Determination of toxic trace metals (Ni, Pb, Cd, Cr, As, Se, Hg) in whole tobacco: T-306
1 Scope of application
1.1
Applicable to the determination of the toxic trace metals: nickel (Ni), lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), selenium (Se) and mercury (Hg) in whole tobacco. The method is designed to quantify these toxic trace metals from a single digestion, of which aliquots are taken for independent analysis.
1.2
Different digestion and analytical techniques that are specifically designed for one particular element may be less labour intensive and should be considered if the analysis of a single element is desired.
2 Normative references
2.1
Health Canada Official Method T-115. Determination of Tar, Water, Nicotine and Carbon Monoxide in Mainstream Tobacco Smoke, 2016.
2.2
Health Canada Official Method T-402. Preparation of Sample for Testing of Cigarettes, Tobacco Sticks, Cigarette Tobacco, Tobacco Sticks, Cigars, Little Cigars, Kreteks, Bidis, Leaf, Pipe and Smokeless Tobacco, 2016.
2.3
International Organization for Standardization, ISO 8243 Cigarettes - Sampling. 2013.
2.4
International Organization for Standardization, ISO 15592-1 Fine-Cut tobacco and smoking articles made from it - Methods of sampling, conditioning and analysis - Part 1: Sampling. 2001.
2.5
AOAC INTERNATIONAL, AOAC Official Method 966.02 Loss on Drying (Moisture) in Tobacco, Official Methods of Analysis of AOAC INTERNATIONAL, 20th Ed., 2016.
3 Definitions
3.1
Refer to T-301 for definitions of terms used in this document.
4 Method summary
4.1
This method is a microwave digestion method used to prepare samples for atomic absorption spectrometer (AAS), Inductively Couple Plasma – Atomic Emission Spectrometer (ICP-AES) and Inductively Coupled Plasma - Mass Spectrometer (ICP-MS) analysis. Freeze-dried tobacco is ground and placed into the microwave digestion vessel. The tobacco is then treated with a mixture of hydrochloric acid, nitric acid and hydrogen peroxide. The vessel is then sealed and placed in the microwave digestor for dissolution. When digestion is complete, the vessel is removed from the digestor, allowed to cool and transferred to a volumetric flask where it is made to volume with Type I water.
4.2
Aliquots of the digestate are analyzed for Ni, Pb, Cd, Cr, As, and Se by either Graphite Furnace Atomic Absorption Spectrometer (GF-AAS) or ICP-AES or ICP-MS. While analyzing As and Se on GF-AAS, use of matrix modifiers are required to prevent loss of analyte.
4.3
An aliquot of the digestate is analyzed by using cold vapour atomic absorption spectroscopy for Hg. This method uses a continuous flow vapour generator to react the mercury with stannous chloride. A peristaltic pump pushes the reducing agent and sample through a mixing coil to a gas liquid separator. Nitrogen (or any inert) gas carries the mercury vapour into a flow cell positioned in the burner compartment.
Warning: The testing and evaluation of certain products against this test method may require the use of materials and/or equipment that are potentially hazardous and this document does not purport to address all the safety aspects associated with its use. Anyone using this test method has the responsibility to consult with the appropriate authorities and to establish health and safety practices in conjunction with all existing applicable regulatory requirements prior to its use.
5 Apparatus and equipment
5.1
Freeze drier or equivalent.
5.2
Disposable borosilicate culture tubes, 20 mm × 150 mm.
5.3
Culture tube for macerating, 15 mm × 125 mm.
5.4
Volumetric flasks, 10-100 mL.
5.5
Pipettor or micro-pipettes.
5.6
Eppendorf pipette, 1-5 mL adjustable volume or equivalent.
5.7
High Density Polyethylene (HDPE) storage bottles, 125 mL or equivalent.
5.8
Scintillation vials with plastic lined caps, 20 mL.
5.9
Atomic absorption spectrometer with:
5.9.1
Hollow cathode lamps for: Ni, Pb, Cd, Cr, As, Se and Hg.
5.9.2
Partition tubes, pyrolitic coated or equivalent.
5.9.3
Graphite tube atomizer.
5.9.4
Vapour generation assembly.
5.10
Alternatively, ICP-AES or ICP-MS or equivalent.
5.11
Mercury analyzer or equivalent cold vapour technique.
5.12
Microwave digestion system with temperature and/or pressure controls or equivalent.
5.13
Closed digestion vessel assembly, (× 2) or equivalent.
5.14
Analytical balance measuring to at least 4 decimal places.
6 Reagents and supplies
6.1
All reagents shall be at least analytical reagent grade.
Note: Wherever possible, reagents are identified by their Chemical Abstract Service [CAS] registry numbers in square brackets.
6.2
Hydrochloric acid - [7647-01-0] concentrated, trace metals analysis grade or equivalent.
6.3
Hydrogen Peroxide - [7722-84-1] 32 %.
6.4
Nitric Acid - [7697-37-2] concentrated, trace metals analysis grade or equivalent.
6.5
Ortho-phosphoric Acid - [7664-38-2] trace metals analysis grade or equivalent.
6.6
Stannous Chloride - [7772-99-8].
6.7
Water, Type I (as outlined in ASTM D1193, Table 1: Processes for Reagent Water Production, Note A).
6.8
Reference standards - individual standard solutions at 1000 µg/mL.
7 Preparation of glassware
7.1
Clean and dry glassware in a manner to ensure that contamination from residues on glassware does not occur.
Note: The cleaning of glassware and the cleanliness of the environment in which the analysis is performed, has a direct effect on the accuracy and precision of the method. In order to achieve accurate results, all glassware and digestion vessels must be cleaned immediately prior to use with dilute HCl (1:1) and then rinsed with Type I water.
8 Preparation of solutions
8.1
Stannous Chloride Solution
(25 % w/v SnCl2 in 20 % v/v HCl)
8.1.1
Weigh 125 g of stannous chloride into an acid-washed 500 mL volumetric flask.
8.1.2
Add 100 mL of concentrated HCl to completely dissolve the solid material.
Note: Gentle heating may be applied in order to speed up this process.
8.1.3
Allow the solution to cool before carefully adding Type I water to make up to the 500 mL volume.
8.1.4
Mix well and transfer the contents to the 500 mL bottle for the reducing agent channel of the vapour generation assembly.
Note: If any precipitate appears in the bottle or flask, discard the solution and prepare a fresh sample. It is necessary to keep the stannous chloride in solution and as contaminant free as possible.
9 Preparation of standards
9.1
Elemental Standards Stocks and Required Dilutions
9.1.1
Make all standards to a 10 % (v/v) acid solution.
Note: For stability purposes, it is desirable to dilute the analytical run standards in the same acid in which the stock solution came.
9.1.2
All purchased standards are in 1000 µg/mL concentrations for stability purposes.
9.1.3
Primary Standard is 1000 µg/mL.
9.1.4
Secondary Standard (As and Se) is 1 mL of Primary Standard to 10 mL acid solution = 100 µg/mL.
9.1.5
Mixed Standard: 100 µL of each Primary Standard (Pb, Ni, Cd); 25 µL Cr Primary Standard and 100 µL As/Se Secondary Standard to 100 mL acid solution. Concentration: Pb, Ni and Cd is 1 µg/mL; Cr is 0.25 µg/mL; As/Se is 0.10 µg/mL.
9.1.6
Preparation of Working Standards (ng/mL)
| Standard No. |
Mixed Standard (µL) |
Final Volume (mL) |
|---|---|---|
| 0 | 0 | 100 |
| 1 | 250 | 100 |
| 2 | 500 | 100 |
| 3 | 1500 | 100 |
| 4 | 3000 | 100 |
| 5 | 5000 | 100 |
Note: Additional standards may have to be prepared to cover the range of anticipated responses for test samples.
9.1.7
Mercury Standard
9.1.7.1
Prepare Hg standards for cold vapour analysis in the same acid concentration and ratio as the samples. Using the recommended digestion procedure, that would be 8 % HCl (v/v) and 5 % HNO3 (v/v).
9.1.7.2
The purchased stock standard is in a 10 % (v/v) HNO3 acid solution at a concentration of 1000 µg/mL for stability purposes.
9.1.7.3
In order to make the proper dilutions, prepare a secondary stock standard at a concentration of 1 µg/mL also in a 10 % (v/v) HNO3 acid solution. This secondary stock solution is considered to be stable for one week.
9.1.7.4
Primary standard is 1000 µg/mL
9.1.7.5
Secondary standard is 100 µL of primary stock to 100 mL = 1 µg/mL.
9.1.7.6
Preparation of Working Standards (ng/mL)
| Standard No. |
Secondary Standard (µL) |
Final Volume (mL) |
Standard Concentration [ng/mL] |
|---|---|---|---|
| 1 | 30 | 100 | 0.3 |
| 2 | 50 | 100 | 0.5 |
| 3 | 150 | 100 | 1.5 |
| 4 | 300 | 100 | 3.0 |
| 5 | 500 | 100 | 5.0 |
Note: Additional standards may have to be prepared to cover the range of anticipated responses for test samples.
10 Sampling
10.1
The sampling of cigarettes for the purpose of testing shall be in accord with ISO 8243.
10.2
The sampling of kreteks, little cigars, bidis, tobacco sticks for the purpose of testing shall be in accord with ISO 8243, but modified such that the term "cigarette" is substituted with "kreteks", "little cigars", "bidis" or "tobacco sticks", whereby the term "carton" is equivalent to 200 units.
10.3
The sampling of cigars for the purpose of testing shall be in accord ISO 8243, but modified such that the term "cigarette" is substituted with "cigar", whereby 200 units of cigarette is equivalent to 200 grams of cigar.
10.4
The sampling cigarette tobacco for the purpose of testing shall be in accord with ISO 15592-1.
10.5
The sampling of leaf tobacco, pipe tobacco or smokeless tobacco shall be in accord with ISO 15592-1 but modified such that the term "fine-cut" is substituted with "leaf tobacco", "pipe tobacco" or "smokeless tobacco".
11 Tobacco product preparation
11.1
The preparation of tobacco products for the purpose of testing shall be as specified in T-402.
12 Sample preparation
12.1
Drying of Samples
12.1.1
Transfer approximately 3 g of tobacco or tobacco-type product into the pre-weighed 20 mL scintillation vial with cap.
12.1.2
Weigh and record the total weight of the capped scintillation vial with tobacco.
12.1.3
Place the samples in the freezer or freeze dryer system to freeze the product below eutectic temperature for a minimum of one hour before freeze-drying.
12.1.4
Loosen the caps of the vials to allow the moisture to be driven off before placing in the freeze-dryer system or connecting the freezer system to freeze-dryer system for vacuum drying.
12.1.5
After a minimum of 48 hours, remove the vials and tighten the caps immediately to prevent re-absorption of moisture from the air.
12.1.6
Weigh and record the total weight of the capped scintillation vial with tobacco after freeze-drying and calculate the percent moisture content.
Note: Weighing of the scintillation vials is not necessary; however, it is a useful tool to ensure that samples are dried properly.
Note: A minimum of three blank scintillation vials should be used to monitor any changes in weight as a result of external moisture.
12.2
Grinding of Samples
12.2.1
Grind tobacco by placing a 15 mm × 125 mm centrifuge tube directly into the scintillation vial containing the dried tobacco and using the tube to grind the sample, similar to a mortar and pestle.
12.2.2
After grinding the tobacco, wipe off the remaining tobacco particles from the tube using a laboratory tissue before proceeding to the next sample.
Note: Contamination or cross-contamination from one sample to another is negligible.
Note: This technique of grinding does not necessarily create a uniform sample, but it does result in an easier and more reproducible digestion.
12.3
Digestion of Sample
12.3.1
Weigh 1 g (± 0.1 g) of ground tobacco into the liner of the digestion vessel.
Note: Increasing the sample weight to 2 g will enhance method detection limits but may require longer digestion times.
Note: For difficult-to-digest samples, the sample size may be decreased provided the concentration of the analyte of interest falls within the range limits for the analysis.
12.3.2
Add 8 mL of concentrated HCl and gently swirl to ensure all the tobacco is covered by the acid.
12.3.3
Add 3 mL of concentrated HNO3 to the sample, swirling in the acid, and allow the vessel to sit until the original frothing subsides and there is no longer evidence of orange/brown fumes (NOx formation).
12.3.4
Add 10 mL of 10 % HNO3.
12.3.5
Carefully add 2 mL of hydrogen peroxide so that there is no excessive effervescence.
12.3.6
Allow the samples to sit until the effervescence subsides (approximately 30 minutes).
12.3.7
Add 10 mL of 10 % HNO3.
12.3.8
Cap the digestion vessel.
12.3.9
Place the digestion vessel into the turntable and lock it into position.
12.3.10
Place the largest sample, by weight, (the most reactive) in the reference vessel for monitoring pressure and/or temperature to control the digestion.
12.3.11
Load the turntable of samples into the microwave digestor and digest. (See appendix 1: microwave digestion parameters.)
12.3.12
When the digestion is complete, remove the turntable from the microwave and before opening, allow the samples to cool to room temperature.
12.3.13
Inspect the digestate. If the digestion appears to be incomplete, carefully add 2-4 mL of hydrogen peroxide and return to the microwave for a secondary digestion.
12.3.14
Transfer the digestate to a 100 mL volumetric flask and make to volume using the washings of the digestion vessel with Type I water.
12.3.15
Perform Hg determination within 48 hours of completing the digestion.
12.3.16
Transfer the contents of the flask into a pre-rinsed, 125 mL HDPE storage bottle.
Note: Samples should be stored in the highest concentration of both analyte and acid for stability purposes. Manual dilutions of the digestate should only take place at the time of analysis.
12.4
Sample Dilutions Required for Individual Elemental Analysis
12.4.1
Samples may require dilution when using graphite furnace for analysis so their absorbances fall within the desired calibration range with a good signal-to-noise ratio and very little matrix effect.
Note: This dilution must be accounted for when calculating the results on a ng/g basis.
Note: For As and Se, a multiple injection technique may be required for adequate instrument response.
Note: When using an ICP-AES or ICP-MS for quantification, the samples are normally analyzed without further dilution for Ni, Cr, Pb and Cd. However, the concentration range may need to be increased depending on the sample size and matrix.
12.4.2
The analysis of Hg requires no dilution.
13 Sample analysis
Note: Metal analysis can be performed by one of the following techniques.
13.1
Analysis of Ni, Pb, Cd, Cr, As, and Se by Graphite Furnace Atomic Absorption
13.1.1
Analyze the samples using the suggested parameters in appendix 2: typical instrument parameters
Note: Adjustment to the operating conditions may be required depending on instrument conditions and resolution of the analyte from potential interferences.
13.2
Analysis of Ni, Pb, Cd and Cr by ICP-AES
Note: Ni, Pb, Cd, and Cr may also be analyzed by Inductively Coupled Argon Plasma Atomic Emission Spectrometer (ICP-AES) in conjunction with an Ultrasonic nebulizer in order to increase sensitivity.
13.2.1
Analyze the samples using the suggested parameters in appendix 3: ICP-AES parameters
Note: Adjustment to the operating conditions may be required depending on instrument conditions and resolution of the analyte from potential interferences.
13.3
Analysis of Ni, Pb, Cd, Cr, As and Se by ICP-MS
13.3.1
Analyze the samples using the suggested parameters in appendix 4: ICP-MS parameters.
Note: Adjustment to the operating conditions may be required depending on instrument conditions and resolution of the analyte from potential interferences.
13.4
Analysis of Hg by Cold Vapour Atomic Absorption
Note: The reaction is very sensitive to fluctuations in temperature so the response must be checked frequently against standards.
13.4.1
Analyze the samples using the parameters in appendix 5: typical instrument parameters.
Note: Adjustment to the operating conditions may be required depending on instrument conditions and resolution of the analyte from potential interferences.
13.4.2
Analyze the samples for Hg within 48 hours (24 hours is desirable) of completing the digestion.
13.4.3
If samples are not analyzed within this time frame, the digestate should be returned to the digestion vessel and the secondary digestion procedure performed.
13.5
Analysis of As and Se by Hydride Generation
Note: Arsenic and selenium may also be analyzed by hydride generation using sodium borohydride. Extreme care, and a secondary digestion procedure, must be used to ensure these metals are in the proper oxidation state for the hydride reaction to quantitatively occur.
13.5.1
Analyze the samples for arsenic and selenium by hydride generation. Refer to appendix 6 for suggested parameters.
13.6
Calculations
13.6.1
Results based on the calibration are expressed as [ng/mL] in solution. This result, multiplied by the dilution of the sample and divided by the original sample weight being digested will give the result in a [ng/g] basis.
13.6.2
The [ng/g] results can be converted to [µg/g] by dividing this result by 1000.
13.6.3
All results are expressed on a 'dry matter' basis. These may be expressed on an 'as received' basis using the appropriate moisture result.
Representative calculations are as follows:
Analytical Result (on a 'dry matter' basis):
Analyte [ng/g] = (Analytical result [ng/mL] × 100 mL × Additional Dilution) / Sample Weight (g)
Conversion to an 'as received' basis:
Analyte [ng/g]as received = Analyte [ng/g]dry matter × {1- (% Moisture / 100)}
where the % moisture is determined by AOAC Official Method 966.02
14 Quality control
14.1
Typical Control Parameters
Note: If the control measurements are outside the tolerance limits of the expected values, appropriate investigation and action must be taken.
14.1.1
Laboratory Reagent Blank (LRB)
To detect potential contamination during the sample preparation and analysis processes, include a laboratory reagent blank (LRB). The LRB consists of all reagents and materials used in performing the analysis on test samples and is analyzed as a test sample.
14.1.2
Laboratory Fortified Blank (LFB)
To detect potential loss of analyte during the sample preparation and analysis processes, include a laboratory fortified blank (LFB). The LFB consists of all reagents and materials used in performing the analysis on test samples plus fortification with a known concentration of at least one of the analytes of interest. The level of fortification should reflect the range of typical results for that sample. The LFB is then analyzed as a test sample.
14.1.3
Laboratory Fortified Matrix (LFM)
To detect potential matrix interferences, include a laboratory fortified matrix (LFM). During the sample preparation and/or analysis processes, divide a test sample and fortify an aliquot with at least one of the analytes of interest in known concentration. The level of fortification should reflect the range of typical results for that sample. The LFM is then analyzed as a test sample.
Note: Run an LFM whenever there is a question about the validity of the results.
14.1.4
Laboratory Control Sample
To assess the overall performance of an analysis, a control sample is analyzed. The results of the control sample should be compared, using appropriate statistical techniques, to 'expected values' generated by the laboratory or, if none exist, to values found in literature. This provides information to the laboratory, on test accuracy and precision.
14.1.5
Standard as Sample
To assess the stability of the analytical system, a standard is analyzed as a sample. The results of this standard should be compared, using appropriate statistical techniques, to expected concentrations.
14.2
Recoveries and Levels of Contamination
14.2.1
The typical LRB is less than the LOD.
14.2.2
Typical LFB recoveries:
| Element | LFB Recovery (%) |
|---|---|
| As, Cd, Cr, Ni, Hg | 100 ± 20 |
| Pb | 90 ± 20 |
| Se | 50 ± 10 |
Note: The low LFB of Se is due to stability problems.
14.2.3
Typical LFM recoveries for all elements fall in the range 80-120% due to the protective effects of the matrix.
14.3
Limit of Detection (LOD) and Limit of Quantification (LOQ)
14.3.1
For Hg, As, and Se, the LOD can be determined as a signal to noise (S/N) ratio of 3 to 1.
14.3.2
For Ni, Pb, Cd and Cr, the LOD can be determined as 3 times the standard deviation of results obtained by analyzing the appropriate blank (LRB depending on the analyte of interest) a minimum of 10 times over several days.
14.3.3
For Hg, As, and Se, the LOQ can be determined as the lowest standard used in the preparation of the calibration curve (excluding a blank).
14.3.4
For Ni, Pb, Cd and Cr, the LOQ can be determined as 10 times the standard deviation of results obtained by analyzing the appropriate blank (LRB depending on the analyte of interest) a minimum of 10 times over several days.
Note: Individual instruments will have different LODs and LOQs depending on the optimization of the instrument.
14.3.5
Typical values are:
| N/A | Sample Weight (g) |
LOD [ng/g] |
LOQ [ng/g] |
Dilution Factor |
|---|---|---|---|---|
| Arsenic | 1 | 25.0 | 60.0 | 100 |
| Cadmium | 1 | 43.3 | 144 | 100 |
| Chromium | 1 | 11.9 | 39.7 | 100 |
| Lead | 1 | 37.9 | 126 | 100 |
| Mercury | 1 | 25.0 | 30.0 | 100 |
| Nickel | 1 | 39.3 | 131 | 100 |
| Selenium | 1 | 25.0 | 60.0 | 100 |
14.4
Stability of Reagents and Samples
14.4.1
Analysis of Analytes Other Than Hg
14.4.1.1
Secondary and mixed standards are stable for one week.
14.4.1.2
Prepare working standards every other day.
14.4.1.3
Analyze all samples within one week of the digestion or samples will have to be redigested.
14.4.2
Hg Analysis
14.4.2.1
All samples and analytical run standards must be analyzed within 48 hours of the digestion (24 hours is desirable).
14.4.2.2
All solutions for the analysis (i.e. hydride generation solution) are stable for only 2 weeks because of probable contamination problems.
15 References
15.1
Gawalco, E. J. et al. 1997. Comparison of closed-vessel and focused open-vessel microwave dissolution for determination of cadmium, copper, lead and selenium in wheat, wheat products, corn bran, and rice flour by transverse-heated graphite furnace atomic absorption spectrometry. Journal of AOAC International. 80, 2: 379-387.
15.2
IARC Scientific.1986. Environmental Carcinogens - Selected Methods of Analysis, Volume 8 - Some Metals: As, Be, Cd, Cr, Ni, Pb, Se, Zn. IARC Scientific Publication. 71: 129-138.
15.3
Perinelli, M. A. and Carugno, N. 1978. Determination of trace metals in cigarette smoke by flameless atomic absorption spectrometry. Beitrage zur Tabakforschung International. 9, 4: 214-217.
15.4
Varian Australia Pty. Ltd. September 1985. Varian Instruments at Work: Automated Cold Vapor Determination of Mercury: EPA Stannous Chloride Methodology. AA-51.
15.5
Varian Australia Pty. Ltd. May 1986. Varian Instruments at Work: Rapid Determination of Mercury in Fish Tissue, a Rapid, Automated Technique for Routine Analysis. AA-60.
15.6
Westcott, D.T. and D. Spincer. 1974. The cadmium, nickel and lead content of tobacco and cigarette smoke. Beitrage zur Tabakforschung International. 7, 4: 217-221.
15.7
ASTM International, ASTM Standard D1193-06(2011). Standard Specifications for Reagent Water.
Appendix 1: Microwave digestion parameters (Example)
- Manufacturer:
- CEM
- Model:
- MDS 2100
- Digestion Vessel Type:
- ACV - Advanced Composite Vessel
The following tables provides the ICP-MS analysis Parameters.
Table 1. Pressure/Temperature/Time Program for the Digestion of Whole Tobacco
| N/A | Stage | |||
|---|---|---|---|---|
| 1 | 2 | 3 | 4 | |
| Power (%) | 70 | 70 | 70 | 0 |
| Pressure (psi) | 45 | 125 | 175 | 20 |
| Run Time (min) | 20 | 10 | 30 | 20 |
| Time at Parameter (min) | 8 | 8 | 25 | 20 |
| Temperature (°C) | 95 | 135 | 190 | 25 |
| Fan Speed (%) | 50 | 50 | 50 | 80 |
Note: Both pressure and temperature are set as the controlling parameters in this digestion program. If the preset pressure or temperature is not reached, the microwave oven delivers the designated power for the time programmed in the Run Time function.
Table 2. Pressure/Temperature/Time Program for a Secondary Digestion
| N/A | Stage | |||
|---|---|---|---|---|
| 1 | 2 | 3 | 4 | |
| Power (%) | 75 | 75 | 75 | 0 |
| Pressure (psi) | 95 | 125 | 185 | 20 |
| Temperature (°C) | 105 | 130 | 160 | 25 |
| Run Time (min) | 15 | 20 | 20 | 20 |
| Time at Parameter (min) | 10 | 15 | 15 | 20 |
| Fan Speed (%) | 50 | 50 | 50 | 80 |
Note: These are only suggested parameters as a starting point. The digestion procedure must be optimized for the specific application and instrument used.
Appendix 2: Typical instrument parameters for graphite furnace atomic absorption analysis of Ni, Pb, Cd, Cr, As, Se
Note: Adjustment to the operating conditions may be required depending on instrument conditions and resolution of the analyte from potential interferences.
- Instrument Mode:
- Absorbance
- Calibration Mode:
- Concentration
- Measurement Mode:
- Peak Height
| Instrument Parameters | Ni | Pb | Cd | Cr | As | Se |
|---|---|---|---|---|---|---|
| Lamp Current (mA) | 4 | 5 | 4 | 7 | 5 | 10 |
| Slit Width (nm) | 0.2 | 0.5 | 0.5 | 0.2 | 0.2 | 1 |
| Slit Height | Normal | Normal | Normal | Reduced | Normal | Normal |
| Wavelength (nm) | 232.0 | 283.3 | 228.8 | 357.9 | 193.7 | 196.0 |
| Sample Introduction | Sampler Premixed | Sampler Premixed | Sampler Premixed | Sampler Premixed | Sampler Premixed | Sampler Premixed |
| Measurement Time(s) | 3.1 | 3.0 | 3.1 | 3.2 | 3.0 | 3.0 |
| Replicates | 1 | 1 | 1 | 1 | 1 | 1 |
| BGD Correction | On | On | On | Off | On | On |
| Matrix Modifier | N/A | Ortho-Phosphoric Acid | N/A | Ortho-Phosphoric Acid | Nickel Nitrate | Nickel Nitrate |
| Matrix Modifier Concentration (µg/mL) | N/A | 1000 | N/A | 1000 | 100 | 100 |
Appendix 3: ICP-AES parameters (Example)
- Power (kW):
- 1.20
- Plasma Flow (L/minute):
- 15.0
- Auxiliary Flow (L/minute):
- 1.50
- Nebulizer Flow (L/minute):
- 0.65
Table 1. Emission Wavelength Settings
| Ni | Pb | Cd | Cr | |
|---|---|---|---|---|
| Emission Wavelength (nm) | 221.648 | 220.353 | 214.439 | 267.716 |
Table 2. Machine Settings
| Sample Introduction Settings | Sample Uptake Delay (s) | 40 |
|---|---|---|
| Pump rate (rpm) | 20 | |
| Instrument Stabilization Delay (s) | 15 | |
| Rinse Time (s) | 10 | |
| General Settings | Replicates | 3 |
| Replicate Read Time (s) | 3.0 | |
| Number of Standards Defined | 5 | |
| Ultrasonic Nebulizer Set-up | Heater (°C) | 140 |
| Cooler (°C) | 2 |
Note: Adjustment to the operating conditions may be required depending on instrument conditions and resolution of the analyte from potential interferences.
Appendix 4: ICP-MS parameters
Table 1. Isotope Parameters
The internal standard isotopes are listed for each analyte isotope.
| Analyte Isotope | Internal Standard Isotope |
|---|---|
| Cr52, Cr53 | Sc45 |
| Ni60, Ni62 | Ga71 |
| As75 | Ga71 |
| Se77, Se78 | Ga71 |
| Cd111, Cd114 | In115 |
| Pb206, Pb207, Pb208 | Tl205 |
| Hg202 | TI205 |
Note: The use of these internal standards should not exclude the use of other internal standards provided their use has been appropriately validated.
Table 2. Instrument Starting Parameters
| N/A | Starting Parameters |
|---|---|
| Plasma Flow (L/min) | 15 |
| Auxiliary Flow (L/min) | 1.5 |
| Nebulizer Flow (L/min) | 0.88 |
| Sampling Depth (mm) | 5.5 |
| RF Power (kW) | 1.30 |
| Sample Uptake Delay (s) | 60 |
| Stabilization Time (s) | 10 |
| Pump Rate (rpm) | 15 |
Note: These are suggested parameters only, as a starting point. The ICP and MS must be optimized for the specific instrument being used.
Note: Adjustment to the operating conditions may be required depending on instrument conditions and resolution of the analyte from potential interferences.
Appendix 5: Typical instrument parameters for cold vapour atomic absorption analysis Hg
Suggested Instrument Operating parameters for Mercury
| Parameters | Mercury Analyzer | Cold Vapour Atomic Absorption |
|---|---|---|
| Wavelength (nm) | 254 | 253.7 |
| Lamp Current (mA) | 9.6 | 5 |
| Slit Width (nm) | - | 0.5 |
Appendix 6: Typical instrument parameters for hydride generation atomic absorption analysis of Arsenic and Selenium
Selenium by Hydride Generation
Method Parameters:
Oxidation state of Se: Se(IV)
Instrument Mode: Absorbance
Instrument Parameters
| Parameter | Value |
|---|---|
| Reductant Conc. | As per manufacturer's specification |
| Reductant Flow | As per manufacturer's specification |
| Acid Conc. | As per manufacturer's specification |
| Acid Flow: | As per manufacturer's specification |
| Standard/ Sample Flow: | As per manufacturer's specification |
| Lamp Current | 10.0 mA |
| Wavelength: | 196.0 nm |
| Slit Width | 1 nm |
| Flame: | Air-Acetylene |
| Background correction | ON |
Arsenic by Hydride Generation
Method Parameters:
Oxidation state of As: As(III) (reduce with 1% KI and analyze within 30 min)
Instrument Mode: Absorbance.
Instrument Parameters
| Parameter | Value |
|---|---|
| Reductant Conc. | As per manufacturer's specification |
| Reductant Flow | As per manufacturer's specification |
| Acid Conc. | As per manufacturer's specification |
| Acid Flow: | As per manufacturer's specification |
| Standard/ Sample Flow: | As per manufacturer's specification |
| Lamp Current | 10.0 mA |
| Wavelength: | 193.7 nm |
| Slit Width | 0.5 nm |
| Flame: | Air-Acetylene |
| Background correction | ON |
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