Unlock Regulation Standard Sample Preparation Techniques
How To Guide
Last Updated: June 26, 2024
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Published: June 24, 2024
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Demand for reproducible sample preparation is on the rise as testing laboratories handle increasingly important and diverse samples.
The latest analytical techniques – such as atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectroscopy (ICP-OES) and ICP mass spectrometry (ICP-MS) – require stringent preparation protocols to meet regulation standards and can be used across various sample types, from environmental and food to industrial and pharmaceutical.
This handbook explores practical examples of sample preparation that can elevate analytical accuracy and efficiency.
Download this handbook to discover:
- Step-by-step guides for preparing diverse sample types
- Straightforward preparation of samples for AAS, ICP-OES and ICP-MS analysis
- How to achieve regulation level sample preparation
Sample preparation techniques
for AAS, ICP-OES and ICP-MS for
regulated testing laboratories
This handbook contains examples of typical sample
preparation methods recommended for AAS, ICP-OES
and ICP-MS analysis of a variety of sample types.
Disclaimer: The described sample preparation
protocols require the use of hazardous chemicals.
Appropriate personal protective equipment as
recommended by local safety requirements should
be used. A full risk assessment should be carried
out prior to undertaking any activities.
Introduction
Contents
Part 1 Environmental samples 4
Water samples 4
Hot plate digestion 4
a. Generic procedure
b. U.S. EPA 3010A4
Acid Digestion of Aqueous Samples and Extracts for Total Metals for
Analysis by FLAA or ICP Spectroscopy
Microwave digestion 5
a. U.S. EPA 3015A5
Microwave Assisted Acid Digestion of Aqueous Samples and Extracts
Soil samples 5
Hot plate digestion 5
a. Generic procedure
b. U.S. EPA 3050B6
Acid Digestion of Sediments, Sludges, and Soils
Microwave digestion 6
a. Generic procedure
b. U.S. EPA 3051A7
Microwave Assisted Acid Digestion of Sediments, Sludges, and Oils
c. China HJ 832-201711
Soil and sediment – Digestion of total metal elements – Microwave assisted
acid digestion method
Part 2 Food and beverage samples 8
Food samples 8
a. Rice flour
b. Milk powder
c. Fruits
d. Meat
e. U.S. FDA methods33
Beverage samples 9
a. Juice
b. Carbonated Nonalcoholic Beverages
Part 3 Industrial samples 10
Metal samples 10
Oil samples 10
Refinery products 10
Electronic waste 11
Part 4 Clinical research and pharmaceutical samples 12
Blood 12
Serum 12
Urine 12
Pharmaceutical 12
Part 5 Plant and vegetation samples 14
Plant 14
Part 6 References 15
4
Part 1 Environmental samples
1-1 Water samples:
Hot plate digestion for water samples:
a. General procedure:
This procedure is a suitable digestion method for the
preparation of water samples for AAS, ICP-OES and
ICP-MS analysis. If samples are being prepared for ICP-MS
analysis, it is recommended to dilute them further due to
the acid concentration in the final solution.
Step 1:
Add 25 mL of the water sample to a PTFE beaker and
acidify with 2.0 mL of concentrated HNO3
and 6.0 mL of
concentrated HCl (trace metal grade acid for AAS and
ICP-OES and high purity acid for ICP-MS). Heat the beaker
on a hot plate located in a fume extraction hood until the
sample is just below boiling. This should continue until the
solution becomes clear and transparent.
Step 2:
After cooling to room temperature, transfer the sample to
a 50 mL volumetric flask. Rinse the inner wall of the beaker
with ultrapure water (resistivity of 18.2 MΩ∙cm), then add
the rinse water to the sample in the volumetric flask. Bring
the sample up to volume with ultrapure water.
Equivalent procedures are described in the HJ700-20149
method.
b. U.S. EPA SW-846 Method 3010A4
This digestion procedure is used for the preparation of
water samples, mobility-procedure extracts, and wastes
that contain suspended solids for analysis by flame atomic
absorption spectroscopy (FLAA) or inductively coupled
argon plasma spectroscopy (ICP). The procedure is used
to determine total metals and is not suitable for volatile
sample analytes.
Step 1:
Transfer a 100 mL representative aliquot of the wellmixed sample to a 150 mL Griffin beaker. Add 3 mL of
concentrated HNO3
to the beaker and cover with a ribbed
watch glass or equivalent and place on a hot plate or
equivalent heating source. Slowly evaporate the sample to
a low volume (e.g., around 5 mL), without boiling and with
avoiding taking the sample to dryness. Cool the sample
and add another 3 mL portion of concentrated HNO3
to the
beaker. Cover the beaker with a non-ribbed watch glass
and returned to the hot plate. Increase the temperature of
the hot plate so that a gentle reflux action occurs.
Step 2:
Continue heating, with additional HNO3
added as
necessary, until the digestion is complete (generally
indicated when the digestate is light in color or does not
change in appearance with continued refluxing). Again,
uncover the beaker or use a ribbed watch glass, and
evaporate to a low volume (3 mL), while not allowing
any portion of the bottom of the beaker to go dry. Cool
the beaker. Add a small quantity of 1:1 HCl, cover the
beaker, and reflux for an additional 15 min to dissolve any
precipitate or residue resulting from evaporation.
5
Step 3:
Rinse the beaker walls and watch glass with ultrapure
water and, when necessary, filter or centrifuge the sample
to remove silicates and other insoluble material that could
clog the nebulizer. Filtration (Whatman™ quantitative filter
paper, ashless, Grade 41) should be done only if there is
concern that insoluble materials may clog the nebulizer.
This additional step can cause sample contamination
unless the filter and filtering apparatus are thoroughly
cleaned. Rinse the filter and filter apparatus with dilute
HNO3
and discard the rinsate before filtering each sample.
Filter the sample and adjust the final volume to 100 mL with
ultrapure water and the final acid concentration to 10%.
The sample is now ready for analysis.
Samples that are digested using the 3010A4
digestion
method can be analyzed using U.S. EPA SW-846 Method
6010D and Method 6020B.
Microwave digestion:
a. U.S. EPA SW-846 Method 3015A5
This microwave method is designed to perform extraction
using microwave heating with HNO3, or alternatively, with
a mixture of HNO3
and HCl. Due to the rapid advances
in microwave technology, consult the manufacturer's
recommended instructions for guidance on their microwave
digestion system. This method is generic and may be
implemented using a wide variety of laboratory microwave
equipment.
Step 1:
Add a 45 mL aliquot of a well-shaken, homogenized
sample using an appropriate volumetric measurement and
delivery device to an appropriate vessel equipped with a
controlled pressure relief mechanism.
Step 2:
Add 5 ±0.1 mL of concentrated HNO3
or, alternatively,
4 ±0.1 mL of concentrated HNO3
and 1 ±0.1 mL of
concentrated HCl to the vessel in a fume hood (or fume
exhausted enclosure).
Step 3:
Seal the vessel according to the manufacturer's directions.
Properly place the vessel in the microwave system
according to the manufacturer's recommendations and,
when applicable, connect appropriate temperature and
pressure monitoring equipment to vessels according to
manufacturer’s specifications.
Step 4:
The temperature of each sample should rise to 170 ±5 ˚C in
approximately 10 min and remain at 170 ±5 ˚C for 10 min,
or for the remainder of the 20 min digestion period.
Step 5:
At the end of the microwave program, allow the vessels to
cool for a minimum of 5 min before removing them from the
microwave system. When the vessels are cooled to near
room temperature, determine if the microwave vessels have
maintained their seal throughout the digestion.
Step 6:
Complete the preparation of the sample by venting the
microwave containers in a fume hood before uncapping,
to avoid a rush of acid vapor that may still be in the
headspace. When sufficiently cool to handle, carefully
uncap the vessels using the procedure recommended
by the vessel manufacturer. Quantitatively transfer the
sample to an acid-cleaned bottle. If the digested sample
contains particulates that may clog nebulizers or interfere
with injection of the sample into the instrument, the sample
should be centrifuged, allowed to settle, or filtered.
Step 7:
Transfer or decant the sample into a volumetric flask and
dilute the digest to a known volume. The sample is now
ready for analysis.
Samples that are digested using the 3015A5
digestion
method are suitable for analysis by ICP-MS, ICP-OES,
FLAA and graphite furnace AA.
1-2 Soil samples:
Hot plate digestion:
The described sample preparation protocol requires the
use of hazardous chemicals, especially hydrofluoric acid
(HF) and perchloric acid (HClO4
). Because of the ability
of these acids to penetrate tissue, poisoning can occur
readily through exposure to skin or eyes, or when inhaled
or swallowed. Appropriate personal protective gear such
as laboratory coat, safety glasses, and gloves specifically
for handling HF and HClO4
are required. When using HF,
it is also essential to ensure that calcium gluconate gel is
immediately available for application to any areas of skin
that come into contact with this acid, after rinsing the
affected areas with water and drying thoroughly.
6
a. General procedure:
This procedure is a suitable digestion method for the
preparation of soil, sediment, and solid waste samples
for ICP-OES and ICP-MS analysis. If samples are being
prepared for ICP-MS analysis, it is recommended to
dilute samples further due to the acid concentration in the
digestate.
Step 1:
Homogenize and accurately weigh 0.1 g of the soil or
sediment sample into a polytetrafluoroethylene (PTFE)
crucible and moisten with 3 mL of ultrapure water. Add
4 mL of an acid mixture (HF:HClO4 = 5:1,) to the crucible, and
heat the sample to 260 ˚C on an electric hot plate digestion
system in a fume hood. Add a further 4 mL of the acid
mixture and heat until emission of white smoke has ended.
Step 2:
Add 2 mL of aqua regia (HCl:HNO3 = 3:1) to re-dissolve the
mixture. Then add 10 mL of 10% aqua regia to the extract;
the sample solution should become clear and transparent.
Cool the solution, add 2 mL HNO3, transfer the sample
extract to a 100 mL PTFE volumetric flask and make up
to volume with ultrapure water.
Equivalent procedures are described in method
HJ803-201610.
b. U.S. EPA 3050B6
For this digestion procedure, weigh to the nearest 0.01 g
and transfer a 1–2 g sample (wet weight) or 1 g sample
(dry weight) to a digestion vessel. For samples with high
liquid content, a larger sample size may be used as long
as digestion is completed.
Step 1:
For the digestion of samples for analysis by GFAA or
ICP-MS, add 10 mL of 1:1 HNO3
, mix the slurry, and cover
with a watch glass or vapor recovery device. Heat the
sample to 95 ˚C ±5 ˚C and reflux for 10 to 15 min without
boiling in a fume hood. Allow the sample to cool, add 5 mL
of concentrated HNO3
, replace the cover, and reflux for
30 min. If brown fumes are generated, indicating oxidation
of the sample by HNO3
, repeat this step (addition of 5 mL
of concentrated HNO3
) over and over until no further brown
fumes are given off by the sample indicating complete
reaction with HNO3
. Using a ribbed watch glass or vapor
recovery system, either allow the solution to evaporate to
approximately 5 mL without boiling or heat at 95 ˚C ±5 ˚C
without boiling for two hours. Always maintain a covering of
solution over the bottom of the vessel.
Step 2:
After the first step is completed and the sample is cooled,
add 2 mL of water and 3 mL of 30% H2O2
. Cover the vessel
with a watch glass or vapor recovery device and return the
covered vessel to the heat source for warming and to start
the peroxide reaction.
Care must be taken to ensure that losses do not occur
due to excessively vigorous effervescence. Heat until
effervescence subsides and cool the vessel. Continue
to add 30% H2O2
in 1 mL aliquots with warming until
the effervescence is minimal or until the general sample
appearance is unchanged. NOTE: Do not add more than a
total of 10 mL 30% H2O2
.
Step 3A for ICP-MS:
Cover the sample with a ribbed watch glass or vapor
recovery device and continue heating the acid-peroxide
digestate until the volume is reduced to approximately
5 mL or heat at 95 ˚C ±5 ˚C without boiling for two hours.
Always maintain a covering of solution over the bottom of
the vessel. After cooling, dilute to 100 mL with ultrapure
water. Particulates in the digestate should then be removed
by filtration, by centrifugation, or by allowing the sample to
settle. The sample is now ready for analysis by GFAA or
ICP-MS.
Step 3B for ICP-OES:
For the digestion of samples for analysis by FLAA or
ICP-OES, add 10 mL concentrated HCl to the sample
digested from Step 2 and cover with a watch glass or
vapor recovery device. Place the sample on/into the
heating source and reflux at 95 ˚C ±5 ˚C for 15 min. Filter
the digestate through Whatman™ No. 41 filter paper (or
equivalent) and collect the filtrate in a 100 mL volumetric
flask. Make to volume and analyze by FLAA or ICP-OES.
Samples that are digested using the 3050B6
digestion
method can also be analyzed using U.S. EPA SW-846
Method 6010D and Method 6020B.
Microwave digestion:
a. General procedure
This procedure is a suitable digestion method for the
preparation of soil, sediment, and solid waste samples
for ICP-OES and ICP-MS analysis. If samples are being
prepared for ICP-MS analysis, it would be recommended
to dilute them further due to the acid concentration in the
final solution.
7
Weigh 0.20 ±0.001 g of sample into a microwave digestion
vessel and add 9 mL of concentrated HNO3
and 3 mL of
concentrated HCl. Digest the sample according to the
manufacturer's guidelines or method for the sample. Once
cooled, transfer the sample to a 50 mL volumetric flask and
make up to volume with ultrapure water.
b. U.S. EPA 3051A7
This microwave extraction method is designed to mimic
extraction using conventional heating with HNO3, or
alternatively, HNO3
and HCl, according to U.S. EPA Method
200.22
and Method 30506.
Step 1:
Weigh a well-mixed sample to the nearest 0.001 g into an
appropriate vessel equipped with a controlled pressure
relief mechanism. For soils, sediments, and sludges, use
not more than 0.50 g. For oil or oil contaminated soils,
initially use not more than 0.25 g.
Step 2:
Add 10 ±0.1 mL concentrated nitric acid (HNO3) or,
alternatively, 9 ±0.1 mL concentrated HNO3
and 3 ±0.1 mL
concentrated hydrochloric acid HCl to the vessel in a fume
hood (or fume exhausted enclosure).
Step 3:
Seal the vessel according to the manufacturer's
directions. Properly place the vessel in the microwave
system according to the manufacturer's recommended
specifications and, when applicable, connect appropriate
temperature and pressure sensors to vessels according to
manufacturer’s specifications.
Step 4:
The temperature of each sample should rise to 175 ±5 ˚C
in approximately 5.5 ±0.25 min and remain at 175 ±5 ˚C
for 4 min 30 s. When using temperature feedback control,
the number of samples to be simultaneously digested
may vary, from one sample up to the maximum number
of vessels that can be heated by the magnetron of the
microwave unit according to the heating profile specified
previously in this section. The number will depend on the
power of the unit, the number of vessels, and the heat loss
characteristics of the vessels.
Step 5:
At the end of the microwave program, allow the vessels to
cool for a minimum of 5 min before removing them from the
microwave system. When the vessels are cooled to near
room temperature, determine if the microwave vessels have
maintained their seal throughout the digestion.
Step 6:
Complete the preparation of the sample by venting the
microwave containers in a fume hood before uncapping
to avoid a rush of acid vapor that may still be in the
headspace. When sufficiently cool to handle, carefully
uncap the vessels using the procedure recommended by
the vessel manufacturer. Quantitatively transfer the sample
to an acid-cleaned bottle. If the digested sample contains
particulates that may clog nebulizers or interfere with
injection of the sample into the instrument, the sample may
be centrifuged, allowed to settle, or filtered (Whatman™
quantitative filter paper, ashless, Grade 41).
Step 7:
Transfer or decant the sample into volumetric ware
and dilute the digest to a known volume. The digest is
now ready for analysis of the elements of interest using
appropriate elemental analysis techniques.
Samples that are digested using the 3051A7
digestion
method can also be analyzed using U.S. EPA SW-846
Method 6010D and Method 6020B.
c. HJ 832-201711
Soil and sediment – Digestion of total metal elements –
Microwave assisted acid digestion method. Also refer to
GB 17378.38
and HJ/T 16612.
Step 1:
Weigh a well-mixed sample 0.25–0.50 g to the nearest
0.001 g into an appropriate vessel equipped with a
controlled pressure relief mechanism. Add 6 ±0.1 mL
concentrated HNO3, 3 ±0.1 mL concentrated HCl and
2 ±0.1 mL HF to the vessel in a fume hood.
Step 2:
The temperature of each sample should rise to
160–190 ˚C in approximately 12 min and remain at
160–190 ˚C for 5 min. At the end of the microwave
program, allow the vessels to cool to room temperature.
Step 3:
Rinse the inner surface walls of the vessel with a small
amount of dilute HNO3, then transfer the sample to a 25 mL
volumetric flask. Continue to rinse the inner walls with nitric
acid, transfer the sample solution to the volumetric flask,
and then dilute with ultrapure water to the mark.
8
Part 2 Food and beverage samples
2-1 Food samples:
a. Rice flour: (refer to Thermo Scientific™ AN 4332618)
Weigh 0.5 g of sample into a microwave digestion vessel
and add a mixture of 5 mL HNO3
and 1 mL HCl. Digest the
sample according to the manufacturer's guidelines. Ensure
the samples are heated to at least a temperature of 200 ˚C
for 15 min.
After digestion, transfer the sample to a 50 mL volumetric
flask and make up to volume with ultrapure water.
b. Milk powder:
Method 1. This procedure is for analysis by AAS:
(refer to Thermo Scientific AN 4437122)
Weight 1 g of the sample into a 15 mL centrifuge tube
and add 5 mL of Thermo Scientific™ Triton™ X-100 solution
(0.2% m/v). Seal the tube and mix by vortex oscillation.
Place the tube in an ultrasonic bath and sonicate for 1 hr.
Afterwards, add Triton X-100 solution to bring sample to a
volume of 10 mL. The samples are then mixed a final time
by vortex oscillation prior to analysis.
Triton™ X-100: CAS9002-93-1, Sigma Aldrich
Method 2. This procedure is for analysis by ICP-OES:
(refer to Thermo Scientific AN 4439224)
Weigh 0.5 g of sample into a PTFE high pressure
microwave vessel and add 7 mL of concentrated HNO3.
Carefully wash down material adhering to the walls of the
vessel with the nitric acid. Add 1 mL of concentrated H2O2
;
this will increase the oxidation potential for decomposition
of the organic matrix. Digest the sample in the microwave
as per the manufacturer's guidelines.
After digestion and cool down to room temperature,
transfer the sample into a 50 mL volumetric flask. Rinse
the digestion vessels with ultrapure water and transfer the
resulting liquid to the flask. Finally, make up to volume with
ultrapure water.
c. Fruits (freeze-dried sample): (refer to
Thermo Scientific AN 4447431)
Weigh an aliquot of 0.3–0.4 g of sample into a microwave
digestion vessel. Add a mixture of 5 mL HNO₃ and 1 mL
HCl (35% Optima™ grade, Fisher Chemicals) to the vessel
and place in the microwave digestion system (Milestone
ETHOS 1 used in this study/application note). After
digestion, transfer the sample into a 50 mL volumetric flask
and bring up to volume with ultrapure water. The amount of
total dissolved solids is around 0.6% in the sample solution.
No further dilution is applied prior to analysis by ICP-MS.
9
d. Meat: (refer to Thermo Scientific AN 4445928)
Step 1:
Weigh 0.5 g of homogenized sample into a pre-cleaned,
dry 75 mL microwave digestion vessel.
Step 2:
Add gold, to stabilize mercury, to the sample so that the
final concentration is 200 μg·L-1 in the sample solution.
Add 2 mL of HNO₃, 1 mL H₂O₂, and 0.2 mL HCl and
keep the sample in a fume hood for 60 min to allow for
pre-digestion.
Step 3:
Add 1 mL of ultrapure water and digest the samples using
a microwave digestion system (CEM Mars 6 used in this
study/application note). Ensure the samples are ramped
over 40 minues to a temperature of 200 ˚C and then held
at this temperature for 30 min.
Step 4:
After digestion is complete, allow the vessels to cool to
room temperature. Quantitatively transfer the sample to
a pre-cleaned 50 mL volumetric flask and add ultrapure
water to volume. Mix thoroughly with a vortex mixer prior
to analysis by ICP-MS.
e. U.S. FDA method33 – Elemental Analysis Manual
for Food and Related Products:
Step 1:
Transfer an analytical portion of the sample with a pipette
or spatula or by pouring into a tared, clean digestion vessel
liner. Measure the weight of the sample to an accuracy of
0.001 g. For safety purposes, limit the sample weight to
0.5 g if the composition is unknown.
Step 2:
Pipette 8 mL or weigh 11.3 g of high purity HNO3
into the
vessel liner and wash down any material on the vessel
walls. Add 1 mL of high purity 30% H2O2
. Seal the vessels,
tighten pressure relief nuts, and run the microwave
digestion program as prescribed by the analytical method.
Step 3:
After digestion, allow the vessels to cool to below
50 ˚C and then transfer them to an exhaust hood and vent
excess pressure slowly. Quantitatively transfer and dilute
the digestion solution with deionized water as prescribed
by the analytical method. This analytical solution should be
transferred to a plastic bottle or a capped polypropylene
centrifuge tube for storage.
A typical microwave digestion program is given in the
Table below.
2-2 Beverage samples:
a. Juice: (refer to Thermo Scientific AN 4315115)
For determination of trace elements, weigh 20 g of sample
into a 100 mL volumetric flask. For determination of major
elements, weigh 2 g of sample into a 100 mL volumetric
flask. Make all samples to 100 mL volume with ultrapure
water.
b. Carbonated non-alcoholic beverages:
(refer to Thermo Scientific AN 4442125)
Prior to analysis by ICP-OES, reduce the influence of
dissolved CO2
gas on nebulization and transport by
degassing the samples in an ultrasonic bath. Weigh 10 g
of each sample into a 50 mL volumetric flask. Make the
samples up to volume with ultrapure water.
Digestion Peroxide oxidation
Maximum power (W) 1200
Control pressure (psi) 800
Ramp time (min) 25
Hold time (min) 15
Control temperature (˚C) 200
10
Part 3 Industrial samples
3-1 Metal samples:
a. Steels and alloys (refer to Thermo Scientific
AN 4314614)
The samples are digested in a microwave digester.
Weigh 0.5 g of sample into a microwave digestion vessel
and add 10 mL of concentrated HCl and 2.0 mL of
concentrated HNO3. Seal the vessel and digest at 180 ˚C
for 20 min.
When the microwave program is finished, allow the vessels
to cool, transfer the sample into a 100 mL volumetric flask
and bring to volume with ultrapure water.
b. Titanium alloys (refer to Thermo Scientific
AN 4098813)
Alloy samples can be dissolved and diluted (1 g to 50 mL)
according to ASTM Method E2371-131
. This includes the
digestion of the sample in 15 mL HCl followed by 2 mL
HF and 2 mL HNO3. Clear solutions on completion of the
digestion step indicates complete dissolution.
3-2 Oil samples:
Lubricating oil (refer to Thermo Scientific AN 4442626)
Homogenize the sample by heating to 60 ˚C and
sonicating. Weigh a portion of the sample and dilute by
weight with a suitable solvent, such as kerosene or xylene,
so that the diluted sample contains 10% of the original
sample by weight.
3-3 Refinery products:
(refer to Thermo Scientific AN 4446529)
A major challenge when analyzing different types of
petrochemical samples is the difference in vapor pressure
and viscosity, which ultimately requires a dedicated
configuration of the sample introduction system. Whereas
samples with high viscosity, such as crude oil or fuel
oil, require heating of the sample introduction system
components to remain fluid, samples with a lower boiling
point, such as naphtha, need cooling of the spray chamber
to avoid overloading the plasma and sudden extinction.
To homogenize the properties of samples, and with the
objective to accommodate different sample types in a
single batch, samples are prepared differently in each case.
Fuel oil/crude oil sample preparation: Heat the oil
sample in a water bath to 40–60 ˚C and mix thoroughly to
ensure the homogeneity. Weigh 1 g of homogenized oil
sample into a 50 mL volumetric flask. Dilute the sample by
300-fold using xylene as the diluent using serial dilutions.
Heavy naphtha: Directly aspirate into the ICP-MS after
addition of the required amount of internal standards stock
solution.
Light naphtha: Dilute 10-fold using xylene followed by
addition of the required amount of internal standards stock
solution before aspiration into the ICP-MS.
11
3-4 Electronic waste:
(refer to Thermo Scientific AN4446630)
Sample powders of electronic waste samples like mobile
phone screens, printed circuit boards, etc. are prepared
using a grinder. Small (<5 cm) metal components like
magnets may be left whole.
Weigh 1 to 2 g of sample material into a beaker and digest
overnight in a concentrated acid mixture (HCl:HNO3
= 1:1).
If the sample is a magnet, digest with aqua regia. Filter the
samples and dilute so that the final solution contains
10% (v/v) acid.
12
Part 4 Clinical research and pharmaceutical samples
4-1 Blood:
(refer to Thermo Scientific AN 4445327)
To prepare blood samples for analysis by ICP-MS, pretreat with chelating agents such as tetramethylammonium
hydroxide (TMAH) or ethylenediamine-tetra acetic acid
(EDTA) to avoid coagulation of the blood. Alternatively, a
closed vessel microwave digestion can be used to reduce
the impact of the matrix.
Blood samples can be diluted manually to a final acid
concentration of 0.5%. In brief, a 0.1 mL aliquot of whole
blood is transferred into pre-cleaned sample tubes followed
by the addition of 4 mL of ultrapure water. After addition
of 25 μL of concentrated HNO3
(Optima™ grade,
Fisher Scientific), the sample is made up to a total volume
of 5 mL with deionized water, mixed thoroughly using a
vortex shaker, and analyzed.
4-2 Serum:
(refer to Thermo Scientific AN 4328316)
The sample can be gravimetrically diluted by a factor of
10 in pre-cleaned (72 hr in 2% HNO3, washed in ultrapure
water) polypropylene bottles with HNO3
(0.5% m/m,
Fisher Scientific) and tetramethylammonium hydroxide
(TMAH, 2% m/m, Sigma-Aldrich) in ultrapure water.
4-3 Urine:
(refer to Thermo Scientific TN 4335719)
A 2 mL aliquot of urine sample is filtered through a 0.45 μm
PTFE membrane filter (Sartorius, Göttingen, Germany) and
diluted with 0.5% (v/v) HNO3.
4-4 Pharmaceutical:
a. (refer to Thermo Scientific AN 4438523)
In this study/application note, a cough medicine in the
form of an effervescent tablet is diluted with a few mL
of ultrapure water to degas the CO2
. After the reaction
subsides, the aliquot is acidified to a final concentration
of 5% HCl, spiked accordingly for the various tests of the
validation procedure, and filled up with ultrapure water to
a final volume of 50 mL.
b. (refer to Thermo Scientific AN 4332517)
Pharmaceutical products are brought into solution via a
microwave digestion system (Milestone Inc., Shelton, CT,
USA). Different microwave procedures are available to
address specific sample matrices.
Samples of each drug (0.5 g) are weighed into 15 mL
disposable glass vials. 3 mL of HNO3
is added to each
tube. In compliance with the repeatability requirements
defined in USP <233>32, six separate preparations of each
material are prepared.
13
Sample vials are transferred into the microwave digestion
system, which is then closed, pressurized with nitrogen at
40 bar, and maintained at a temperature of 200 ˚C for
15 min. High pressure digestions are recommended due
to the use of lower temperatures to minimize the loss of
volatile elements.
When sufficiently cooled, the clear, colorless digested
material is transferred to polypropylene vials and made up
to 50 mL with ultrapure water.
14
Part 5 Plant and vegetation samples
5-1 Plants:
a. (refer to Thermo Scientific AN 4344620)
Approximately 0.3 g of sample is digested using a
mixture of 5 mL HNO3
and 1 mL HCl in a closed vessel
microwave digestion system. The samples are heated to
and maintained at a temperature of 200 ˚C for 15 min. After
digestion, the samples are made up to a volume of 10 mL
using ultrapure water.
b. (refer to Thermo Scientific AN 4436621)
Prior to digestion each sample is weighed (0.5 to 0.8 g) into
a PTFE high pressure vessel, HNO3
(6 mL, concentrated,
Fisher Scientific) and H2O2
(2 mL, concentrated,
Fisher Scientific) are added. If material is adhered to
the walls of the vessel, it is washed down carefully with
the acid. Hydrogen peroxide is added to aid digestion of
the organic matrix.
A microwave digestion system equipped with a segmented
rotor and a temperature sensor is used for the digestion.
The samples are heated to a temperature of 200 ˚C for
15 min.
After digestion, each sample is transferred to a volumetric
flask (50 mL). The digestion vessel is washed with ultrapure
water and the wash solution is transferred to the flasks. The
flask is then made up to volume with ultrapure water prior
to analysis by ICP-OES.
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its subsidiaries. This information is presented as an example of the capabilities of Thermo Fisher Scientific products. It is not intended to
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Part 6 References
1. ASTM E2171-13: Standard Test Method for Analysis of Titanium and Titanium
Alloys by Direct Current Plasma and Inductively Coupled Plasma Atomic Emission
Spectrometry
2. U.S. EPA 200.2: Sample Preparation Procedure for Spectrochemical Determination of
Total Recoverable Elements
3. U.S. EPA 200.7: Determination of Metals and Trace Elements in Water and Istes by
Inductively Coupled Plasma-Atomic Emission Spectrometry
4. U.S. EPA 3010A: Acid digestion of aqueous samples and extracts for total metals for
analysis by FLAA or ICP spectroscopy
5. U.S. EPA 3015A: Microwave Assisted Acid Digestion of Aqueous Samples and
Extracts
6. U.S. EPA 3050B: Acid digestion of sediments, sludges, and soils
7. U.S. EPA 3051A: Microwave assisted acid digestion of sediments, sludges, soils,
and oils
8. GB 17378.3: Marine Monitoring Specification, Part 3: Sample Collection, Storage
and Transportation
9. HJ 700-2014: Water quality. Determination of 65 elements. Inductively coupled
plasma-mass spectrometry
10. HJ 803-2016: Soil and sediment-Determination of aqua regia extracts of 12 metal
elements – Inductively coupled plasma mass spectrometry
11. HJ 832-2017: Soil and sediment - Digestion of total metal elements – Microwave
assisted acid digestion method
12. HJ/T 166: Technical specification for soil environmental monitoring
13. Thermo Scientific AN40988: The analysis of trace impurities in titanium alloys using
the Thermo Scientific iCAP 7000 Plus Series ICP-OES
14. Thermo Scientific AN43146: Determination of trace elements in steels and alloys
using the Thermo Scientific iCAP 7400 ICP-OES
15. Thermo Scientific AN43151: Analysis of elemental contaminants in beverages using
the Thermo Scientific iCAP 7200 ICP-OES Duo
16. Thermo Scientific AN43283: Total elemental analysis in clinical research using the
Thermo Scientific iCAP TQ ICP-MS
17. Thermo Scientific AN43325: Analysis of pharmaceutical products for their elemental
impurities with the Thermo Scientific iCAP RQ ICP-MS
18. Thermo Scientific AN43326: Total elemental analysis of food samples for routine
and research laboratories using the Thermo Scientific iCAP RQ ICP-MS
19. Thermo Scientific TN43357: Arsenic speciation in human urine by hyphenated ion
chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS)
20. Thermo Scientific AN43446: Total elemental analysis of food samples using triple
quadrupole ICP-MS with auto dilution
21. Thermo Scientific AN44366: Determination of nutritional elements in plant leaves
using the Thermo Scientific iCAP 7400 ICP-OES Duo
22. Thermo Scientific AN44371: Determination of lead in powdered milk using the
Thermo Scientific iCE 3500 AAS
23. Thermo Scientific AN44385: Analysis of elemental impurities in drug products using
the Thermo Scientific iCAP 7400 ICP-OES Duo
24. Thermo Scientific AN44392: Analysis of infant formulae and milk powders using the
Thermo Scientific iCAP 7400 ICP-OES Duo
25. Thermo Scientific AN44421: Analysis of elemental contaminants in beverages using
the Thermo Scientific iCAP PRO X Duo ICP-OES
26. Thermo Scientific AN44426: Lubricating oil analysis according to ASTM D5185
using the Thermo Scientific iCAP PRO XP ICP-OES
27. Thermo Scientific AN44453: Fast and accurate determination of essential and toxic
elements in whole blood using ICP-MS for clinical research
28. Thermo Scientific AN44459: Trace level quantification of multiple elements in meat
and meat products using ICP-MS
29. Thermo Scientific AN44465: Analytical testing of trace elements in refinery
products using a robust ICP-MS approach
30. Thermo Scientific AN44466: Robust analysis of REE in electronic waste: High
sample throughput with analysis times of less than 2 minutes per sample with the
iCAP PRO Series ICP-OES
31. Thermo Scientific AN44474: Maximizing laboratory throughput: Robust and
accurate analysis of trace metals in food samples with triple quadrupole ICP-MS
32.USP 233: <233> Elemental impurities—procedures
33.US FDA Elemental Analysis Manual (EAM) for Food and Related Products
https://www.fda.gov/food/laboratory-methods-food/
elemental-analysis-manual-eam-food-and-related-products
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