NGA User Guide

Introduction


Natural gas analysis for hydrocarbons and hydrogen sulfide (H2S) is required to avoid natural gas and oil escaping from the hole and is part of the ship's standard drilling safety plan.
The absolute quantity of hydrocarbons is the primary safety risk during shipboard operations. Gas monitoring via gas chromatography is a means of quantifying the hydrocarbon risk. H2S is another significant risk factor for individuals working in the area. Emergency monitors on the drill floor provide early detection of H2S, while later quantification is performed on the natural gas analyzer (NGA). A primary method of monitoring safety conditions is the concentration ratio of methane to ethane versus temperature (Figure 1). 

Figure 1. Risk Assessment for Drilling Safety (IODP).

Hydrocarbon Generation

Hydrocarbon generation in sediments is a result of thermal decomposition (maturation) of biogenic organic matter. C1–C4 hydrocarbons may be generated in significant quantities in sediment via two processes:

  • Biogenic: biogenic hydrocarbons, typically characterized by methane, are produced in a sulfate-free environment via the reduction of dissolved bicarbonate.
  • Thermogenic: thermogenic hydrocarbons are produced in sediments in direct proportion to temperature. C5 and other heavier hydrocarbons are almost always the result of thermal generation of hydrogen-rich organic matter at temperatures typically ~100°C or greater.

The evolution of sedimentary biogenic organic matter under increasing burial depth and consequent temperature rise is divided into three stages:

  • Diagenesis
    • biological, physical, and chemical alteration of sedimentary organic matter that occurs at low temperature (<50°C) in relatively recently deposited sediments (Peters et al., 2005).
  • Catagenesis
    • principal zone of oil formation, refers to a temperature range of 50°C~150°C. Liquid and gaseous hydrocarbons together with organic compounds with heteroatoms (oxygen, sulfur, and nitrogen) are released from the kerogen (Figure 2), so the catagenesis stage is called the "oil window."
  • Metagenesis
    • Dry gases (mainly methane) are derived from liquid hydrocarbon accumulation in the crust (Figure 3). C1–C4 hydrocarbons may be generated in significant quantities in sediment via biogenic and thermogenic processes.



Figure 2. Hydrocarbon Formation Pathways in Geological Situations (Rullkotter, 1993).

Figure 3. Hydrocarbon Generation Resulting from Burial of Organic Matter during Geologic Time.


Hydrogen Sulfide

Sulfate-reducing bacteria produce hydrogen sulfide in euxinic sediments. This may occur in a relatively shallow part of the sediment. Thermochemical sulfate reduction of sulfate by hydrocarbons in reservoirs occurs under high temperature (>127°C ~ 140°C).

Instruments

The NGA systems are both based on an Agilent 7890 GCs. These systems were further customized with specialized gas injection inlets and various column, detector, and valving systems for gas monitoring

Gases

The GC requires that hydrogen and air are connected to the marked fittings on the back of the instrument. The type of makeup gas must be identified in the method file.

  • Air, compressed (Zero-Air +): >50 psi
  • Helium, compressed (99.9995% +): >50 psi
  • Hydrogen, compressed (99.9995% +): >50 psi


Method


Theory of method

The NGA gas chromatograph is equipped with 2 detectors:

  • Flame ionization detector (FID)
  • Thermal conductivity detector (TCD)

The TCD flow path travels through a 6 ft x 2.0 mm ID stainless steel (SS) column packed with Poropak T (50/80 mesh), a 3 ft x 2.0 mm ID SS column packed with molecular sieve 13x (60/80 mesh), and 6 ft x 2.0 mm ID SS column packed with 80/100 mesh HayeSep R (acid washed).
The FID flow path traverses a 60 m x 0.25 mm ID capillary column with 0.25 µm DB-1 film.

This instrument measures C1–C7 hydrocarbons as well as some additional compounds:

  • Methane (CH4)
  • Ethene (C2H4)
  • Ethane (C2H6)
  • Propene (C3H6)
  • Popane (C3H8)
  • n-Butane (C4H10)
  • iso-Butane (CH3-C3H7)
  • n-Pentane (C5H12)
  • iso-Pentane (CH3-C4H9)
  • n-Hexane (C6H14)
  • iso-Hexane (CH3-C5H11)
  • n-Heptane (C7H16)
  • iso-Heptane (CH3-C6H13)
  • Nitrogen (N2)
  • Oxygen (O2)
  • Carbon dioxide (CO2)

NGA Sample Flow Schematics

Standby Mode

He gas flow for standby mode (green lines).

  • Line 1: Aux-3—V1-4—V2-5—V2-3—capillary column—V2-4—V2-1—FID
  • Line 2: Aux-4—sample inlet—V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V4-3—V4-2—V4-5—V4-4—Vent
  • Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD
  • Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—Vent



Figure 9. NGA in Standby Mode.


Injection mode

He carrier gas (green line) and sample gas (red line) flows in the NGA in injection mode. Sample gas fills the sample loops connected to V1 (25 µL), V3 (1 cm3), and V4 (0.5 cm3). He flushes the separation columns.
He gas flow (green):

  • Line 1: Aux-3—V1-4—V1-5—V2-3—V2-2—capillary column—V2-4—V2-1—FID
  • Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD
  • Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—Vent


Sample gas flow (purge; red):

  • Sample inlet—V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-2—V4-5—V4-4—Vent



Figure 10. NGA in Injection Mode.


Run Mode at 0.01 min (open Valve V4)

He (green) and sample gas (red) flows in the NGA 0.01 min after start of run. Sample gas remains in the sample loop connected to V1 (25 µL) and V3 (1 cm3). After V4 opens, He returning from the back inlet pushes the sample gas out of the sample loop and into the molecular sieve column. Separated elements are detected by TCD.
He gas flow:

  • Line 1: Aux-3—V1-4—V1-5—V2-3—V2-2—capillary column—V2-4—V2-1—FID
  • Line 2: Aux-4—V1-2
  • Line 3: Front inlet—V3-5—V3-6—HayeSep R column—V3-8—V3-7—V4-9—V4-10—Vent
  • Line 4: Back inlet—V4-6—V4-5


Sample gas flow (purge):

  • V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-4—out


Sample gas flow with He:

  • V4-5—V4-2—V4-1—MolSieve column—V4-7—V4-8—TCD



Figure 11. NGA in Run Mode: 0.01 min after starting run.


Run Mode at 0.07 min (open Valves V1 and V2)

He (green) and sample gas (red) flows in the NGA 0.07–1.79 min after start of run. Sample gas remains in the sample loop connected to V3 (1 cm3). After V1 and V2 open, He from Aux-3 pushes the sample gas out of the sample loop connected to V1 (25 µL) and into the capillary column (60 m) through V2, where it passes into the FID.
He gas flow:

  • Line 1: Aux-3—V1-4
  • Line 2: Aux-4—V1-2
  • Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-10—vent
  • Line 4: Back inlet—V4-6—V4-5—V4-2—V4-1—MolSieve column—V4-7—V4-8


Sample gas flow (purge):

  • V3-4—V3-1—V3-2—V4-3—V4-4—out


Sample gas flow with He:

  • V4-8—TCD
  • V1-3—V1-6—V1-5—V2-3—V2-4—capillary column—V2-2—V2-1—FID
  • V1-1—V3-3



Figure 12. NGA in Run Mode: 0.07–1.79 min after starting run.


Run Mode at 1.80 min (open Valve V3)

He (green) and sample gas (red) flows in the NGA 1.80–1.82 min after start of run. After V3 opens, He from the front inlet pushes the sample gas out of the 1 cm3 sample loop into the HaySep column.
He gas flow:

  • Line 1: Aux-3—V1-4—V1-3—V1-6—V1-5—V2-3—V2-4
  • Line 2: Aux-4—V1-2—V1-1—V3-3—V3-2—V4-3—V4-4—out
  • Line 3: Front inlet—V3-5—V3-4
  • Line 4: Back inlet—V4-6—V4-5—V4-2—V4-1—MolSieve column—V4-7—V4-8—TCD


Sample gas flow with He:

  • Capillary column—V2-2—V2-1—FID
  • B3-4—V3-1—V3-8—HaySep R column—V3-6—V3-7



Figure 13. NGA in Run Mode: 1.80–1.82 min after starting run.


Run Mode at 1.83 min (close Valve V4)

He (green) and sample gas (red) flows in the NGA 1.83–8.49 min after start of run. After V4 closes, He from the back inlet flushes the molecular sieve column (backflush). Gas samples separated by the HaySep column enter the TCD through V4.
Helium gas flow:

  • Line 1: Aux-3—V1-4—V1-3—V1-6—V1-5—V2-3—V2-4—capillary column—V2-2—V2-1—FID
  • Line 2: Aux-4—V1-2—V1-1—V3-3—V3-2—V4-3—V4-2—V4-5—V4-4—out
  • Line 3: Front inlet—V3-5—V3-4—V3-1—V3-8


Sample gas flow with He:

  • HaySep R column—V3-6—V3-7—V4-9—V4-8—TCD

Backflush:

  • Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—vent



Figure 14. NGA in Run Mode: 1.83–8.49 min after starting run.


Run Mode at 8.50 min (close Valve V3)

He gas (green) and sample gas (red) flows in the NGA 8.50–9.09 min after start of run. After V3 closes, He from the front inlet flushes the HaySep column and the line leading to the TCD (backflush).
He gas flow:

  • Line 1: Aux-3—V1-4—V1-3—V1-6—V1-5—V2-3—V2-4—capillary column—V2-2—V2-1—FID
  • Line 2: Aux-4—V1-2—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-2—V4-5—V4-4—out
  • Line 3: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—vent


Backflush:

  • Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD



Figure 15. NGA in Run Mode: 8.50–9.09 min after starting run.


Run Mode at 10.0 min (close Valves V1 and V2)

He (green) and sample gas (red) flows in the NGA 9.09–10.0 min after start of run. After V1 and V2 close, He flow returns to standby mode.
He gas flow:

  • Line 1: Aux-3—V1-4—V1-5—V2-3—V2-2—capillary column—V2-4—V2-1—FID
  • Line 2: Aux-4—V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-2—V4-5—V4-4—out
  • Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD
  • Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—vent



Figure 16. NGA in Run Mode: 9.09–10.0 min after starting run.



NGA Startup

The chromatography application ChemStation controls GC data acquisition and processing. It can be run either online or offline. Offline mode can be run without communication with the GCs, so it is useful for reintegrating or reprocessing chromatograms. Online mode requires communication with the GC.

  • Turn on the GC. WARNING: Before turning on the GC, make sure the gas lines are open.
    The 6890 GC performs a comprehensive self-evaluation and shows real-time diagnostics on the screen. Warning, Fault, or Bad Main Board & Fatal Error messages require troubleshooting before moving to the next step (see Maintenance & Troubleshooting (HP6890GC)).
  • Click the Agilent Control Panel, then select NGA1 or NGA2, then Launch to start ChemStation. The Method and Run Control window opens. At startup, ChemStation uses the method last used (shown on the main screen). In addition, the GC LCD shows the loaded settings from ChemStation. Settings changed on the GC using the GC control panel are also made to ChemStation, and parameter changes entered into ChemStation are made to the GC. ChemStation will prompt to save changes.
  • To load a different method in Chemstation:

    • Click Method > Load Method, select the method from the list, and press OK or
    • Click the Method tab on the left side of the window and select a method to load
  • The system automatically loads the new method selected in ChemStation to the appropriate GC. Oven and detector temperatures may increase immediately after a new method is loaded, and the FID will ignite when the detector temperature reaches 150°C. Sometimes, the GC beeps because the FID flame is out, especially after a long idle period. See Maintenance & Troubleshooting (HP6890GC).
  • If the GC has been turned off for longer than a week, then bake the column for 8 hr with gas flowing (manually set the oven temperature to 175°C for GC3 or 275°C for NGA).



Instrument Operation


Before unknown samples can be analyzed for headspace gases, each GC system must have a valid calibration curve and the calibration curve must have been verified using a calibration verification standard.

Creating a Calibration Curve

1

Prepare 5–7 registered standard gases.

2

Activate NGA LIMS uploader located at Start > Program Files > IODP > MegaUploadaTron. The uploader must be activated before the calibration is run.

3

In the ChemStation Main menu, click Run Control > Sample Info.

4

Fill in the specific fields on the screen as follows:

  • Operator name: LIMS user account (your last name)
  • Sample name: name of the standard (e.g., STD_D) and the replicate number (STD_D-1, STD_D-2, etc.)
  • Comment: text ID of the standard (scan the label)
    Click OK to close screen.

5

Slowly inject 5000 µL of the first standard gas and observe the floating ball in the flow meter move upward.
Keep the outflow rate on the flow meter <80 mL/min.

6

When the ball in the flow meter indicates flow has fallen to just above 0 (is about to hit 0), press the Start button on the control panel of the GC.

7

When the run has finished, open the Data Analysis screen in ChemStation and click Calibration.

8

On the Main ChemStation menu, select Calibration > Recalibrate.

9

On the Recalibration screen, select Level # and Replace (or Average) as applicable for that level.

10

Repeat Steps 5–9 for 3 replicate standards (CH4: A 25%, B = 50%, C 75%, D = 99%).

11

Click OK to change the calibration value. For NGA calibration, the same standard can be applied to both the appropriate TCD and FID level; you do not need separate standards for TCD and FID.

Running a Calibration Verification Standard

1

Ensure the uploader is activated and the CV standard is registered in LIMS.

2

Click Run Control in the main menu of ChemStation and select Sample Info.

3

Fill in the specific section on the window as follows:

  • Operator name: LIMS user account (your last name)
  • Sample name: common name for standard (e.g., STD_D-1)
  • Comment: text ID of the standard (scan the label)
    Click OK to close the sample info screen.

4

Prepare the CV standard at approximately the mid-point concentration of the curve.

5

Slowly inject 5000 µL of the standard gas, keeping the outflow rate <80 mL/min.

6

Press Start on the GC control panel when the flow meter is just above 0.

7

When the run is finished, the report will automatically display the values. Click Upload in the uploader to submit the data to LIMS.

Running a Blank

1

To run a blank, in the Main menu click RunControl > Sample Info.

2

Fill in the following fields:

  • Operator name: your last name
  • Sample name: "BLANK"
  • Comment: text ID of the blank (scan the label)
    Click OK to close window and save information.

3

Prepare laboratory air (5000 µL) and inject it into the GC in the same fashion as the standards above when the ChemStation software shows Ready.

4

Press the Start button on the GC control panel to start the run.

5

Confirm the chromatogram on the screen shows no peaks. If peaks are present, the system contamination must be found (injector, detector, sample loop, etc.).

Running a Gas Sample

1

Ensure the uploader has been activated.

2

Click Run Control in the main menu of ChemStation and select Sample Info.

3

Fill in the specific section on the window as follows:

  • Operator name: LIMS user account (your last name)
  • Sample name: Exp/site/hole/core/coretype/section/interval (e.g., 324-U1351A 5H4 32-35)
  • Comment: text ID of sample (scan label)
    Click OK to close sample info screen.

4

Prepare a headspace or void gas sample.

5

Slowly inject 5000 µL of the gas sample, keeping the maximum gas outflow <80 mL/min.

6

Press Start on the GC control panel when the ball on the flow meter is just above 0.


Sample Preparation 


There are two primary sample types used for natural gas analysis.

  • Headspace gas, which is obtained from core samples by heating a sample to ~70°C.

  • Void gas collected with a vacuum vial.

Occasionally, cores that come on deck have voids with large amounts of free gas. Free gas must be sampled using a sampling device that penetrates the liner and provides a channel for the gas to be drawn into a gas-tight syringe, vacuum vial, or gas sampling bag.

Headspace Gas

Collect samples from a freshly cut core section at a position within 0.5 inch of the inner side of the core liner (where sample has not been disturbed by contact with drilling fluid or core liner). In addition, the sample must be taken prior to the use of acetone or any other organic solvent in the catwalk area.
The curator authorizes the sampling plan before coring; therefore, the chemistry specialist must know the catwalk sampling plan before taking samples.

1

Locate a freshly sectioned core (consult with the curator).

2

Gently push the sample coring tool into the core section slightly inward of the edge.

3

Gently pull out the tool. If the sample recovery (% of coring tool with sample) is >80% (~5–7 cm3), proceed; otherwise repeat Steps 1 and 2.

4

Place the open end of the sample coring tool over a clean headspace gas vial and use the plunger to push the sediment into the vial.

5

Immediately place a gasket with a crimp top over the vial and crimp shut.

6

After sealing the vial, immediately write down the sampling interval, location, and any other information for the sample that was just taken. Generate a proper label and apply it to the vial as soon as possible.

7

Place the vial with the sample in a 70°C oven for 30 min to degas the sediment (use timer).

8

Inject extracted gas sample into the GC using syringe (see
Running a Sample).


Collecting a Void Gas Sample

1

Use the puncture tool to make a hole in the core liner to make a channel for the gas.

2

Quickly collect a free gas sample from the small hole with a syringe.

3

Immediately introduce the gas sample into the GC instruments in the same manner as the headspace samples.

Data Upload


Data is uploaded from the NGA via a multi-step process:

  1. When the run is complete, a macro (NGA_MUT.MAC) is automatically called, as configured in the method file. The macro copies information from the method directory to C:\LIMS\NGA\data
  2. An in-house program called MegaUploadaTron (MUT) monitors the data folder locations and when a file is copied in initiates the next steps of the upload process.
  • The file is opened and read, and data points are uploaded to LIMS
  • The data files are compressed (zipped) and uploaded as well
  • LIMS analysis codes are NGAFID, and NGATCD
  1. After the upload to LIMS is complete, MUT moves the data files to an archive directory at C:\DATA\GC3\archive or C:\DATA\NGA\archive.
  2. If an upload error occurs, the files are not archived and MUT will report the error in the main window (only).

Quality Assurance/Quality Control


QA/QC for GC3/NGA analysis consists of instrument calibration and continuing calibration verification using check standards, instrument blanks, and replicate samples.

Analytical Batch

An analytical batch is a method-defined number of samples with which QC samples including calibration verification, blank, and replicate samples are run. Samples are implicitly grouped into batches based on the spacing between CV samples.

QC Samples

Blank

  • The blank determines the level of contamination originating from the laboratory environment (air) and sample path in the GC (injection port with screen, sample loop, and separation column).
  • Run a blank with each batch of samples by injecting 5 mL of ambient laboratory air into the GC using the same syringe used to inject headspace gas samples.
  • All calibrated values other than O2 and N2 should be nondetectable in the blank. If aberrant peaks appear, bake the column for 8 hr and repeat the blank analysis.


Calibration Sample

  • Five to seven levels of calibration samples (standard gases) are used to create a calibration curve, which is saved with the measurement data (see Instrument Calibration/Calibration Verification).
  • Correlation coefficient values for calibration curves should be 0.99 or better, except O2 and N2, which should be 0.95 or better.

Calibration Verification (CV) Sample

  • Select one of the 5–7 calibration samples from the calibration curve for the calibration verification sample.
  • Run a CV sample at least every shift that samples are taken (see Instrument Calibration/Calibration Verification).
  • The CV should fall within 3% of the calibrated value; O2 and N2 should be within 10% of the calibrated value.

Control Limits

For a system to be considered in control, all QA/QC samples (blank and calibration verification) must be in control.

In Control

A QA/QC sample is in control when the sample analysis result is within a certain tolerance of acceptable limits (see above). Calibration verification samples should be within acceptable limits of the actual value calculated against the calibration curve (see Calibration Verification (CV) Sample) and blanks should be within acceptable limits of background levels of headspace hydrocarbons and gases (see Blank). When the system is in control, as indicated by acceptable results on QA/QC samples, analytical results for unknown samples are considered to be reliable.

Out of Control

If the control limits are exceeded, the instrument system is considered out of control and all samples in the current analytical batch are invalid and must be rerun after the system is proved to be in control.

LIMS Integration


LIMS Components

Analysis

Component

Unit

Description

GC3

dat_asman_id

Serial number of chromatographic data file in digital asset management database (ASMAN)


dat_filename

File name of chromatographic data file containing measurements


run_test

Test number of related calibration or QA/QC test


propene

ppmv

Relative concentration of propene in the sample


propane

ppmv

Relative concentration of propane in the sample


ethene

ppmv

Relative concentration of ethene in the sample


ethane

ppmv

Relative concentration of ethane in the sample


methane

ppmv

Relative concentration of methane in the sample

GC3_QAQC

dat_asman_id

Serial number of chromatographic data file in ASMAN


dat_filename

File name of chromatographic data file containing measurements


run_test

Test number of related calibration or QA/QC test


propene

ppmv

Relative concentration of propene in the sample


propane

ppmv

Relative concentration of propane in the sample


ethene

ppmv

Relative concentration of ethene in the sample


ethane

ppmv

Relative concentration of ethane in the sample


methane

ppmv

Relative concentration of methane in the sample

GC3_QCAL

mtd_asman_id

Serial number of chromatographic method in ASMAN


mtd_filename

File name of the chromatographic method file containing measurements


ethene_corr2

R2

Ethene calibration coefficient


ethene_intercept

Intercept of ethene calibration curve


ethene_slope

Slope of ethene calibration curve


ethane_corr2

R2

Ethane calibration coefficient


ethane_intercept

Intercept of ethane calibration curve


ethane_slope

Slope of ethane calibration curve


propene_corr2

R2

Propene calibration coefficient


propene_intercept

Intercept of propene calibration curve


propene_slope

Slope of propene calibration curve


propane_corr2

R2

Propane calibration coefficient


propane_intercept

Intercept of propane calibration curve


propane_slope

Slope of propene calibration curve


methane_corr2

R2

Methane calibration coefficient


methane_intercept

Intercept of methane calibration curve


methane_slope

Slope of methane calibration curve

NGAFID

dat_asman_id

Serial number of chromatographic data file in ASMAN


dat_filename

File name of chromatographic data file containing measurements


run_test

Test number of related calibration or QA/QC test


iso_butane

ppmv

Concentration of iso_butane in a sample


iso_heptane

ppmv

Concentration of iso_heptane in a sample


iso_hexane

ppmv

Concentration of iso_hexane in a sample


iso_pentane

ppmv

Concentration of iso_pentane in a sample


n_butane

ppmv

Concentration of n_butane in a sample


n_heptane

ppmv

Concentration of n_heptane in a sample


n_hexane

ppmv

Concentration of n_hexane in a sample


n_pentane

ppmv

Concentration of n_pentane in a sample


ethane_ethene

ppmv

Concentration of ethane + ethene in a sample


propane_propene

ppmv

Concentration of propane + propene in a sample


methane

ppmv

Concentration of methane in a sample

NGAFID_QA

dat_asman_id

Serial number of chromatographic data file in ASMAN


dat_filename

File name of chromatographic data file containing measurements


run_test

Test number of related calibration or QA/QC test


iso_butane

ppmv

Concentration of iso_butane in a sample


iso_heptane

ppmv

Concentration of iso_heptane in a sample


iso_hexane

ppmv

Concentration of iso_hexane in a sample


iso_pentane

ppmv

Concentration of iso_pentane in a sample


n_butane

ppmv

Concentration of n_butane in a sample


n_heptane

ppmv

Concentration of n_heptane in a sample


n_hexane

ppmv

Concentration of n_hexane in a sample


n_pentane

ppmv

Concentration of n_pentane in a sample


ethane_ethene

ppmv

Concentration of ethane + ethene in a sample


propane_propene

ppmv

Concentration of propane + propene in a sample


methane

ppmv

Concentration of methane in a sample

NGAFID_QC

mtd_asman_id

Serial number of chromatographic method in ASMAN


mtd_filename

File name of the chromatographic method file containing measurements


iso_butane_corr2

R2

Iso-butane calibration coefficient


iso_butane_intercept

Intercept of iso-butane calibration curve


iso_butane_slope

Slope of iso-butane calibration curve


iso_heptane_corr2

R2

Iso-heptane calibration coefficient


iso_heptane_intercept

Intercept of iso-heptane calibration curve


iso_heptane_slope

Slope of iso-heptane calibration curve


iso_hexane_corr2

R2

Iso-hexane calibration coefficient


iso_hexane_intercept

Intercept of iso-hexane calibration curve


iso_hexane_slope

Slope of iso-hexane calibration curve


iso_pentane_corr2

R2

Iso-pentane calibration coefficient


iso_pentane_intercept

Intercept of iso-pentane calibration curve


iso_pentane_slope

Slope of iso-pentane calibration curve


n_butane_corr2

R2

n-butane calibration coefficient


n_butane_intercept

Intercept of n-butane calibration curve


n_butane_slope

Slope of n-butane calibration curve


n_heptane_corr2

R2

n-heptane calibration coefficient


n_heptane_intercept

Intercept of n-heptane calibration curve


n_heptane_slope

Slope of n-heptane calibration curve


n_hexane_corr2

R2

n-hexane calibration coefficient


n_hexane_intercept

Intercept of n-hexane calibration curve


n_hexane_slope

Slope of n-hexane calibration curve


n_pentane_corr2

R2

n-pentane calibration coefficient


n_pentane_intercept

Intercept of n-pentane calibration curve


n_pentane_slope

Slope of n-pentane calibration curve


ethane_ethene_corr2

R2

Ethane + ethene calibration coefficient


ethane_ethene_intercept

Intercept of ethane + ethene calibration curve


ethane_ethene_slope

Slope of ethane + ethene calibration curve


propane_propene_corr2

R2

Propane + propene calibration coefficient


propane_propene_intercept

Intercept of propane + propene calibration curve


propane_propene_slope

Slope of propane + propene calibration curve

NGAFID_QC

methane_corr2

R2

Methane calibration coefficient


methane_intercept

Intercept of methane calibration curve


methane_slope

Slope of methane calibration curve

NGATCD

dat_asman_id

Serial number of chromatographic data file in ASMAN


dat_filename

File name of chromatographic data file containing measurements


run_test

Test number of related calibration or QA/QC test


carbon_dioxide

ppmv

Concentration of carbon dioxide in a sample


ethane

ppmv

Concentration of ethane in a sample


ethene

ppmv

Concentration of ethene in a sample


hydrogen_sulfide

ppmv

Concentration of hydrogen sulfide in a sample


methane

ppmv

Concentration of methane in a sample


nitrogen

ppmv

Concentration of nitrogen in a sample


oxygen

ppmv

Concentration of oxygen in a sample


propane

ppmv

Concentration of propane in a sample


propene

ppmv

Concentration of propene in a sample


Health, Safety & Environment


Safety

  • The following parts are dangerously hot. Avoid touching these areas and cool completely to room temperature before servicing them:
  • Inlets
  • Oven
  • Detectors
  • Column nuts
  • Be careful when working behind the instrument; during cooldown cycle the oven emits hot exhaust that can cause burns.
  • Do not place temperature-sensitive items (e.g., gas cylinders, chemicals, regulators, and plastic tubing) in the path of the heated exhaust.
  • Insulation around inlets, detectors, and valve box contains refractory ceramic fibers. Avoid inhaling particles and wear personal protective equipment including gloves, safety glasses, and dust/mist respirator when working in these areas.
  • Do not leave flammable gas flows on if GC will be unmonitored for long periods of time (however, leave carrier gas on for column flow).
  • Always operate the instrument with the cover properly installed.

Maintenance & Troubleshooting (HP6890GC)


Use the Status and Info keys on the GC keypad as a first check when something goes wrong.

Troubleshooting

Faults

  • Beeping instrument (cancel beep by pressing Clear on the instrument keyboard)
  • One beep: instrument fault, warning, or shutdown
  • Series of beeps: gas flow cannot reach setpoint and flow will be shut down after 1–2 min
  • Continuous beep: thermal shutdown
  • Blinking setpoint on GC display
  • Control table setpoint blinking: gas flow, valve, or oven shutdown
  • Detector On/Off line blinking: pneumatics or detector failure
  • Instrument screen messages (press Clear to remove message)
  • Caution: configuration problems
  • Error: setpoint out of range or incorrect hardware
  • Popup: shutdown, fault, or warning (see error table)
  • FID will not stay lit
  • Make sure the dessicant in the hydrogen generator is not saturated with water (replace/recharge as necessary).
  • Check water level in hydrogen generator

Leak Checking

When checking for leaks, check both parts of the system:

  • External leaks: gas cylinders, gas purifiers/traps, regulator fittings, supply shutoff valves, GC supply fittings.
  • GC leaks: inlets, purge vents; column connections to inlets, detectors, valves, splitters, adapters, and unions.


For safe leak-checking and flow measurement:

  • Purge flowmeters with inert gas after measuring a flammable gas (such as hydrogen).
  • Measure gases individually.
  • Turn off detectors while measuring gas flows.

Column Size and Carrier Gas Flow Rate

Column type

Column ID

Carrier gas flow rate (mL/min)

 



Hydrogen

Helium

Packed

1/8 inch


30


1/4 inch


60

Capillary

50 µm

0.5

0.4


100 µm

1.0

0.8


200 µm

2.0

1.6


250 µm

2.5

2.0


320 µm

3.2

2.6


530 µm

5.3

4.2

These flow rates at normal temperature and pressure (25°C and 1 atm) are recommended for all column temperatures.
For capillary columns, flow rates are proportional to column diameter and are 20% lower for helium than for hydrogen.




LIMS Component Tables

The following tables represent all of the LIMS components for the following analysis codes:

  • NGAFID - C1-C7 hydrocarbons by flame ionization detector
  • NGATCD - C1-C3 hydrocarbons and fixed gases by thermal conductivity detector
  • GC3 (legacy) - C1-C3 hydrocarbons by flame ionization detector; this system is no longer aboard, but at the time was faster than the previous version of the NGA; the Agilent 7890 NGA GCs are fast enough to make the separate GC3 unnecessary
ANALYSISTABLENAMEABOUT TEXT
NGAFIDSAMPLEExpExp: expedition number
NGAFIDSAMPLESiteSite: site number
NGAFIDSAMPLEHoleHole: hole number
NGAFIDSAMPLECoreCore: core number
NGAFIDSAMPLETypeType: type indicates the coring tool used to recover the core (typical types are F, H, R, X).
NGAFIDSAMPLESectSect: section number
NGAFIDSAMPLEA/WA/W: archive (A) or working (W) section half.
NGAFIDSAMPLEtext_idText_ID: automatically generated database identifier for a sample, also carried on the printed labels. This identifier is guaranteed to be unique across all samples.
NGAFIDSAMPLEsample_numberSample Number: automatically generated database identifier for a sample. This is the primary key of the SAMPLE table.
NGAFIDSAMPLElabel_idLabel identifier: automatically generated, human readable name for a sample that is printed on labels. This name is not guaranteed unique across all samples.
NGAFIDSAMPLEsample_nameSample name: short name that may be specified for a sample. You can use an advanced filter to narrow your search by this parameter.
NGAFIDSAMPLEx_sample_stateSample state: Single-character identifier always set to "W" for samples; standards can vary.
NGAFIDSAMPLEx_projectProject: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises
NGAFIDSAMPLEx_capt_locCaptured location: "captured location," this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2
NGAFIDSAMPLElocationLocation: location that sample was taken; this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2
NGAFIDSAMPLEx_sampling_toolSampling tool: sampling tool used to take the sample (e.g., syringe, spatula)
NGAFIDSAMPLEchanged_byChanged by: username of account used to make a change to a sample record
NGAFIDSAMPLEchanged_onChanged on: date/time stamp for change made to a sample record
NGAFIDSAMPLEsample_typeSample type: type of sample from a predefined list (e.g., HOLE, CORE, LIQ)
NGAFIDSAMPLEx_offsetOffset (m): top offset of sample from top of parent sample, expressed in meters.
NGAFIDSAMPLEx_offset_cmOffset (cm): top offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset, converted to cm)
NGAFIDSAMPLEx_bottom_offset_cmBottom offset (cm): bottom offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset + length, converted to cm)
NGAFIDSAMPLEx_diameterDiameter (cm): diameter of sample, usually applied only to CORE, SECT, SHLF, and WRND samples; however this field is null on both Exp. 390 and 393, so it is no longer populated by Sample Master
NGAFIDSAMPLEx_orig_lenOriginal length (m): field for the original length of a sample; not always (or reliably) populated
NGAFIDSAMPLEx_lengthLength (m): field for the length of a sample [as entered upon creation]
NGAFIDSAMPLEx_length_cmLength (cm): field for the length of a sample. This is a calculated field (length, converted to cm).
NGAFIDSAMPLEstatusStatus: single-character code for the current status of a sample (e.g., active, canceled)
NGAFIDSAMPLEold_statusOld status: single-character code for the previous status of a sample; used by the LIME program to restore a canceled sample
NGAFIDSAMPLEoriginal_sampleOriginal sample: field tying a sample below the CORE level to its parent HOLE sample
NGAFIDSAMPLEparent_sampleParent sample: the sample from which this sample was taken (e.g., for PWDR samples, this might be a SHLF or possibly another PWDR)
NGAFIDSAMPLEstandardStandard: T/F field to differentiate between samples (standard=F) and QAQC standards (standard=T)
NGAFIDSAMPLElogin_byLogin by: username of account used to create the sample (can be the LIMS itself [e.g., SHLFs created when a SECT is created])
NGAFIDSAMPLElogin_dateLogin date: creation date of the sample
NGAFIDSAMPLElegacyLegacy flag: T/F indicator for when a sample is from a previous expedition and is locked/uneditable on this expedition
NGAFIDTESTtest changed_onTEST changed on: date/time stamp for a change to a test record.
NGAFIDTESTtest statusTEST status: single-character code for the current status of a test (e.g., active, in process, canceled)
NGAFIDTESTtest old_statusTEST old status: single-character code for the previous status of a test; used by the LIME program to restore a canceled test
NGAFIDTESTtest test_numberTEST test number: automatically generated database identifier for a test record. This is the primary key of the TEST table.
NGAFIDTESTtest date_receivedTEST date received: date/time stamp for the creation of the test record.
NGAFIDTESTtest instrumentTEST instrument [instrument group]: field that describes the instrument group (most often this applies to loggers with multiple sensors); often obscure (e.g., user_input)
NGAFIDTESTtest analysisTEST analysis: analysis code associated with this test (foreign key to the ANALYSIS table)
NGAFIDTESTtest x_projectTEST project: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises
NGAFIDTESTtest sample_numberTEST sample number: the sample_number of the sample to which this test record is attached; a foreign key to the SAMPLE table
NGAFIDCALCULATEDTop depth CSF-A (m)Top depth CSF-A (m): position of observation expressed relative to the top of the hole.
NGAFIDCALCULATEDBottom depth CSF-A (m)Bottom depth CSF-A (m): position of observation expressed relative to the top of the hole.
NGAFIDCALCULATEDTop depth CSF-B (m)Top depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user.
NGAFIDCALCULATEDBottom depth CSF-B (m)Bottom depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user.
NGAFIDRESULTdata_asman_idRESULT data ASMAN_ID: serial number of the ASMAN link for the data file (binary format)
NGAFIDRESULTdata_filenameRESULT data filename: file name of the data file (binary format)
NGAFIDRESULTethane (ppmv)RESULT ethane (ppmv): ethane (C2H6, also shown as C2) concentration of the headspace or void space
NGAFIDRESULTethene (ppmv)RESULT ethene (ppmv): ethene (C2H4, also shown as C2=) concentration of the headspace or void space
NGAFIDRESULTiso_butane (ppmv)RESULT iso-butane (ppmv): iso-butane (HC(CH3)3) concentration of the headspace or void space; also known as 2-methyl propane
NGAFIDRESULTiso_heptane (ppmv)RESULT iso-heptane (ppmv): iso-heptane (HC(CH3)6) concentration of the headspace or void space; also known as 2-methyl hexane
NGAFIDRESULTiso_hexane (ppmv)RESULT iso-hexane (ppmv): iso-hexane (HC(CH3)5) concentration of the headspace or void space; also known as 2-methyl pentane
NGAFIDRESULTiso_pentane (ppmv)RESULT iso-pentane (ppmv): iso-pentane (HC(CH3)4) concentration of the headspace or void space; also known as 2-methyl butane
NGAFIDRESULTmethane (ppmv)RESULT methane (ppmv): methane (CH4, also shown as C1) concentration of the headspace or void space
NGAFIDRESULTmethod_asman_idRESULT method ASMAN_ID: serial number of the ASMAN link for the method file (binary format)
NGAFIDRESULTmethod_filenameRESULT method filename: file name of the method file (binary format)
NGAFIDRESULTn_butane (ppmv)RESULT n-butane (ppmv): n-butane (C4H10) concentration of the headspace or void space
NGAFIDRESULTn_heptane (ppmv)RESULT n-heptane (ppmv): n-heptane (C7H16) concentration of the headspace or void space
NGAFIDRESULTn_hexane (ppmv)RESULT n-hexane (ppmv): n-hexane (C6H14) concentration of the headspace or void space
NGAFIDRESULTn_pentane (ppmv)RESULT n-pentane (ppmv): n-pentane (C5H12) concentration of the headspace or void space
NGAFIDRESULTn_propaneRESULT n-propane (ppmv): n-propane (C3H8) concentration of the headspace or void space
NGAFIDRESULTpropene (ppmv)RESULT propene (ppmv): propene (C3H6, also shown as C3=) concentration of the headspace or void space
NGAFIDRESULTrun_testRESULT run test: number of the run, not always populated
NGAFIDSAMPLEsample descriptionSAMPLE comment: contents of the SAMPLE.description field, usually shown on reports as "Sample comments"
NGAFIDTESTtest test_commentTEST comment: contents of the TEST.comment field, usually shown on reports as "Test comments"
NGAFIDRESULTresult commentsRESULT comment: contents of a result parameter with name = "comment," usually shown on reports as "Result comments"
ANALYSISTABLENAMEABOUT TEXT
NGATCDSAMPLEExpExp: expedition number
NGATCDSAMPLESiteSite: site number
NGATCDSAMPLEHoleHole: hole number
NGATCDSAMPLECoreCore: core number
NGATCDSAMPLETypeType: type indicates the coring tool used to recover the core (typical types are F, H, R, X).
NGATCDSAMPLESectSect: section number
NGATCDSAMPLEA/WA/W: archive (A) or working (W) section half.
NGATCDSAMPLEtext_idText_ID: automatically generated database identifier for a sample, also carried on the printed labels. This identifier is guaranteed to be unique across all samples.
NGATCDSAMPLEsample_numberSample Number: automatically generated database identifier for a sample. This is the primary key of the SAMPLE table.
NGATCDSAMPLElabel_idLabel identifier: automatically generated, human readable name for a sample that is printed on labels. This name is not guaranteed unique across all samples.
NGATCDSAMPLEsample_nameSample name: short name that may be specified for a sample. You can use an advanced filter to narrow your search by this parameter.
NGATCDSAMPLEx_sample_stateSample state: Single-character identifier always set to "W" for samples; standards can vary.
NGATCDSAMPLEx_projectProject: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises
NGATCDSAMPLEx_capt_locCaptured location: "captured location," this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2
NGATCDSAMPLElocationLocation: location that sample was taken; this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2
NGATCDSAMPLEx_sampling_toolSampling tool: sampling tool used to take the sample (e.g., syringe, spatula)
NGATCDSAMPLEchanged_byChanged by: username of account used to make a change to a sample record
NGATCDSAMPLEchanged_onChanged on: date/time stamp for change made to a sample record
NGATCDSAMPLEsample_typeSample type: type of sample from a predefined list (e.g., HOLE, CORE, LIQ)
NGATCDSAMPLEx_offsetOffset (m): top offset of sample from top of parent sample, expressed in meters.
NGATCDSAMPLEx_offset_cmOffset (cm): top offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset, converted to cm)
NGATCDSAMPLEx_bottom_offset_cmBottom offset (cm): bottom offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset + length, converted to cm)
NGATCDSAMPLEx_diameterDiameter (cm): diameter of sample, usually applied only to CORE, SECT, SHLF, and WRND samples; however this field is null on both Exp. 390 and 393, so it is no longer populated by Sample Master
NGATCDSAMPLEx_orig_lenOriginal length (m): field for the original length of a sample; not always (or reliably) populated
NGATCDSAMPLEx_lengthLength (m): field for the length of a sample [as entered upon creation]
NGATCDSAMPLEx_length_cmLength (cm): field for the length of a sample. This is a calculated field (length, converted to cm).
NGATCDSAMPLEstatusStatus: single-character code for the current status of a sample (e.g., active, canceled)
NGATCDSAMPLEold_statusOld status: single-character code for the previous status of a sample; used by the LIME program to restore a canceled sample
NGATCDSAMPLEoriginal_sampleOriginal sample: field tying a sample below the CORE level to its parent HOLE sample
NGATCDSAMPLEparent_sampleParent sample: the sample from which this sample was taken (e.g., for PWDR samples, this might be a SHLF or possibly another PWDR)
NGATCDSAMPLEstandardStandard: T/F field to differentiate between samples (standard=F) and QAQC standards (standard=T)
NGATCDSAMPLElogin_byLogin by: username of account used to create the sample (can be the LIMS itself [e.g., SHLFs created when a SECT is created])
NGATCDSAMPLElogin_dateLogin date: creation date of the sample
NGATCDSAMPLElegacyLegacy flag: T/F indicator for when a sample is from a previous expedition and is locked/uneditable on this expedition
NGATCDTESTtest changed_onTEST changed on: date/time stamp for a change to a test record.
NGATCDTESTtest statusTEST status: single-character code for the current status of a test (e.g., active, in process, canceled)
NGATCDTESTtest old_statusTEST old status: single-character code for the previous status of a test; used by the LIME program to restore a canceled test
NGATCDTESTtest test_numberTEST test number: automatically generated database identifier for a test record. This is the primary key of the TEST table.
NGATCDTESTtest date_receivedTEST date received: date/time stamp for the creation of the test record.
NGATCDTESTtest instrumentTEST instrument [instrument group]: field that describes the instrument group (most often this applies to loggers with multiple sensors); often obscure (e.g., user_input)
NGATCDTESTtest analysisTEST analysis: analysis code associated with this test (foreign key to the ANALYSIS table)
NGATCDTESTtest x_projectTEST project: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises
NGATCDTESTtest sample_numberTEST sample number: the sample_number of the sample to which this test record is attached; a foreign key to the SAMPLE table
NGATCDCALCULATEDTop depth CSF-A (m)Top depth CSF-A (m): position of observation expressed relative to the top of the hole.
NGATCDCALCULATEDBottom depth CSF-A (m)Bottom depth CSF-A (m): position of observation expressed relative to the top of the hole.
NGATCDCALCULATEDTop depth CSF-B (m)Top depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user.
NGATCDCALCULATEDBottom depth CSF-B (m)Bottom depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user.
NGATCDRESULTcarbon_dioxide (ppmv)RESULT carbon dioxide (ppmv): concentration of CO2 in the headspace or void space
NGATCDRESULTdata_asman_idRESULT data ASMAN_ID: serial number of the ASMAN link for the data file (binary format)
NGATCDRESULTdata_filenameRESULT data filename: file name of the data file (binary format)
NGATCDRESULTethane (ppmv)RESULT ethane (ppmv): ethane (C2H6, also shown as C2) concentration of the headspace or void space
NGATCDRESULTethene (ppmv)RESULT ethene (ppmv): ethene (C2H4, also shown as C2=) concentration of the headspace or void space
NGATCDRESULThydrogen_sulfide (ppmv)RESULT hydrogen sulfide (ppmv): concentration of H2S in the headspace or void space
NGATCDRESULTmethane (ppmv)RESULT methane (ppmv): methane (CH4, also shown as C1) concentration of the headspace or void space
NGATCDRESULTmethod_asman_idRESULT method ASMAN_ID: serial number of the ASMAN link for the method file (binary format)
NGATCDRESULTmethod_filenameRESULT method filename: file name of the method file (binary format)
NGATCDRESULTnitrogen (ppmv)RESULT nitrogen (ppmv): concentration of N2 in the headspace or void space
NGATCDRESULToxygen (ppmv)RESULT oxygen (ppmv): concentration of O2 in the headspace or void space
NGATCDRESULTpropane (ppmv)RESULT n-propane (ppmv): propane (C3H8) concentration of the headspace or void space
NGATCDRESULTpropene (ppmv)RESULT propene (ppmv): propene (C3H6, also shown as C3=) concentration of the headspace or void space
NGATCDRESULTrun_testRESULT run test: number of the run, not always populated
NGATCDSAMPLEsample descriptionSAMPLE comment: contents of the SAMPLE.description field, usually shown on reports as "Sample comments"
NGATCDTESTtest test_commentTEST comment: contents of the TEST.comment field, usually shown on reports as "Test comments"
NGATCDRESULTresult commentsRESULT comment: contents of a result parameter with name = "comment," usually shown on reports as "Result comments"


ANALYSISTABLENAMEABOUT TEXT
GC3SAMPLEExpExp: expedition number
GC3SAMPLESiteSite: site number
GC3SAMPLEHoleHole: hole number
GC3SAMPLECoreCore: core number
GC3SAMPLETypeType: type indicates the coring tool used to recover the core (typical types are F, H, R, X).
GC3SAMPLESectSect: section number
GC3SAMPLEA/WA/W: archive (A) or working (W) section half.
GC3SAMPLEtext_idText_ID: automatically generated database identifier for a sample, also carried on the printed labels. This identifier is guaranteed to be unique across all samples.
GC3SAMPLEsample_numberSample Number: automatically generated database identifier for a sample. This is the primary key of the SAMPLE table.
GC3SAMPLElabel_idLabel identifier: automatically generated, human readable name for a sample that is printed on labels. This name is not guaranteed unique across all samples.
GC3SAMPLEsample_nameSample name: short name that may be specified for a sample. You can use an advanced filter to narrow your search by this parameter.
GC3SAMPLEx_sample_stateSample state: Single-character identifier always set to "W" for samples; standards can vary.
GC3SAMPLEx_projectProject: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises
GC3SAMPLEx_capt_locCaptured location: "captured location," this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2
GC3SAMPLElocationLocation: location that sample was taken; this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2
GC3SAMPLEx_sampling_toolSampling tool: sampling tool used to take the sample (e.g., syringe, spatula)
GC3SAMPLEchanged_byChanged by: username of account used to make a change to a sample record
GC3SAMPLEchanged_onChanged on: date/time stamp for change made to a sample record
GC3SAMPLEsample_typeSample type: type of sample from a predefined list (e.g., HOLE, CORE, LIQ)
GC3SAMPLEx_offsetOffset (m): top offset of sample from top of parent sample, expressed in meters.
GC3SAMPLEx_offset_cmOffset (cm): top offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset, converted to cm)
GC3SAMPLEx_bottom_offset_cmBottom offset (cm): bottom offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset + length, converted to cm)
GC3SAMPLEx_diameterDiameter (cm): diameter of sample, usually applied only to CORE, SECT, SHLF, and WRND samples; however this field is null on both Exp. 390 and 393, so it is no longer populated by Sample Master
GC3SAMPLEx_orig_lenOriginal length (m): field for the original length of a sample; not always (or reliably) populated
GC3SAMPLEx_lengthLength (m): field for the length of a sample [as entered upon creation]
GC3SAMPLEx_length_cmLength (cm): field for the length of a sample. This is a calculated field (length, converted to cm).
GC3SAMPLEstatusStatus: single-character code for the current status of a sample (e.g., active, canceled)
GC3SAMPLEold_statusOld status: single-character code for the previous status of a sample; used by the LIME program to restore a canceled sample
GC3SAMPLEoriginal_sampleOriginal sample: field tying a sample below the CORE level to its parent HOLE sample
GC3SAMPLEparent_sampleParent sample: the sample from which this sample was taken (e.g., for PWDR samples, this might be a SHLF or possibly another PWDR)
GC3SAMPLEstandardStandard: T/F field to differentiate between samples (standard=F) and QAQC standards (standard=T)
GC3SAMPLElogin_byLogin by: username of account used to create the sample (can be the LIMS itself [e.g., SHLFs created when a SECT is created])
GC3SAMPLElogin_dateLogin date: creation date of the sample
GC3SAMPLElegacyLegacy flag: T/F indicator for when a sample is from a previous expedition and is locked/uneditable on this expedition
GC3TESTtest changed_onTEST changed on: date/time stamp for a change to a test record.
GC3TESTtest statusTEST status: single-character code for the current status of a test (e.g., active, in process, canceled)
GC3TESTtest old_statusTEST old status: single-character code for the previous status of a test; used by the LIME program to restore a canceled test
GC3TESTtest test_numberTEST test number: automatically generated database identifier for a test record. This is the primary key of the TEST table.
GC3TESTtest date_receivedTEST date received: date/time stamp for the creation of the test record.
GC3TESTtest instrumentTEST instrument [instrument group]: field that describes the instrument group (most often this applies to loggers with multiple sensors); often obscure (e.g., user_input)
GC3TESTtest analysisTEST analysis: analysis code associated with this test (foreign key to the ANALYSIS table)
GC3TESTtest x_projectTEST project: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises
GC3TESTtest sample_numberTEST sample number: the sample_number of the sample to which this test record is attached; a foreign key to the SAMPLE table
GC3CALCULATEDTop depth CSF-A (m)Top depth CSF-A (m): position of observation expressed relative to the top of the hole.
GC3CALCULATEDBottom depth CSF-A (m)Bottom depth CSF-A (m): position of observation expressed relative to the top of the hole.
GC3CALCULATEDTop depth CSF-B (m)Top depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user.
GC3CALCULATEDBottom depth CSF-B (m)Bottom depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user.
GC3RESULTdata_asman_idRESULT data ASMAN_ID: serial number of the ASMAN link for the data file (binary format)
GC3RESULTdata_filenameRESULT data filename: file name of the data file (binary format)
GC3RESULTethane (ppmv)RESULT ethane (ppmv): ethane (C2H6, also shown as C2) concentration of the headspace or void space
GC3RESULTethene (ppmv)RESULT ethene (ppmv): ethene (C2H4, also shown as C2=) concentration of the headspace or void space
GC3RESULTmethane (ppmv)RESULT methane (ppmv): methane (CH4, also shown as C1) concentration of the headspace or void space
GC3RESULTmethod_asman_idRESULT method ASMAN_ID: serial number of the ASMAN link for the method file (binary format)
GC3RESULTmethod_filenameRESULT method filename: file name of the method file (binary format)
GC3RESULTpropane (ppmv)RESULT propane (ppmv): propane (C3H8, also shown as C3) concentration of the headspace or void space
GC3RESULTpropene (ppmv)RESULT propene (ppmv): propene (C3H6, also shown as C3=) concentration of the headspace or void space
GC3RESULTrun_testRESULT run test: number of the run, not always populated
GC3RESULTssup_asman_idRESULT spreadsheet uploader ASMAN_ID: serial number of the ASMAN link for the spreadsheet uploader file
GC3RESULTssup_filenameRESULT spreadsheet uploader filename: file name for the spreadsheet uploader file
GC3RESULTc1_c2_gc3RESULT C1/C2 ratio (unitless): ratio of the C1 (methane) peak to the total C2 (ethane + ethene) peak
GC3RESULTc1_heavyRESULT C1/heavy ratio (unitless): ratio of the C1 (methane) peak to the total of all heavier hydrocarbon peaks
GC3SAMPLEsample descriptionSAMPLE comment: contents of the SAMPLE.description field, usually shown on reports as "Sample comments"
GC3TESTtest test_commentTEST comment: contents of the TEST.comment field, usually shown on reports as "Test comments"
GC3RESULTresult commentsRESULT comment: contents of a result parameter with name = "comment," usually shown on reports as "Result comments"

Archive Version

NGA User Guide: 29th September 2022

LMUG-GC3-NGAUG2011-230220-1904-144.pdf