Author Archive

EPA Method 541 on the Stabilwax Column

I recently posted some chromatograms for our new EPA Method 541 UCMR4 Standards, and wanted to focus on the column in a separate post. EPA Method 541 was developed on a 30m x 0.25 mm ID x 0.50 µm wax column from another manufacturer. I used the Stabilwax because it is a relatively low bleed […]

New Custom UCMR4 Standards for EPA Method 541

We recently stocked custom EPA Method 541 standards made specifically for labs participating in Unregulated Contaminant Monitoring Rule 4 (UCMR4). Quantitative Certificates of Analysis with Data Packs are available for each item. Contact Customer Service to place your order (items are not available at Restek.com).   Cat# 572263 – Method 541 UCMR4 Standard (in P&T Methanol) Contaminant […]

New Custom UCMR4 Standard for EPA Method 530 on the Rtx-1701

We recently stocked custom EPA Method 530 standards made specifically for labs participating in Unregulated Contaminant Monitoring Rule 4 (UCMR4). Quantitative Certificates of Analysis with Data Packs are available for each item. Contact Customer Service to place your order (items are not available at Restek.com). Cat# 572262 – Method 530 UCMR4 Standard (in Methanol) Contaminant CAS Registry […]

New Custom UCMR4 Standard for EPA Method 525.3

We recently stocked a custom EPA Method 525.3 standard made specifically for labs participating in Unregulated Contaminant Monitoring Rule 4 (UCMR4). Quantitative Certificates of Analysis with Data Packs are available for each item. Contact Customer Service to place your order (items are not available at Restek.com) Cat# 572261 – Method 525.3 UCMR4 Standard – Eight Pesticides […]

Quadrupole Scan Speed and the 8270 Instrument Checkout Mix – Part II – The DFTPP Evaluation

Yesterday’s blog gave an overview of how choosing the wrong scan speed could be detrimental to the tailing factor evaluation. Before someone asks, I thought we’d spend today looking at the impact of scan speed on the decafluorotriphenylphosphine (DFTPP) tune evaluation. I know I’ve covered this before, but here are the tuning criteria from EPA […]

Quadrupole Scan Speed and the 8270 Instrument Checkout Mix

In my last blog (here), I promised an update on the impact of the detector scan speed on the tailing factor. I had speculated that a pentachlorophenol tailing factor value of 0.94 was more likely < 1.0 because of the scan rate, rather than column overload. The examples I put forward here were collected on […]

An introduction to the benefits of using split injection when performing semivolatiles analysis by 8270D – the instrument checkout mix

This blog is part of a series; the previous installments can be found here and here. We have mentioned several times that the reduced residence time resulting from the fast sample transfer that occurs during a split injection reduces in-inlet degradation and adsorptive loss. Proof of this can be seen in the first run of […]

A quick evaluation of some disadvantages to performing semivolatiles analysis by EPA Method 8270D with splitless injection

This blog is part of a series; the previous installment can be found here. Semivolatile calibrations on the 30 m x 0.25 mm ID x 0.25 µm df column format often range from 1.0 to over 100 ng/µL; however, a 0.25 mm ID column usually experiences peak overload as the mass on column approaches 10 […]

Split vs splitless injection GC-MS: A head-to-head evaluation of calibration performance on a Rxi-5ms GC column using EPA Method 8270 semivolatile organic standards and calibration criteria.

My colleagues and I have been extolling the virtues of split injection for a while now. We’ve demonstrated that fast sample transfer often yields better chromatographic results (especially for early eluting volatile compounds). We’ve established that starting oven temperatures can be elevated, shortening run time and increasing sample throughput. Most importantly, we’ve shown that inlet […]

Use Isotope Dilution when Reporting 1,4-Dioxane by EPA Method 8270x

1,4-dioxane results are prone to a low bias when analyzing hazardous waste by methods that incorporate an extract concentration step. Due to its high vapor pressure, 1,4-dioxane is driven off with the extraction solvent (typically dichloromethane). The authors of EPA Method 522 explicitly forbade extract concentration; they saw  losses of over 30% when concentrating their extracts […]