Translation Series No. 4511

Transcription

1 FISHERIES AND MARINE SERVICE Translation Series No The use of high-pressure liquid chromatography in inorganic analysis. III. Determination of selenium in drinking-, surface- and waste water by G. Sèhwedti and A. Schwarz Original title: Zur Anwendung der Hochdruck-Flussigkeits-Chromatographie in der anorganischen Analyse III. Bestimmung von Selen in Tripk-, Oberflachen- und Abwasser. From: J. Chromatogn160: , 1978 Translated by the Translation Bureau (KMF) Multilingual Services Division Department of the Secretary of Stete of Canada Department of the Environment Fisheries and Marine Service Maritimes Regional Library Halifax, N.S. 8 pages typescript

2 . -, i 1' S-11 DEPARTMENT OF THE SECRETARY OF STATE TRANSLATION BUREAU, SECRÉTARIAT D'ÉTAT BUREAU DES TRADUCTIONS MULTILIMGUAL SERVICES DIVISION CANADA DIVISION DES SERVICES MULTILINGUES TRANSLATED FROM - TRADUCTION DE German AUTHOR - AUTEUR G. Schwedt and A. Schwarz INTO - EN English TITRE ANGLAIS The use of high-pressure liquid chromatography in inorganic analysis. III. Determination of selenium in drinking-, surface- and waste water. TITLE IN FOREIGN LANGUAGE (TRANSLITERATE FOREIGN CHARACTERS) TITRE EN LANGUE ÉTRANGÉRE (TRANSCRIRE EN CARACTÈRES ROMAINS) Zur Anwendung der Hochdruck-Fliissigkeits-Chromatographie in der anorganischen Analyse III. Bestiinmung von Selen in Trink-, Oberflâchen- und Abwasser. REFERENCE IN FOREIGN LANGUAGE (NAME OF BOOK OR PUBLICATION) IN FULL. TRANSLITERATE,FOREIGN CHARACTERS. RÉFÉRENCE EN LANGUE ÉTRANGÉRE (NOM DU LIVRE OU PUBLICATION),,AU COMPLET, TRANSCRIRE EN CARACTÈRES ROMAINS. Journal of Chromatography REFERENCE IN ENGLISH - RÉFÉRENCE EN ANGLAIS Journal of Chromatography PUBLISHER - ÉDITEUR Elsevier Scientific Publishing Company PLACE OF PUBLICATION LIEU DE PUBLICATION Amsterdam (The Netherlands) YEAR ANNÉE 1978 DATE OF PUBLICATION DATE DE PUBLICATION VOLUME 160 ISSUE NO. NUMÉRO PAGE NUMBERS IN ORIGINAL NUMÉROS DES PAGES DANS L'ORIGINAL NUMBER OF TYPED PAGES NOMBRE DE PAGES DACTYLOGRAPHIÉES 8 REQUESTING DEPARTMENT TRANSLATION BUREAU NO. DFO NOTRE DOSSIER N BRANCH OR DIVISION DIRECTION OU DIVISION Fisheries/Sc. Info. & Pub. Br. TRANSLATOR (INITIALS) TRADUCTEUR (INITIALES) KEF PERSON REQUESTING DEMANDÉ PAR G.R. Sirota YOUR NUMBER VOTRE DOSSIER N 0 DATE OF REQUEST DATE DE LA DEMANDE April 30, 1979 MAY t) N LAT!Orq TR ADU Cfl N NON IniorrnMiz)n :41ty SOS (REV. 2/68)

3 I I+ r,..1cretary of State Secrétariat d'état MULTILINGUAL SERVICES DIVISION - DIVISION DES SERVICES MULTILINGUES TRANSLATION BUREAU BUREAU DES TRADUCTIONS Client's No. No du client Department Ministère Division/Branch Division/Direction City Ville DFO Fisheries/Sc. Info. & Pub.Br. Halifax Bureau No. No du bureau Language Langue Translator (Initials) Traducteur (Initiales) FAA Y German Me mal,- (.' Journal of Chromatography 160 (1978) pp The use of high-pressure liquid chromatography in inorganic analysis. III. Determination of selenium in drinking-, surface- and waste water G. Schwedt and A. Schwarz (University of Siegen, Department 8 - Analytical Chemistry, Adolf-Reichwein Str. 2, D-5900 Siegen 21 Federal Republic of Germany) Submitted June 14, 1978 Piazine selenate compounds and selenium diethyldithiocarbamate (309) have proven suitable for the high-pressure liquid chromatographic analysis (HPLC) of selenium with reversed-phase column materials 1-3. In the following we report on the applicability of these methods for the determination of selenium in drinking-, surface- and waste water. Instruments for HPLC Experimental part HPLC pump type (Knauer, Oberursel/Taunus, Federal Republic of Germany), Rheodyne 6-way universal valve with 50 mm3 UNFMTI:r.) For Inf,,rmation only TRADUCTPC:IN NON REVE Information seulernen-? SEC 5-25 (Rev. 6/78)

4 2 sample loop (Knauer), spectrophotometer type (Knauer): singlebeam instrument with grid monochromator (8 mm 3 flow-through cell, 10 mm sample thickness), ready-to-use column (Knauer) of alloy steel, packed with LiChrosorb RP-8 (grain size 10 m), 250 x 4.6 mm inside diameter. Chemicals 4-chloro-1,2-diaminobenzene tech. grade (Fluka, Buchs, Switzerland); 1,2-phenylenediamine, reagent grade (Merck-Schuchardt, Munich, FRG); sodiumdiethyldithiocarbamate (trihydrate) analytical grade (Merck, Darmstadt, FRG); selenium dioxide analytical grade (Merck); Titriplex III analytical grade (Merck); 98% formic acid analytical grade (Merck). Solutions Selenium stock solution: mg selenium dioxide is dissolved in 100 ml twice dist. water (= 1 mg Se/ml); 4-chloro-1,2- phenylenediamine solution: 0.1% in 0.1 N hydrochloric acid (dissolve while heating, filter hot); EDTA solution: 0.1 M Titriplex III; citrate buffer ph 2.5 : 0.1 M. Analytical method (310) After filtering of the water sample (drinking-, surface- or waste water) 100 ml each is purified by 5 minutes shaking with 30 ml chloroform each. After the addition of 10 ml citrate buffer, 2 ml 98% formic acid and 5 ml EDTA solution, the aqueous phase is reacted with 4 ml freshly prepared 4-chloro-1,2-phenylenediamine solution for

5 3 10 minutes in a sealed Erlenmeyer flask in a waterbath of 40 C. After cooling we extracted twice for 1 minute each with 10 ml chloroform, filtered the organic phase through a folded filter into a 10-ml pearshaped flask and removed the filtrate under reduced pressure at room temperature. The residue is dissolved in 1 ml methanol for chromatographic analysis. High-pressure liquid chromatographic analysis Column: c.f. instruments for HPLC; mobile phase: methanolwater (80:20); volume: 50 mm3 ; flow rate: 1.5 cm3 /min-1 ; pressure: 75 bar; sample detector: c.f. instruments for HPLC; detector sensitivity: E = 1/32; uncorrected wavelength adjustment: 320 nm. Results and Discussion Piazine selenates The temperature dependence of the reaction of selenic acid with the diamines 1,2-phenylenediamine and 4-chloro-diaminobenzene as well as the enrichment of the formed piazine selenates were examined and optimized. Increasing the reaction temperature to 40 C permitted a reduction of the reaction time from 90 to 10 minutes in both cases. If the sample volume of 14 ml (c.f. analytical method in Ref. 1) is increased to 100 ml enrichment by a factor of 3.5 can be achieved. However, compared to a volume of 14 ml the recovery rate drops to approx. 50%). Under these extraction and reaction conditions the limits of detection for selenium were determined, with 1/20 of the total amount of extracted piazine selenate reaching the HPLC column (Table I).

6 4 Analytical method Detection limit Method in mg/1 (ppb) ng in column/ml chloroform Photometric determination as piazine selenate HPLC determination as piazine selenate HPLC determination as 5-chloropiazine selenate HPLC determination as carbamate 5.3 x 10-3 (5.3) x 10-4 (0.68) x 10-4 (0.32) x 10-3 (5.0) 25 Table I Detection limits of various methods of selenium determination In 1974 Wheeler and Lott 3 reported on the determination of selenium after reaction with 2,3-diaminonaphthalin with the aid of HPLC. The detection range was stated as ppb for the detection with a UV photometer or a fluorimeter after reversed-phase or partition chromatography with carbowa as the stationary phase. The method with chloro-piazine selenate described here affords a detection (311) limit of 0.32 ppb (corresponding to 1.6 ng in the HPLC column) for measurements in the near UV range (340 nm). Selenium carbamate In previous examinationsl) we obtained for the determination of selenium as diethyldithiocarbamate the highest measuring sensitivity at 30 pg for 1% stylus deflection at a.u.f.s.* despite two * Translator's note: unable to locate a.u.f.s.

7 5 signals in the reversed-phase HPLC (filter photometer: 254 nm). This sensitivity could not be achieved with the spectrophotometer used by us (c.f. experimental part): it lay at 0.56 ng and a.u.f.s. 4 ). For a more detailed examination of the reaction of selenic acid with sodium diethyldithiocarbamate the two reaction products indicated in the chromatogram were collected in separate fractions and examined for selenium after reaction with concentrated nitric acid. Approximately 78% of the total selenium was determined in the first fraction. Even with thin-layer chromatography on silica gel with benzene as the solvent, two spots were detected after reaction of selenium to carbamate (RF values: 0.24 and 0.56); these probably correspond to the different valencies of selenium (II and IV). In the further course of the examinations it also became apparent that the signal ratio is not constant. Depending on the time of sample injection measured from the dissolving of the residue of the chloroform extraction, the second signal increases with respect to the first although the sum of the areas under both signals remains approximately constant. In order to obtain reproducible results the samples must therefore be injected immediately after dissolving the residue. In contract to the piazine selenates, enrichment of the selenium carbamate from solution by increasing the sample from 5 to 100 ml aqueous phase causes only a 10% reduction in the recovery rate. However, very short retention times, i.e. a low retarding effect of the chromatographic system on the first selenium compound (presumably the selenium (II) carbamate) cause considerable disturbances

8 6 in the nanogram range through unspecific absorptions from the decomposition of the reagent which can not be quantitatively separated by reversed-phase chromatography. Despite good measuring sensitivity a more unfavourable detection limit was therefore obtained with this method than with the determination of selenium as piazine selenate (see Table I). Water analyses The chloro-piazine selenate method with the lowest detection limit was used for the examination of various water samples. The drinking water regulation of the Federal Republic of Germany dated February 15, ) stipulates a permissible limit of concentration of 0.1 mmol/m 3 (i.e mg/litre or 7.9 ppb) mmol/m3 (i.e mg/litre or 2.4 ppb) is listed as permissible error of the measured value 5 ). The prescribed photometric analytical method as piazine selenate is just able to detect this limit value with its detection limit of mg per litre, However, the described method for the determination of selenium as chloro-piazine selenate with the HPLC exhibits a detection limit of mg/litre (i.e ppb) which is lower by a factor of almost 20. No selenium could be detected in the examined drinking-water samples. In one sample of surface- and waste water each, selenium (312) contents of 0.8 and 2.1 ppb were determined (see Table II). For the determination in waste water a relative standard deviation of 5.5% was established (c.f. Fig. 1).

9 7 Water sample Result (ppb) Drinking water River water Waste water Not detectable (below 0.32 ppb) (Peak 1 (2)) 0.80 ppb (Peak 1 (3)) ppb, n = 11 (Peak 1 (4)) Table II Results of analyses ("5-chloro-piazine selenate method") Fig. 1 Chromatograms of HPLC determination of selenium as 5-chloro-piazine selenate. For conditions see experimental part. (1) Blank value; (2) drinking water; (3) surface water (river water), 0.8 ppb Se; (4) waste water, 2.1 ppb Se.

10 I Literature d'::,sciiwedt, Fresenias Z. Anal. Chem., 288 (1 977) G. Schwedt, Chromatographia, 11 (1978) G. L. Wheeler und P. F. Lott, Microchem. J., 19 (1974) 390. A. Schwarz, Dip/omarbeit, Gesamthochschule Siegen, Siegen, Juni Bundesgesetzblatt 1975 (B.R.D.), Tell I, S. 459ff. 4. Thesis 5. Federal Law Gazette