Ensure there is adequate storage space and ventilation for high-pressure argon gas bottles. Bottles must be secured to a rack, and the racks must be secured to the ship. The steel cap for each bottle must be in place whenever the bottles are not connected to the gas manifold. Use Swagelok Snoop Liquid Leak Detector to ensure proper seals at argon bottle and gas manifold connections.
Samples and standards are made up in dilute solutions of concentrated nitric acid. Use proper PPE (nitrile gloves and eye protection) when handling acids. Always add acid to water. Be aware of the location of acid spill control and neutralization kits.
Ensure the fume hood ventilation above the instrument is operational before igniting the plasma.
The plasma torch is extremely hot during operation (6000 K). Do not handle the torch, RF coil, or other items within the torch compartment until ample time (>5 mins) has been given for the glassware to cool after operation. Wear heat resistant gloves if necessary.

The plasma emits ultraviolet and intense visible light. Ensure the torch compartment door is closed and sealed whenever igniting the plasma. Instrument safety interlocks will extinguish the plasma If the door is opened during operation, however, do not attempt to open the door while the plasma is active.

Empty the waste container of acid residue after every batch analysis.

In This User Guide

Apparatus, Reagents and Materials

Hardware

The complete Agilent 5110 ICP-OES system includes:

Agilent 5110 Single View/Dual-View (SVDV) ICP-OES system equipped with the Automatic Valve Switching (AVS 6/7) option
Agilent SPS4 4-rack autosampler
Agilent G8481A Recirculating Chiller
Mettler Toledo XS204 motion-compensated dual balance system
Cahn Microbalance motion-compensated dual balance system
Barnstead Reverse Osmosis Water Purification System
Burrell Wrist-Action Shaker

Thermolyne Muffle Furnace

Consumables

Reagents

Reagent Water: 18 MΩ deionized water
Sodium Chloride: Trace metal clean
Nitric Acid (HNO₃): Trace metal grade, 70% concentrated. Warning: Always add acid to water.
Element Stock Solutions: Certified 1000 ppm: Al, Ba, Ca, Co, Cr, Cu, Fe, Ge, K, Mg, Mn, Na, Nb, Ni, P, Sc, Si, Sr, Ti, V, Y, Zn, Zr
Element Internal Standards: Certified 1000 ppm: Be, In, Sb, Sc, Y
Argon Gas: Ultra high purity (UHP) grade
IAPSO standard seawater is produced to have a specific conductivity, K₁₅, referenced to a known concentration of KCl at 15°C. It has been shown by Bacon et al. (2007) to be extremely consistent and stable over a reasonable period of time. It is assumed within this method that the concentration of the constituents in IAPSO standard seawater is, for all intents and purposes, the same as that of standard reference seawater. Using the numbers found in Millero (2008), substituting the averaged value for Gieskes (1991) and Summerhayes (1996) for lithium and alkalinity, the working concentrations are therefore:

Constituent¹	Concentration²	Concentration³	Concentration⁴	Concentration⁵	Working Concentrations
Lithium (µM)	27	25.7	N/A	N/A	26.4
Sodium (mM)	480	480.2	480.2	480.7	480.7
Potassium (mM)	10.44	10.46	10.46	10.46	10.46
Magnesium (mM)	54	54.4	54.1	54.1	54.1
Calcium (mM)	10.55	10.54	10.54	10.54	10.54
Strontium (µM)	87	92	92.8	93.0	93.0
Chlorine (mM)	559	559.6	559.4	559.6	559.6
Sulfate (mM)	28.9	N/A	28.9	28.94	28.94
Alkalinity (mM)	2.325	N/A	2.38	N/A	2.353

1. The molarity values in this table except for Gieskes et al. (1991) were calculated from the g/kg values in the reference using the density of standard seawater at 15°C (1.025 kg/L) in order to match the standardized K₁₅ value for IAPSO seawater. 2. Gieskes et al. (1991) already given in terms of molarity. 3. Summerhayes et al. (1996); also quoted by the OSIL website as their reference for IAPSO constituents. 4. Pilson (1998). 5. Millero et al. (2008). N/A = not available from this author.

Methods for Preparation of Standards

Preparing Interstitial Water Standards

Preparing Reagents at the Start of Expedition

Prepare the following reagents at the beginning of an expedition and afterwards on an as-needed basis. For the relevant reagents listed below, the lithium carbonate (Li₂CO₃) is an optional addition.

Internal Standards:
- Interstitial Waters: 100 ppm Be, In, Sc, 200 ppm Sb: Add 10 mL of each Be, In, Sc and 20 mL Sb elemental reference standards (1000 ppm) to a 100 mL volumetric flask, make up with 2% trace metal clean nitric acid. 100 mL is enough for 1000 samples
- Hardrock/Sediment: Same as the interstitial waters internal standard except no scandium (Sc) is added as it is present in rock/sediment matrices.
- Acidified Synthetic Seawater: 35 g trace metal clean NaCl + 29 mL concentrated HNO₃ made up to 1 L with MQ water.
- Nitric Acid Solutions: Add 14.3 mL of concentrated HNO₃ per 1 L of MQ water for each percentage point increase in concentration of acid solution (v/v), e.g. 1% HNO₃: 14.3 mL, 2%: 28.6 mL, 3%: 43 mL HNO₃. Warning: Always add acid to water.
  - Rinse Solutions: Make 5-10 L at a time.
    - Interstitial waters: 3% nitric
    - Hardrock/sediment: 10% nitric
Matrix:
- Interstitial waters: 2% nitric
- Hardrock/sediment: 10% nitric, Optional: 53.25 g of ultrapure Li₂CO₃ may be added as an ionization buffer. Ensure the Li₂CO₃ is fully dissolved

Preparing the Calibration Standards

The calibration standards follow a matrix-matched internal standard approach that spans the range of expected concentrations of the pore water analytes. The recipe may need to be adjusted on a case-by-case basis. For the Interstitial Waters Method, two batches of standards must be prepared—a serial dilution of an in-house elemental cocktail and a serial dilution of IAPSO Seawater.

Preparing and Measuring Major Cation Salt Solutions:

Frequently, dissolved major cations increasing downhole surpass the upper bound of IAPSO concentrations and the certified 1000 ppm standards at working dilutions. These elements may be constrained within calibration curves by increasing the dynamic range of the calibration solutions with major cation salt doping. Primary salt solutions are prepared and concentrations are determined by ICP once at the beginning of an expedition and carried through further standard cocktails. There is no need to heat salts in the oven to desiccate. Note: magnesium chloride hexahydrate decomposes to magnesium tetrahydrate at 116.6°C:

1% Potassium: Make up 1.94 g of potassium chloride (KCl, 74.5513 g/mol) in 100 mL MQ water
1% Magnesium: Make up 9.13 g of magnesium chloride hexahydrate (MgCl₂H₁₂O₆, 203.31 g/mol) in 100 mL MQ water
1% Calcium: Make up 3.8 g of calcium chloride dihydrate ( CaCl₂H₄O₂, 147.008 g/mol) in 100 mL MQ water
3.5% NaCl: Acidified Synthetic Seawater reagent

Measure each solution against certified reference standards to acquire accurate concentrations for further standard dilutions.

Working salt solutions: Pipette 1 mL of each 1% K, Mg, and Ca salt solution, and 286 µL of 3.5% NaCL into a single 100 mL volumetric flask and make up with 2% HNO₃. With this solution, prepare 5-7 replicates of a 1:10 dilution (1 mL solution + 9 mL 2% HNO₃) to be run by ICP. Vortex mix the aliquots. Each yields roughly a 10 ppm solution containing each major cation.
Primary Certified Standard: Pipette 5 mL of each the 1000 ppm Ca, K, Mg, and Na standards into a 50 mL volumetric flask and make up with 2% HNO₃.

Make up 6 calibration standards according to the following scheme:

Standard conc. (ppm)	Volume Primary Certified Standard (µL)	Volume 2% HNO₃ (mL)
Blank	0	10
4 ppm	400	9.6
8 ppm	800	9.2
12 ppm	1200	8.8
16 ppm	1600	8.4
20 ppm	2000	8.0

Use the template IODP_STANDARD_SALTSOLUTIONS_TEMPLATE to evaluate the 5-7 replicates against the above calibration standards. For each wavelength used, average the concentrations for the 5-7 replicates. Multiply the Ca, K, and Mg concentrations by a factor of 1000, and Na by a factor of 3500 to give the original 1% salt concentrations in ppm. In judging each element’s concentration, average all samples across all wavelengths after removing any erroneous/problematic lines. To start this analysis follow the steps given in Performing an ICP-OES Analysis. Adjust and update the concentrations of Na, Mg, Ca, and K listed in Table 1 to reflect the values measured in the 1% salt solutions

Preparing Interstitial Water Working Standards:

Prepare a primary cocktail standard according to the recipe shown in columns 2 and 3 of Table 1. Pipette all individual standards into a single 100 mL volumetric flask and bring to volume with 2% HNO₃. Na, Mg, Ca, and K values are from the major salt solutions which are determined in the preceding step, the remaining standards are 1000 ppm SPEX CertiPrep reference standards.

Table 1: Recipes of the primary cocktail and IAPSO (highlighted in blue) used to create working standards, and final concentrations of the working standards. Serially dilute the in-house cocktail and IAPSO according to the scheme given in Table 2. Na, Mg, Ca, and K are from the major salt solutions. Adjust concentrations accordingly. Iron and manganese values were excluded from IAPSO due to their low concentrations, and barium due to its precipitation with sulfate. Be wary of silicon concentrations in IAPSO due to its storage in glass containers.

				Final Concentrations of In-House Working Standards (ppm, 100 mL)
Element	Primary CRM (ppm)	Volume (mL)	Cocktail (ppm)	200 %	100 %	75 %	50 %	25 %	10 %	5 %	1 %	0 %
B	1000	3	5	1	0.5	0.375	0.25	0.125	0.05	0.025	0.005	0
Ba	1000	5	5	1	0.5	0.375	0.25	0.125	0.05	0.025	0.005	0
Fe	1000	0.5	5	1	0.5	0.375	0.25	0.125	0.05	0.025	0.005	0
Li	1000	0.5	5	1	0.5	0.375	0.25	0.125	0.05	0.025	0.005	0
Mn	1000	0.5	50	10	5	3.75	2.5	1.25	0.5	0.25	0.05	0
P	1000	0.5	25	5	2.5	1.875	1.25	0.625	0.25	0.125	0.025	0
Si	1000	2.5	30	6	3	2.25	1.5	0.75	0.3	0.15	0.03	0
Sr	1000	5	50	10	5	3.75	2.5	1.25	0.5	0.25	0.05	0
Na	~13000	62	13000	1612	806	929.5	1053	1176.5	1250.6	1275.3	1295.1	1300
Mg	~10000	12	10000	240	120	90	60	30	12	6	1.2	0
Ca	~10000	4.5	10000	90	45	33.75	22.5	11.25	4.5	2.25	0.45	0
K	~10000	4	10000	80	40	30	20	10	4	2	0.4	0
				Final Concentrations of IAPSO Working Standards (ppm, 100 mL)
Element	IAPSO (ppm)				100 %	75 %	50 %	25 %	10 %	5 %	1 %	0 %
Na	10760	1076	807	538	269	107.6	53.8	10.76	0
Mg	1293	129.3	96.97	64.65	32.325	12.93	6.465	1.293	0
Ca	413	41.3	30.975	20.65	10.325	4.13	2.065	0.413	0
K	399	39.9	29.925	19.95	9.975	3.99	1.995	0.399	0
S	904	90.4	67.8	45.2	22.6	9.04	4.52	0.904	0
Sr	7.89	0.789	0.592	0.395	0.197	0.0789	0.0395	0.00789	0
Li	0.202	0.0202	0.0152	0.0101	5.05E-3	2.202E-3	1.01E-3	2.02E-4	0
P	0.07	7E-3	5.25E-3	3.5E-3	1.75E-3	7E-4	3.5E-4	7E-5	0
Si	2.8	0.28	0.21	0.14	0.07	0.028	0.014	2.8E-3	0
B	4.5	0.45	0.338	0.225	0.113	0.045	2.25E-2	4.5E-3	0

As listed in Table 2, create one set of working standards by making serial dilutions of the in-house synthetic cocktail (Table 1) using separate 100 mL volumetric flasks, adding the required amount of 3.5% sodium chloride, 100 ppm internal standard and bringing to volume with 2% HNO₃. Prepare a set of IAPSO serial dilutions in the same fashion (do not add 3.5% sodium chloride). Note: Both sets of standards are analyzed in order to constrain Ba and S (predominately SO₄^2-) which precipitate if present in the same vial (even if acidified), and to measure Na—which is necessarily kept constant to be used as an ionization buffer for the minor elements in the synthetic standards.

Table 2: Recipes for two sets of standard serial dilutions, one of the synthetic standard cocktail and the other of IAPSO. Prepare each standard in a 100 mL volumetric flask, make up to volume with 2% nitric acid. The final concentrations are listed in Table 1. Note:

In-House Working Standard Name	Volume In-House Cocktail (mL)	Volume Acidified 3.5% Seawater (mL)	Volume 100 ppm Internal Standard (mL)	IAPSO Working Standards	Volume IAPSO (mL)	Volume 100 ppm Internal STD
0%	0	10	2	0%	0	2
1%	0.1	9.9	2	1%	0.1	2
5%	0.5	9.5	2	5%	0.5	2
10%	1	9	2	10%	1	2
25%	2.5	7.5	2	25%	2.5	2
50%	5	5	2	50%	5	2
75%	7.5	2.5	2	75%	7.5	2
100%	10	0	2	100%	10	2
200%	20	0	2	2

Preparing Hard Rock and Sediment Standards:

Hard rock and sediment standards are prepared according to the ICP-OES Hard Rock Preparation User Guide. Standards are fused with lithium metaborate (LiO₂) at a 1:4 sample:flux ratio and then dissolved in a 10% HNO₃ solution (Optional: doped with Li₂CO₃) for a total dilution factor of 1:2000. Lithium carbonate may be employed as an ionization buffer to maintain a relatively constant number of free electrons in the plasma to mitigate ionization and matrix effects and enhance peaks intensities of minor elements.

Major elements are reported in weight % (mass of oxide/mass of sample) of the respective oxide, with iron species being normalized to Fe₂O₃ (the designation Fe₂O_3t is used, where t = total). Minor elements are reported in units of ppm (mass of element/mass of sample).

Flux-Fusion Preparation of Rocks

Consult the IODP Hard Rock ICP Sample Preparation Guide for a complete, in-depth explanation of the hard rock and sediment sampling procedure. The amount of time necessary to prepare a single sample for analysis according to Table 4 is approximately 48 hours.

Table 3: ICP hard rock and sediment sampling and bead preparation timeline

Step	Time	Single (S) or Batch (B)
Cutting the samples to size	5 min	S
Cleaning the samples on the diamond wheel	5 min	S
Cleaning samples in methanol/DI	30 min	B
Drying samples	12 hr	B
Crushing samples in the X-Press	15 min	S
Grinding samples in the Shatterbox	15 min	3 samples
Determining Loss-On-Ignition (LOI)	20 hrs	B
Making the sample beads	15 min	S
Diluting samples	2 hrs	B
Acid Cleaning Platinum Crucibles	12 hrs	B
Total	48 hrs	B

Dilution of Sediment/Hard Rock standards

Choose a suite of hard rock or sediment standards which matrix-match and span the range of expected concentrations within the sediment samples. Consult Appendix 4: Table of Values for Hard Rock and Sediment Certified Reference Materialswhen choosing analytical standards. Standards are prepared in the same fashion as samples, as described in the proceeding section (see Hard Rock and Sediment (Solids Method)).

Characteristics of Flux Fusion Solutions

Flux fusion solutions become unstable over time; major and trace elements precipitate or form a gel, which is not always visible (since it is clear), so inspect solutions prior to analysis. The stability of the solution is proportional to the dilution factor and acid content and inversely proportional to the SiO₂ content. A dilute solution is more stable than a concentrated one, and a solution becomes more stable with higher HNO₃ presence. A flux-fusion solution enriched in SiO₂ is likely to be more unstable than a basalt or shale solution. Analyze samples on the ICP shortly after they are dissolved.

Methods for Preparation of Samples

Interstitial Water (Waters Method)

This method applies to water samples in a 2% nitric acid solution at a 1:10 (v/v) dilution factor.

Acidify pore water, rhizon or other aqueous samples with 5-10 uL of concentrated trace metal grade nitric acid and store refrigerated in sealed vials.
When preparing an analytical batch, pipette 500 µL of sample (using an Eppendorf set-volume pipette) + 100 µL internal standard + 4.4 mL of matrix solution into a 15 mL vial. Cap and mix using a vortex stirrer for 10 seconds.

Hard Rock and Sediment (Solids Method)

This method applies to hard rock and sediment samples in a 10% nitric acid solution at a 1:2000 (m/v) dilution factor

Prime the 25 mL dispensette atop a 1 L bottle containing the appropriate dilution solution. Ensure there are no air bubbles present in the spigot.
Add 50 mL of dissolution solution to a 125 mL HNO₃ acid-cleaned Nalgene wide-mouthed bottle.
Carefully place the sample bead (and all chipped pieces) in the 125 Nalgene bottle, close the lid, and agitate with the Burrell wrist-action shaker for 1 hr.
Using a new or acid-washed 20 mL syringe, extract solution from the sample bottle and then using a 0.45 µm Acrodisc syringe filter, filter the solution into a 60 mL acid-cleaned Nalgene wide-mouth bottle. Repeat until the entire sample is filtered.
Pipette 500 µL of the filtered solution into a 15 mL scintillation vial and dilute it with 100 µL hardrock internal standard + 4.4 mL dissolution solution. Cap and mix using a vortex stirrer for 10 seconds.
Analyze samples within 48 hours of dilution.

Preparing an Analytical Sequence

Correct setup of the analytical sequence is integral to monitoring and troubleshooting the analytical results. Adhere to the following scheme in all cases:

Bracket samples and with check standards. Use the 100% Level (IAPSO and the In-house) standards as checks. Prepare a large volume of the check standards in a volumetric flask and, after mixing, decant it into several aliquots to be analyzed intermittently every 8-10 samples.
IMPORTANT: Analyze a blank before running the calibration standards, and periodically throughout a run. The blank must be diluted in the same fashion as the samples. It must contain the same amount of internal standard. The blank must be analyzed first.
Analyze the standards at the beginning of a sequence. They can be in a random order.
Always analyze the samples in a random order, do not sequence them by depth in hole.

Performing an ICP-OES Analysis

Figure 1: ICP Expert instrument dashboard.

Starting the Instrument
Verify that the instrument is connected to the electrical mains (voltage requirement: 200 V), and that instrument is connected to the PC and network via Ethernet.
Verify the Ar line is connected and the wall-mounted pressure gauge reads 90 psi. In the Upper Tweens ensure that two Ar gas manifold lines are each connected to a series of four Ar bottles. Open the manifold valve to only one set of four bottles. A fresh rack yields a pressure of ~2200-2400 psi—displayed on the pressure gauge connected in-line to the manifold above the Ar bottle racks. The regulator should be set around ~400 psi. The Ar usage is ~100 psi/hour with the plasma on, and ~2.5 psi/hr during standby. Use the Gas Status Monitor (http://eiger.ship.iodp.tamu.edu/GASSTATUS/) to monitor gas levels during an analysis. Note: Ar leaks may cause asphyxiation by displacing oxygen. Notify a coworker when manipulating gas lines in the Upper Tweens.
Open the wall-mounted Ar valve above the ICP workstation.
Turn on the water chiller. The default temperature setpoint should be at 20°C and the pressure setpoint at 59 psi.
Power on the instrument by first enabling the kill-switch located on the rear-left, then press the power button located on the front-left of the instrument. The LED for the power button will flash green for a few seconds before steadying.
Start the ICP Expert software.
Wait approximately 30-45 minutes for the polychromator temperature to stabilize at 35.0°C. The temperature may periodically fluctuate by 0.1°C. The Peltier cooling temperature should be at -40°C. If measuring wavelengths below 189 nm it is best to allow the polychromator to purge for a total time of 2-3 hours with Boost purge enabled.
In ICP Expert click the ICP instrument button located on the top tool bar to bring up the instrument parameters menu. Click Plasma on. Over the next 60 seconds the plasma will ignite. Allow the plasma to stabilize for more than 20 minutes. If the plasma suddenly extinguishes during ignition, it is usually due to air drawn up through the tubing for the spray chamber rinse solution. Repeat this step while covering the end of the tubing with a gloved finger.
Important: Ensure the peristaltic pump tubing is correctly seated. Place the tubing collars within the beams located above and below the pump wheel. Seat the collars within the beam grooves, not stretched along the outsides. Allow the pump to turn several times (enabling fast pump helps) for the tubing to work itself into position, then engage the pressure bars and if necessary adjust the tension of each. Bands of air or sample flowing through the lines leading to the pump should be unvarying in speed. If there is a chugging motion in fluid flow the pressure bars are too tight. If there is no flow, the pressure bars are too loose or there is blockage.
Selecting Elements, Wavelengths and Internal Standards to Measure
The ICP Expert software is designed in such a way that a method “template” may be set up and re-used for any number of subsequent analyses. When a run commences, the template file is converted to an ICP ExpertWorksheetFile (.esws)—which is identical to the template file except that it stores analysis results and archives instrument measurement conditions. It is important to keep in mind that all updates must be applied to the template file in order to be present in future runs. Altering the worksheet file (e.g. changing a calibration type, internal standard, removing or adding new lines, adjusting the standards table, etc) only applies to the respective worksheet.
Figure 2: ICP Expert Elements Menu for selecting analytical lines and assigning internal standards

Specifying Instrument Measurement Conditions
A considerable amount of finesse is required to improve elemental results by changing the measurement conditions. By default, use the method developed on x369. It is stored under the name ICP-Template-Master on the ICP host PC. Table 5 lists the parameter values necessary to recreate the measurement conditions. If certain instrument components or parameters are changed, then all conditions must again be optimized as they are interlinked. In particular, adjust measurement conditions if:

The sample isolation loop or any of the sample introduction lines are exchanged for one of different length and/or internal diameter.
The pump rate is altered, or any time events are changed (e.g. valve uptake delay, rinse time, etc).

The number of condition sets changes from two, or SVDV is used.

Figure 3: ICP Expert Conditions Menu for specifying instrument measurement parameters, assigning condition sets to individual lines, and setting integration areas. Note: These parameters cannot be changed once the sequence has started.

Table 4: List of standard measurement parameters for ICP-OES analysis of interstitial water, sediment and hard rock. The first condition set to be run must include a 30 second plasma stabilization time, the plasma will remain stabilized for all subsequent condition sets provided the RF power and Ar flows are the same.

Parameter	Common Conditions	Condition Set 1	Condition Set 2
Replicates	3
Pump Speed (rpm)	12
Pump Rate –Uptake (mL/min)	28
Pump Rate –Inject (mL/min)	0.5
Valve uptake delay (s)	18.0
Bubble Injection Time (s)	2.0
Pre-emptive Rinse Time (s)	2.0
Rinse Time (s)	5
Read Time (s)		5	5
RF Power (kW)		1.20	1.20
Stabilization Time (s)		30	0
Viewing mode		Axial	Radial
Viewing Height (mm)		8	8
Nebulizer Flow (L/min)		0.70	0.70
Plasma Flow (L/min)		12.0	12.0
Auxiliary Flow (L/min)		1.00	1.00
Make up Flow (L/min)		0.00	0.00

Parameters for Common Conditions:

Replicates: The number of integrations for each condition set per sample.

Pump speed (rpm): The instrument peristaltic pump speed.

Pump rate – Uptake (mL/min): The rate at which sample is drawn through the sample isolation loop connected to the AVS.

Pump rate – Inject (mL/min): The rate at which sample is pumped into the nebulizer/spray chamber from the sample isolation loop.

Valve uptake delay (s): The length of time sample is pumped from the sample vial into and through the sample isolation loop.

Bubble injection time (s): The amount of time Ar is pumped into the sample isolation loop after sample uptake but before rinse uptake. This allows a bubble to separate the sample and standard within the uptake lines.

Pre-emptive Rinse Time (s):

Rinse time (s): The amount of time rinse solution is drawn through the sample lines after a sample uptake.

Parameters for Condition Sets

Read time (s): The length of time for a single replicate integration.

RF Power (kW): The forward power supplied by the RF coil to maintain the plasma.

Stabilization Time (s): The amount of time allotted for sample to be introduced from the AVS sample isolation loop to the plasma before performing integrations.

Viewing Mode: The angle from which the plasma is viewed. In “Axial” view the instrument views the plasma from the top facing downwards. In radial view, the instrument views the plasma from the side.

Viewing Height (mm): 8: The position of the radial optics when viewing the plasma from the side.

Nebulizer Flow (L/min): The argon flowrate introduced to the nebulizer which carries sample through the spray chamber

Plasma Flow (L/min): The argon flowrate introduced to the outer sheath of the torch in order to contain the plasma.

Aux flow (L/min): The argon flowrate introduced to the torch to maintain the plasma

Make up flow (L/min):

...

Ensure there are no spectral interferences overlapping the peaks of interest.
If spectral interferences are present, inspect the interference level in the blank versus the level in the standards. If the interference is not constant between all standards, disregard the line.
Ensure the linear/quadratic/rational relationship of each wavelength calibration curve.
Ensure the sample concentrations are less than the greatest calibration point. Remove standards from the calibration which greatly over range elemental abundances in the samples as they may bias the calibration curve slope.
Do not remove a point from the calibration unless:
The RSD % is outside of the allowable.
A student T-Test or Grubbs Outlier Test has been performed on the point. Use the signal intensity-to-concentration ratios to compare the point against the mean and standard deviation of the population of the other points making up the calibration curve.
The liquid level of the vial in the autosampler rack indicates some sample volume was not introduced.
For each line, verify that the accuracy (% difference) of any check standards is within tolerance.
Ensure the % change in drift standards throughout the course of the analytical run is insignificant, or, if it is not, take into account drift with linear drift factors. If the drift is random (non-systematic), then ignore drift corrections and consider troubleshooting precision issues.
Ensure there is not a significant deviation in the slopes of calibration curves as compared to the same curves in previous runs.
Before uploading to LIMS, flag values below detection limit, higher than the highest calibration point, or have poor %RSD. AIDR has capabilities for this.

Sediment/Rock Standards

For a given sample/standard, ensure that the total % recovery of major oxides is 100 ± 2 wt%.
Periodically ensure that sediment and rock standard certified reference material values are up to date with the literature.

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