Concepts of air Segmented Flow Analysis (SFA) and Flow Injection Analysis (FIA) are discussed and compared with the performance of a new method based on comprehensive flow programming. The ...programmable Flow Injection (pFI), miniaturized on the lab-on-valve platform, can perform tasks that can not be done in any other way, such as Auto calibration by a single standard solution or analysis in a flow-batch mode that exactly simulates the traditional manual batch technique. Performance of pFI is documented by examples of nutrient determinations in sea water.
The commercial Hexin Single particle aerosol mass spectrometer (SPAMS) has been widely used for environmental aerosol monitoring and source apportionment. However, particle size measurement is easily ...affected by environment pressure fluctuation and sampling orifice clogging. The capability for quantitative analysis is poor, and few isotope measurement has been reported. This paper aims to evaluate the analytical performance of SPAMS and extend its application. First, the flight time of standard particles having different densities and sizes was measured under various conditions (aerodynamic lens upstream pressure and carrier gas). We proposed a universal method for particle size calibration, measurement and correction, taking into account the effects of lens geometry (acceleration nozzle diameter), particle parameters (density, diameter, and shape factor), and operating conditions (lens upstream pressure and carrier gas). Then, isotope measurement was performed when introducing a solution droplet containing a single element. Metal oxide and metal cluster ions were observed in the mass spectrum, indicating incomplete ionization of the sample droplet. The mass discrimination effect was carefully evaluated to correct the measured isotope ratio. Results show that the achievable accuracy of the corrected isotope ratio for elements investigated was 5%. The instrumental performance was relatively poor for elements having great ionization potential or bond energy. Finally, Ag/Eu2O3 suspension and yellow cake/ethanol suspension were analyzed for size, elemental and isotopic analysis. We confirmed that the mass discrimination effect during suspension introduction could be corrected using the mass discrimination correction factor obtained during solution introduction. The Ag, Eu and U in these suspension particles were all found to be at natural abundance. The uranium in the yellow cake was identified as sodium duranyate (Na2U2O7) with volumetric equivalent diameter of approximately 65 nm. The work presented here is beneficial for instrument improvement and wide application.
•Analytical performance of a widely-used commercial Single Particle Aerosol Mass Spectrometer for accurate sizing and isotopic analysis of individual particles is evaluated.•A universal method was proposed and verified for particle size calibration, measurement and correction, taking into account the effects of lens geometry, particle parameters and operating conditions.•After mass discrimination correction, the accuracy of the isotope ratio for elements in individual droplets was better than 5%, which is beneficial for source identification of particulate matter.•Ag/Eu2O3 suspension and yellow cake/ethanol suspension were identified to be at natural abundance, while the uranium in the yellow cake was identified as nanosized sodium duranyate (Na2U2O7).
► First worldwide interlaboratory study on organophosphorus flame retardants (PFRs). ► Blank contamination is the biggest challenge in the analysis of PFRs. ► Variations acceptable for standard ...solutions, but not under control for real samples. ► CVs were 7–48% for dust, 13–68% for fish oil, and 15–96% for sediment (except TiBP). ► Recommendations and precautions aim to provide better analytical performance.
The first worldwide interlaboratory study on organophosphorus flame retardants (PFRs) was organized to improve the quality of the data reported in the literature. The study involved standard solutions, dust, fish oil and sediment samples.
The differences in coefficients of variation (CV) between the samples were related more to PFR concentration (with high blanks being reported by some laboratories) and less to matrix type. Not all participating laboratories suffered from blank problems, which indicated that it was possible to control the blanks.
We include recommendations on how to improve analytical performance, especially to reduce contamination of blanks.
In this work, monitoring the effect of packaging type and storage temperature on the short term stability of calibration standard solution KCl 1 M were conducted. The KCl 1M were packaged in two ...types of packaging i.e., high-density polyethylene (HDPE) and glass bottle. The effects of packaging type and storage temperature were monitored for four weeks at 25 °C and 40 °C. The conductivity values of KCl 1 M in the HDPE and glass bottle were 111.61 mS/cm and 111.62 mS/cm, respectively. The results indicated that the KCl 1M solution at 25 °C in both HDPE and glass bottle were found to be good in short term stability and there was no significant different between the two packaging types. At temperature of 40 °C, however, short term stability of the KCl 1 M in a glass bottle was better than the HDPE bottle.
ABSTRACT
Taste is an essential factor for evaluating the quality of agricultural products. However, it is usually difficult to compare data acquired at different times or by different people because ...there is no invariant reference and because the evaluation methods are largely subjective. Here, we addressed these problems by developing a method for standardizing strawberry sourness and sweetness intensities using a taste sensor approach with a taste standard solution composed of sour and sweet compounds. This standard solution allows highly efficient sensor measurements because it contains the standard compounds citric acid and sucrose. In addition, we found that polyphenol destabilized the sensor response for strawberry sweetness, and its removal from the sample by appropriate treatment with polyvinylpolypyrrolidone allowed stable evaluation of the sweetness intensity. The taste sensor data obtained using this method were in good agreement with the chemical analysis values related to human sensory evaluation.
Graphical Abstract
Graphical Abstract
Standard solution prepared using pure chemicals is reproducible, and thus, all taste intensity values calibrated based on the standard can be compared with each other.
In this study, the authors are concerned with the long‐standing mixed H2/H∞ problem for discrete linear systems. The main contribution is to derive the standard solution of the mixed H2/H∞ problem by ...a regular Riccati equation. Firstly, in H∞‐optimisation procedure, the optimal strategy (u,w) is explicitly given where the H∞‐norm is maximised by w and H2‐norm is minimised by u at the same time. It is noted that there exists an arbitrary item in the optimal strategy for the positive semi‐definite weighting matrices. Secondly, the H2‐optimisation problem is explicitly solved with respect to the arbitrary item. Finally, the standard solution of the mixed H2/H∞ problem is explicitly given in terms of regular Riccati equations by combining the optimal strategy (u,w) in H∞ optimisation procedure and the optimal solution of H2 optimisation procedure. Examples are presented to show the effectiveness of the proposed approach.
Analyses of chlorate ion are essential in evaluating water quality; however, there is no standard solution of chlorate ion characterized by a metrologically valid procedure. This paper describes the ...measurement procedures and assays of chlorate ions with the linkage to the International System of Units (SI) by multipath gravimetric titration techniques. Three different titration techniques were employed to assay chlorate ions: oxidimetric-reductometric back titration with an iron(II) solution standardized with standard potassium dichromate, precipitation titration with a silver nitrate solution standardized with standard sodium chloride, and oxidimetric-reductometric titration with a thiosulfate solution standardized with standard potassium iodate. The results obtained through three different reactions were in good agreement with each other within their uncertainties. A certified reference material of chlorate ions with the linkage to the SI was first established by evaluating the storage stability of the solution and estimating measurement uncertainties. The assay (mass fraction) of sodium chlorate was characterized by using a weighted mean of the results of three methods; 99.829% ± 0.029% (the value following ± gives a level of confidence of approximately 95%, coverage factor k = 2). Providing with the standard solution through Japan Calibration Service System (JCSS) under Japanese Measurement Act widely allows all analysts to obtain their reliable analytical results.
•Instrumental analyses require a standard solution of chlorate to quantify in controlling water quality.•Certified reference material of chlorate ions was first established with the linkage to the SI units on an absolute basis.•Multipath titration techniques based on different reactions were performed to assay the concentration.•High accuracy of each titration reaction was newly ascertained.•This new certified reference material of chlorate ions enables analysts to obtain reliable results throughout the world.
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