Environmental testing for electronics

RoHS, REACH, California Proposition 65, PFAS… Following supply chain audits and risk assessments, you may have to conduct environmental testing for your electronics. Let’s uncover some of the main analytical instruments to determine controlled chemicals.

XRF fluorescence

X-ray fluorescence (XRF) is the most well-known instrument for RoHS testing. Indeed, XRF instruments enable the detection of heavy metals like lead, mercury, or cadmium.

First, the XRF’s non-destructive nature makes it favorable, requiring minimal sample preparation, often just cleaning the sample’s surface. During analysis, X-ray beams stimulate the emission of fluorescence in the sample. This phenomenon occurs as electrons undergo transitions between energy states. This transition results in emitting photons whose energy levels are characteristic of the elements present in the sample. However, XRF has limitations. It can only detect individual elements, not compounds. Despite this, portable XRF devices offer on-site analysis of heavy elements.

In short, XRF’s non-destructive nature, minimal sample preparation, and applicability in various industries make it a valuable analytical tool, particularly for heavy metal detection and regulatory compliance.

The portable XRF analyzer is one type of X-ray, which is fluorescent. Source: Enviropass

FTIR enviro testing for electronics

Like XRF, Fourier Transform Infrared Spectroscopy (FTIR) is a widely utilized analytical tool across scientific fields. Notably, FTIR proves effective in detecting phthalates, crucial for compliance with regulations like RoHS, although achieving detection limits below regulatory thresholds presents challenges.

How does the FITR technology work? FTIR operates by characterizing molecular structures through infrared absorption within distinct regions of spectrum. Two sampling techniques employed in FTIR are Attenuated Total Reflectance and Transmission Mode, each suitable for various sample types.

The greatest challenge of FTIR may be the detection level. As a result, advanced sample preparation methods, like thin filmmakers and meticulous calibration, are essential for improving detection limits, emphasizing FTIR’s role as a pre-screening technique alongside other analytical methods.

The unavoidable GC-MS

Gas Chromatography Mass Spectrometry (GC-MS) emerges as a vital tool for ensuring compliance with regulations in electronics, like EU REACH or RoHS. This analytical technique combines gas chromatography and mass spectrometry, enabling efficient analysis. In the GC-MS process, the sample undergoes gas chromatography to convert it into the gas phase, followed by separation through a stationary phase, which determines elution time and helps identify substances.

After gas chromatography, the sample proceeds to the mass spectrometer, where electron beams ionize it and enable its analysis. This process aids in qualitative and quantitative analysis of compounds present in the sample. GC-MS is advantageous for testing electronic products for restricted substances like phthalates and volatile organic compounds. Additionally, it facilitates root cause analysis by detecting unknown substances interfering with product functionality.

Despite its benefits, GC-MS has limitations, such as the inability to test non-volatile heavy metals, unlike XRF. Matrix interference and low analyte concentrations pose challenges, particularly in electronic components with intricate layers. Consequently, the gas chromatography-tandem mass spectrometry (GC-MS/MS) technique is employed, offering enhanced sensitivity and specificity by conducting mass spectrometry analysis twice.

DART-MS

Direct Analysis in Real-Time Mass Spectrometry (DART-MS) is a groundbreaking technique in chemical analysis, swiftly detecting substances like flame retardants, phthalates, and polyaromatic amines without extensive sample preparation. Combining Direct Analysis in Real Time (DART) and Mass Spectrometry (MS), DART-MS ionizes molecules in the sample using DART as the ionization source, then separates and detects them based on the mass-to-charge ratio (m/z).

The DART-MS process involves sample introduction, ionization, mass spectrometry, ion detection, and data analysis.

DART-MS offers advantages such as speed, ambient ionization, sensitivity, minimal sample requirement, minimal sample preparation, versatility, and relatively low cost. However, it also has limitations, including limited ionization efficiency, matrix effects, and limited structural information compared to other techniques. Despite these drawbacks, DART-MS finds wide-ranging applications in environmental analysis, detecting substances like persistent organic pollutants and volatile organic compounds. It is also instrumental in flame retardant testing, phthalate analysis, and screening for polyaromatic amines, making it invaluable in regulatory compliance and consumer safety enforcement.

ICP-MS

Another analytical instrument is ICP-MS, which stands for Inductively Coupled Plasma Mass Spectrometry. This method involves coupling an inductively coupled plasma (ICP) ion source with a mass spectrometer (MS).

Here’s how it works:

1. Inductively Coupled Plasma (ICP): Introducing a carrier gas (typically argon) into a radio frequency (RF) coil creates a high-temperature plasma source. ICP creates a high-energy environment where atoms are stripped of their electrons, forming ions.
2. Ionization: The sample, often in liquid form, is introduced into the ICP for vaporization and atomization. The high temperature of the plasma causes the atoms to lose electrons, forming positively charged ions.
3. Mass Spectrometry (MS): Similarly to CC-MS and DART-MS, the ions are then introduced into the mass spectrometer.
4. Detection and Quantification: The mass spectrometer detects the ions whose abundance is measured. Finally, if we compare the signal obtained for each ion to known standards, we can determine the concentration of the elements present in the sample.

Interestingly, ICP-MS is highly sensitive and capable of detecting traces of elements in a wide range of samples.

Other Instrument option

Additional technologies may be necessary depending on the type of tested material and the desired detection level. Here are some of them:

ICP-OES

This Inductively Coupled Plasma Optical Emission Spectroscopy analyzes metals in samples by measuring emitted light wavelengths.

LC-MS-MS

The Liquid Chromatography-Tandem Mass Spectrometry combines chromatography and MS for sensitive and selective analysis of compounds.

HPLC

High-Performance Liquid Chromatography separates and quantifies components in a liquid sample using a high-pressure solvent flow.

GFAA

Graphite Furnace Atomic Absorption Spectroscopy detects trace metals in samples through the absorption of light.

GC-ECD

Gas Chromatography with Electron Capture Detection detects halogenated compounds using electron capture.

GC-FID

Finally, Gas Chromatography with Flame Ionization Detection quantifies organic compounds by measuring ionization produced in a flame.

What’s the bottom line? Since more restricted chemicals impact manufacturers of electronic products, it becomes critical to develop the right strategy and find the appropriate analytical testing method.

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