You are asking a multipart question.

1. Water/aqueous media. You can very efficiently extract the aromatics into pentane. Benzene is recovered at around 70% efficiency, and the extraction efficiency increases with increasing ring size up to ring size 6. We run from benzene through benzo(ghi)perylene. We take 35 mL of sample, add 3 mL of saturated salt and 4 mL of pentane in a VOA vial (43 mL septum vial), shake it out for a couple of minutes and analyze the extract without further preparation.

2. Solids/sediments. We use a variant of EPA method 3570. We weigh 10 grams of the solid matrix into a VOA vial, add 5 mL of methanol (dispersing/drying agent) and 5 mL of pentane. We place the vial on a Vortex shaker for 2 minutes to completely mix the sample and solvents. We then add water to fill the vial, and centrifuge for 5 minutes. We then take the pentane and analyze the extract without further preparation.

Obviously your analytical method will need to cover the range of benzene through the heaviest aromatic you are looking for. We use GC-MS, which allows us to efficiently quantify the benzene even in the presence of the residual tail of the pentane, and are able to obtain low part-per-billion (ug/Kg) results with excellent recovery.

they are not available in my Lab, any other alternative

@ Marzieh thank u 4 ur imput, but kindly give me the detailed procedure for the head space single drop microextraction

You can use also:

1) PAHs: liquid-liquid extraction for water matrix, and liquid-solid extraction for soil and sedment - a good solvent mix (v/v) is 25% n-hexane: 75% methanol, in a separation vessel - very simple and good for all PAHs;

2) BTEX: head-space in vials into a sand batch (80 celsius degree), or head-space-SPME in same condition, for any matrix.

Thank u silvio appreciate ur advice

For PAH in sediments and soil you can use Soxhlet extration or Utra-sonic bath extraction.For PAH in water the most simple methods are liquid-liquid extraction or solid phase extraction (using cardrige or dish)

For soils and sediments, you can use ultrasonic bath and microwave. They are more simple and faster methods in comparison with classical soxhlet extraction. Any way, you must find your best operational conditions to work with them. They proper volatil and semi volatil characteristics make difficult to obtain reliable and accurate results. Toluene, acetonitrile, n-hexane, acetone or mixtures of them are suitable solvents depending of the analytical tecnique employed.

You are asking a multipart question.

1. Water/aqueous media. You can very efficiently extract the aromatics into pentane. Benzene is recovered at around 70% efficiency, and the extraction efficiency increases with increasing ring size up to ring size 6. We run from benzene through benzo(ghi)perylene. We take 35 mL of sample, add 3 mL of saturated salt and 4 mL of pentane in a VOA vial (43 mL septum vial), shake it out for a couple of minutes and analyze the extract without further preparation.

2. Solids/sediments. We use a variant of EPA method 3570. We weigh 10 grams of the solid matrix into a VOA vial, add 5 mL of methanol (dispersing/drying agent) and 5 mL of pentane. We place the vial on a Vortex shaker for 2 minutes to completely mix the sample and solvents. We then add water to fill the vial, and centrifuge for 5 minutes. We then take the pentane and analyze the extract without further preparation.

Obviously your analytical method will need to cover the range of benzene through the heaviest aromatic you are looking for. We use GC-MS, which allows us to efficiently quantify the benzene even in the presence of the residual tail of the pentane, and are able to obtain low part-per-billion (ug/Kg) results with excellent recovery.

Hello Mark, Could you please tell me little bit more details on the following

(1) Composition of above saturated salt solution

(2) How many ul of pentane extract do you inject to GC

(3) Your detection limit

Thanks

Hello Asanka!

Saturated salt is exactly that - add enough sodium chloride to deionized (organic-free) water so that not all of it goes into solution. It takes somewhere around 350 grams per liter.

We inject 20 uL using large volume techniques (concurrent solvent recondensation). Depending upon your detection limit needs you may be able to get by with less. Our detection limits are on the order of 0.1-1 ug/Kg of analyte (ppb); obviously, it depends upon the compound.