Automated SPE disk extraction method for the analysis of nonyl phenol and bisphenol A in water samples

Scope

This application note will outline methods for the extraction of nonyl phenol and bisphenol A using Biotage automated or manual SPE solutions and the DryVap® Concentrator System. The first section will highlight the use of the Biotage® Horizon 5000 fully automated extraction system and the method used for this application. Additionally, there will be an Application Modification section that will highlight the use of the Biotage® VacMaster™ Disk for this application.

Introduction

Nonyl phenol and Bisphenol A are both of great environmental concern as they have been classified as endocrine disruptors. Endocrine disruptors are those compounds that mimic estrogen and thus could induce hormonal responses. Nonyl phenol has been banned in the European Union as a hazard to both human and environmental safety because of this concern.

Figure 1. Nonyl Phenol Chemical Structure (Several common isomers of p-nonyl phenol (also known as 4-nonyl phenol))

Nonyl phenol

Nonyl phenol is an organic compound formed during the alkylation process of phenols. Nonyl phenol is not a single chemical compound, but rather a term used to refer to a family of compounds, all of which have a central aromatic (or benzene) ring and a nine-carbon side chain. Because of their man-made origins, nonyl phenol is classified as xenobiotic. See Figure 1 for the chemical structure.
One use of nonyl phenol is as a surfactant, which reduces the surface tension of water forming a bridge between two compounds that normally do not mix. This is one reason nonyl phenol is commonly found in water samples. It is also used in pesticide products as “inert” ingredients, with the purpose of increasing the amount of spray solution that remains on leaf surfaces and in general to make the pesticide product more potent.

Bisphenol A (BPA)

Bisphenol A was first synthesized in 1891 and evidence of its estrogenicity came from experiments in the 1930s. However, the use of bisphenol A was shelved for this role as an estrogen mimic when diethylstilbesterol was invented. Both nonyl phenol and bisphenol A are now deeply imbedded in consumer products and the concern of these compounds to mimic hormonal responses has raised the need for adequate testing of these compounds. This application note will discuss the sample preparation method used to analyse for these compounds in drinking and wastewater.

Currently, bisphenol A has many uses. It is used in the synthesis of polyesters, polysulfones, and polyether ketones, as an antioxidant in some plasticizers, and as a polymerization inhibitor in PVC. It is also a key monomer in production of polycarbonate plastic, which is used to make a variety of consumer products including baby bottles, water bottles, sports equipment, medical devices, CDs, and household electronics. See Figure 2 for the chemical structure.

Figure 2. Bisphenol A Chemical Structure

Instrumentation

• Biotage Instruments:
  • Biotage® Horizon 5000 Automated Extraction System
  • DryVap® Concentrator System

• • DryDisk® Separation Membranes
  • Atlantic® DVB SPE disk (47 mm)
• Agilent 5890/5971 GC/MS
• Column: 30 M x 0.25 mm x 0.5um HP-5ms
• Injection Liner: Splitless, double gooseneck

Method summary

1. Obtain 1 L samples and spike any laboratory control or matrix spike samples to a concentration of 5 µg/L.
2. Place the sample bottle on the Biotage® Horizon 5000 Automated Extraction System and place the Atlantic® DVB disk in the standard 47mm disk holder.
3. Start the Biotage® Horizon 5000 using the extraction method in table 1 and collect the final sample extract.
4. Pour the final sample extract into the DryDisk® Separation Membrane reservoir on the DryVap® Concentrator System to remove the residual water in the organic solvent extract.
5. Concentrate the extract to a final volume of 1 mL.
6. The sample was analyzed by GC/MS using Selected Ion Monitoring (SIM) mode and the conditions and methods listed in tables 2, 3, and 4.

Application modifications

Biotage® VacMaster™ Disk method summary

1. Repeat the following steps for each active Biotage® VacMaster™ Disk station.
2. Setup the VacMaster Disk manifolds ensuring all waste lines and vacuum lines are attached. Set the vacuum pump to -24”Hg.
3. Prepare the disk holder assembly (47mm): ensure the support screen is flat in the center of the disk holder. Place the Atlantic® DVB Disk on top of the support screen with the ripples of the disk on top and add any prefilters on top of the disk. Place the disk holder assembly on the VacMaster® Disk manifold ensuring there is a tight seal with the luer fitting.
4. If using the multifunnel, place onto the disk holder assembly. If not using the multifunnel, omit those directions throughout the method.
5. Condition the SPE Disk:
a. Guide for each conditioning step in table 5 below:
I. Measure the appropriate VOLUME of SOLVENT into a graduated cylinder and pour into the disk holder assembly.
II. Using a Nalgene Wash Bottle (phthalate free), rinse the multifunnel and disk holder in a circle for about 3 seconds using the same SOLVENT (approximately 5 additional mL).
III. SATURATE the disk for the indicated time (in SECONDS). (Saturate means: quickly turn the knob to the appropriate waste destination and back to the “OFF” position. This brings the solvent into the disk media bed).
IV. SOAK the disk for the indicated time (in SECONDS).
V. DRAIN to the appropriate waste destination for the indicated time (in SECONDS). Switch to the “OFF” position.
6. Load the Sample:
a. For multifunnel: quickly and efficiently angle the bottle to rest on the multifunnel upside-down.
b. For no multifunnel: pour a portion of the sample into the disk holder.
c. Adjust the vacuum between -10”Hg and -15”Hg for sample load (please note, if the sample is flowing too slowly,
the vacuum can be increased). Drain the sample to “AQUEOUS” waste. Continue to pour the sample into the disk holder ensuring the disk does not go dry or overflow for the duration of sample load.
 7. Air Dry the SPE Disk:
a. Return the vacuum to -24”Hg and continue to air dry the SPE disk to “AQUEOUS” waste for an additional 60 SECONDS. Switch to the “OFF” position.
b. Remove the sample bottle from the multifunnel if it was used.

8. Elute the SPE Disk: (Please note: the elution solvent will go into the collection flask inside the chamber, not to waste containers)
a. Place a clean 125 mL 24/40 tapered Erlenmeyer flask into the Biotage® VacMaster™ Disk collection chamber. Place the cover on the chamber. Remove the disk holder assembly and place the disk holder assembly into the lure fitting on top of the collection chamber. Attach the lure fitting of the collection chamber assembly onto the manifold.
b. Guide for each elution step in table 6 below:
I. Measure the appropriate VOLUME of SOLVENT into a graduated cylinder, pour into the sample bottle, and swirl around. Pour the solvent in the sample bottle into the disk holder assembly.
II. Using a Nalgene Wash Bottle (phthalate free), rinse the multifunnel and disk holder in a circle for about 3 seconds using the same SOLVENT (approximately 5 additional mL).
III. SATURATE the disk for the indicated time (in SECONDS) to “ORGANIC”.
IV. SOAK the disk for the indicated time (in SECONDS).
V. DRAIN to “ORGANIC” for the indicated time (in SECONDS). Switch to the “OFF” position.
VI. Remove the chamber lid to release the vacuum from inside the chamber.

Literature number: AN002