3292 DSC XP2_ad2_Layout 1 3/25/13 11:30 AM Page 1


Pipet-Aid® XP2


Figure 2 – ESI-HPIMS mobility spectra for detecting dicyclohexyl phthal- ate (DCHP) in cola using Directspray ESI in positive ion mode.


µL of cola was prepared, but this sample was spiked with 6 ppm of DCHP. As clearly seen in Figure 2, a distinct DCHP peak can be detected using Directspray ESI and HPIMS with resolving power of 66 at 6 ppm, a level 25 times below the detection limits of the Chinese liquid chromatography method for phthalate mixtures.21,22


However, the data acquisition only


required 30 sec with HPIMS. Furthermore, only three rinses of the syringe between the samples were used, increasing the method throughput.


Another area of concern is overexposure to antibiotics that can lead to resistance to their therapeutic effects.23


The prevalent use of antibi-


otics in the livestock industry for infection prevention has prompted the legislation of residue limits for veterinary drugs in muscle tissue for consumption.24 (75 µg L–1


Figure 3 (left) shows the spectrum for 0.075 ng µL–1 fluoroquinolone antibiotic and metabolite of enrofloxacin,24


) of a ciprofloxacin standard (Sigma Aldrich, St. Louis, MO), a measured


with ESI-HPIMS in positive ion mode with resolving power of 64 in 30 sec without sample preconcentration. Moreover, the linear response range for ciprofloxacin covers two orders of magnitude vs sample concentra- tion with excellent precision.


Another prime detection target is additives such as food dyes, both legal and illegal. In addition to detecting industrial dyes illicitly added to inex- pensively enhance food color,25


the legal azo-based food grade dyes (e.g.,


FD&C artificial colorants) have been cited as potential triggers for food sen- sitivities.26


the azo-based artificial food colorings and controlled artificial sweeteners.11 Figure 4 shows ESI-HPIMS mobility spectra in negative ion mode for Sunset Yellow FCF (FD&C Yellow 6). A distinct peak for the dye anion at concentra- tions as low as 0.050 ng µL–1


(~60 ppb) can be seen in Figure 4 (blue curve)


from a 30-sec acquisition, compared to the over 6-min elution time with HPLC.27


Previous ESI-HPIMS studies have shown that the mobility peaks cor-


respond to the dye anion from the commonly produced azo dye-salts. These dyes can also be detected with two-order-of-magnitude linear response range in concentration.11


ESI-HPIMS has previously shown excellent response for detecting Advanced


Ergonomics for Working on a Bench


Comfort The most comfortable pipettor you ever laid a hand on


Convenience Uninterrupted extended operation


Control Quiet precision pump responds instantly to the touch of the button


Drummond Pipet-Aids have set the standard for making pipetting in the laboratory safer, easier, and more convenient. The Pipet-Aid® XP2 delivers more. More comfort…more convenience…better control.


For a copy of our new 2013 catalog or more information on the Pipet-Aid XP2 visit drummondsci.com.


From the Developers of the Original Pipet-Aid®


MADE IN USA


500 Parkway, Box 700 Broomall, PA 19008


AMERICAN LABORATORY • 13 • JUNE/JULY 2013


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