Welding dust

Coal ash, coal fly ash, power station fly ash, incinerator ash, vehicle exhaust particulates, urban dust, atmospheric dust, metal smelter dust, welding dust, diesel particulates, particulates on filter media Sewage sludge, wastewater... 

Currently available CRMs for Cr(lll)/(VI) species There exist a lyophilized water certified for Cr(III)/Cr(VI) and a binder-free glass fiber filter loaded with welding dust certified for Cr(VI) and total Cr (Vercoutere et al. 1998 Christensen et al. 1999) issued by the BCR. They consist of a set of specimens for single use. There is a need for more CRMs, such as a Cr(VI) in industrial effluents and in river water containing, e.g. humic substances. 

Christensen JM, Byrialsen K, Vercoutere K, Cornelis R, and Quevauviller Ph (1999) Certification of Cr(VI) and total leachable Cr contents in welding dust loaded on a filter (CRM 545). Fresenius J Anal Chem 363 28-32. 

The Standards, Measurements and Testing Programme of the European Commission launched a few years ago a project dealing with the development and, ultimately, the production of air filters realistically exposed to welding dust occurring during stainless steel welding (Christensen et al. 1999). This project resulted in the production and certification of a batch of 1100 filters for the Cr (VI) content (40.16 0.60 pg/g dust) (CRM 545). In addition, the total leachable Cr content ( 39.37 1.30 pg/g dust) was certified as a means to check for total Cr recovery. 

Welding dust CRM 545 Crvl 40.2 0.6jug kg"1 as Crvl Vercoutere et al. (1997b)... 

Chromium species in lyophilised water and welding dust... 

Total chromium and Cr in samples of stainless steel welding dusts were determined after extraction of the samples with a pH 4 buffer solution (Girard and Hubert, 1996). The analytical method involved the use of an FI system equipped with two detectors. The first detector (spectrophotometer) measured Crvl as the diphenylcarbazide complex. The second detector (AA spectrometer) measured total chromium. The recovery of chromium was 96%, and the lower detection limit was 0.005 mg ml-1. 

There are no CRMs for chromium at concentration levels suitable for environmental work. Development of aqueous and lyophilised reference materials (Dyg et al., 1994b) and of filters loaded with welding dust (Dyg et al., 1994a) has been described. 

Dyg, S., Anglov, T. and Christensen, J.M. (1994a) Preparation of filters loaded with welding dust. A homogeneity and stability study of hexavalent chromium. Anal. Chim. Acta, 286, 273-282. 

Girard, L. and Hubert, J. (1996) Speciation of chromium (VI) and total chromium determination in welding dust samples by flow injection analysis coupled to atomic absorption spectrometry. Talanta, 43,1965-1974. 

The results accepted after both technical and statistical scrutiny were used for the calculation of the certified values which were based on 11 sets of results in the case of Cr(VI) for a certified content of (40.2 0.6) g kg dust and on 7 sets of results in the case of total leachable Cr for a certified content of (39.5 1.3) g kg dust. The fact that the total leachable Cr content of the welding dust is somewhat lower than the Cr(VI) content is only due to the uncertainty on the results used for calculation of the certified values. 

Specific chapters then focus on different projects on speciation analysis. Chapter 4 deals with interlaboratory studies on methylmercury in fish and sediment Chapter 5 describes the collaborative projects to certify organotins in sediment RMs and mussel tissues Chapter 6 gives an overview of the certification project on trimethyllead in simulated rainwater and urban dust Chapter 7 describes the certification project on arsenic species in fish tissues Chapter 8 focuses on the intercomparison and tentative certification of Se(IV) and Se(VI) in simulated freshwater Chapter 9 deals with a feasibility study to stabilize Cr species in solution followed by the certification of Cr(III) and Cr(VI) in lyophilized solutions and welding dust Chapter 10 gives a review of methods used for A1 speciation Chapter 11 develops the overall collaborative project to standardize single and sequential extraction procedures for soil and sediment analysis, followed by interlaboratory studies and certification of soil and sediment reference materials. 

A filter loaded with welding dust as normally encountered on the personal filter monitors of stainless steel welders, CRM 545... 

The interlaboratory study and certification campaign were coordinated by the Laboratorium voor Analytische Scheikunde, Universiteit Gent (Belgium), which also performed the preparation of the lyophilized solutions the filters loaded with welding dust were prepared by the Arbejdsmiljoinstituttet in Copenhagen (Denmark). 

The techniques described below correspond to the determination of Cr(VI) (and total leachable Cr) in welding dust loaded on a filter, following a procedure based on leaching with Na0H-Na2C03 buffer and agitation and/or sonication [150]. 

A batch of 1100 filters, loaded with welding dust containing approximately 100 pg of Cr(VI), was produced. The procedure described by Dyg et al. [146] was followed in general. 

To check the between-filter homogeneity, 40 filters were randomly set aside after loading them with welding dust. They were taken from the different batches. 

The total Cr content of the welding dust, including metallic Cr, Cr(III), etc., was determined by instrumental neutron activation analysis (INAA) and was (49.57 2.79) mg kg dust. 

The certified values (unweighted mean of p accepted sets of results) and their uncertainties (half-width of the 95% confidence intervals) are given in Table 9.7. The fact that the total leachable Cr content of the welding dust is... 

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