variety of drugs. Using this procedure, whole capsules are dissolved in an appropriate aqueous medium and the drug dialyzed into a suitable recipient stream. The dialyzate is diluted if necessary, and then pumped to a spectrophotometer for final reading and assay. The use of this technique completely eliminates the need for opening capsules and making quantitative transfers of the drug contents.This technique was so successful that it was extended to tablets containing both water-soluble and water-insoluble drugs. Water-insoluble drugs such as steroids are handled by conducting the dialysis from aqueous alcoholic solutions. Excellent results have been obtained using this technique on chemically dissimilar compounds; examples of these assays will be given.

Comparison of the Stannous Chloride and Vanadate Methods for Estimation of Serum Inorganic Phosphorus by Use of the "SMA 12/60"

Abstract We compared results of the stannous chloride and vanadate methods for estimating serum inorganic phosphorus on the "SMA 12/60" (Technicon). The technically simpler vanadate method gave better linearity and reproducibility, with virtually no carry-over or baseline drift; the reagents were stable, and it was most important to ensure that the concentration of sulfuric acid in the recipient and sample streams was identical. Instability in the stannous chloride method was due to precipitation in the stannous chloride-hydrazine working solution.

Automated Serum Calcium Analyses Corrected for Dialysis Effects

Serum calcium assays by conventional continuous flow methods use aqueous standards. Less calcium diffuses across the dialyzer from aqueous standards than from the serum samples, producing falsely elevated serum values, especially when a miniature manifold and dialyzer are employed. The difference between the rates of dialysis of calcium in serum and in water has been attributed to the Donnan effect of polycationic protein at an acid pH. The differences in electrical potential across the dialyzer membrane were measured directly. Serum produced a negative difference in potential, the opposite of that required by the Donnan effect. Therefore, other factors, such as osmotic pressure, must be considered. For the continuous flow cresolphthalein complexone (CPC) method, the dialysis error can be corrected by 8% polyvinylpyrrolidone in the calcium standards, and an HC1 concentration of 0.3 N in the diluent stream and 1 N in the recipient stream. Ethylene diamine-tetraacetate (EDTA) in the base reagent subtracts a constant amount of calcium (about 3 mg. per dl.) from all the samples, allows the recorder scale to be expanded, and reduces sample carryover. A revised miniature manifold, used with a one-piece Gilford debubbler flow cell and a linear absorbance spectrophotometer, allows analysis of 100 samples per hour. Peak heights are directly proportional to concentration, thereby eliminating logarithmic conversion.

Results for Three Generations from Transfers of Pink Salmon (Oncorhynchus gorbuscha) Spawn to the Qualicum River in 1963 and 1964

Transfers of pink salmon (Oncorhynchus gorbuscha) eggs were made to the Qualicum River in two years, utilizing 5.79 million eggs from Cheakamus River stock in 1963 and 6.85 million eggs from Bear River stock in 1964. Adult returns to the Qualicum River were 100 spawners in 1965, 1967, and 1969; 11,940 in 1966; 3000 in 1968; and 300 in 1970. Differences between the odd- and even-year plants were noted in times of egg-take (equivalent to time of spawning of donor stock), incubation, and fry emigration, lengths of emigrating fry, possibility of losses through predation by herring on estuarine fry, and direction of orientation to the recipient (Qualicum River) stream. Pronounced differences between donor stock in rate of return are thought to be primarily related to differences in spawning times and stream temperature. The decrease in numbers of adults in the even-year generation may have been due to lower freshwater survival during incubation as a result of suspected superimposition of chum salmon on the earlier deposited pink salmon eggs; the loss was estimated to be in the order of 46%.

Automated determination of serum iron.

A modification of the automated method of Zak Epstein for determination of serum iron is described. The main improvements of the system are: 1. Better wash between the samples by means of citrate solution instead of water. 2. A more efficient dialysis achieved by complexing the dialyzed ferrous ion in the recipient stream, enabling the use of single dialysis instead of the original double dialysis.As a consequence of these improvements the flow line has been shortened, thus decreasing the possibility of cross-contamination and allowing an analysis rate of 30 per hour instead of 20 per hour. Furthermore, the sensitivity has been increased so that the necessary sample volume can be reduced from 2 ml to 0.8 ml and still yield higher readings than in the original method.The data for precision, accuracy and reliability, as well as the results from the recovery tests, are presented and discussed.