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LC Multiresidue Pesticide Standard #7 (7 components)

Organonitrogen Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #8 (Hydramethylnon)

Organonitrogen Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #9 (7 components)

Carbamate/Uron Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #10 (Carbendazim)

Carbamate/Uron Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #9 (8 components)

Organophosphorus Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

FlatLine Pulse Damper

... technology provides reliable long-term operation without the downtime associated with ruptured or leaking...

LC Multiresidue Pesticide Standard #1 (13 components)

Organophosphorus Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #2 (16 components)

Carbamate/Uron Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #5 (30 components)

Organonitrogen Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #6 (28 components)

Organonitrogen Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #1 (16 components)

Organophosphorus Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #3 (25 components)

Organonitrogen Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #4 (28 components)

Organonitrogen Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #5 (34 components)

Organonitrogen Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #6 (18 components)

Synthetic Pyrethroid Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #7 (10 components)

Herbicide Methyl Esters

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #8 (24 components)

Organophosphorus Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #3 (38 components)

Carbamate/Uron Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Standard #4 (63 components)

Organonitrogen Compounds

... for maximum long-term stability* and well-balanced chromatographic performance. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

GC Multiresidue Pesticide Standard #2 (40 components)

Organochlorine Compounds

.... Formulated and grouped for maximum long-term stability*. Quantitatively tested to confirm , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

Rtx-1301 (G43) Columns (fused silica)

low- to midpolarity phase

... to ensure long-term reproducibility, column-to-column consistency, and low bleed...

Rtx-1701 Columns (fused silica)

midpolarity Crossbond phase

... column. The polymer is fully characterized to ensure long-term reproducibility, column...

GC Multiresidue Pesticide Kit

...; individual ampuls also sold separately. Formulated and grouped for maximum long-term stability ensuring maximum long-term stability and reliability. For quantitative analysis, we recommend analyzing ... Formulated and grouped for maximum long-term stability*. Quantitatively , then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

LC Multiresidue Pesticide Kit

... ampuls also sold separately. Formulated and grouped for maximum long-term stability* and well maximum long-term stability and reliability. For quantitative analysis, we recommend analyzing each mix ... Formulated and grouped for maximum long-term stability. Quantitatively , and then grouped them into as few mixes as possible while still ensuring maximum long-term stability...

QuEChERS Performance Standards Kit

... to ensure maximum long-term storage stability. For analysis, a fresh working standard should be prepared ... into three mixes to ensure maximum long-term storage stability. For analysis, a fresh working standard should...

SafeLok Sorbent Tubes

...L/min (<10 L total volume)Brass caps for long-term storage are supplied with conditioned tubes...

Aldehyde-Ketone-DNPH TO-11A Calibration Mix (15 components)

... formaldehyde and other carbonyls. Short-term exposure to formaldehyde and other specific aldehydes...

Thermal Desorption (TD) Tubes

(Unconditioned and Conditioned & Capped)

....01–0.20 L/min (<10 L total volume)Long-term storage caps...

14″ PTFE Ferrules

..., Benefits and Uses, Long-term storage caps., ... Long-term storage caps....

Solvent Compatibility Chart for Syringe Filters (PDF 360kB)

... in physical properties. The filter may be suitable for short term, non-critical use. N = Not Recommended be suitable for short term, non-critical use. N = Not Recommended. The membrane may be unstable...

The Role of Selectivity in Liquid Chromatography Method Development (PDF 1332kB)

... factor kfavg, calculated from the retention of both analytes, is used in the third term. As we be minimal. The magnitude of contributions of each of the three terms in Equation 1 to resolution varies...

Parker Balston Zero Air Generators (PDF 475kB)

... operation, and long term performance. Parker Balston zero air generators are much easier to install than and dependence on outside vendors. Uncontrollable price increases, contract negotiations, long term commitments...

Restek Liquid Chromatography (LC) Columns - Usage & Care (PDF 144kB)

... to remove buffers, acids, or bases. For short-term storage, all columns should be flushed with a solvent components. For long-term storage, reversed phase columns should be stored with 50% water/50% organic solvent...

Parker Balston FID Gas Stations (PDF 482kB)

..., and long term performance. They eliminate all the inconveniences and cost of zero air and hydrogen cylinder , long term commitments, and tank rentals are no longer a concern. With an FID gas station, you control...

USLC Columns Put the Right Tools in Your LC Method Development Toolbox (PDF 1474kB)

... column can be so advantageous. Resolution is the result of 3 cumulative terms: efficiency (N), retention upon our ability to control these 3 factors. Of the 3, the selectivity term mathematically affects...

A Primer on Control Systems (PDF 1532kB)

..., or gain, in practice they are often interpreted in terms of time. If error is defined as the differential control term to the system. Figure 5 shows the system with an appropriate integral control parameter...

Concerns Regarding 24-hr Sampling for Formaldehyde, Acetaldehyde, and Acrolein Using 2,4-Dinitrophenylhydrazine (DNPH)-Coated Solid Sorbents (PDF 627kB)

... and acetaldehyde gas standards, and the long-term (i.e., 24 hour or greater) sampling collection efficiencies (CEs was unsuccessful in increasing the CEs. The mechanism behind low acetaldehyde CEs for long-term sampling with DNPH...

10 Critical Steps to World-Class Reference Standards (PDF 3190kB)

... is scrutinized during both formulation and review. We also conduct ongoing, long-term stability and short-term...

NIST Traceability Document: Gas Flowmeter Calibration Using the Restek Calibration System (PDF 754kB)

..., and the subsequent uncertainty described in terms of flow. The temperature values shown are in the range of room with the transducer, and the subsequent uncertainty described in terms of flow. The pressure values shown...

Guide to GC Column Selection and Optimizing Separations Brochure (PDF 3879kB)

... ciency. This term is aected by: A measure of Retention. This term is aected by: A measure of Peak Separation. This term is aected by: Resolution Equation—The Key to Column Selection and Optimizing GC...

ETP Electron Multipliers: Care and Handling Instruction Sheet (PDF 211kB)

... supplied by ETP is suitable for long term storage. The multiplier is enclosed in two sealed plastic bags...

Solvent Compatibility Chart for Filters Vials (PDF 304kB)

... term, non-critical use. N = Not Recommended. The membrane may be unstable. - = Insufficient Data...

Opiate Analysis (PDF 20kB)

...Applications note cat.# 59576 Clinical Forensic Opiate Analysis Opiates or opioids are terms...

New D3606 Column Set Outperforms TCEP Columns for Benzene Analysis (PDF 271kB)

... expensive choice in terms of costper-injection and downtime required for frequent column changes...

Restek’s ProFLOW 6000 Electronic Flowmeter (PDF 2506kB)

..., open source options are available online (i.e. RealTerm, etc.). You can download RealTerm* software . Finally, click Open on the Port tab in RealTerm and you will see the serial data stream begin...

ETP Active Film Multiplier for the HP/Agilent Technologies 5970 MSD Instruction Sheet (PDF 208kB)

... to the air with no loss in performance. The original packaging is designed for long term storage...

Florisil SPE Cleanup for Chlorinated Pesticides Analysis (PDF 936kB)

... banned for use because of their short- and long-term toxicity, carcinogenicity, and environmental...

Accurately Quantify 380 Pesticides Using LC-MS/MS and GC-MS/MS (PDF 5930kB)

... for maximum long-term stability. ■ Manufactured and QC-tested in our ISO-accredited labs. ■ Accurately and grouped for maximum long-term stability.* ■ Quantitatively tested to confirm composition; detailed...

ETP Active Film Multiplier for Shimadzu QP5000 MS Instruction Sheet (PDF 239kB)

... is designed for long term storage. The multiplier is delivered in two sealed plastic bags, the outer bag...

Accurately Quantify Methanol and Ethanol in E85 Biofuel by D5501 with New Rtx-DHA-150 Column (PDF 1828kB)

...,000 theoretical plates. The long-term partnership with Neil was instrumental in the development of Restek’s DHA...

Introducing New Restek EPA 524.3 Certified Reference Materials (PDF 1516kB)

... Syringes Volume Needle Needle SGE Restek Term. Gauge Model cat.# qty. cat.# 5 mL LL * 5MDR-LL-GT 008760 ea. 24757 50 mL LL * 50MR-LL-GT 009660 ea. 24761 Volume Needle Needle Needle Point SGE Restek Term...

Why do smaller particle size columns improve resolution? Learning Links

... separations. The resolution equation comprises three terms: selectivity, retention capacity, and efficiency . Each of these terms is affected by the specific components of an analytical method. A column...

Analysis of Trace Hydrocarbon Impurities in 1,3-Butadiene Using Optimized Rt-Alumina BOND/MAPD PLOT Columns (PDF 408kB)

... of an inhibitor, small amounts of 1,3-butadiene dimer (4-vinylcyclohexene) form during long term storage...

Airmail, 2012 vol. 2 (PDF 832kB)

... priority projects, and a long-term process is under development to continually identify and resolve...

Fast, Accurate Semivolatiles Analysis! Using Rxi-5Sil MS GC Columns

... in terms of bleed, efficiency, and activity ... ) columns. Here we evaluate the performance of Rxi-5Sil MS columns for semivolatiles analysis in terms...

Improve Results for Chlorinated Pesticides With Resprep CarboPrep SPE Cleanup (PDF 1430kB)

... pesticides have been banned for use because of their short- and long-term toxicity, carcinogenicity...

Rxi-5Sil MS: Exceptionally Inert Columns for GC/MS and Trace-Level Analyses (PDF 995kB)

... columns consistently outperform competitor columns in terms of bleed, inertness, and reproducibility...

How do small particle size columns increase sample throughput? Learning Links

.... The Van Deemter equation is governed by three cumulative terms: (A) eddy diffusion, (B) longitudinal , and therefore, these three terms can also be viewed as factors that contribute to band broadening. Figure 1...

Will Pro EZGC Chromatography Modeling Software Work For You? We Put It to the Test! (PDF 2272kB)

... match the empirical results in terms of relative peak resolution. Actual retention times may shift in terms of relative peak resolution. This allows method developers, who will ultimately use a different...

LC and GC Multiresidue Kits

Restek's new LC-MS/MS and GC-MS/MS multiresidue pesticide standards kits include comprehensive lists of pesticides of global concern that are frequen...

Accurately Quantify PAHs Down to 5 pg On-Column GC/MS SIM Analysis with the Rxi®-5Sil MS Column

... analysis in terms of bleed, efficiency, and activity. Excellent sensitivity and resolution are seen, even...

Integra-Gap technology and Metal columns: Biodiesel Glycerides Analysis Made Easy... (PDF 673kB)

... 2 shows the impact of long-term exposure at 430°C: the polyimide hardens, becomes black...

A Guide to the Analysis of Chiral Compounds by GC (PDF 3410kB)

... ARE CHIRAL COMPOUNDS? Any carbon atom that is bonded to four different functional groups is termed a chiral , or clockwise, are termed dextrorotary {denoted as (d) or (+)}, Optical isomers that rotate in the left...

Using Alternative Carrier Gases with Accelerated ASTM D2887 Simulated Distillation Analysis (PDF 1098kB)

... the excellent performance of the method in terms of response factor and peak asymmetry. Figure 6: Analysis...

Restek Reference Standards (PDF 4407kB)

..., and during production, compound compatibility is continuously scrutinized. We also conduct ongoing, long-term...

Vacuum/Pressure Station Operating Manual (PDF 140kB)

... warranty period, and (c) the purchaser complies with proce-dures for returns set forth in the general terms...

Determination of Omega-3 (n-3) and Omega-6 (n-6) Fatty Acid Composition in Evening Primrose Oil, Flax Seed Oil, Black Currant Oil, and Borage Oil (PDF 1655kB)

... injections. Volume (µL) 5 5 5 10 10 10 Needle Term. ASN/F ASN/F ASN/F ASN/F ASN/F ASN/F Gauge 23s 26s 23s-26s...

Reliable Low-Level Analysis of Glycols in Water Using Split Injection (PDF 767kB)

... and are suitable for aqueous injections. Here, we present analytical conditions established during a long-term...

Growing Analytical Solutions for Cannabis Testing (PDF 6781kB)

... into as few mixes as possible while still ensuring maximum long-term stability and reliability. Several are separated into three mixes to ensure maximum long-term storage stability. For analysis, a fresh working...

GC Columns Installation Guide (PDF 989kB)

... a connection to the detector and repeat procedure above, starting at Step 12. Standby Conditions Short-Term : Leave the column in the GC with the carrier gas flow on at an oven temperature of 100-150 °C. Long-Term...

ChromaBLOGraphy: What is SPP and when should I use a Raptor column?

While this sounds like a very broad question, I’m sure it is crossing some of your minds. To start out, SPP stands for superficially porous particles. It has also been called “core-shell”.   If you are a veteran in the world of HPLC, this term is old hat for you. If you are new to the […]

Restek Advantage, 2011.1 (PDF 3826kB)

... demonstrates the advantages of split injection in terms of sam-ple throughput, sensitivity, and linearity in short column lifetimes, makingTCEP columns a relatively expensive choicein terms of cost...

Optimize Analysis of Polar and Coeluting VOCs in Whole Air Canister Samples Using an Rtx®-VMS GC Column (PDF 329kB)

... flexibility in GC column selection both in terms of stationary phase and column dimensions. In regards...

Overcoming the Effects of Highly Organic Protein Precipitation Extracts on LC Peak Shape Using Direct Injection (PDF 585kB)

... by comparing direct injection to dilution in terms of peak shape, intensities, and recovery values for five...

Trace-Level Analysis of Metanephrines in Plasma by HILIC LC-MS/MS (PDF 712kB)

... measurement of in vivo concentrations is critical for correct diagnosis, treatment, and long-term patient...

Direct Analysis of Morphine, M3G and M6G Metabolites, and Related Compounds in Urine by LC-MS/MS (PDF 778kB)

... in terms of retention, resolution, peak shape, and peak response. It is notable that attempting a similar...

Raptor ARC-18 LC Columns Brochure (PDF 4942kB)

... compounds involved, then grouped them into as few mixes as possible while still ensuring maximum long-term...

ChromaBLOGraphy: Technical Service “Red Flags” – GC

For those of you not familiar with the term “red flag”, or phrase “It raised a red flag”, it basically means that something does not sound correct, or is very unusual or uncommon. In tech service, we listen for these “red flags” and if we hear one, we will either offer a cautionary statement if […]

News: Restek Celebrates 3 Years of Employee Ownership

On December 31, 2008, Restek Corporation announced the purchase of all outstanding corporate shares, officially becoming 100% employee owned under an Employee Stock Ownership Program (ESOP) structure. The transition to 100% employee ownership was made to ensure both our long-term … Continue reading

ChromaBLOGraphy: Synthetic Stimulants Sold as “Bath Salts” Now Under Federal Control and Regulation

The United States Drug Enforcement Administration (DEA) just issued a  news release on its efforts to control three synthetic stimulants (Mephedrone, 3,4 methylenedioxypyrovalerone (MDPV) and Methylone) used in products sold as “bath salts” and “plant food”.  According to the DEA, “users have reported impaired perception, reduced motor control, disorientation, extreme paranoia, and violent episodes”, and the long-term [...]

ChromaBLOGraphy: VOCs via Static Headspace/GC/MS is not old hat – new DIN 38407-43

Introduction Clean water is a valuable asset to mankind. Every government therefore has its own regulation on water quality. For the territory of the European Union the “EU Water Framework Directive” gives the governmental frame for water quality monitoring.  The chemical composition of surface water and ground water is described in terms of  Priority Substances, [...]

ChromaBLOGraphy: Why are my acetaldehyde concentrations off… has someone been drinking? A multi-blog series on airborne carbonyls, part III.

Ask yourself the following questions: (1) Are you using 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents (i.e., U.S. Environmental Protection Agency (EPA) Compendium Method TO-11A) to measure ambient levels of airborne acetaldehyde? (2) Are you sampling for long-term (i.e., 24 hr or greater) durations? (3) Have you compared the results you generated with a DNPH-based method and another [...]

ChromaBLOGraphy: Large volume splitless injection WITHOUT a PTV!

Recently while trying to create backflash in an Agilent splitless injector, I noted linear compound responses as I injected up to 25µL for PAHs from naphthalene to benzo(ghi)perylene! I went to the literature (note to self: start with the literature) and found papers from Magni and Porzano, and Grob’s group, where they termed the technique [...]

ChromaBLOGraphy: Worried about Quenching? Don’t be! All is well when analyzing PAHs with Methanol Mobile Phase.

The acetonitrile shortage does not seem to have an end in sight. Finding solutions for reducing overall acetonitrile usage can decrease dependency on this now very costly solvent. In a previous post I recommended switching your HPLC mobile phase from acetonitrile to methanol for polycyclic aromatic hydrocarbon (PAH) analysis. The data from the previous post [...]

The Role of Selectivity in Liquid Chromatography Method Development

... capacity factor k’avg, calculated from the retention of both analytes, is used in the third term and k’avg would be minimal. The magnitude of contributions of each of the three terms...

Achieving Faster GC

.... A significant source of this confusion is the fact that authors often neglect to define the terms "analysis that the term "total analysis time" also is not very well defined. Is it the time-to-result for a sample...

Storage Stability of 66 Volatile Organic Compounds (VOCs) in Silicon-Lined Air Canisters for 30 Days (PDF 795kB)

...] and is generally considered a short-term (i.e., takes place on the order of minutes to hours) process [2]. 2 considered short-term (minutes to hours) [2]. Holdren et al. [14] and Hsieh et al. [22] evaluated...

GC-MS Analysis of Phthalates: Comparison of GC Stationary Phase Performance (PDF 1195kB)

... with the best overall results in terms of speed and the most peaks resolved was selected for this direct column...

Whole Air Canister Sampling and Preconcentration GC-MS Analysis for pptv Levels of Trimethylsilanol in Semiconductor Cleanroom Air (PDF 944kB)

... relatively quick (i.e., ~10 seconds) grab samples, the fl exibility to sample for long-term (i.e., a few...

News: Restek’s New EFSA PAH4 Standard Offers Low-Volatility Accuracy and High-Concentration Versatility

The formulations chemists at Restek have developed a new certified reference material (CRM) of four PAHs—benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, and chrysene—designed for greater convenience, longer shelf life, and increased long-term accuracy. Its high 1,000 µg/mL concentration gives analysts the freedom to … Continue reading

Pack In a Box: Dual Piston Pump Operator's Manual (PDF 3731kB)

....5.5Long Term Pressure Calibration Accuracy2.6Preparation for Storage or Shipping2.6.1Isopropanol Flush2 20 mL).Close the prime/purge valve and stop the pump.2.5.5 Long Term Pressure Calibration Accuracy...

Restek Liquid Chromatography (LC) Columns — Cleaning Recommendations

... securely fastened and be sure to include information describing the storage solvent. For short-term used mobile phase minus any buffered, acidic, or basic components. For long-term storage...

ChromaBLOGraphy: Let me help you schedule your technical journey at Pittcon 2011 this year.

Nearly 20,000 people attend Pittcon from over 90 countries and there is a staggering amount to see on the technical front. Luckily the show has the presentation titles on-line and easily searched in the PDF format. Simply enter in your search term and quickly find your area of interest. Below is an excel sheet that will [...]

ChromaBLOGraphy: Dilute, Shoot, and Elute – am I missing anything? YES!

  Everyone’s lab is different in terms of how many samples per day are processed, but they all share the common pain point of sample preparation. Some samples like blood and plasma need a significant amount of prep to remove proteins, phospholipids, and salts, whereas labs running urine or drinking water samples can “get by” […]

The "Replacement" Column A Recurring Problem in Gas Chromatography

...c x L/u. The three terms of course are the distribution constant, the reciprocal to column, under the same program parameters, and one can usually ignore this term if the two stationary...

ChromaBLOGraphy: Why are there different resolution equations in chromatography?

  It must be confusing for people that see the resolution equations that are used to “explain” chromatography in GC or LC. The challenge is that for different equations, assumptions are made, which are not listed with each equation. Resolution, R, is dependent on 3 main parameters: The capacity factor, “k”, the theoretical plate number [...]

QuEChERS Made Even Easier: Comprehensive Solutions Simplify Sample Prep and Analysis (PDF 5489kB)

... lists of pesticides of global concern. ■ Formulated for maximum long-term stability. ■ Manufactured...

Thermal Desorption: A Practical Applications Guide: II. Residual Volatiles & Materials Emissions Testing (PDF 1445kB)

...-products of microbial or mould / fungal growth and have been termed microbial volatile organic compounds (MVOCs)1...

News: Building the Foundation of Medical Cannabis Testing – Understanding the Use of Standards and Reference Materials – Part 2

Author: Joe Konschnik Restek Corporation Published By: Cannabis Industry Journal Year of Publication: 2016 Link: https://www.cannabisindustryjournal.com/column/building-the-foundation-of-medical-cannabis-testing-understanding-the-use-of-standards-and-reference-materials-part-2/ Abstract: In the last article I referred to the analogy of the analytical reference material being a keystone of the laboratory foundation, the stone upon which all data relies. I then described … Continue reading

A Guide to Preparing and Analyzing Chlorinated Pesticides (PDF 4038kB)

... important step in maintaining long-term instrument performance. Generally, when instrument problems arise . Sample extract cleanup is probably the most important step in maintaining long-term instrument...

Guide to Preparing and Analyzing Semivolatile Organic Compounds (PDF 6275kB)

... in maintaining long-term instrument performance. Many times, when instrument problems arise, they are caused...

New Market Opportunities for VOC Air Sampling Labs

.... Long product lifetime. Long-term sample stability. Blank certification required prior coefficients for each compound. Passive sampling, no sampling pump required. Long-term sampling...

Reduce Downtime with Robust Lipidomics Method

...®-5ms column shown here, are rugged and built for consistent long-term performance...

ChromaBLOGraphy: Understanding packed column mesh size ranges

If you have ever ordered a packed column, you are aware that mesh size of the solid support (packing) is one of the specifications you will need to know.  But have you ever wondered what mesh size actually means? To find the answer, let’s look at the products and process.  The necessary products are ASTM […]

A Primer on Control Systems

... scaling variables, or gain, in practice they are often interpreted in terms of time. If error is defined . If this is not appropriate, a way to eliminate steady state error is to apply an integral control term to the system...

ChromaBLOGraphy: Restek’s Searchable Chromatogram Database How-To

Jack’s recent mention of “hidden gems” on www.restek.com got me thinking that Restek’s website indeed abounds with cool things that many people might not know about. Jack went mining for treasure at Mponeng; now it’s our turn. One of the most powerful aspects of the new website is analyte searching, which drives both our chromatogram [...]

News: Appropriate Instrumentation for the Chemical Analysis of Cannabis and Derivative Products: Part 1

Author: Rebecca Stevens Restek Corporation Published By: Cannabis Industry Journal Year of Publication: 2016 Link: https://www.cannabisindustryjournal.com/column/appropriate-instrumentation-for-the-chemical-analysis-of-cannabis-and-derivative-products-part-1/ Abstract: The introduction of a series of articles focusing on the applications of instruments for different types of chemical analyses. Election Day 2016 resulted in historic gains for … Continue reading

Quality Control in Metabolomics

... in metabolomics means that the short-term and long-term influence of matrix effects is carefully evaluated...

Analysis of Nicotine and Impurities in Electronic Cigarette Solutions and Vapor (PDF 862kB)

... of Occupational Safety and Health (NIOSH) short-term exposure limit (STEL) of 350 ppbv. Furthermore, assuming 40...

USLC Columns Put the Right Tools in Your LC Method Development Toolbox Understanding Selectivity in Reversed Phase Separations – A Simplified Approach to HPLC and UHPLC Column Selection

... is the result of 3 cumulative terms: efficiency (N), retention capacity (k), and selectivity (α). How well we . Of the 3, the selectivity term mathematically affects resolution to the greatest degree (Equation 1). Put...

How to Maximize Column Oven Accuracy and Stability Tips & Techniques for Long-term Instrument Performance

... Improve long-term data reproducibility through calibration. Reduce...

ChromaBLOGraphy: Extending the expiration date on a reference standard

Restek occasionally receives requests from customers on extending the expiration date on their certified reference material or standards that we manufacture. The short answer to this question is no, Restek conducts real-time stability studies and accelerated stress tests to establish reliable expiration dates. Use beyond the identified expiration date is neither recommended nor guaranteed. While […]

ChromaBLOGraphy: GC columns – when one is not enough

Often we get asked for a column recommendation for a complex GC analysis.   This is especially true for gas analysis.  Probably the most common request is for separation of fixed (permanent) gases (like O2, N2, CO, CO2, N2O, etc…) plus separation of larger (higher-boiling point) compounds (light hydrocarbons, moisture, sulfur compounds, etc.).  Unfortunately, there is […]

Column Choice: A Critical Factor for Successful UHPLC Integration

... micron (termed “fines”), clogging of the column frit and unwanted column backpressure can result the efficiency, or N term, of the resolution equation. While this can improve and speed up a separation...

ChromaBLOGraphy: 1st Annual Medical Cannabis Summit at Pittcon 2014

Happy post-Pittcon, everyone! It was a very productive week, and as always, I had a wonderful time. This year was special for me in that amid the talks, posters, and general bustle of the show, I had the pleasant opportunity to finally meet some folks from the medical cannabis industry face-to-face. Even though Restek has […]

News: Restek Announces New President and Head Coach

The Board of Directors of Restek Corporation has announced a change in the senior leadership of the company. Bryan Wolcott, Restek’s current CFO of 11 years, will be taking the role of Head Coach and President. Bryan joined Restek in … Continue reading

Carrier Gases for GC

... what they get. It compares separation efficiencies measured in terms of Trennzahl (TZ) indicating . Table II:  Separation efficiencies in terms of separation numbers (Trennzahl, TZ...

ChromaBLOGraphy: Air Columns – Part III: My favorite column phase for EPA Method TO-15!

In part I of this blog series I told you my theory on why most air laboratories are using a 60 m x 0.32 mm x 1.00 µm 1-type column to separate what I refer to as the standard suite of 65 VOCs for U.S. EPA Method TO-15. Then in part II I showed you […]

ChromaBLOGraphy: Multi/Multi Methods (MMM) in Food Analysis

More and more laboratories are facing more and more pressure in both, time and price. More work has to be done in shorter time. Customers are deciding on a cent-to-cent base per analysis whether they will place an order to one contract laboratory or to another. Production laboratories are requested for shorter Turn-Around-Times (TAT) to […]

News: Learn More About Rosetta, Philae, and the Restek® MXT® GC Capillary Columns They Carry

In November 2014, the Rosetta spacecraft’s Philae lander made history by achieving the first soft landing on a comet. Earlier last year, we told you about four different phases of our metal MXT® columns being selected for this decade-long mission … Continue reading

News: Fortify or Calibrate for 203 Pesticides by GC-MS/MS With This Single Restek® CRM Kit

GC-MS/MS is the technique of choice for analyzing pesticide residues in many fruits, vegetables, botanicals, and herbals like tea, ginseng, ginger, Echinacea, and dietary supplements. And Restek’s new GC-MS/MS pesticide reference standards kit contains over two hundred compounds pulled from … Continue reading

ChromaBLOGraphy: Do you love your pet? Then you will love our Raptor™ Biphenyl LC column.

Have you ever faced this? Your pet has a stomach problem and nothing helps except to visit the veterinarian? Most likely, your beloved dog or cat is infected with parasitic protozoans, causing a disease called coccidiosis. Help is in sight; the veterinarian will use a pharmaceutical out of the group of coccidiostats and there is […]

ChromaBLOGraphy: A Simple Tip for Quicker Searching

One of the questions that Restek’s Technical Service Group is asked frequently is “how do I find ____ on your website?” The Restek website contains tens of thousands of products and supporting resources. In the past, my colleagues have written posts on using our online search function and how to use our searchable chromatogram database. […]

News: QuEChERS: The Concept

Author(s): Julie Kowalski, Amanda Rigdon, and Jack Cochran Restek Corporation Published By: Separation Science Issue: vol. 5, issue 8 Year of Publication: 2013 Link: For the full print issue, visit http://www.sepscience.com/docs/Bespoke/Editions/SepSci/Sepsci0813eu.pdf?utm_source=iContact&utm_medium=email&utm_campaign=eLearning%20Newsletter%20-%20Europe%20Sep%20Sci&utm_content= Abstract: The original QuEChERS sample preparation methods were designed for … Continue reading

GC Inlet Maintenance: Restek’s Quick-Reference Guide (PDF 8496kB)

..., the key term is “preventative.” You are trying to prevent unwanted downtime by replacing your inlet...

ChromaBLOGraphy: So what are we to do about all the TO-11A issues? A multi-blog series on airborne carbonyls, part V – THE FINALE!!!

It is time to recap and wrap this series up. In part I I simply highlighted the fact that the sampling and analysis of airborne aldehydes and ketones (carbonyls) with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents (i.e., United States (U.S.) Environmental protection Agency’s (EPA) Compendium Method TO-11A or some derivation thereof (e.g., California Air Resources Board (CARB) [...]

ChromaBLOGraphy: [3]Troubleshooting HPLC- Tailing Peaks

Patterns in your HPLC chromatography can exhibit telltale signs that point toward probable sources of error.  In this brief series of posts, we will look at possible scenarios that you may encounter in the laboratory and how you might approach resolving those difficulties. If you are having difficulty with tailing, it is likely that you […]

ChromaBLOGraphy: How Do I Scale Up to a Prep LC Column?

  As mentioned in my previous post What is Different about Prep LC?, we ask that you start by developing your method on an analytical scale column. Once you have accomplished this, and wish to start using prep scale HPLC for purification, you will need to determine what size preparative scale (“prep”) column would be […]

Will Pro EZGC Chromatography Modeling Software Work For You? We Put It to the Test!

... results closely match the empirical results in terms of relative peak resolution. Actual retention times chromatogram simulator produces a very close match to the experimental separation in terms of relative peak...

A Guide to the Analysis of Halogenated Environmental Pollutants Using Electron Capture Detection (PDF 8131kB)

... Pesticides and PCBs Sample extract cleanup is probably the most important step in maintaining long-term...

Mitigating Matrix Effects: Examination of Dilution, QuEChERS, and Calibration Strategies for LC-MS/MS Analysis of Pesticide Residues in Diverse Food Types (PDF 1561kB)

... accurate quantification extremely difficult. We use the term “matrix effect” to discuss this ionization...

Advanced Capillary Column Technology Improves Analysis of Volatile Amines

.... While, using a properly deactivated analytical column provides a better long-term solution, priming can...

New D3606 Column Set Outperforms TCEP Columns for Benzene Analysis

... a relatively expensive choice in terms of cost-per-injection and downtime required for frequent column changes...

ChromaBLOGraphy: CSI-Type Shows: Their Lab Work is a Crime

My second-biggest* pet peeve about TV shows is the unrealistic depiction of lab technology, which seems to be almost a requirement on any show dealing with criminal investigations. There are two subcategories. On the one hand there’s ridiculous made-up stuff, which is really only a problem if the show isn’t sci-fi (so, almost always). Futuristic [...]

ChromaBLOGraphy: Now you see it, now you don’t – Troubleshooting method recovery problems

We sometimes get calls from analysts that just can’t seem to get acceptable recovery results for the method they’re performing.  Regardless of the analytical technique, a methodical approach to identifying the problem is always essential. The first step should be to define the problem. Answer the following questions: Does the chromatography for your quantitation standards [...]

Frequently Asked Questions (FAQs): Reference Standards

... the ampul before opening.) Short-term exposures (≤ seven total days) to higher temperatures is acceptable and should not, based on our studies, negatively affect the long-term stability of your product...

ChromaBLOGraphy: How to decrease run time for reversed phase LC

There are several ways to accomplish this, although it boils down to roughly 4 possibilities. Use a shorter column length. This may be appropriate if you have plenty of retention for your analyte(s), if you only have one or a few analytes AND if you do not have interference peaks in your chromatogram. It does, […]

Matrix Effects in Multi-Residue Pesticide Analysis When Using Liquid Chromatography-Tandem Mass Spectrometry

... error, in terms of accuracy and precision, for quantitative results. Additionally, optimal dilution...

Using Guard Columns and Retention Gaps in GC (Part 2)

... the connector and associated risks. This technology, available from Restek, is termed Integra...

Preventive Maintenance for GC

... addicted to a short-term solution: they simply install a new column and the problem disappears...

Analysis of Trace Hydrocarbon Impurities in 1,3-Butadiene Using Optimized Rt®-Alumina BOND/MAPD PLOT Columns

... amounts of 1,3-butadiene dimer (4-vinylcyclohexene) form during long term storage. Typically, alumina PLOT...

Faster DHA Analyses Using Helium or Hydrogen

.... Restek has worked in a long-term collaboration with Neil Johansen, one of the original DHA method...

Frequently Asked Questions about Melamine

... sites and the target analytes. These matrix components are termed analyte protectants...

Totally Reliable Column-to-Column Performance

...,900.) In practical terms, this means peaks will be better resolved on a Restek column than on a competitor column...

ChromaBLOGraphy: Restek – PhD Student Award at the PhD Student Conference of the German Separation Science Working Group

Every year, in the beginning of January, a wonderful conference takes place in Germany. For the past 24 years the Separation Science Working Group (part of the German Chemical Society) is the host for a completely student organized seminar conference. One university group has the duty to organize the event each year.  The intention of […]

ChromaBLOGraphy: Quantifying FAMEs at ppm Levels in a Petroleum Diesel and Biodiesel Blend with GCxGC-FID and Rtx-200 x Rxi-17Sil MS

I promised in the previous blog on petroleum diesel:biodiesel analysis using GCxGC-FID to tell you why it’s important to determine fatty acid methyl ester (FAME) levels in some fuel blends.  It’s because the US Federal Aviation Administration (FAA) has set a maximum limit of 30 ppm for FAME in aviation fuel.  FAMEs can cause fuel [...]

ChromaBLOGraphy: The Most Useful Pesticide Standard Ever…monitoring GC inlet “dirtiness”

I have spent most of my time over the past several years testing pesticides and there is one standard that I simply can’t live without…QuEChERS Performance Standards Kit. It is based on a really interesting article* on analyte protectants with a few compounds added. The standard has 40 compounds housed in three vials for long […]

ChromaBLOGraphy: [2]Troubleshooting HPLC- Loss in Response for Some, but Not All Analytes

[2]Troubleshooting HPLC- Loss in Response for Some, but Not All Analytes Patterns in your HPLC chromatography can exhibit telltale signs that point toward probable sources of error.  In this brief series of posts, we will look at possible scenarios that you may encounter in the laboratory and how you might approach resolving those difficulties. When […]

ChromaBLOGraphy: Pittcon 2011: Poster on the Analysis of BTEX in Crude Oils Using Purge-and-Trap GC-MS.

Our original study focused on recoveries of light aromatic hydrocarbons in crude oil with and without dispersant compounds added. The results clearly showed there was no difference since the single-ringed aromatics are soluble in water at low ppm levels and readily partition out of the heavy crude. Even Maya (medium crude) and California (heavy crude) [...]

ChromaBLOGraphy: Blogging about rough pumps is a ballast!!!

In my previous blog we learned that the oil in a rotary vane rough pump acts as a sink for compounds in the vapor stream you are vacuuming. This ties in nicely with my most recent blog in which we learned that the color of your rough pump oil is not always a reliable indicator [...]

ChromaBLOGraphy: What do Chromatograms tell us? Peak Shape: Overload using Liquid Phases

Chromatograms are like fingerprints.  If you can “read” chromatograms well, you often can find a plausible cause. In this series, we will show a series of chromatograms that are obtained from users and discuss some potential causes for the phenomena. Then we can move into some solutions for improvement.   A peak shape is observed [...]

ChromaBLOGraphy: TO-15 Canister Relative Humidity: Part I (Introduction)

From time- to-time I receive inquiries on how to humidify a TO-15 canister blank and/or standard. See… Method TO-15 clearly states the use of humidified zero air several times throughout the document. For example: “10.7.3 Procedure. Fill a cleaned and evacuated canister with humidified zero air (RH >20 percent, at 25 °C). Pressurize the contents [...]

ChromaBLOGraphy: Calibration Curves for Cannabinoids Based on PCP Internal Standard – Medical Cannabis GC-FID

Yesterday’s ChromaBLOGraphy post concerned the use of internal standards (ISTDs) for GC-FID potency testing of medical cannabis.  In that post I defined desirable characteristics for an ISTD and said that one of the benefits of ISTD use is better quantitative accuracy.  Good quantitative accuracy starts with good calibration, which I demonstrate in this post by showing a […]

ChromaBLOGraphy: Cannabis Analysis – We’ve Come a Long Way, Baby!

A little less than a year ago at Pittcon in Chicago, my colleague Frank Dorman from the Pennsylvania State University and I sat down over beers with Ken Snoke and Wes Burk from Emerald Scientific, a small startup distribution business for cannabis labs. We were joined by Bill and Christi Schroeder and Ted Flood from […]

News: Being the County’s Top Business Group of Blood Donors is Not Enough for Restek Employees

Restek donors roll up their sleeves every 8 weeks and donate more blood than any other local business, but organizers have their sights set on bigger goals. On March 13, 2017, when Winter Storm Stella was about to dump more … Continue reading

ChromaBLOGraphy: The Promise of True Peak Capacity Increase GCxGC Realized

I mentioned in my last ChromaBLOGraphy post, Phthalate-Free Personal Care Products?, that we used GCxGC-TOFMS to determine phthalates in a Las Vegas Wash water sample.  While it doesn’t dive into specific compound identification, we recently published the first demonstration of a near theoretical maximum peak capacity gain for GCxGC (approximately 9x) in an open access […]

ChromaBLOGraphy: What is the pressure limit for my LC column?

This is a question we get in Tech Services fairly often.  Unfortunately, we are not able to provide a published limit for every column that we produce, but here are a few of them that we have specified: For 3 and 5 um fully porous particle ROC LC columns, the maximum operating pressure is 400 […]

News: Attend Restek’s Vendor Seminar on GC-MS/MS Performance at RAFA 2015

In addition to exhibiting, Restek will hold a vendor seminar at the 7th International Symposium on Recent Advances in Food Analysis (RAFA). Presented by Restek’s own Julie Kowalski on November 5 at 1:30 p.m., this valuable seminar will explore prolonging … Continue reading

ChromaBLOGraphy: Is the column shown on the COA for a chemical reference standard the best column for these compounds?

  In some cases the answer is “yes”. In most cases the answer is “no”.   So why would we choose a column that is not the optimal for a specific standard? It’s because of the large number of reference standards we sell. Each mix needs to have its own validated method. If we were […]

News: International GC Specialist Jaap de Zeeuw to Speak at Advances in GC IV Meeting

UPDATE: For a detailed review of Advances in GC IV, including more information on Jaap’s presentation, visit Chromatography Today’s Meeting Report. On October 30, 2013, The Chromatographic Society (ChromSoc) and the North West Region of the Analytical Division of the … Continue reading

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