Date post: | 06-Jul-2015 |
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Water in HPLC
Under the Supervision of: PROF.DR. Sawsan Elmasry
Presented by: Reem Tawfeek
Points to be discussed
• Water used in HPLC.
• Lab water grades.
• Specifications of HPLC-grade water.
• how to determine water purity?
• Problems caused by poor quality water.
• Package and storage.
• Conclusion.
Water used in HPLC
• Water for HPLC may be prepared IN HOUSE (analytical labs may prepare its own HPLC water)
• (N.B. that what most frequently happens in Egyptian labs)
• Freshly prepared double distilled
water (within 24 hours) will be
convenient for HPLC applications
Water used in HPLC
• De-ionized water will be INCONVENIENT for HPLC application due to uncertainty of the absence of the microbial contamination
• OR labs could obtain water from HPLC-grade chemicals supplie
Lab Water GradesType 3 water r is the lowest grade, for
-glassware rinsing,
-heating baths and filling autoclaves,
-feed Type 1 lab water systems.
Type 2 water
- general laboratory applications eg.buffers
- as feed to Type 1 water systems,
- preparation of reagents for chemical analysis or synthesis
Type 1 water(reagent grade)) eg. milli-Q water
-HPLC mobile phase preparation
- blanks and sample dilution in GC, HPLC
- other advanced analytical techniques
the different water specifications based on the different water types
HPLC-water specifications
• According to B.P. 2010 water for chromatography isdeionized water with a resistivity of not less than 18 MΩ-cm
But is this enoughIt’s possible to have 18 MΩ-cm soup!
Can we use soup for HPLC?????
How to measure water purity?contaminants in water either
• Measured by resistivity( MΩ-cm at 25.00°C )
ionic
• Measured by TOC(ppb)organic
Sources of organic contaminants [Total organic carbon(TOC)]
• Leaching from purification media, tubing and containers,
• bacterial contamination
• absorption from the atmosphere
Poor quality water reduces chromatographic performance by
• affecting resolution and integration.
• introducing ghost peaks.
• altering stationary phase selectivity.
• and impacting baselines.
Ghost peaks
Isocratic baseline monitoring at 210 nm using 100% high TOC reagent water(10 Mᾩ·cm resistivity, 100 ppb TOC) (1 mL/min).
Using high-purity water(3 ppb TOC)
According to American Society for Testing and Materials ASTM Reagent grade water should contains
• Total organic carbon (TOC), max , 50 ppb
• Resistivity not less than 18 MΩ-cm
Packing and storage
• packaged in amber glass bottles
• sealed under a nitrogen with Teflon-lined fluorocarbon caps .
• Unless other instructions stated by SOP(standard operating procedures) Once the bottle is opened it should be used within 24 hours.
Conclusion
• We should switch from simple resistivity measurement to resistivity and TOC monitoring in order to be able to take reagent water quality for granted.
references
• W.M.A. Niessen, J. Chromatogr., A 856(1,2), 179–197 (1999).
• W. Byrne, Reverse Osmosis — A Practical Guide for Industrial Users. 2nd ed. (Tall Oaks Publishing,Littleton, Colorado, 2002).
• Standard Specification for Reagent Water American Society for Testing and Materials International 2001 Annual Book of Standards – Volume 11.01
• B. Srikanth, Ultrapure Water 15(3), 40–46(1998).
• K. Clark, M. Retzik, and D. Darbouret, Ultrapure Water 14(2), 21–24, (1997).
• C. Regnault, I. Kano, D. Darbouret, and S.Mabic, J. Chromatogr., A 1030(1–2), 289–295(2004).
• B. Stewart and B. Williamson, Am. Biotechnol. Lab., 16–18, December 2001.
• http://www.high-q.com/pdf/q&a_reagent_water_screen.pdf