Depending on the matrix the digestion conditions may need to be varied

Dear college,

The matrix constituents in environmental samples: Al, Ca, Mg, Fe and Ti.

The analytical task requires complete dissolution of the sample. I offer the corresponding digestion procedure [1]

1. Digestion Procedure with HCl-HNO3-HF in a Microwave System[1]

The digestion was performed in a microwave digestion system (Milestone 1200, USA) at 230∘C and at pressure of 70 bar. 0.5 g sample was weighed in a PTFE vessel. The digestion procedure in three steps was used: 1st —4mL nitric acid (65%) and 1mL hydrochloric acid (30%); 2nd — 1mL hydrofluoric acid (40%) for complete dissolution of the sample; 3rd — 10mL boric acid, saturated at 20∘C for complexing insoluble fluorides. Afterwards, boric acid (in excess to HF) was added in order to bind the HF as a HBF4 complex. . HBF4solutions do not etch glassware used (volumetric flasks, etc.) as well as the conventional ICP sample introduction system (glass nebulizer, glass chamber, and silica ICP-torch). So a conventional ICP-OES sample introduction system was used for the analysis of such solutions. The duration of one digestion step, including cooling period,

2. Determination of aluminum:

The precision of the determination was improved using two selected analysis of Al, free of interferences in the presence of Ca, Mg, Fe and Ti: Al II 237.324 nm and Al II 394.401nm. The sample solutions were diluted (dilution factor = 4) in order to eliminate the multiplicative interference. The reference solutions were prepared on the basis of an acid blank by using Merck ICP-AES mono-element standard solutions in the presence of 1 mol l_1 HNO3 [2].

The standard reference material sediment SD-N-1/2 was used for experimental demonstration of accuracy of analytical results.

The experiments were performed with radial viewing ICP-OES system HORIBA Jobin Yvon ULTIMA 2 (Jobin Yvon, Longjumeau, France) equipment. Practical spectral bandwidth 5 pm in the 2nd order from 160nm to 320nm; and 10pm in the 1st order from 320 to 800 nm.

REFRENCES

[1]. Nikolaya Velitchkova,1 Olga Veleva,1 Serafim Velichkov,2and Nonka Daskalova2*,

Possibilities of High Resolution Inductively Coupled Plasma Optical Emission Spectrometry in the Determination of Trace Elements in Environmental Materials,

Hindawi Publishing Corporation, Journal of Spectroscopy, Volume 2013, Article ID 505871, 12 pages ,http://dx.doi.org/10.1155/2013/505871

[2]. N. Velitchkova, E.N. Pentcheva N. Daskalova,* Determination of arsenic, mercury, selenium, thallium, tin and bismuth in environmental materials by inductively coupled plasma emission spectrometry, Spectrochimica Acta Part B 59 (2004) 871– 882

With kind regards, N. Daskalova