Evaluation of adsorbents for volatile methyl siloxanes sampling based on the determination of their breakthrough volume

Talanta ◽  
2013 ◽  
Vol 115 ◽  
pp. 881-886 ◽  
Author(s):  
L. Lamaa ◽  
C. Ferronato ◽  
L. Fine ◽  
F. Jaber ◽  
J.M Chovelon
Keyword(s):  
2019 ◽  
Vol 63 (7) ◽  
pp. 797-805
Author(s):  
Ehsan Partovi ◽  
Abdulrahman Bahrami ◽  
Abbas AfKhami ◽  
Farshid Ghorbani Shahna ◽  
Farhad Ghamari ◽  
...  

Abstract This research develops a rapid method for sampling and analysis of maleic anhydride (MA) in air using a one-step hollow fiber (HF) membrane in the liquid phase followed by high-performance liquid chromatography. A sampling chamber was prepared for sampling of MA with HF-supported de-ionized water absorbency. Several important parameters, such as sampling flow rate, sampling time, and breakthrough volume (BTV), were optimized at different concentrations using a central composite design. The results showed that sampling could be performed at the maximum period of 4 h with a flow rate of 1 mL min–1 for different concentrations (in the range of 0.05–2 mg m–3). The BTV was 240 mL. The relative standard deviations for the repeatability of interday and intraday were 7–10%, 10%, respectively, and the pooled standard deviation was 0.088. The limit of detection and limit of quantitation values were 0.033 and 0.060 mg m–3, respectively. Moreover, our findings revealed that the samples could be stored in sealed HF flexible plastic tubes in a cover at refrigerator temperature (4°C) for up to 7 days. The HF method was compared with method number 3512 National Institute Occupational Safety and Health for determination of MA. There was a good correlation (R2 = 0.99) between the two methods at a concentration of 0.05 to 2 mg m–3 in the laboratory and the average concentration of MA for both methods was 0.11 mg m–3 in the ambient air at an adhesive manufacturer. Our findings indicated that the proposed HF can act as a reliable, rapid, and effective approach for sampling of MA in workplaces.


2003 ◽  
Vol 86 (1) ◽  
pp. 39-43 ◽  
Author(s):  
John D Donaldson ◽  
Susan M Grimes ◽  
Lina Mehta ◽  
Ahmad J Jafari

Abstract A fast and accurate analytical method, which uses commercially available adsorbents (Tenax TA, Carbotrap B and C, and Carbosieve S-III), was developed for the sampling and determination of aromatic hydrocarbons, chloroaromatic compounds, and 2,3,7,8-tetrachlorodibenzo-p-dioxin. The breakthrough volume data show that Carbotrap C has a good capacity for compounds of high molecular weight, whereas Carbosieve S-III and Tenax TA are efficient for volatile compounds. The organic components are thermally desorbed and transferred to a gas chromatograph/mass spectrometer. Importantly, thermal desorption avoids conventional solvent extraction procedures and also allows reuse of adsorbent tubes. Preliminary results for recovery of analytes from tubes packed with single adsorbent prove that a single-adsorbent bed is not capable of sampling a wide range of compounds. The best method to obtain the desired collection and desorption properties is to use adsorbent tubes containing several different materials. The results of optimization studies are summarized.


2008 ◽  
Vol 91 (6) ◽  
pp. 1430-1434 ◽  
Author(s):  
Daryoush Afzali ◽  
Ali Mostafavi

Abstract The application of organo nanoclay 1-(2-pyridylazo)-2-naphthol (PAN)-immobilized as a new, easily prepared, and stable solid sorbent for preconcentration of trace amounts of Cu2, Ni2, and Mn2 ions in aqueous solution is presented. The organo nanoclay was prepared by adding tetradecyldimethylbenzylammonium chloride onto montmorillonite and then saturating with PAN. A simple, rapid, selective, sensitive, and economical method was developed for the simultaneous separation of trace amounts of copper, nickel, and manganese in aqueous medium using PAN as an analytical reagent. The sorption was quantitative in the pH range of 69.5, and quantitative desorption occurred instantaneously with 5.0 mL 3 M HNO3. Linearity was maintained at 0.2637 ng/mL for copper, 152 ng/mL for nickel, and 0.221 ng/mL for manganese in the original solution. The detection limits were 0.04 ng/mL for Cu(II), 0.15 ng/mL for Ni(II), and 0.03 ng/mL for Mn(II) in the original solution (2bl; standard deviation and bl blank). Various parameters, such as the effect of pH, breakthrough volume, and interference of a large number of anions and cations, have been studied, and the proposed method was used to determine these metal ions in water and standard samples. Determination of these metal ions in standard samples showed that the proposed method has good accuracy.


2001 ◽  
Vol 84 (3) ◽  
pp. 713-718 ◽  
Author(s):  
Yadollah Yamini ◽  
Nayyereh Amiri

Abstract A simple and reliable method is presented for the rapid extraction, separation, preconcentration, and determination of iron as its bathophenanthroline complex by the use of octadecylsilica membrane disks and spectrophotometry. We evaluted extraction efficiency, the influence of sample matrix, type and optimum amount of extractant, flow rates of sample solution and eluent, pH, amounts of bathophenanthroline and hydroxylamine hydrochloride, breakthrough volume, and limit of detection. We also studied the effects of various cationic interferences on percent recovery of iron. Complete elution of the complex from disks was obtained with a minimal amount of solvent. The limit of detection of the proposed method is 0.080 ppb. The method was applied to the recovery and determination of iron in natural waters.


2012 ◽  
Vol 95 (4) ◽  
pp. 1125-1130
Author(s):  
Manjusha Karve ◽  
Durgesh Pandey

Abstract A simple and rapid method using an octadecyl-bonded silica membrane disk impregnated with Cyanex302 is described for the pre-concentration and determination of iron. The influence of various parameters on sorption and elution of Fe(III) were systematically investigated. The sorption of Fe(III) at pH 3.2 was quantitative (99.3 ± 1.1%). It was completely recovered using 20 mL 5.0 M HCl and determined by flame atomic absorption spectrometry. Breakthrough volume of the modified disk for Fe(III) was >2000 mL, pre-concentration factor was >100, and reusability up to 28 cycles. The LOD and LOQ for Fe(III) were 0.45 μg/L and 1.51 μg/L, respectively, while precision for its determination in terms of RSD was ≤ 2.1%. This method was applied for Fe(III) determination in milk, fortified flour, cocoa powder, tea, and black pepper. To validate the procedure, EPA Method Standard (QC standard 21) was analyzed for Fe(III).


2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Mahmood Payehghadr ◽  
Sousan Esmaeilpour ◽  
Mohammad Kazem Rofouei ◽  
Laleh Adlnasab

Silica-C18 bonded disk modified by a four-dentate Schiff base has been used for preconcentration of cadmium in table salt samples followed by flame atomic absorption spectrometry. The method is based on the adsorption of Cd on 1,2-bis(pyridin-2-ylmethylene) hydrazine as Schiff base ligand on silica-C18 disk. The effects of several factors such as type and concentration of the eluent, pH of sample solution, amount of ligand, and breakthrough volume have been optimized based on one variable at a time. In optimum conditions (type of eluent, HNO31.0 mol/L; volume of eluent, 5.0 mL; solution pH, 9.0; breakthrough volume, 1000.0 mL), preconcentration factor of the present method is about 200. The resultant limit of detection is 5.0 μg/L. Finally, the performance of the method has been evaluated for extraction and determination of Cd (II) in salt samples at milligram per liter concentration, and satisfactory results have been obtained (RSD ≤ 2.0%).


1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.


1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.


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