Evaluation and Comparison between a Conventional Acid Digestion Method and a Microwave Digestion System for Heavy Metals Determination in Mentha Samples by ICP-MS.

Abstract

Mentha is the most common plant species grown in Saudi Arabia's Madinah city. Locally, the two popular types of mint are commercially called (Hasawi or Habaq) and (Mograbi). Both species are used in herbal teas, alone or as spice mixtures for many foods to offer aroma and flavour. In this research Hasawi mint samples were collected from three different locations and digested by two methods (acid digestion method and a microwave digestion system). Then, they were analysed for their metal contents by ICP-MS. The results from both digestion methods revealed that the following 10 metals were presented: V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb. The microwave digestion system was the best for all studied heavy metals in term of sample preparation procedures, linearity (≥ 0.999), recovery (97%-101%, n=2) and precision (R.S.D% ≈ 1-2 %, n=2). Mint samples from first location contained 7 metals within the permissible limit while the remaining three metals (Cr, Cu and Zn) had higher levels. The second location contained 9 metals within the permissible limit but only one metal (Cu) had a higher level. The third location contained 6 metals within the permissible limit while it had 4 metals (Cr, Ni, Cu, Cd) with higher level. All locations contained As, Cd and Pb within permissible limit except the third location which had a cadmium amount of (0.6 mg/kg) while the cadmium permissible level is (0.3 mg/kg). Some farmers use composts (from inorganic sources), fertilizers and plant nutrients in relatively large amounts that are rich in some metals and this might explain some of the higher value of metals in the mint. Moreover, contamination from industrial activities nearby mint farms might also be expected.

Heavy metals content in ashes of wood pellets and the health risk assessment related to their presence in the environment

“…Then, the digest was filtered, transferred to a 25 mL volumetric flask, and filled up with redistilled water to the mark. All samples and blank were prepared in three replicates 19 – 21 .…”

Synthesis and characterization of fluorescent gold clusters encapsulated in PNIPAM and PAAM hydrogels for selective detection of mercury in water

“…The hydrogel free radical polymerization was carried out in a glass tube at room temperature (22 °C) for 3 h, using APS (0.01 mmol) and TEMED (0.03 mL) as redox initiators. After the polymerization, the hydrogel pieces were immersed in distilled water at room temperature for 48 h. The distilled water was renewed every hour to remove soluble by-products 4,38 Then, the hydrogels were dried for 48 h at 25 °C and moderate vacuum (0.1 atm) for later use.…”

“…2,3 The determination and quantification of these contaminants demand expensive and sophisticated instruments and complicated sample preparation processes. 4 A fast, simple, and efficient alternative for the sensitive optical detection of heavy metals is the use of highly fluorescent metal nanoclusters (MNCs) supported on different matrices. 5 MNCs consist of only a few atoms of the metal ( M n , n = 2–20) and are interesting because of their ultra-small size, excellent fluorescent properties, low toxicity, and high stability.…”

The Effect of Sample Preparation and Measurement Techniques on Heavy Metals Concentrations in Soil: Case Study from Kraków, Poland, Europe

“…Four different methodologies were tested across four different sample locations with the conclusion that of the four methods used to prepare mosses for later exposure in active biomonitoring, the best method is averaging with simultaneous conditioning of mosses in demineralised water. Another published paper shows evaluation and comparison between a conventional acid digestion method and a microwave digestion system for heavy metals determination in Mentha samples by ICP-MS [38]. The concentrations of selected heavy metals were measured in the stems and leaves of the Artemisia herba-alba medicinal plant and soil samples were evaluated by Massadeh et al [39].…”