RoHS/Trace Element Analysis

FISCHER offers special measurement solutions with which you can determine the presence of pollutants such as heavy metals in minimal concentrations, both in electronic components and in plastics. In this way you can monitor adherence to guidelines such as RoHS and test the safety of purchased goods.

RoHS/Trace element analysis

Application notes

Determination of Harmful Substances in Very Small Concentrations – RoHS

It is critical for manufacturers and distributors of many products to be able to detect harmful substances. Various regulations, such as RoHS (Restriction of Hazardous Substances), DIN EN 71 (Safety of Toys Standard) and CPSIA (Consumer Product Safety Improvement Act), specify maximum permissible values, particularly for heavy metals. 

For example, the RoHS limits concentrations of lead (Pb), mercury (Hg), hexavalent chromium (Cr VI) and bromine compounds (PBB, PBDE) to 1000 ppm, while the limit for Cadmium (Cd) is just 100 ppm.

X-ray fluorescence instruments with silicon drift detectors, such as the FISCHERSCOPE® X-RAY XDV®-SDD, are exceptionally well suited for easy, non-destructive determination of these harmful substances in a wide range of products.

Plastics

Aluminum/
Ceramics

Brass

Steel

Solder

2 ppm

6 ppm

50 ppm

30 ppm

60 ppm

Housing cable sheathing, PCBs

Housing,
SMD components

plug contacts

Housing

Solder points,
bailed samples

Permissible limits:   RoHS:           1000ppm

                                    DIN EN 71:       90ppm

                                    CPSIA:            100ppm

Table 1: Detection limits of Pb in various materials/components measured using the FISCHERSCOPE® X-RAY XDV®-SDD compared to the limit values of various regulations.

WinFTM®, FISCHER’s powerful analysis software, includes a mode specifically developed for RoHS analysis which provides for automatic evaluation of adherence to limit values.

Thus, compliance with legal requirements can be verified quickly, with typical measuring times of 60-300 seconds.

Fig. 1: The FISCHERSCOPE® X-RAY XDV®-SDD

Table 1 illustrates the detection limits for Pb in various materials using the X-ray fluorescence method. While direct measurement is possible for Pb, for Cr and Br only total concentrations – not the exact concentrations of the harmful compounds – can be determined. Compliance is established when the total concentration is below the limit values, otherwise additional analysis methods must be employed. The required detection limits can also be met for other heavy metals as well, such as Cd, Hg, As, and Ba.

Your local contact person for FISCHER products will be happy to assist you in selecting a suitable X-ray fluorescence instrument for measuring very small concentrations of harmful substances – FISCHERSCOPE® X-RAY XDV®-SDD, XAN® 150 with SDD detector, or XDAL® with PIN detector.

Trace Element Analysis in Materials for Fashion Jewelery and Accessories

Because articles that come in contact with human skin should be free of harmful materials and allergenic substances, new regulations for consumer protection are in the works to restrict the content of lead (Pb), cadmium (Cd) and other toxic or allergenic elements in fashion jewelery, watch parts, and accessories, as well as in the metal fastenings and ornaments on handbags, wallets or clothing. This analytical challenge requires measuring equipment that can quickly and easily detect even the tiniest amounts of these substances.

Under this new regulation, not only harmful organic substances but also heavy metals, in particular Pb, Cd and Ni, should be severely limited. Depending on the industry and country, the threshholds can be extremely low, often in the range of 100 ppm.

Fig.1: Typical fashion jewelery items are in constant contact with human skin. For this reason, the quantity of hazardous materials must be restricted.

For cost purposes, the metal parts in fashion jewelery and accessories are not always made of solid materials. The underlying forms are made of easily workable, inexpensive alloys which are then plated with decorative coatings. Both the coatings and the substrate materials must be free of Pb and Cd. Therefore, it is most time and cost effective to analyze such base materials as brass and zinc alloys prior to shaping and coating.

In contrast to the huge effort required with chemical analysis, it is straightforward and simple to test for contaminants using X-ray fluorescence (XRF) systems. Their high detection strength and low detection limits – indispensable in any measurement method – make the XRF-systems from FISCHER ideal for such screening purposes.


Matrix

Std. dev. Pb [ppm]

ABS

0.5

Al

2

Cu

13

Zn

20

Sn

0.6

Brass, actual

10 - 30

SnBi2, actual

5 - 15

SnBi50 actual

50 - 100

Table 1: Typical repeatability precision values (Std. dev.) in lead measurements, measured with FISCHERSCOPE® X-RAY XDV®-SDD.

The standard deviation of repeated measurements is a direct indication of the lowest concentrations detectable by an instrument (detection limit ~ 3 x std. dev.). The impressive results in Table1 show that the XRF method and the FISCHERSCOPE® X-RAY XDV®-SDD are exceptionally well suited for trace analysis – and therefore, for controlling whether legal target values have been met.

Worldwide, FISCHERSCOPE® X-RAY XDV®-SDD instruments are in use for the screening of materials used in the manufacture of fashion jewelery and accessories. These instruments are characterized by their easy handling and their excellent repeatability precision and are therefore best suited to oversee the compliance of new regulations. Your local FISCHER agent will gladly assist you with further questions.

Detecting heavy metals in toys using X-ray fluorescence

Children’s toys contaminated with traces of heavy metals and other hazardous substances – sometimes in dangerously high concentrations – repeatedly make for alarming headlines. Thus, toy manufacturers are under considerable pressure to prove that their products are free of harmful substances so that they qualify for the appropriate safety labels.

Within Europe, children’s playthings are subject to both the toy safety directive and the standard DIN EN 71, which defines, for example, the criteria for testing mechanical and physical properties and organic compounds, electric toy safety, and the upper limits for certain heavy metals and other hazardous substances. This standard dictates that the object be exposed for one or two hours to 0.07 mol/l hydrochloric acid, which simulates gastric juices. The dissolved product is then analysed, usually with AAS or ICP. The disadvantages of this approach are that the sample is destroyed in the process and the tests are very time-consuming.

Fig.1: Analysis of hazardous substances in various toys using a
FISCHERSCOPE® X-RAY XDV®-SDD

In contrast, X-ray fluorescence (XRF) analysis is a straightforward method for the quick and non-destructive determination of the concentrations of Pb, Hg, Cd and other heavy metals. Table 1 shows the detection limits for various plastics measured with a FISCHERSCOPE® XDV®-SDD. In this way, the precise measurement results can be easily checked against the prescribed limiting values.


element

limitingvalues

DIN EN 71

Detection limits

Measuring
example

ABS brown

[standard
deviation]

POM

PVC

ABS blue

Sb

60

42.6

43.2

24.9

45159 [180]

As

25

3.9

8.7

2.7

42 [3.8]

Ba

1000

138.0

87.0

60.0

2740 [79]

Cd

75

17.4

19.2

22.2

10 [8.4]

Pb

90

8.7

12.6

6.5

4 [4.3]

Hg

60

2.4

8.1

1.5

-3 [2.6]

Se

500

1.5

4.2

1.2

5 [1.7]

Cr

60

11.7

54.0

7.5

12134 [281]

Tab.1: Limiting values specified in DIN EN 71 and detection limits in ppm for three different plastic materials, as measured with a FISCHERSCOPE® XDV®-SDD. Average values are shown for a brown ABS sample (as well as standard deviations in brackets).The limiting values for Sb, As, Ba and Cr have been clearly exceeded.

Used as a screening method, the XRF warns the user if a given value has been exceeded. Further wet chemical analyses can then be carried out to crosscheck the result.

The pollutant concentration can also be measured very selectively, for example on the painted eye of a plastic figure. With the help of the XRF, an entire batch can be tested quickly, allowing the selective removal of individual contaminated parts – which might never have been detected in random tests. A further advantage is that the concentration of all heavy metals can be determined simultaneously in one measurement step.

With the FISCHERSCOPE® X-RAY XDV®-SDD, even the smallest concentrations of heavy metals and other hazardous substances in toys can be detected quickly and, above all, non-destructively. This makes it possible to verify compliance with specified regulations and standards. For further information please contact your local FISCHER representative.

Your contact to FISCHER

Fischer Technology Inc.
Windsor/United States

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Phone: (860) 683-0781
E-Mail: info@fischer-technology.com
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