Extraction of Acrylamide from Fried Potato Chips (Crisps) Using ISOLUTE® SLE+ Prior to LC–MS–MS Analysis

Acrylamide has been found to occur in many cooked carbohydrate-rich foods and is of concern as a possible carcinogen. The supported liquid extraction (SLE) method described in this application note achieves high recoveries of acrylamide in fried potato chips (crisps). The method is sensitive enough to potentially measure levels as low as 10 ppb in a popular brand and flavour and has also been tested in flavoured varieties that were both machine and hand fried.

Extraction Procedure

Format: ISOLUTE® SLE+ 1 mL Sample Volume Columns, part number 820-0140-C

Sample pre-treatment: Add 10 mL water to 1 g crushed sample (previously spiked with ¹³C₃ acrylamide internal standard), and mix for 1 h. Centrifuge and remove a 0.65 mL aliquot of the aqueous layer, taking care not to include any of the thin upper oil layer.

Sample loading: Load the pre-treated sample (0.65 mL) onto the ISOLUTE SLE+ column. Apply a pulse of vacuum or positive pressure to initiate flow. Allow the sample to absorb for 5 min.

Analyte elution: Elute with ethyl acetate–tetrahydrofuran, (1:1, v/v, 2 × 2.5 mL) and allow to flow under gravity into tubes containing 2 µL ethylene glycol. Apply vacuum or positive pressure to elute any remaining extraction solvent.

Post elution: Dry the volatile constituents of the eluate in a stream of air or nitrogen. Reconstitute in water (200 µL).

HPLC Conditions

Instrument: Waters Acquity

Column: Phenomenex Hydro 4 µm 50 mm × 2 mm C18 column with a C18 guard cartridge and on-line filter

Mobile phase A: 0.1% formic acid in water

Mobile phase B: 0.1% formic acid in methanol

Flow rate: 0.3 mL min^-1

Injection volume: 10 µL

Gradient: Initial 100% A, hold for 0.6 min; Linear ramp to 100% B over 0.25 min (0.85 min), hold 1.65 min (2.5 min); Linear ramp to 100% A in 0.01 min (2.51 min), hold 2.49 min (5 min)

Column temperature: 40 °C

Sample temperature: 20 °C

Table 1: Positive ion mode – MRM parameters.

MS Conditions

Ions were selected on the basis of achieving maximum sensitivity using multiple reaction monitoring.

Instrument: Waters Quattro Premier

Ionization mode: ES+

Desolvation temperature: 450 °C

Source temperature: 120 °C

Figure 1: Chromatogram of untreated potato chip (crisp) extract showing level of incurred acrylamide.

Results and Conclusion

A method has been developed which measures acrylamide from a challenging matrix at highly sensitive levels. Despite acrylamide being a relatively polar molecule, excellent separation was demonstrated between this and matrix interferences on the ISOLUTE SLE+ material. The method delivers good recovery (90%), low %RSD (<10%), and is significantly easier, quicker, and more cost-effective to perform than SPE-based procedures, making it ideal for routine analysis of fried and baked foods.

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