Manual EDX 700 Shimadzu

Instruction Manual P/N 305-32056A

About this manual

This manual describes how to make analytical condition for measuring hazardous elements elements (Cd, Pb, Hg, Cr and Br) in EDX series. The descriptions are based on the functionality offered offered by EDX software version 1.00, release 017. Furthermore, the parameters described described in this man ual are based primarily on examples of settings for elements in plastic.

Contents

About this manual

1. Sensitivity and Precision in X-Ray Fluorescence Spectrometry.. Spectrometry........ ............ ............ ............ ............ ........... ..... 1.1 Precision Precision of X-Ray X-Ray Spectrome Spectrometry try ...................................................... 1.1.1 Standa Standard rd Deviation Deviation ...................................................... 1.1.2 Lower Lower Detectio Detection n Limit Limit ...................................................... 1.2 Differences Differences in Sensitivity Due to Sample Material and Shape ............ ...... ............ ............ ............ ........ 1.2.1 Differences Differences in Sensitivity Due to Sample Material .......... ............ ...... ............ ............ ............ ........ .. 1.2.2 Differences Differences in Sensitivity Due to Sample Size or Thickness ............ ...... ............ ............ ......... ... 1.2.3 Scattered X-ray and Fluorescent X-ray ............ ...... ............ ............ ............ ............ ............ ............ ............ ...... 1.2.4 Correcti Correcting ng for for Sample Sample Shape Shape and Material Material ...................................................... 2. Analytical Analytical Conditions Conditions ...................................................... 2.1 Example Example of Setting Setting Paramete Parameters rs ...................................................... 2.1.1 Example Example of Setting Setting Paramete Parameters rs ...................................................... 2.2 Key Points for for Setting Setting Paramete Parameters rs ...................................................... 2.2.1 Overview Overview ...................................................... 2.2.2 Element Element Registra Registration tion ...................................................... 2.2.3 Element Element Informatio Information n ...................................................... 2.2.4 Measurem Measurement ent Conditions Conditions ...................................................... 2.2.5 Proces Processs for Spectra Spectra ...................................................... 2.2.6 Internal Internal Standa Standard rd Correctio Correction n ...................................................... 2.2.7 Result Result Format Format ...................................................... 2.2.8 Standa Standard rd Sample Sample Registra Registration tion ...................................................... 2.2.9 Standa Standard rd Sample Sample Measurem Measurements ents ...................................................... 2.2.10 Calibratio Calibration n Curve Curve Preparatio Preparation n ...................................................... 3. Controlling Controlling Precisio Precision n ...................................................... 3.1 Drift Drift Check Check Analysis Analysis ...................................................... 3.1.1 Analyzing Analyzing Control Control Sample Sample ...................................................... 3.1.2 Results Results Outside Outside the Control Control Range ...................................................... 3.2 Drift Drift Standar Standardizat dization ion ...................................................... 3.2.1 What What is Drift Drift Standard Standardizatio ization? n? ...................................................... 3.2.2 Registration of Reference Intensities for Standardization Standardization Samples ............ ...... ............ ...... 3.2.3 Drift Drift Coeff Coefficient icient Renewal Renewal ...................................................... 3.2.4 Drift Drift Coeff Coefficient icient Criteria Criteria ...................................................... 3.3 Measureme Measurement nt Time Time Reductio Reduction n ...................................................... 3.3.1 Measurem Measurement ent Time Time Reductio Reduction n ...................................................... 4. Interpreti Interpreting ng Data Data and Making Making Determina Determination tion ...................................................... 4.1 The possibility possibility of Determina Determination tion Errors Errors ...................................................... 4.1.1 Determination Determination Errors Due to Overlapping Spectra ......... ............ ...... ............ ............ ............ ......... ... 4.1.2 Determination Determination Errors Due to Diffracted Diffracted Lines ....... . ............ ............ ............ ............ ............ ............ ........... ..... 4.2 ExReport ExReport Function Function ...................................................... 4.2.1 ExReport ExReport Function Function ...................................................... 5. Hints Hints for for Configuri Configuring ng Conditions Conditions ......................................................

1 1 1 2 3 3 4 4 5 6 6 6 6 6 8 9 10 12 13 14 15 17 18 22 22 22 22 23 23 23 27 28 29 29 30 30 30 31 32 32 33

1. Sensitivity and Precision of X-Ray Fluorescence Spectrometry

The precision level of x-ray fluorescence analysis is related to th e standard deviation of the x-ray intensity from target elements. In general, the standard deviation of the x-ray count for an x-ray measurement is expressed as the square root of the x-ray counts, where Standard Deviation of X-Ray Intensity (Count) =

X-Ray Counts

In the case of x-rays per unit time (cps), the standard deviation is as follows. Standard Deviation of X-Ray Intensity (cps) =

X-Ray Counts

/

Measurement Time (sec)

The x-ray count is proportional t o the measurement time, having the following relationship. When Time is Doubled -->

Std. dev. of x-ray intensity (count) is multiplied by  Std. dev. of x-ray intensity (cps) is multiplied by 1/2 (or 2/2)

When Time is Quadrupled --> Std. dev. of x-ray intensity (count) is multiplied by 2 (or 4) Std. dev. of x-ray intensity (cps) is multiplied by 1/2 (or 4/4) Therefore, when the measurement time is increased, the standard deviation of intensity (cps) decreases. In other words, the longer the m easurement time, the higher the reliability of measurement values.

1


The minimum level of target elements that can be detected is determined by th e following parameters. a) Standard deviation Bo f intensity for a sample containing no target elements. b) Calibration curve coefficient b In general, the lower detection limit is defined as 3 x B x b.

2


The minimum detectable quantity will vary depending on the sample material. The reasons for this variation are as follows. a) X-ray fluorescence emission from target elements is absorbed by surrounding materials. b) Primary x-rays from the x-ray tube are absorbed by the surrounding material and do not excite the target elements. Generally high atomic number materials absorb more x-ray than low atomic number material. In addition, absorption also increases if the material has a hi gher density. Therefore, in general, sensitivity is higher in plastics and lower in metals, as shown in the example below.

Differences in Lower Detection Limits Due to Sample Material (as a proportion of the detection limit for target elements in polyethylene) Polyethylene

PVC

Aluminum

Copper

Tin

Lead

Cd

1

1.2

1.5

6

50

200

Pb

1

2.3

2.5

20

30

---------

Note that even though they are both plastics, the lower detection limit for polyethylene and polyvinyl chloride (PVC) is quite different. This is due t o x-ray fluorescence from target elements being absorbed by the chlorine contained in polyvinyl chloride.

3


Theoretically, the larger the sample is, th e greater the x-ray intensity is. This also applies to thickness. X-ray intensity is greater for thicker samples.

The x-ray irradiation diameter can be changed using an optional collimator. Using a smaller diameter for analysis generally decreases x-ray intensity levels. However, for samples comprised of di ffering sections, this can reduce the undesirable x-rays emitted from non-target areas, improving the relative sensitivity for the target area.

In general, thicker samples result in higher x-ray intensities, but x-ray intensity does not increase when it reaches a certain constant thickness. That saturation thickness varies depending on th e sample material. For the EDX series, the following table shows the saturation thickness of X-ray intensity for different sample materials. Polyethylene

PVC

Aluminum

Copper

Tin

Lead

Cd

5mm

5mm

3mm

100m

150m

20m

Pb

5mm

0.7mm

0.5mm

20m

30m

---------

When primary x-ray from x-ray tube irradiates to a sample, fluorescent x-ray and scattered x-ray are both detected. Fluorescent x-ray is x-ray generated when primary x-ray excites target elements in a sample. Scattered x-ray is detected as background intensity. This scattered x-ray includes valuable information also, such as the sample size, thickness and composition.

4


Even for samples having the same concentration level, intensities vary depending on sample size and thickness. This affects the calculated quantitative values. To avoid th is bias, differences in quantitative values due to sample size and thickness can be corrected by preparing calibration curves using the ratio between fluorescent x-ray and scattered x-ray intensities.

In the case of plastics, there is a significant difference in sensitivity between polyethylene and PVC. Therefore, if calibration curves are prepared without factoring in intensity ratios, the calibration curve coefficient values for lead, for example, will differ by 3 t o 5 times. Using BG internal standard correction compensates to some degree for the difference in calibration curve coefficients, but even so, the difference can be 1.2 to 2 times, depending on the element. For that reason, th ese spectrometers allow switching between calibration curves prepared using standard samples containing chlorine and not containing chlorine.

5

2.Analytical Conditions

As an example of how to set up parameters for analyzing hazardous elements, the EDX software includes the following file. Folder:

c:\edx\user\grpqn\rohs_ex

Group Name: [Quantitative] Plastic5Elem

Refer to Section 4.2 in the main EDX unit instruction manual regarding calibration curve measurements using standard samples. For p lastic samples, commercially marketed 5-element standard samples for EDX systems can be used as standard samples. This section indicates some important points for preparing calibration curves using standard plastic samples.

6

2. Analytical Conditions

[Example] Element



Register Cd,Pb,Hg,Cr,Br in Periodic Table.

Registration



Also register Cl,Sb.

Element



“Quant.” – Calibration

Information



“Correct”



Change Line to La.



Change Unit to ppm.

Measurement Condition ( For EDX-720 )

Curve

For Cd,Pb,Hg,Cr,Br

For Cl,Sb For Pb For Cd,Pb,Hg,Cr,Br

Voltage

Meas. Time (sec)

Filter (*1)

DT%(*2)

Cd

50kV

100

MoNi

40

Sb

50kV

100

MoNi

40

Pb

50kV

100

Ag

40

Hg

50kV

100

Ag

40

Br

50kV

100

Ag

40

Cl

50kV

100

Ag

40

Cr

30kV

100

Al

40

Smoothing

Process for

No. of Points

Spectra

Repeat

BG Calculation Repeat Times

Times

Calculation Points

Cd

11

1

100

20

Sb

11

1

100

20

Pb

11

1

100

5

Hg

11

1

100

5

Br

11

1

100

5

Cl

5

1

100

5

Cr

11

1

100

5

Internal Standard



With internal standard correction

For Cd,Pb,Hg,Cr,Br,Cl

Correction



Without internal standard correction

Calibration



Multiple calibration curve -- Set “Co-Exist”m ode with Cl.

For Sb

For Pb,Hg,Br,Cr

Curve Result Format



Digit -- Set “Place of Decimal” to 1. For Cd,Pb,Hg,Br,Cr

(*1) For EDX-700HS/800HS, use Mo filter instead of MoNi filter. Use Ni filter instead of Ag filter. For EDX-900HS, use Zr filter instead of a MoNi filter. Use Ni filter instead of Ag filter. (*2) For EDX-700HS/800HS spectrometers, set DT% to 25. For EDX-900HS, set DT% to 10. 7


Register Cd, Pb, Hg, Cr and Br via the periodic table. In a ddition, register Cl and Sb as elements for correction.

8


For Cd, enter the following element information. 0û

Proc. – Calc.

Quant.

0û

Type of Quantification

Calibration Curve

0û

Unit

ppm

Enter settings for Pb, Hg, Cr and Br in the same way. However, in the case of Pb, also change the line to “La”.

For Cl and Sb, enter the following element information. 0û Proc. – Calc.

Correct

9


For Cd, enter the following measurement conditions. Voltage :

50 kV

Current :

Auto

Filter(*1) :

MoNi

Integration Time :

Live Time and

DT%(*2) :

40

Intensity Calculation :

Fitting

Analysis Range (keV) :

22.72 – 23.52

10

100 sec


Similarly, use the following table t o enter settings for the other elements. Regarding other parameters, set Current to “Auto”f or all of th e elements, and Intensity Calculation Method to “Fitting”. The initial voltage setting for Cl is 15 kV. In this case, change it to 50 kV to allow simultaneous measurement with Pb, Hg and Br. Voltage

Meas.Time (sec)

Analysis Range(keV)

Filter(*1)

DT%(*2)

Cd

50kV

LiveTime

100

22.72-23.52

MoNi

40

Sb

50kV

LiveTime

100

25.88-26.68

MoNi

40

Pb

50kV

LiveTime

100

10.32-10.82

Ag

40

Hg

50kV

LiveTime

100

9.74-10.24

Ag

40

Br

50kV

LiveTime

100

11.66-12.16

Ag

40

Cl

50kV

LiveTime

100

2.42-2.82

Ag

40

Cr

30kV

LiveTime

100

5.12-5.62

Al

40

(*1) For EDX-700HS/800HS, use Mo filter instead of MoNi filter. Use Ni filter instead of Ag filter. For EDX-900HS, use Zr filter instead of a MoNi filter. Use Ni filter instead of Ag filter. (*2) For EDX-700HS/800HS spectrometers, set DT% to 25. For EDX-900HS, set DT% to 10.

11


For Cd, enter the following peak integration settings. Smoothing

BG Calculation

Number of Points :

11

Repeat Times :

1

Method:

Savitzky-Golay

Repeat Times :

100

Calculation Points :

20

Similarly, use the following table t o enter settings for the other elements. Smoothing

BG Calculation

No. of Points

Repeat Times

Repeat Times

Calculation Points

Cd

11

1

100

20

Sb

11

1

100

20

Pb

11

1

100

5

Hg

11

1

100

5

Br

11

1

100

5

Cl

5

1

100

5

Cr

11

1

100

5

12


For Cd, enter the following internal standard correction settings. Correction :

On

Internal Std. Line :

CdKa_BG

Similarly, enter the internal standard settings for Pb, Hg, Br, Cr and Cl. However, do not enter int ernal standard settings for Sb.

13


For Cd, enter the following format settings for the number of digits to di splay. Place of Decimal

1

Similarly, enter the result format settings for Pb, Hg, Br and Cr.

14


Register standard sample names via “Standard Sample Name” window.

Example: Using both standard PVC samples and standard PE samples. Standard PVC Samples

Standard PE Samples

PVC-1

PE-1

PVC-2

PE-2

PVC-3

PE-3

PVC-4

PE-4

PVC-5

PE-5

PVC-6

PE-6

15


Next, enter standard values via “Standard Value Input” window.

After entering the values, close the window by clicking [OK]. Then click [Apply] in the Standard Sample window to confirm the settings.

Once all the necessary settings have been entered, save the current parameters via the “File”m enu in the Group Condition window, then close the Group Condition window.

16


Next, measure x-ray intensities of the standard samples. From the Sample Schedule in the Analysis window, open the Sample Registration window and select the group file just created. Select “Standard” from “Purpose of Measurement”f ield. Then the standard samples registered appear automatically in th e Sample Name fields.

Click [Apply] to register the standard samples in th e Sample Schedule. Place the first standard sample in the instrument. Then click [Start] button in the Analysis window to start measurement. After the first sample has been measured, the sample chamber will open automatically. After exchanging samples, click the [Start] button to resume measurement.

17


Open the group condition a fter the standard sample measurements finished. Open Calibration Curve window to calculate calibration curve coefficient. Click [Calculate] to calculate coefficient and click [Apply] to save the r esult.

18


If standard samples of both PVC and PE are measured, it is possible to switch automatically between calibration curves calculated with and without chlorine. An example for Pb is shown below.

Set parameters as follows. a) Click [Multiple Calibration Curve] to open “Multiple Calibration Curve” window. b) Choose [Co-Exist] as “Use for ”. c) Select Cl from the list of choice displayed. d) Set “ Number of Curves” to 2. e) Enter 2.0 in the “Boundary” field. Once the settings have been entered, click [OK]. Now that settings are configured for multiple calibration curves, back in the Calibration Curve window, a choice of 1 or 2 is available in the “Curve No.”f ield.

19


Select calibration curve number 1 and click [Calculate]. This will calculate a calibration curve using standard sample Cl intensities ratio that are below 2.0.

In other words, this calculates the calibration

curve for the standard PE sample.

Next, select calibration curve number 2 and click [Calculate]. This will calculate a calibration curve using standard sample Cl intensities (ratio) that are 2.0 or higher.

In other words, this calculates the

calibration curve for the standard PVC sample.

Once both calibration curves are calculated, click [Apply] to save th e results.

20


Settings for Pb, Hg, Br and Cr are also configured for automatic switching between calibration curves. For Cd, the difference between coefficients for PVC and PE is not large, so the process of configuring automatic switching between calibration curves may be skipped.

21

3. Controlling Precision

It is possible to determine whether an instrument is working normally or not by analyzing control samples and confirming whether the quantitative values are within their respective control ranges. Normally, of the standard samples used to prepare calibration curves, the sample with the highest concentration is analyzed and the qu antitative values are checked to determine whether they are within the control range. The control range is determined as approximately three times the standard deviation for repeated measurements of a control sample or approximately three times the standard deviation indi cated in the quantitative results for a single measurement. Make sure the energy calibration has been done before analyzing control samples.

There is a possibility that x-ray intensity changes due to changes in the instrument over time or due to other reasons. If energy calibration is normal and values of control sample analysis are outside the control range, x-ray intensity values can be corrected using drift standardization.

22


The intensity of standardization samples are measured and registered in advance. Then, if th e control sample analysis results in values outside the control range, re-measure the intensity of th e standardization sample. Any change in intensity can be corrected by multiplying the ratio of reference intensity to the current intensity of the standardization sample. This is referred to as drift standardization.

Register standardization samples to the group condition used to create calibration curve. Open “Standardization Sample” tab of

indow “Standardization”w

23

to register standardization samples.


Next, open “Drift Coefficient”t ab and turn drift standardization on by checking the checkbox to the left of each element name. Also, set “alpha-Control Range”t o 0.8 to 1.2. If low concentration standardization samples will also be analyzed, set “ beta-Control Range” to -1.0 to 1.0.

Once the settings have been entered, click [OK] to close “Standardization”w indow. Then save the group condition via the File menu.

24


The intensity of standardization samples is registered via the Analysis window, in the same manner as for standard sample measurements. From “Sample Schedule”i n the Analysis window, open “Sample Registration”w indow and select the group condition that was just saved. Then select “Drift Standardization” and “Purpose

“Intensity Registration” from

of Measurement”s ection. This will cause th e standardization samples, registered when

parameters were entered, to appear automatically in the sample name fields.

Click [Apply] to register the standardization samples in the Sample Schedule. Place the first standardization sample in the instrument. Then click [Start] button in the Analysis window to start measurement.

25


The measured intensities are automatically registered in the original group condition. The intensities can be confirmed via “Standardization Sample”t ab in

“Standardization” window.

26


If control samples are analyzed and results are not within control range, try to measure the standardization samples and calculate drift coefficient. Drift coefficient can be calculated via the Analysis window, in the same manner as for registering intensities for standardized samples. From “Sample Schedule”i n the Analysis window, open “Sample Registration”w indow and select the group condition that was just saved. Then select “Drift Standardization” and “Purpose

“Coefficient

Renewal” from

of Measurement”s ection.

Click [Apply] to register the standardization samples in the Sample Schedule. Place the first standardization sample in the instrument. Then click [Start] button in the Analysis window to start measurement.

27


The drift coefficient is calculated automatically after the measurement is finished and displayed on “Result

Display”w indow. These results are automatically saved into the original group condition only if

the drift coefficient is within th e control range.

If the alpha drift coefficient is n ot between 0.8 and 1.2, n ew calibration curves need to be prepared. Refer to Sections 2.2.8 “Standard Sample Registration”t hrough 2.2.10 “Calibration Curve Preparation” regarding preparing calibration curves.

28


Generally you need longer measurement times for measuring trace elements, but if target elements are present in larger quantities they can be detected with shorter measurement times. If you set the allowable relative error of intensity in “Measurement Condition”, program can reduce measurement time adequately. These settings are only applicable for quantitative analysis.

Given relative error (CV) = std. dev. of x-ray in tensity / x-ray intensity x 1 00, there is an approximately 99% probability that the true value for the x-ray intensity is with in the range ±(x-ray intensity x relative error x 3.0).

29

4. Interpreting Data and Making Determination

Depending on the sample composition, peaks for other elements can appear near the target peaks, making it difficult to interpret results. Overlapping peaks that might appear for the five elements Cd, Pb, Hg, Cr and Br, are listed below. In the case of overlapping peaks, the accuracy of quantitative values could suffer if measuring trace quantities. Cd

When Pb is present in large quantities (PbSUM)

PbLa

When As is present (AsKa) When Bi is present (BiLa)

Hg

When Ge is present (GeKa) When Zn is present in large quantities (ZnKb) When Br is present in large quantities (BrKaESC) When W is present (W Lb2)

BrKa

When Hg is present (HgLb1)

Cr

When Cl is present in large quantities (ClSUM) When Fe is present in large quantities (FeKbESC) When Ba is present (BaLb2,BaLg1) When V is present (V Kb) When Ni is present in large quantities (NiKaESC) When Co is present in large quantities (CoKaESC)

PbLb1

When Bi is present (BiLb1) When Br is present (BrKb) When Se is present (SeKb) When Fe is present in large quantities (FeKaSUM)

BrKb

When Pb is present in large quantities (PbLb5) When Au is present in large quantities (AuLg1)

30


In general, when a sample is irradiated with x-rays, in addition to fluorescent x-rays, scattered incident x-rays are also observed. With some samples, the scattered x-ray intensity increases significantly at specific energies by X-ray diffraction. For EDX series spectrometers, these diffraction lines are observed at the following energies.

E: Energy of Diffracted X-ray (keV) n: Order(1,2,3, … ) d: Crystal Face Distance in Sample (A)

Note, this diffraction phenomenon only occurs when the angle between the crystal face and x-ray tube and the angle between the crystal face and detector are the same. However, crystal faces are oriented in multiple directions and samples are generally not singl e crystals, so it is not possible to accurately predict which crystal faces will generate intense diffraction line emissions. Diffraction lines observed with EDX series have t he following properties. a)

They mainly appear between 3 keV and 15 keV.

b)

The line widths are often about the same or wider than x-ray fluorescence peaks.

c)

The diffraction pattern may change if the sample orientation or tilt angle is changed.

d)

They are rarely observed in plastic samples. Tiny diffraction lines appear in metal samples.

e)

They become lower when you use x-ray filter.

Currently program cannot determine automatically whether detected peaks are fluorescent x-ray lines or diffraction lines. Therefore, be aware that the program treats diffraction lines as though they were peaks from fluorescent x-rays, so peaks could be misidentified as other elements. In some cases, using a primary x-ray filter for measurements can reduce the diffraction lines more than peaks from fluorescent x-rays. If in doubt regarding whether a peak is a diffraction line or not, measure the sample using a filter and compare the results to not using the filter. Currently, the following cases have been reported. Fe-based samples – T iny peaks near 10 keV may appear to be Hg peaks. Ag-based samples – T iny peaks near 5.4 keV may appear to be Cr peaks. Sn-based samples – T iny peaks near 5.4 keV may appear to be Cr peaks.

31


The quantitative value determination results can be summarized in a one-page report. For more information regarding report creation features (ExReport), refer to the separate instruction manual of ExReport.

32

5. Hints for Configuring Conditions

[Method 1] Uncheck “Do Analysis” in

“Element Information” window

[Method 2] Uncheck the checkbox to the left of “Analyte” in rogram.. “Analysis”p

33

“Change

of “Condition”p rogram.

Measuring Time” window of


1. Select standard sample name to be ch anged in “Standard Sample” window of

“Condition”

program.

2. Manually input a different name in “Standard Sample”f ield. And click any other location in the window.

34


[Method 1]

Delete the samples not to be measured in “Sample Registration” window.

[Method 2] Measure the sample as an “Unknown”s ample and load the standard sample intensities by clicking [Read Intensity from Data] in “Standard Sample” window. Then reenter standard values as n ecessary.

35

Manual EDX 700 Shimadzu

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