Branch General analytical chemistry Keywords IC 881 / Metrosep A Supp 5-150/4.0 / MMS 5000 / 920 / Absorber Module / Combustion Module / combustion ion chromatography / CIC / matrix elimination / fluoride / chloride / sulfate / branch 1 Summary In this application work different types of clay samples have been analyzed for the fluoride, chloride and sulfur content. These clays are used to make tiles. Samples The samples were already grinded well and could be directly analyzed. Clay as a sample is suspected to have quite some alkali and earth alkali metal content. They can deteriorate the pyrolysis tube. Therefore to protect the pyrolysis tube tungsten oxide was used. Each sample was combusted with about 100 mg of tungsten oxide. The sample was mixed well with the tungsten oxide. Instruments 881 Compact IC pro Anion MCS 2.881.0030 IC conductivity detector 2.850.9010 Combustion Module 2.136.0700 Autosampler MMS 5000 2.136.0800 Kit for solid sampling 6.7302.000 920 Absorber Module 2.920.0010 MagIC Net TM 2.4 Compact 6.6059.241 Metrosep A Supp 5-150/4.0 6.1006.520 Metrosep A Supp 4/5 Guard/4.0 6.1006.500 Metrosep A PCC 1 HC/4.0 6.1006.310 Metrosep I Trap 1-100/4.0 6.1014.200 Metrosep A Trap 1-100/4.0 6.1014.000 Reagents Ultrapure water, resistivity >18 MΩ cm (25 C), type I grade (ASTM D1193) Anion Standards for IC, TraceCert, from Sigma Aldrich Fluoride β(f - ) = 1 g/l in H2O, No. 77365 Chloride β(cl - ) = 1 g/l in H 2O; No. 39883 Bromide β(br - ) = 1 g/l in H 2O; No. 43147 Sulfate β(so 4 ) = 1 g/l in H2O, No. 90071 Sodium carbonate, Na 2CO 3, puriss. p.a 99.5%, Sigma Aldrich 71350, CAS 497-19-8 Sodium bicarbonate, puriss. p.a. 99.7%, Sigma Aldrich 31437, CAS 144-55-8 Sulfuric acid, H 2, ultrapure 96%, CAS 7664-93-9, Merck 100714 Hydrogenperoxide, 30% H 2O 2, TraceCert, from Sigma Aldrich 16911 Tungsten(VI)oxide, WO 3, puriss, 99.9%, Fluka 95410 Solutions A stock solution with c(h 2) = 2 mol/l sulfuric acid was prepared out of the concentrated sulfuric acid. Eluent anions Suppressor regeneration solution Suppressor rinsing c(na 2CO 3) = 3.2 mmol/l c(nahco 3) = 1.0 mmol/l c(h 2) = 100 mmol/l detector outlet Absorber Solution 100 ppm H 2O 2 Page 1 of 11
Standard solutions One multi-ion standard ( 1) was prepared for the calibration with Metrohm intelligent Partial Loop Technique (MiPT). Calibration is achieved by adjusting the injection volumes. The standard injection volumes are set to 4 µl in the sample table. The true injection volume for the standards is calculated by MagIC Net by multiplication with the standard number. Calibartion A β [mg/l] 1 2 5 10 25 50 F - 0.7 1.4 3.5 7 17.5 35 Cl - 0.7 1.4 3.5 7 17.5 35 Br - 0.7 1.4 3.5 7 17.5 35 4.5 9 22.5 45 112.5 225 For the concentration of F in sample No. 1 a second calibration was done to reach the percentage range. Calibration B β [mg/l] 1 2 5 10 25 50 F - 4.5 9 22.5 45 112.5 225 Cl - 0.7 1.4 3.5 7 17.5 35 Br - 0.7 1.4 3.5 7 17.5 35 0.7 1.4 3.5 7 17.5 35 Check standard solutions A separate solution of all analytes has been prepared as check standard for both calibrations. Again the injection mode was the same as for the standards. This means the prepared check standard solution has the concentration of the respective 1 A B β [mg/l] Check 5 Check 25 F - 3.5 17.5 Cl - 3.5 17.5 Br - 3.5 17.5 22.5 112.5 β [mg/l] Check 5 Check 25 F - 22.5 150 Cl - 3.5 17.5 Br - 3.5 17.5 3.5 17.5 Parameters Ion chromatography Recording time 20 min Column Metrosep A Supp 5-150/4.0 Flow Polarity + Temp. coefficient Peri. pump rate 2 0.7 ml/min 2.3 %/ C Sample loop 250 µl Inj. Vol. (Standards) 4-200 µl Inj. Vol. (Sample) Temperature 30 C Parameters Combustion IC Argon (4.6) Oxygen (5.0) 5, 20, 60 µl depending on the sample 100 ml/min 300 ml/min Oven temperature 1050 C Post-combustion time Initial volume of absorption solution Water inlet Post-combustion rinse Final rinse after combustion finshed Calculation 240 sec 2 ml 0.1 ml/min 0.2 ml/min 1 ml Automatic integration with MagIC Net TM 2.4 using peak area for all components. Comments Due to the type of samples alkali and earth alkali metals are expected to be present. To minimize the deterioration of the pyrolysis tube 100 mg tungsten(vi)oxide was added. The blank value given by the tungsten(vi)oxide is very low (close to boat blanks) and is not relevant for these measurements. Date 20 th of December 2012 Author Christian Emmenegger Competence Center Ion Chromatography Metrohm International Headquarters Page 2 of 11
Appendix Setup Scheme Ion Chromatography Liquid Handling and Absorption Combustion Liquid handling of absorbing solution is performed by the 10 ml-dosino, i.e. the initial volume is set into the absorber vessel in advance of combustion. During combustion absorbing solution is dosed (0.2 ml/min) to the T-piece located at the end of the combustion tube to achieve immediate absorption of combusted products (Post-combustion rinse). The connection between absorption vessel and combustion tube is rinsed after combustion has finished with 1 ml (final rinse). Water inlet into the combustion tube for pyrohydrolytic environment is carried out by the 5 ml-dosino with a rate of 0.1 ml/min. As MagIC Net TM 2.4 exactly records all volumes added to the absorbing solution during and after combustion there is no need for the use of an internal standard. The transfer of samples and standards into the loop of the 920 Absorber Module was performed by the 5 ml-dosino using partial loop injection (MiPT) giving full flexibility to injection volumes in a range from 4 to 200 µl. Page 3 of 11
Results for Sample 1 The results in this section are given in mass per weight of the sample, therefore the units are mg/kg. Each sample was combusted three times. Sample N CTMNC No. 16 (with calibration A) No. Fluoride [mg/kg] Chloride [mg/kg] Sulfur [mg/kg] Sample weight [mg] 1 42.1 33.1 153.5 23.99 2 44.5 33.4 142.5 25.41 3 44.4 31.5 141.5 23.52 average 43.7 32.7 145.8 RSD [%] 3.1 3.1 4.6 Sample N CTMNC No. 21 (with calibration A) No. Fluoride [mg/kg] Chloride [mg/kg] Sulfur [mg/kg] Sample weight [mg] 1 2790.2 289.6 5314.1 14.89 2 2648.9 260.9 4998.1 12.31 3 2701.5 270.9 4979.9 14.97 average 2713.5 273.8 5097.4 RSD [%] 2.6 5.3 3.7 Sample N CTMNC No. 12 (with calibration A) No. Fluoride [mg/kg] Chloride [mg/kg] Sulfur [mg/kg] Sample weight [mg] 1 71.7 1128.4 95.6 18.65 2 70.7 1144.2 95.8 14.66 3 62.1 1064.6 98.6 16.92 average 68.2 1112.4 96.7 RSD [%] 7.7 3.8 1.7 Sample N CTMNC No. 1 (with calibration B) No. Fluoride [mg/kg] Chloride [mg/kg] Sulfur [mg/kg] Sample weight [mg] 1 94646.0 3166.9 283.1 10.18 2 97715.4 3444.5 346.8 10.78 3 97409.4 3332.2 349.2 11.06 average 96590.3 3314.5 326.4 RSD [%] 1.8 4.2 11.5 Page 4 of 11
Calibration A Page 5 of 11
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Calibration B Page 7 of 11
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Check Standards for Calibration A β [%] Recovery Check 5 Recovery Check 25 F - 96.9 101.3 Cl - 97.9 103.4 Br - 96.5 101.4 96.3 101.5 Check Standards for Calibration B β [%] Recovery Check 5 Recovery Check 25 F - 100.3 99.4 Cl - 95.5 103.1 Br - 95.1 100.6 94.6 100.1 Chromatograms The concentrations indicated refer to the liquid concentration in the absorption solution measured by the IC in mg/l. Standard 50 of Calibration A Page 9 of 11
Sample No. 16 (60 µl injection) Sample No. 21 (20 µl injection) Page 10 of 11
Sample No. 12 (20 µl injection) Sample No. 1 (5 µl injection) Page 11 of 11