by Vlad Orlovsky, Tatiana Sgibnev and Konstantin Tchalukov AL
Compact HPLC Systems for the Analysis of Pesticides, Dyes and Drugs
Despite advances in stationary phase chem- istry, liquid chromatography instrumentation and particle miniaturization, the development of a portable LC system has remained elusive because of the difficulty of downscaling hard- ware and reducing solvent consumption.
The compact, standalone Alltesta HPLC- based analyzer (Figure 1) (SIELC Technologies, Wheeling, Ill.) overcomes these limitations and offers the following features:
• Provides preliminary testing for further downstream analysis
• Assesses hazardous compounds that are difficult or dangerous to transport
• Handles sensitive samples such as those collected from a crime scene
• Performs testing in emergency situations, such as biowarfare and catastrophic environmental pollution events
• Analyzes unstable radioactive compounds that have a short half-life
• Analyzes pharmaceuticals and nutraceuticals.
System features Field technicians may not be experienced ana-
lytical chemists. The Alltesta analyzer includes over 1000 HPLC methods preset for a diverse array of compounds, which eliminates the need
for expertise in method development. Preset methods may be customized by end users for specific applications and for use in qual- ity control. Lifetime free method-development screening (vetting of methods developed by users) is included, as is a continually growing library of methods from SIELC.
A 12” touchscreen tablet is the only external hardware required for operation. This interface eliminates the need for a computer, monitor, keyboard and other bulky accessories while facilitating easy operation in the field or labora- tory; wireless connectivity allows user mobility during analysis.
The Alltesta pump precisely delivers fluid at flow rates from 0.10 mL/min to 4.0 mL/min using up to 5000 psi (350 bar) of continuous pressure. Pulsation is reduced by a built-in dampener that contains minimal dead volume and is free of dampener fluid. A two-channel degasser removes dissolved air from the pumping liquid, increasing accuracy and performance.
The system shuts down operation when a speci- fied pressure or time is reached. A two-channel proportional valve enables selection of two different solvents in any ratio from 0 to 100% in 1% increments, which allows running gradient and isocratic methods. In the most common configuration, the built-in autosampler accepts
40 standard vials; a 96-well-plate format is op- tionally available.
Using only a three-wire connection, the RS485/ CAN interface permits control of multiple de- vices. Additional features include adjustable nee- dle depth and an optional patented wash system that minimizes sample cross-contamination.
An LED-based detector delivers a narrow, intense bandwidth; the long-lasting, low-noise light source provides high sensitivity. Its small internal flow path volume minimizes band spreading, and only very chemically stable materials, i.e., PEEK, PTFE and quartz, contact the fluid.
Applications
Analysis of pesticides and contaminants Drug residues commonly contaminate agricul- tural products,1
and may enter through a variety
of means, such as being present in water during the irrigation process. The Alltesta analyzer was used to identify several contaminants in black and green tea products (Figure 2). Atorvastatin, a common cholesterol medication, and two fungi- cides—picoxystrobin and pyrimethanil—were separated from native tea compounds and from each other by more than 1 minute. Analysis was performed after merely extracting tea products in water, which attests to the minimal sample
Figure 2 – Separation of contaminants in tea with no sample preparation: 1) atorvastatin, 2) picoxystrobin, 3) pyrimethanil. Column: Primesep 200, 4.6 × 150 mm; mobile phase: 50% MeCN, 0.05% H3
PO4 Figure 1 – Alltesta Mini HPLC analyzer. tea extracts after spiking of samples). AMERICAN LABORATORY 26 JANUARY/FEBRUARY 2017
; flow rate: 1.0 mL/min; detection: 270 nm; sample preparation: none (direct injection of
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68