Porous extraction paddle: a solid‐phase extraction technique for studying the urine metabolome

Abstract

RATIONALE A method was needed to accomplish solid phase extraction of a large urine volume in a convenient way where resources are limited, towards a goal of metabolome and xenobiotic exposome analysis at another, distant location. METHODS A porous extraction paddle (PEP) was set up, comprising a porous nylon bag containing extraction particles that is flattened and immobilized between two stainless steel meshes. Stirring the PEP after attachment to a shaft of a motor mounted on the lid of the jar containing the urine accomplishes extraction. The bag contained a mixture of nonpolar and partly nonpolar particles to extract a diversity of corresponding compounds. RESULTS Elution of a urine-exposed, water-washed PEP with aqueous methanol containing triethylammonium acetate (conditions intended to give a complete elution), followed by MALDI-TOF/TOF-MS, demonstrated that a diversity of compounds had been extracted ranging from uric acid to peptides. CONCLUSION The PEP allows the user to extract a large liquid sample in a jar simply by turning on a motor. The technique will be helpful in conducting metabolomics and xenobiotic exposome studies of urine, encouraging the extraction of large volumes to set up a convenient repository sample (e.g. 2 g of exposed adsorbent in a cryovial) for shipment and re-analysis in various ways in the future, including scaled-up isolation of unknown chemicals for identification.

Nontargeted analysis of the urine nonpolar sulfateome: a pathway to the nonpolar xenobiotic exposome

“…The rigidified, urine‐exposed PEP bags were kept at −20°C in Puerto Rico in a FEP bag until overnight shipment on dry ice to Northeastern University in Boston, MA, USA, for chemical analysis. Upon receipt in Boston, the FEP bags were stored at −80°C until processing as follows: (1) stirred a PEP in 2 L of water for 1 h; (2) recovered the nylon bag from the PEP, blotted excess solvent gently with a Kimwipe, and dried in a jar over Drierite, and (3) cut the bag open and transferred its contents into a 5 mL Cryoware vial (pre‐rinsed with methanol). The vial was gently inverted 20× to thoroughly homogenize the particles, and stored at −80°C.…”

“…In the first stage (steps 1–4), a person furnishes a large volume of urine (about 2 L including acetic acid as a preservative) as an accumulation of first morning voids over a period of 1 week for mainly two reasons: to help in defining an average exposure, and to provide sufficient sample for multiple and scaled‐up re‐analysis in the future. Some of the sample is set aside (8 × 5 mL at −80°C) while most of the remainder (1.8 L) in step 1 is subjected to SPE with a “porous extraction paddle” (PEP) containing a mixture of sorbent particles as described . In steps 2–4 an aliquot of the dried, urine‐exposed sorbent particles is eluted and the eluate is subjected to extraction on a polymeric weak anion exchanger.…”

“…Urine (1.8 L) was collected under IRB approval as accumulated first morning voids (kept dark) over a week from each of six pregnant women in Puerto Rico, preserved with acetic acid (4% final concentration; initially the collection jar contained 200 mL of 40% acetic acid) and subjected to SPE with 2.0 g of SPE particles comprising equal amounts of bonded silicas (strong anion exchange, strong cation exchange, C18, phenyl), a polyamide, and a hydrophilic‐modified styrene polymer. These particles as a mixture were contained in a rigidified porous nylon bag designated as a “porous extraction paddle”, or PEP, as described …”

“…In an accompanying paper we report a solid‐phase extraction (SPE) device termed a “porous extraction paddle” (PEP) for extracting a large volume of urine at a remote location where resources are limited. Here we apply this technique to six urine samples collected from pregnant women in Puerto Rico, towards a long‐term goal of discovering xenobiotics that contribute to preterm birth.…”

Transformation of chlorobenzene and 4-chlorophenol in groundwater by electro-fenton and sono-electro-fenton reactions

“…The performance of the static PD-PVDF/PAA membrane was limited although the solution was stirred under the same speed due to the limited mass transfer to Pd sites within the membrane. Rotating Pd membrane was based on the concept similar to the cage paddle for the solid phase extraction developed by (Shao, MacNeil et al 2016). The rotation of the membrane disk enhances mass transfer and improves the availability of reactive species.…”