Analyzing Feedstock and Metal Powders with the Eltra Elementrac Series

Complex technical products such as airplanes, cars and bicycles will often contain smaller, less complex technical parts including bicycle frames or engines and gears, to guarantee their functionality. These smaller technical components again contain smaller, basic parts such as housings, gear wheels, screws, wires, and so on.

In the end, every single component can be traced back to the raw materials, which include pure metals or alloys such as copper, steel, titanium, or to synthetic organic products, which are also based on natural products like oil, gas or coal.

Besides the diversity of material compositions available for assembling complex technical products, the applied production technology is of particular interest. Traditional technical production methods include drilling, founding or welding, and several more. Additional descriptions and definitions of production methods are detailed in the German DIN 8580 standard.

When building a large, complex machine such as an airplane, more manufacturing steps are required. A fairly recent production method such as additive manufacturing (AM) can help overcome some of the drawbacks found in traditional production techniques, such as founding or welding, because complex structures can be generated in just a single step.

The DIN EN ISO/ASTM 52900:2018 standard (Additive manufacturing- General principles) describes additive manufacturing as a common term that denotes the technologies that produce physical objects by sequential addition of material, based on a geometrical representation. 

An AM machine that has the capacity to build the requested product is essential for this process. Meanwhile, AM products can be found across a variety of industries, including food, fashion and transportation.

Although the additive manufacturing method is completely different from traditional methods like founding or drilling, there is one key detail that they have in common: regardless of the use, size and geometry either of an AM or a traditionally manufactured product, a raw material with specific specifications is always used in production.

Traditional production methods usually require raw materials like solid steel or cast iron which are typically shaped as sheets, bars, tubes or wires.

Founding involves a liquid raw material that could be based on aluminum or any other alloy. AM raw materials are generally solid powders and are known as feedstock (chapter 3.6.6 of ASTM 52900).

Feedstock can be based on aluminum, cobalt, copper, iron, nickel, titanium, precious metals or customized mixtures. Independent of its shape, the chemical composition of the raw material will influence the mechanical properties of the final product.

The content of non-metals, such as carbon, sulfur or gases like oxygen, nitrogen and hydrogen, may impact the eventual brittleness, hardness and ductility of the end product.

Traditional production methods refer to well-established standards such as the ASTM E 1019 for good quality control of the raw material, while quality control of feedstock is a fairly recent development which can be challenging due to the powder shape and a wide range of chemical compositions.

The recent DIN EN ISO /ASTM 52907 from 2020 (Additive manufacturing- Feedstock materials methods to characterize metal powders) outlines the following technical parameters needed to characterize the quality of metal powder:

• Particle size distribution
• Chemical composition
• Characteristic densities
• Morphology
• Flowability
• Contamination
• (Packing, handling, storage) 

This article focuses on the chemical analysis of metal powders, specifically the measurement of oxygen, nitrogen, hydrogen as well as carbon and sulfur while detailing the current status of elemental analysis.

Figure 1. Product Video ELEMENTRAC CS-i analyzer. Video Credit: ELTRA GmbH

Chemical Composition 

The typical chemical characterization of metal powders comprises the identification of various metal elements like Mn, Fe and Cu, which may be present as a major or minor part, or even in traces. It also includes the determination of nonmetals and gases like carbon, sulfur, oxygen, nitrogen and hydrogen. For safe and reliable measurements of metals, nonmetals and gases, different analytical techniques are applied. 

The ASTM 52907 standard stipulates spectrometric methods such as AAS, X-Ray fluorescence analysis for the first group, and combustion and fusion techniques for the second group. 

Generally speaking, spectrometric techniques offer a reliable analysis of the metal parts, whereas combustion and fusion techniques provide a wide determination range of carbon, sulfur, oxygen, nitrogen and hydrogen. 

The ASTM 52907 standard refers to other established standards (table 1) for C/S and O/N/H analysis without additional special recommendations for powder analysis.

Table 1. Recommend standards for C/S and O/N/H analysis (ASTM 52907). Source: ELTRA GmbH

Matrix	Carbon	Sulphur	Oxygen	Nitrogen	Hydrogen
Steel and Iron	ISO 9556, or ISO 15349-2 or ISO 15350 or ASTM E1019	ISO 13902 or ISO 15350 or ASTM E1019	ISO 17053 or ASTM E1019	ISO 10720 and ISO 15351 or ASTM E1019	NN
Titanium and titanium alloys	ASTM E1941	NN	ISO 22963 or ASTM E1409	ASTM E1409	ASTM E1447
Nickel and nickel alloys	ISO 7524 or ASTM E1019	ISO 7526 or ASTM E1019	ASTM E1019	ASTM E1019	NN
Aluminium and aluminium alloys	NN	NN	NN	NN	ASTM E2792
Cobalt alloys	ISO 11873 or ASTM E1019	ISO 11873 or ASTM E1019	ASTM E1019	ASTM E1019	NN
Copper and copper alloys	NN	ISO 7266	ASTM E2575	NN	NN

 

To cover the entire range of C/S and O/N/H analyses, two different types of elemental analyzers are required, both of which are detailed in the ASTM E 1019 or E 1447. Combustion analyzers vary with regards to the integrated furnace type (induction or electrode), the applied carrier gas and the sample carrier (crucible) used. 

The common principle is the melting of the sample in a gas stream and measurement of the released gases in infrared (IR) or thermal conductivity cells (TCD). Table 2 shows some fundamental features of a C/S and O/N/H combustion analyzer.

Table 2. Technical features of combustion analyzers. Source: ELTRA GmbH

Elements	Technique	Carrier gas	Sample carrier	Sample weight (mg)	Suitable analyzer (ELTRA)
C/S	Combustion with induction furnace	Oxygen	Ceramic crucible	50-1000	ELEMENTARC CS-i (Fig.1)
O/N/H	Inert gas fusion via electrode (impulse) furnace	Helium / Nitrogen / (Argon)	Graphite crucible	50-3000	ELEMENTRAC ONH-p 2 (Fig. 2)

 

As previously mentioned, the ASTM 52907 standard refers to the established standards for C/S and O/N/H measurement without offering advice or hints for the appropriate processing of feedstock samples. This may lead to conflicts, as the well-established standards for elemental analysis (table 1) mainly focus on the analysis of solid samples or drillings.

This conflict is generally related to the sample preparation process rather than the technical specifications of the elemental analyzer (see table 3).

Table 3. Requirements for sample preparation according to selected standards (March 2021). Source: ELTRA GmbH

Standard	Carbon & sulfur measurement	Oxygen measurement	Nitrogen measurement
ASTM E 1019-18	Particle size >=0.422 mm (40 mesh)	Use only solid specimens (Caution: surface oxidation!)	Refers to ASTM E 1806 (describes preparation of chips, drillings, slugs, solids) - No powders-
ISO 170 53	NN	Refers to ISO 14284 (preparation of pins for oxygen measurement)	NN
ISO 15350	Refers to ISO 14284 (various techniques for C/S analysis: Usually preparation of drillings)	NN	NN
ASTM E 1409	NN	Describes only solid pieces and required surface treatment

 

Table 3 shows that the correct C/S and O/N/H analysis of feedstock can be a challenge due to the inconsistent requirements of the different standards. Detailed steps of the measuring process, typical analyzers, settings and sample preparation are explained below. 

This article presents analysis data of various powders measured with ELTRA’s ELEMENTRAC ONH-p2 and CS-i analyzers, including the settings applied and sample preparation process. This data shows that the analysis of feedstock samples is safe, reliable and straightforward, as long as certain aspects are taken into account. 

The ELEMENTRAC ONH-p2 Analyzer 

The powerful ELEMENTRAC ONH-p2 is an inert gas fusion analyzer that uses an 8.5 kW electrode furnace, two infrared cells and a wide range thermal conductivity cell for the reliable and safe analysis of oxygen, nitrogen and hydrogen. For trained and untrained users alike, performing an analysis is conveniently straightforward and safe. 

Figure 2.  Product Video ELEMENTRAC ONH-p2. Video Credit: ELTRA GmbH

The sample is logged in the ELEMENTS software with its weight, followed by the application to the sample port and starting the measurement in the software. All subsequent steps are done automatically.

Once software analysis begins, the sample port closes and the sample is flushed with a carrier gas, which stops atmospheric gas (oxygen and nitrogen) from entering the furnace. 

Meanwhile, the outgassing of a graphite crucible is performed in the impulse furnace of the analyzer to eliminate potential contaminations. After a short stabilization phase, the sample is placed into the crucible and melts. 

A sealing of capsules (which contain the powder) is not necessary due to the vertical sample transfer to the crucible (fig. 3) in combination with the effective flushing. This streamlines the whole analysis process of feedstock and any other powdered samples. 

Figure 3. Sample port and furnace of the ELEMENTRAC ONH-p2. Image Credit: ELTRA GmbH

In the following, carbon monoxide is produced by the reaction of carbon in the graphite crucible and oxygen of the sample. Nitrogen and hydrogen are produced in elemental form.  The carrier gas (helium) and sample gasses pass through a filter before crossing a copper oxide catalyst which converts the CO to CO₂. The CO₂ is measured by the infrared cells to establish the oxygen content. CO₂ and water are chemically eliminated, and the nitrogen content is measured in the thermal conductivity cell. 

In the case of hydrogen analysis, both the nitrogen carrier and sample gas pass through a Schuetze reagent rather than a copper oxide catalyst. The less expensive Argon can be used as an option to measure the oxygen and nitrogen content throughout the analysis. 

The ELEMENTRAC CS-i Analyzer 

The elemental analyzer ELEMENTRAC CS-i measures the carbon and sulfur concentration in mostly inorganic samples by means of combustion in an induction furnace and subsequent analysis of the gaseous combustion products carbon dioxide and sulfur dioxide in up to 4 infrared cells.

The high temperature – in excess of 2000 °C – guarantees total decomposition of the sample and, therefore, ensures reliable and accurate elemental analysis across a wide concentration range.​​​​ 

An accelerator like tungsten (approx. 1.7 g) must be added (fig.4) after weighing a feedstock sample in a ceramic crucible and logging the sample in the ELEMENTS software. 

Figure 4. Applying accelerator to a weighed sample. Image Credit: ELTRA GmbH

After positioning the sample on the pedestal (fig. 5) and initiating the analysis, all following steps are automatically processed. In the induction furnace of the elemental analyzer, the sample and accelerator are melted in a pure oxygen atmosphere, causing sulfur to react to sulfur dioxide (SO₂) and carbon to a mixture of carbon monoxide (CO) and carbon dioxide (CO₂). 

Figure 5. Placing sample with accelerator on the pedestal of the ELEMENTRAC CS-i. Image Credit: ELTRA GmbH

For purification, the combustion gases pass a dust filter and moisture absorber. In the subsequent step, sulfur dioxide is found in infrared cells. In the CS-i, infrared cells with varying sensitivities (high/low) can be modified in line with the user’s requirements. 

Oxidation of both carbon monoxide to carbon dioxide and sulfur dioxide to sulfur trioxide follow the sulfur measurement. The SO₃ gas is then eliminated using cellulose wool, and the carbon content is detected by infrared cells. 

Sample-Related Settings and Preparation for ONH Analysis 

For each metal powder, an individual application has to be developed first which considers the sample amount available, the chemical nature of the sample, as well as the particle shape and size. 

These specifications determine the maximum appropriate amount of sample for a single analysis, the sample preparation required and, of course, the analysis power used in the application. The following diagram shows the general procedure:

Image Credit: ELTRA GmbH

Generally, samples for additive manufacturing are fine powders (fig. 6). These samples always require a nickel capsule prior to being applied to an elemental analyzer. Without it, they could cause blockages, meaning the complete transfer to the graphite crucible would be unsafe.

Figure 6. (above) Fine powder needs to be placed in a capsule before analysis in the ONH-p2. (below) Granulate / drilling (ironbased) can be analyzed without capsule. Image Credit: ELTRA GmbH

Depending on the chemical nature of the powder, additional sample preparation steps are necessary for a valid oxygen and nitrogen analysis. 

Refractories and precious metals like titanium, palladium and platinum have a high melting point. To guarantee a complete release of the embedded gases, extra flux needs to be provided. To reduce the melting point of the resulting alloy in the crucible, the nickel capsule with the high-melting sample is inserted into an additional nickel basket. 

For analysis to be reliable, the sample amount is generally restricted to 50-100 mg for oxygen and nitrogen measurement (fig. 7). Since hydrogen is released much easier from the sample in case of hydrogen analysis, the sample amount can be increased, and a nickel basket is not required. 

Figure 7. Application of a nickel basket (flux for precious metals and refractories). Here without the nickel capsule and sample. Image Credit: ELTRA GmbH

ELTRA advises that you apply tin flux to the graphite crucible to ensure a smooth release of the embedded hydrogen. 

Sample-Related Settings and Preparation for CS Analysis

For a reliable CS measurement, fewer parameters must be considered compared to an ONH measurement. In general, the particle size distribution is negligible, but because of the intensive combustion, the potential to lose sample material due to swirling has to be taken into account. With typical sample weights of 250-500 mg, the sample is completely covered with an accelerator, and swirling is negligible. 

For greater sample weights, the ELEMENTRAC CS-i offers special solutions like induction power control and intelligent oxygen supply to guarantee smooth and complete combustion that is free of sample dust caused by swirling or sputtering. 

Depending on the base of the feedstock, various accelerators have to be added to ensure total oxidation of the embedded carbon and sulfur. The table below summarizes conventional sample weights and recommended accelerators:

Table 4. Source: ELTRA GmbH

Feedstock base	Recommended sample weight for analysis (mg)	Recommended accelerator
Iron, nickel, cobalt	250-1000 mg	Tungsten (1.7 g)
Copper	1000 mg	Copper (2 g) alternatively: Copper (1 g) + Iron (0.7 g)
Refractories; precious metals	Up to 250 mg	Tungsten/tin (2 g) ; alternatively tungsten (1.7 g)/iron (0.7 g)

 

Copper is printed in italic letters as the analysis of copper-based or copper-containing samples can be critical regarding precise and reliable sulfur analysis in general. Intensive combustion could result in too low sulfur determination induced by the forming of copper sulfide (ASTM E1941-10; Note 7). 

A technical solution for this situation is implemented in the ELEMENTRAC CS-i. A reliable sulfur analysis in copper or even copper concentrates can be attributed to the intelligent oxygen supply and ramping feature, which facilitates smooth combustion without a form of copper sulfide. For more information, request the ELTRA application notes 1037 and 1066 

Application Examples

In the following, standard analysis data for various sample shapes with different bases are displayed. The data provided is based on both the analysis of customer samples and the analysis of certified reference materials. 

a) Analysis of Steel Granulates (CRM)

Table 5. Source: ELTRA GmbH

.	.
Analysis	Oxygen and nitrogen with ELEMENTRAC ONH-p 2
Sample	EZRM 284-2
Sample preparation	None. Direct application to the furnace (see picture 8)
Settings	Standard steel analysis with 4500 W; 2,5 -3 min. cycle time per sample

 

Figure 8. Direct application of steel granulate. Image Credit: ELTRA GmbH

Table 6. Source: ELTRA GmbH

Typical results
Steel granulate ZRM 284-2*
Weight (mg)	Oxygen (ppm)	Nitrogen (ppm)
1018	99.7	148.8
1057	96.5	152.6
1036	99.3	150.3
1027	99.1	150.6
1015	97.7	151.5
1021	102.0	150.1
1020	98.4	153.4
1035	99.2	150.0
1029	99.8	149.0
1011	98.1	153.4
Mean value
	99.0	151.0
Deviation / Relative deviation (%)
	1.5 (1.5)	1.7 (1.1)

* Certified value: O 99 +- 7 ppm; N 151 +- 2 ppm

Measuring graph
blue peak: oxygen signal	yellow peak: nitrogen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

Table 7. Source: ELTRA GmbH

.	.
Analysis	Carbon and sulfur with ELEMENTRAC CS-i
Sample	JSS003-8
Sample preparation	None
Settings	Accelerator 1.7 g tungsten Cycle time: 90 seconds/ analysis

 

The analysis data may not be representative of a typical feedstock sample, but it shows that even very low carbon and sulfur concentrations can be reliably measured with precision.

Table 8. Source: ELTRA GmbH

Typical results
JSS 003-8 *1
Weight (mg)	Carbon (ppm)	Sulfur (ppm)
1093	3.9	1.5
1069	4.4	1.8
1026	4.0	1.8
1002	4.3	1.7
1095	3.5	1.5
1034	4.0	1.4
1082	4.2	1.5
1007	4.2	1.5
1093	3.9	1.6
1044	4.0	1.5
Average values
	4.1	1.6
Deviation / Relative deviation (%)
	0.26 (6.3%)	0.1 (9.4%)

 

Measuring graph
blue peak: carbon signal	yellow peak: sulfur signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

b) Analysis of Nickel Feedstock

Table 9. Source: ELTRA GmbH

.	.
Analysis	Oxygen and nitrogen with ELEMENTRAC ONH-p 2
Sample	Nickel powder from ASTM Cycle AMPM 2010
Sample preparation	Sample filled in nickel capsule (see picture 9)
Settings	Standard steel analysis with 4500 W; 2,5 -3 min. cycle time per sample

 

Figure 9. Application of open capsule with powder. Image Credit: ELTRA GmbH

Table 10. Source: ELTRA GmbH

Typical results
Nickel powder ASTM AMPM 2010
Weight (mg)	Oxygen (ppm)	Nitrogen (ppm)
260	198	108
250	199	111
225	202	105
243	199	108
227	203	108
287	202	106
233	203	107
291	203	105
270	202	109
255	199	108
Mean value
	201	107
Deviation / Relative deviation (%)
	2.0 (1.0)	1.7 (1.6)

* Certified value: not available

Measuring graph
blue peak: oxygen signal	yellow peak: nitrogen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

The oxygen content measured is informative and was not included in the ASTM cycle. As a result of the fine particle size of the powder oxidizing, a surface oxidizing during storage time may be possible.

Table 11. Source: ELTRA GmbH

.	.
Nickel powder ASTM AMPM 20210: measurement after 12 weeks storage in a sealed, brown glass bottle (150 ml)
Oxygen (N=4)	199 +- 1,2 ppm
Nitrogen (N=4)	109 +- 2 ppm

 

For an initial evaluation of a possible oxidation effect, the measurement was repeated after 12 weeks. For O/N analysis, another aliquot was utilized, which was stored for 12 weeks inside a 150 ml brown glass bottle. 

Table 12. Source: ELTRA GmbH

.	.
Analysis	Oxygen and nitrogen with ELEMENTRAC ONH-p 2
Sample	Nickel powder from ASTM Cycle AMPM 2010
Sample preparation	None
Settings	Accelerator 1.7 g tungsten Cycle time: 90 seconds/ analysis

 

Table 13. Source: ELTRA GmbH

Typical results
Nickel powder ASTM AMPM 2010
Weight (mg)	Carbon (ppm)	Sulfur (ppm)
499.4	250.1	11.2
499.8	250.9	10.4
499.5	248.8	9.1
500.1	250.9	12.5
500.6	248.3	11.8
500.8	242.9	9.9
500.8	248.5	9.9
500.5	246.9	9.0
499.4	250.8	11.8
500.9	250.3	11.1
Mean value
	248.8	10.7
Deviation / Relative deviation (%)
	2.5 (1.0)	1.2 (11.2)

* Certified value: not available

Measuring graph
blue peak: carbon signal	yellow peak: sulfur signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

c) Analysis of Iron/Nickel Feedstock 

Table 14. Source: ELTRA GmbH

.	.
Analysis	Oxygen, nitrogen and hydrogen with ELEMENTRAC ONH-p 2
Sample	Customer sample: iron/nickel powder
Sample preparation	Sample filled in nickel capsule
Settings	Standard steel analysis with 4500 W (ON) Standard steel analysis with 3600 W (H)

 

Table 15. Source: ELTRA GmbH

Typical results
Customer sample Fe/Ni powder
Weight (mg)	Oxygen (ppm)	Nitrogen (ppm)
158	479	327
154	473	328
152	455	330
157	457	330
Mean value
	466	329
Deviation / Relative deviation (%)
	11.8 (2.5%)	1.47 (0.4%)

 

Measuring graph
blue peak: oxygen signal	yellow peak: nitrogen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

For reliable hydrogen measurements, the ELEMENTRAC ONH-p 2 uses a TC cell and the less expensive carrier gas - nitrogen. Generally, hydrogen leaves the sample in elemental form and necessitates a reduced power analysis for a repeatable measurement: 

Table 16. Source: ELTRA GmbH

Typical results
Customer sample Fe/Ni powder
Weight (mg)	Hydrogen (ppm)
399	11.8
400	11.9
402	13.5
399	11.78
Mean value	12.28
Deviation	0.83
Relative deviation (%)	6.8

 

Measuring graph
yellow peak: hydrogen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

After two weeks, the measurement was repeated for additional analysis of the stability of the oxygen results. The customer sample was kept in a sealed transparent plastic bag. 

Table 17. Source: ELTRA GmbH

.	.
Fe/Ni feedstock: New measurement after 2 weeks of storage in a plastic bag
Oxygen (N=4)	469 +- 10.9 ppm
Nitrogen (N=4)	333 +- 3.6 ppm

 

Similar to the ASTM sample, no notable increase of the measured oxygen or nitrogen content could be seen. 

Table 18. Source: ELTRA GmbH

.	.
Analysis	Carbon and sulfur with ELEMENTRAC CS-i
Sample	Iron/Nickel feedstock (customer sample)
Sample preparation	None
Settings	Accelerator 1.7 g tungsten Cycle time: 90 seconds/ analysis

 

Table 19. Source: ELTRA GmbH

Typical results
Customer sample Iron/Nickel Feedstock
Weight (mg)	Carbon (ppm)	Sulfur (ppm)
500.4	176.3	153.5
500.3	186.6	166.1
500.4	183.7	166.2
Mean value
	182.2	161.9
Deviation / Relative deviation (%)
	5.3 (2.9)	7.3 (4.5)

 

Measuring graph
blue peak: carbon signal	yellow peak: sulfur signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

d) Oxygen and Hydrogen Analysis in Precious Metals 

Table 20. Source: ELTRA GmbH

.	.
Analysis	Oxygen and hydrogen with the ELEMENTRAC ONH-p 2
Sample	Customer sample: PD sponge
Sample preparation	Sample filled in nickel capsule for H analysis Sample filled in nickel capsule and basket for ON analysis
Settings	Standard titanium analysis with 5600 W (ON) Standard titanium analysis with 3600 W (H)

 

Due to the expense, precious metals like gold, platinum or palladium are not in extensive use for feedstocks in additive manufacturing. As a result of their high melting point, the analysis of oxygen, nitrogen and hydrogen is almost identical to the analysis of titanium.

Compared to steel- or titanium-based feedstock, the carbon, sulfur and nitrogen content is typically deemed less important, and as such, was not measured in this example. 

Table 21. Source: ELTRA GmbH

Typical results
Customer sample Pd sponge
Weight (mg)	Oxygen (ppm)
69	361
76	330
81	360
Mean value (ppm)	350
Deviation	17
Relative deviation (%)	4

 

Measuring graph
blue peak: oxygen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

Table 22. Source: ELTRA GmbH

Typical results
Customer sample Pd sponge
Weight (mg)	Hydrogen (ppm)
69	30
56	36
56	34
Mean value (ppm)	33
Deviation	3
Relative deviation (%)	9.5

 

Measuring graph
yellow peak: hydrogen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

Table 23. Source: ELTRA GmbH

.	.
Analysis	Oxygen and hydrogen
Sample	Customer sample: Pt sponge
Sample preparation	Sample filled in nickel capsule for H analysis Sample filled in nickel capsule and basket for ON analysis (fig. 7)
Settings	Standard titanium analysis with 5600 W (ON) Standard titanium analysis with 3600 W (H)

 

Table 24. Source: ELTRA GmbH

Typical results
Customer sample Pt sponge
Weight (mg)	Oxygen (ppm)
93	301
86	321
109	327
Mean value (ppm)	316
Deviation	13
Relative deviation (%)	4

 

Measuring graph
blue peak: oxygen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

Table 25. Source: ELTRA GmbH

Typical results
Customer sample Pt sponge
Weight (mg)	Hydrogen (ppm)
74	31
124	26
117	27
Mean value (ppm)	28
Deviation	2.5
Relative deviation (%)	8.9

 

Measuring graph
yellow peak: hydrogen signal
x-axis: time (sec)	y-axis: intensity (voltage)

Image Credit: ELTRA GmbH

Conclusion

The ELTRA ELEMENTRAC series makes analysis of feedstock, granulates and other powders safe, straightforward and reliable. The ELEMENTRAC CS-i and ONH-p2 ensure precise measurements when analyzing different materials such as iron, nickel and even platinum and palladium across a wide concentration range. 

The publication of the DIN EN ISO/ASTM 52907 is an excellent starting point for the quality control process of feedstock, but a more comprehensive guide could prove useful to ensure reliable measurement results. 

This is especially true where process steps such as sampling, preparation and storage of feedstocks are concerned and should be evaluated further in the future to guarantee valid C/S and O/N/H measurements over a broad sample range and a prolonged period of time.

This information has been sourced, reviewed and adapted from materials provided by ELTRA GmbH.

For more information on this source, please visit ELTRA GmbH.