Overview

Most of the samples in this department are analyzed using this method. It also serves as the base for derivative methods like SIM, 624, and 524.2. Samples are prepared using the purge and trap method and analyzed by desorbing the concentrated sample to a GC/MS.

8250B and 8260C are the same thing; the only difference is that for 8260C all target analytes need to have 70-130% recovery for all levels in the ICAL.

Make sure to read the SOP for this method before starting this analysis. I may use compounds and analytes interchangeably within this document; they mean the same thing.

Running QC

We always use DI water when preparing QC in this department. Make sure the water you’re using has a reagent water ID and that the water’s been tested before using it. The ID is written on a green label affixed to the side of the sink. Depending on the instrument, you may need to run a rinse or two before analyzing the instrument blank due to carryover.

Before Starting

Check the DCC from the previous day to see if any target analyte responses are failing. You may need to troubleshoot before starting for the day. See Troubleshooting for general advice.

Standards

All instruments use the same base set of standards, with the more uncommon analytes being analyzed only on specific instruments or ICALs. The base standards are:

• 8260
• KET-AA
• CS2
• GAS
• 4 ADD

The uncommon standards are:

• TAA-224
• FREON
• FREON114

Check the standards logbook or here for instructions on preparation.

APP IX

Some compounds are analyzed under 8260, but the main 8260 mix doesn’t have them so we run a separate ICAL for them. We call this method APP IX. It’s still run under the same method name as 8260 but we use a special standard mix that contains the specific compounds missing from the 8260 mix. We also use this ICAL to calibrate for compounds that have poor visualization when run alongside the regular 8260 mix. These standards are:

• APP IX
• FREON
• 2-butanol

Check the standards logbook or here for instructions on preparation.

Prepping QC

QC can be prepared fairly early before analysis (about an hour in advance is fine for beginning QC). However, there are specific compounds that are temperature-sensitive; be mindful of that when timing your preparation (especially for closing DCC). Try not to prepare QC too early if these compounds are target analytes:

• 2,2-dichloropropane
• vinyl acetate
• pentachloroethane (APP IX; this one degrades FAST)

To spike DCC:

Std	Conc (ppm)	Amt (uL)
8260 (1°)	50/1250	5.0
8260 (1°)(SOIL)	50/500	5.0
KET-AA (1°)	250	5.0
4-ADD (1°)	250/6250	1.0
CS2 (1°)	250	1.0
GAS (1°)	250	1.0

To spike LCS/MS:

Std	Conc (ppm)	Amt (uL)
8260 (2°)	50/1250	5.0
8260 (2°)(SOIL)	50/500	5.0
KET-AA (2°)	250	5.0
3-ADD (2°)	50	5.0
CS2 (2°)	250	1.0
GAS (2°)	250	1.0

Optional standards:

Std	Conc (ppm)	Amt (uL)
FREON (1°)	250	1.0
FREON114 (1°)	250	1.0
TAA-224 (1°)	250/1250	1.0
FREON (2°)	250	1.0
FREON114 (2°)	250	1.0
TAA (2°)	250	5.0
224-TMP (2°)	50	5.0
2-butanol (2°)(25mL)	500	12.5
2-butanol (2°)(SOIL)	500	5.0

Evaluating Data

DCC should be passing 80-120% recovery for all target analytes. Some folders have more lax requirements (EMAX QC only requires SPCC compounds to be 80-120% in the DCC), but most folders have DoD 5.3 requirements so aiming for all analytes is the safest option, especially if you don’t have the target list yet. If running 8260C, make sure all levels in the ICAL are passing 70-130% recovery for all target analytes.

IS recovery must be 50-200% for all QC and samples to be considered valid. For soil samples, data may still be reportable if the IS recovery is failing, but for water samples this is a hard requirement. If the IS is failing low in water samples, either reanalyze the sample or reanalyze the initial run at a dilution. See here to determine which you should do.

SS recovery should be within the ranges specified in the folder to be considered passing. If SS is failing high or low and there is no matrix interference, reanalyze the sample. If the SS failing is a recurring issue in the sequence, it is indicative of an instrument issue and the sample should be reanalyzed on a stable instrument. Do not analyze the last vial on a new instrument unless it has an established history of stability.

Every folder has, at minimum, two columns next to the target list with values ranging from 0.2 to 1.0 usually. The columns are usually labeled something like LOQ/RL, LOD/MDL, and DL.

The TL;DR explanation of this is:

• LOQ/RL: This is the minimum value for compound recovery to be reported as a definite value in the report. When running dilutions, the compound recovery needs to be at this value or higher. Anything lower than this is considered an estimated value (aka a ‘J’ value) and is the reporting equivalent of not running a dilution. Your ICAL must have this level in the calibration curve for the data to be valid.

Ex: If the LOQ for a target analyte is 0.5ppb, you NEED to have this level in your ICAL for the data to be reportable.

• LOD/MDL: This is the lowest concentration at which we can identify the compound with at least 95% accuracy. For a compound to pass LOD, all qualifier ions must be within 30% of the expected recovery based on the ICAL midpoint. You do not need to have this level in your ICAL, but you do need to verify that you can see the compounds at this level before running samples (this is usually done during quarterly MDL aka pink folders).
• DL/MDLW: This is the absolute lowest concentration at which we can even see the compound. Any compound hits that are lower than the folder’s DL will show as ND when reported and can be deleted.

ICAL

Initial calibration (ICAL) is run when QC is no longer passing, when instrument maintenance is performed, or when an instrument is new. When preparing for ICAL we get brand new IS, SS, 1° and 2° standards. We use a separate IS and SS mix for ICAL because we need to recalibrate the SS responses alongside the other compounds. We also change the concentrator trap and retune the instrument prior to testing responses.

See ICAL for a more detailed explanation.

Quarterly MDL Verification

At the beginning of each quarter we need to run MDL verification to establish that the LOD/LOQ are still valid. LOD/LOQ values vary based on the compound. Your verifications must be reported at the MDL level or lower. If a compound fails LOD/LOQ, you need to troubleshoot the instrument and perform corrective action before analyzing any samples that have that compound as a target analyte.