909 UV Digester Sample preparation for trace analysis of heavy metals 909 UV Digester in brief 02 The 909 UV Digester is a modern digestion unit for Digestion of samples in the 909 UV Digester is fully autosample preparation by UV photolysis. Organic molecules matic. The centerpiece of the digester is a UV lamp that in the sample interfere with the determination of heavy provides the necessary UV radiation. The heat generated metals, particularly in voltammetric or spectroscopic me by the lamp is dissipated via an air­cooling system. To en thods such as ICP and AAS. Based on the proven UV sure that digestion takes place under controlled conditech nology, the new 909 UV Digester effectively elimitions, a Pt1000 temperature sensor is used to measure nates organic constituents in liquid samples. UV digestion the digestion temperature in a reference sample. An in provides fast and elegant sample preparation, particute grated microprocessor controls the digestion temperalarly with slightly contaminated samples. ture and the digestion time. Standards that recommend sample preparation using UV photolysis include • DIN 38406, Part 16: Determination of zinc, cadmium, lead, copper, thallium, nickel, cobalt by voltammetry • DIN 38406, Part 17: Determination of uranium – method using adsorptive stripping voltammetry in surface water, raw water and drinking water The key advantages • Controller and wet section in a single housing 03 • Digital input of digestion temperature and digestion time • Microprocessor­controlled regulation of digestion temperature and digestion time • Air cooling, does not need a cooling water supply • Simultaneous digestion of up to 12 samples • Short digestion times • The blank values are practically zero because only very small amounts of reagents are needed • Also suitable for elements that form volatile compounds, e.g. mercury, arsenic, and selenium 04 UV digestion Organic constituents in the sample can interfere with the amount of H O as a radical initiator. The OH radicals are 2 2 analysis in many ways. For example, a complexing agent very reactive and spontaneously react with the organic can mask the analytes during determination or a commolecules. The resulting radical chain reaction breaks pound can generate an interfering analytical signal. UV down all the organic molecules to low molecular­weight digestion is a fast and clean method of decomposing compounds such as CO , H O, N , or NH . These decom2 2 2 3 such organic compounds. The actual reagent in the di position products do not interfere with the subsequent gestion process is UV radiation. Thus the blank values are analysis. practically zero, which is particularly advantageous for trace analysis. UV digestion is suitable for transparent samples with lowto­medium organic contamination (up to approx. 100 mg UV digestion is based on the principle of photolysis. This carbon/L). The classical application field for UV digestion can be described in simple terms as breaking down moleis processing of all types of water samples, e.g. surface cules with light. The 909 UV Digester uses UV radiation waters or wastewaters. However, liquid biological samwith a wavelength of 200­400 nm to produce OH radiples (e.g. urine) or foods (e.g. juices and alcoholic bevercals in the sample. This is facilitated by adding a small ages) too can be digested using an adapted procedure. Application examples Nickel and cobalt in wastewater 05 -200n -200n Co Ni -150n -150n ) ) (A -100n (A I -100n I -50.0n -50.0n 0 0 -0.80 -0.90 -1.00 -1.10 -1.20 -0.80 -0.90 -1.00 -1.10 -1.20 U (V) U (V) Voltammogram for a determination of nickel and cobalt in Determination of nickel and cobalt in the same wastewater wastewater without UV digestion after UV digestion. Concentration of each: 1.8 µg/L Cadmium, lead, and copper in red wine 60.0n Cu Cu 150n 40.0n 100n ) ) (A (A I I Pb 20.0n 50.0n Cd Pb Cd 0 0 -0.60 -0.40 -0.20 0 -0.60 -0.40 -0.20 0 U (V) U (V) Voltammogram for a determination of cadmium, lead, and Determination of cadmium (concentration < detection limit), copper in red wine without UV digestion lead (17.7 µg/L), and copper (192.8 µg/L) in the same red wine after UV digestion. Speciation Volatile analytes Another application field for the 909 UV Digester is spe­ The 909 UV Digester is also highly suitable for the analyciation analysis. Voltammetric measurements can usually sis of samples containing mercury, arsenic, or selenium. detect only one oxidation state of a metal and only if the These elements are volatile at elevated temperatures or metal is not complexed. However, UV radiation can easily readily form volatile compounds. No losses of these eleoxidize chromium(III) to chromium(VI) without rea gents. ments occur during processing in the 909 UV Digester. This is an elegant way of determining the contents of free chromium(VI), total chromium and thus chro mi um(III) as the difference. A similar method can be applied to the reduction of selenium(VI) to selenium(IV) and to the analysis of free tin and organotin compounds. The 909 UV Digester in detail 06 Wet section The samples are arranged concentrically around the UV lamp. A fan located in the base dissipates the heat generated by the operating Controller lamp. A red shield protects the user’s This is used to enter the digestion eyes against harmful UV radiation. temperature and the digestion time. The clearly arranged display provides in formation on the current digestion status, the setpoint and actual temperatures as well as the remaining digestion time. It can also be used to call up the operating time of the UV lamp. This means that the lamp can be replaced before the diminishing radiant power influences the digestion efficiency. Pt1000 temperature sensor The glass­jacketed temperature sensor is placed into a reference sample. In this way the digestion temperature, controlled by the instrument, is directly measured. Sample holder with quartz sample vessels The sample is digested in a UV­transparent quartz vessel. A PTFE stopper acts as a condensation finger and prevents evaporation of the sample during digestion. How ever, it allows release of gaseous reaction products such as CO and N . The rack holds 12 samples. 2 2 Technical data Digestion 07 Digestion temperature 80...100 °C Control accuracy ± 3 °C Lamp power (controlled) 300...600 W Cooling Air cooling Ambient temperature (operating range) 5...35 °C Digestion time 1...999 min UV lamp Type Medium­pressure mercury lamp UV­A (315...400 nm) 35 W UV­B (280...315 nm) 40 W UV­C (200...280 nm) 70 W Discharge tube temperature 700...900 °C Length 137...139 mm Outer diameter approx. 16 mm Useful life 500...1’000 h Temperature measurement Sensor Pt1000 Measuring input Accuracy ± 0.2 °C (under reference conditions) Measuring range ­20...+150 °C Power supply Voltage 220...240 V (± 10%) Frequency 50...60 Hz (± 3%) Power consumption 630 W Dimensions Width 330 mm Height 290 mm Height (with UV shield) 500 mm Depth 310 mm Weight 10.9 kg Ordering information 2.909.0014 909 UV Digester (230 V) Digestion instrument for UV photolysis of water samples with low to medium organic load. For sample preparation in trace element determination by means of voltammetry, ion chromatography and spectroscopy (AAS, ICP). Instrument for 220...240 V and 50...60 Hz. Scope of delivery also includes 6.1110.010 Pt1000 temperature sensor 6.1446.100 PTFE stopper for UV quartz sample vessel (12 ×) 6.2041.240 Sample holder for 12 quartz sample vessels 6.2414.000 Quartz sample vessel 12 mL (12 ×) 6.2745.100 UV protective shield 6.2804.090 UV mercury vapor lamp www.metrohm.com ­9100 Herisau G, CH ohm A witzerland by Metr , printed in S SW ­03 Subject to change Layout by Ecknauer+Schoch A 8.909.5000EN – 2013