MILESTONE H E L P I N G C H E M I S T S Think Blank The analyst must ‘think blank’. He must be aware as to the effect on the blank of every step of the analytical procedure. He must ask himself “If I do this, what is the effect on the blank?” (T. Murphy, The role of analytical blank in accurate trace analysis) Clean Chemistry Line “The analytical blank may be considered the “Achilles’ heel” of trace analysis. The analytical blank is simply the contamination by the element or compound being determined from all sources external to the sample. Modern methods of analysis have lowered the threshold of determining trace elements to the low parts per billion for many elements but the inability to control the analytical blank has seriously affected the accuracy of these methods.” T. Murphy, The role of analytical blank in accurate trace analysis, in: P.D. LaFleur (Ed.), National Bureau of Standards Special Publication 422: Accuracy in Trace Analysis: Sampling, Sample Handling, and Analysis, National Bureau of Standards, Gaithersburg, Maryland, 1976, pp. 509-539. The Milestone Clean Chemistry Line is an innovative and complete portfolio of systems and accessories for reducing and controlling the analytical blank in ultra-trace elemental analysis. There is a growing awareness that sample preparation should evolve to the same standards of the most modern analytical techniques, such as ICP-MS, and there are a number of factors that can critically impact the quality of the data: • The purity of the reagents • The cleanliness of the material in contact with the sample • The sample preparation method Each of these factors is related to the reduction and the control of the analytical blank. To address this issue, Milestone has developed a comprehensive line of products and accessories aimed to reduce and control the analytical blank, which perfectly complement its ETHOS UP and ETHOS EASY microwave digestion systems. DUOPUR Quartz sub-boiling distillation system SUBCLEAN PTFE sub-boiling distillation system TRACECLEAN Acid steam cleaning system for PTFE, quartz and glassware ULTRATRACE INSERTS TFM and quartz accessories for microwave sample preparation duoPUR “In the preparation of high purity reagents, there is only one significant and practical choice for the method of purification: sub-boiling distillation.” US EPA SW-846, Chapter 3, Update IVB. SUB-BOILING TECHNOLOGY QUARTZ SUB-BOILING SYSTEM The chemical reagents used during the analysis The duoPUR consists of two quartz distillation units. are an important source of the analytical blank. Each unit contains two infrared heating elements (1), a Sub-boiling distillation has been demonstrated to be water cooled condenser (2), a high-purity PFA collection the best method of acid purification. It uses contact-bottle (3), and a fully automatic acid loading/discharge less infrared lamps to vaporize the surface liquid at system. The vaporized liquid is collected on the inclined a temperature typically 20 C below the boiling point. water-cooled condenser and drips into the collection In contrast to conventional distillation, where strong bottle. The distillation process is microprocessor boiling action generating aerosolized particles results in controlled, allowing the user to set the distillation time contamination of the original liquid with the distillate, and power level by using a compact control terminal with a gentle surface evaporation during sub-boiling easy-to-read, bright, full-color, touch-screen display. distillation prevents the formation of spray or droplets The distillation rate ranges from 50 to 400 mL per hour, and yields to a very high pure acid. depending on the power setting and the temperature of the cooling water. INFRARED INFRARED 2 1 3 HEATING PLATE HEATING PLATE Sub-boiling vs conventional technology duoPUR schematics INFRARED • 90% cost saving of ultra-pure acids by purifying low-cost reagent grade acids • High productivity, up to 400 mL per hour (duoPUR) and up to 60 mL per hour (subCLEAN) • On-demand acid purification • Re-purification of contaminated acids HEATING PLATE subCLEAN TYPICAL SUBBOILING QUALITY PTFE SUB-BOILING SYSTEM The Milestone subCLEAN is a compact and easy-to-use Element Single distillation Double distillation sub-boiling system, where all parts in contact with acids Ag <46 <1,5 are made of high-purity fluoropolymers. The subCLEAN Al <557 <147 is therefore suitable for the purification of HF, as well as As <3 <0,9 for HNO and HCl. The acid is automatically loaded into Ba <25 <3,5 3 the distillation container, where it is gently heated below Ca <900 <157 Cd <8,1 <1,8 its boiling temperature. All process is microprocessor Co <6 <1 controlled by using a compact control terminal with easy-Cr <118 <4,6 to-read, bright, full-color, touch-screen display. Cu <58 <21 The subCLEAN does not require cooling water or a chiller, Fe <1.000 <210 as acid vapors rapidly condense into a collection bottle by Mg <195 <42 forced air cooling. Mn <9,7 <2,1 Mo <7,1 <0,4 Nitric Acid, all concentrations in pg/g (ppt). Ni <155 <23 Concentrations expressed as the upper limit of the 99% confidence Pb <10 <2,5 limit of the measured result (n=4). On-Demand Production of High-Purity Acids in the Analytical Sb <6,1 <0,5 Laboratory. Robert Richter, Dirk Link and H.M. (Skip) Kingston. Se <3,9 <1,2 Spectroscopy, Volume 15, Number 1, Pages 38-40, January 2000. Sn <22 <9,1 Ti <59 <8,1 V <51 <11 Zn <261 <49 duoPUR subCLEAN traceCLEAN ACID STEAM CLEANING SYSTEM Cleaning various items used in ultra-trace analysis work will continuously reflux within the sealed unit, thoroughly is a critically important laboratory routine. To minimize leaching any metal contaminants from the items. Various contamination, traditional cleaning methods require holders are available for vials, microwave digestion soaking items in hot acids, often for several hours. To be vessels, flasks, glassware, and ICP-MS accessories. effective large volumes of acid are consumed and need to be changes regularly. There is also a substantial risk • Fast, convenient and fully automated of exposure to hot acids and acid vapors using traditional • Best cleaning quality of your TFM, soaking techniques. To address these issues, Milestone glass and quartz parts has developed the traceCLEAN, a fully automated, self- • Perfect accessory for your microwave contained, acid steam cleaning system for trace metal analysis accessories. Place the items to be cleaned in the digestion system traceCLEAN system, program the time and temperature • No operator’s exposure to acid vapors required, then press “Start”. Freshly distilled acid vapors Microwave traceCLEAN Element cleaning cleaning Al 287 ± 46 258 ± 24 Cd <72 <72 Co <56 <56 Cr <85 <85 Cu 144 ± 39 117 ± 12 Fe <474 <474 Mg 289 ± 22 232 ± 15 Na <121 <121 Ni <55 <55 Pb <57 <57 Tl <261 <261 Zn 995 ± 80 <876 Microwave cleaning vs TraceCLEAN cleaning. Trace metal contamination (pg/g, ppt) in 5% HNO blanks prepared 3 after cleaning. The microwave cleaning was performed at 180°C with a mixture of HCl and HNO .3 traceCLEAN The traceCLEAN cleaning performed with HNO .3 New Developments in Automated Cleaning of PTFE, Glass, and Quartz Components used in Ultra-Trace Analysis. Robert Richter. Spectroscopy, June 2001. Ultratrace Inserts “To keep blank levels as low as possible the analyst must exercise care in keeping the volume of reagents to a minimum.” T. Murphy, The role of analytical blank in accurate trace analysis. VESSEL-INSIDE-VESSEL Microwave digestion techniques typically require a acid required for digestion, lowering the dilution factor minimum volume of reagents of about 5 mL to achieve and increasing the detection limit. A variety of inserts are accurate temperature monitoring of the reaction available from Milestone, in different materials (Quartz or conditions. However sometimes it is important to TFM) and with different sizes and shapes, to accomplish maintain a very low dilution factor, particularly when all application requirements. working at concentrations near the method detection limit. This has led Milestone to develop a “vessel-inside- • Less acid volume vessel” technology. Vessel-inside-vessel technology • Higher sample amount uses smaller secondary vessel (2) inside the primary microwave vessel (1). The secondary vessel contains • Lower dilution factor the sample and digestion reagents (3), while the primary • Increased method detection limit vessels contains the solution in which temperature • Less surface contamination control takes place. This setup reduces the amount of 1 2 3 ETHOS UP Vessel-inside-vessel schematics HELPING CHEMISTS Milestone has been active since 1988 in the field of microwave sample preparation. With over 20000 instruments installed worldwide, we are the acknowledged industry leader in microwave technology. Milestone vision is to help chemists by providing the most technologically advanced instrumentation for research and quality control. Our products offer a wide range of applications, such as microwave acid digestion, solvent extraction, synthesis and ashing. Furthermore we create products for acid purification and direct mercury determination in solid, liquid and gas samples. We offer our customers the highest level of application support, building up over the years a relationship based on trust and commitment. 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