1-5 的 5 产品与服务
1-7 的 7 Business Insights
When mining for precious metals, ores are extracted from the ground and subjected to various sample preparation procedures in order to remove the metals of interest. A commonly used procedure to isolate metals from the ore is fire-assay, which leaves a matrix-free “button” of the metal. This work will focus on the analysis of precious metals in simulated digested precious metal buttons, with an added emphasis on assessing the lowest limits which can be accurately measured.
A major challenge in the analysis of food samples is the extremely low analyte levels and the very high matrix levels. For many years, graphite furnace atomic absorption spectroscopy (GFAAS) has been a reliable technique and the preferred method for this analysis, especially for the determination of Cd and Pb. This work will focus on the use of GFAAS for the determination of lead and cadmium in a variety of food samples.
Lead (Pb) and cadmium (Cd) are common pollutants in grains and are extremely toxic. Pb is harmful to human organs even at trace levels, and once it accumulates in the body, it causes inhibition of hemoglobin formation and neurological disorders. Cd is even classified as human carcinogen [Group 1 - according to International Agency for Research on Cancer]. It is reported that Cd leads to severe kidney problems which can be fatal and is also associated with brittle bones and liver problems. Rice, as the most widely consumed cereal grain in Asia/China, can quickly pick up Pb and Cd from toxins, pesticides and fertilizers in the soil, thereby endangering the health of millions of people through their diet. Therefore, it is extremely important to develop a simple, reliable method to monitor the levels of Pb and Cd in rice. According to Chinese national standard GB 2715-2016 Hygienic Standard for Grain, the maximum concentrations of Pb or Cd in grains must be below 0.2 mg/kg; the allowable level in the European Union is the same [EC 1881/2006]. The official technique for the determination of heavy metals in both cases is graphite furnace atomic absorption spectroscopy (GFAAS, GB/T 5009. 12-2017, GB/T 5009-2017. 15 and EN 14083:2003). Samples can be pretreated using various methods, including microwave digestion, hot block digestion, dry ashing, and hot plate digestion. It is found that these conventional digestion procedures are always complicated and time-consuming (two-four hours or even longer). Plus, conventional sample preparation techniques require large quantities of corrosive and oxidizing reagents, increasing the chance for contamination which could lead to inaccurate results. Special PTFE vessels are needed for microwave digestion; however, reusable utensils might also cause cross contamination.
Toxic elements, such as lead (Pb) and cadmium (Cd), are entering the food chain through environmental contamination. Rice, as the most widely consumed cereal grain in Asia, can quickly pick up Pb and Cd from soil, thereby seriously endangering human health through diet. These toxic element levels need to be carefully monitored. Maximum levels of Pb and Cd are strictly regulated in Asian countries, especially in China; therefore, it is extremely important to develop a simple, reliable method for trace levels of Pb and Cd in rice. The allowable maximum levels of Pb and Cd in grains in EU and China are required to be below 0.2 mg/kg (Commission Regulation EC 1881/2006 and Chinese GB 2715-2016 Hygienic Standard). Graphite furnace atomic absorption spectroscopy (GFAAS) is the officially recommended technique for detection of trace elements in various food stuffs (GB/T 5009.15-2017, GB/T 5009. 12-2017 and EN 14083:2003). Food samples are usually pretreated before GFAAS analysis using various methods: microwave digestion, hot block digestion, dry ashing, and hot plate digestion. These conventional digestion procedures are usually complicated and time-consuming (2-4 hours or longer). Plus, they require large quantities of corrosive and oxidizing reagents, increasing the chance for contamination which could lead to inaccurate results. However, fast digestion can effectively speed up the sample preparation procedure while reducing the use of corrosive reagents and the chance for contamination.
Precise and accurate measurements at the regulated levels are an important factor for assuring safe drinking water. U.S. EPA Method 200.91 is the method cited by EPA, Health Canada, and the WHO for the use of graphite furnace atomic absorption spectroscopy (GFAAS). In evaluating a GFAAS system for determination of these elements, it must provide good sensitivity, low noise, limited drift, and accuracy in matrices with high salt content (hard water) that might be found in drinking waters. In this work, the PinAAcle™ 900T, with a unique optical system, is evaluated for the use of EPA Method 200.9 for As, Cd, Pb, Se, and Tl in drinking waters.
Sample preparation is one of the most critical steps in your analytical process. Often accounting for 60% of your analytical timetable, it has a fundamental impact on laboratory throughput and analytical performance. Any errors within the sample preparation process will undermine the quality of your food data at all subsequent stages of your analysis. Here are five tips to improving your sample digestion for food samples.