Reagents & Standards

High-Purity Solvents for UHPLC, LC-MS and GC-Headspace
Broader Selection of Quality Pesticide Standards Now Available from Sigma-Aldrich

High-Purity Solvents for UHPLC, LC-MS and GC-Headspace

Shyam Verma
shyam.verma@sial.com

Solvent impurities are the most common cause of extraneous peaks and unstable baseline. Background noise is typically caused by impurities that enter the system from the sample, by leaching from system components (bottles, tubes, valves, vials, etc.), and from solvents and additives. Solvent-derived impurities do not condition out over time and can interfere in the analysis in multiple ways, such as: a) collect on head of the column and elute as a distinct peak or as baseline rise, b) cause general elevation in baseline, lowering sensitivity of analysis, c) foul or damage sensitive instrument components and d) cause cluster ion formation that prevents reliable identification and quantification. For minimizing or eliminating these issues, sensitive tests like UHPLC, LC-MS and GC Headspace requires the use of highly pure solvents and additives.

Our Fluka brand has added another product line to the family of high-purity CHROMASOLV® solvents, blend and additives for sensitive UHPLC applications. This new product line is tested for UHPLC performance, including gradient applications, under both UV and MS detection. These solvents and reagents, designed for use in these sensitive analytical methods, as well as the sensitive GC-headspace analysis, are manufactured with utmost precision and are tested under strict quality control requirements.

Figure 1. UV drift of the solvent baseline resulting from a gradient application of LC-MS Ultra CHROMASOLV Acetonitrile/water (red) compared with LC-MS grade Acetonitrile/water (blue)

Figure 2. Reserpine spectrum measured in Methanol (Cat. No. 34966); no signals should be greater than [M+H]+=609 (100 ppb reserpine; ESI, positive mode)

LC-MS Ultra CHROMASOLV Grade Solvents
These solvents are tested for performance in UHPLC gradient separations, as well as UV, and positive and negative ion mode MS detection (Figure 1). Compared to standard LC-MS grade solvents, this new grade has significantly lower baseline and fewer minor peaks. In general, these solvents offer the following advantages:

High purity for extremely low detection limits under any detection mode together with UHPLC
Tested for UHPLC-MS
Suitability tested by UHPLC-MS TOF
High lot-to-lot reproducibility
Reliable data, high performance and eliminate system downtime

LC-MS CHROMASOLV Solvents
The LC-MS CHROMASOLV solvents undergo 34 distinct and relevant tests to ensure solvent requirements of sensitive LC-MS analyses. Some of the most important features are:

Application-tested for LC-MS using the reserpine tests (Figure 2)
Very low level of inorganic and metal ions for high sensitivity spectra
Particle/non-volatile compound-free (maintain system integrity)
Low gradient baseline with your own optimized protocols
Significantly reduced level of phthalate contaminants

Pre-Blended LC-MS Solvents
Our pre-blended solutions of the most commonly-used LC-MS mobile phases are prepared with precision and unsurpassed attention to quality. Using the precisely blended solvents eliminates time-consuming mobile phase preparation, and can eliminate lost sample information and instrument downtime caused by impure mobile phase. A special formulation assures that no precipitation or decomposition of the additive occurs under normal laboratory conditions. These high-quality preblended solvents offer:

Time savings
Accurate composition
Minimized baseline and artifacts

LC-MS Mobile Phase Additives
Fluka brand offers a wide range of high-purity additives for LC-MS applications that are already tested for LC-MS application. These high-purity additives offer many advantages for both small and large molecule analysis.

Acids, bases, volatile salts and sodium sources
High purity and LC-MS application tested
Improved ionization and resolution
Sodium ion additives for uniform/stable molecular ions

GC-Headspace Solvents
An important application of GC-Headspace (GC-HS) is for the determination of residual volatile organic impurities (OVIs) in active drug substances or excipients in drug formulations. The allowable limits for these OVIs are listed by the United States Pharmacopeia (USP), European Pharmacopoeia (Ph.Eur.) and in the International Conference on Harmonization (ICH) guidelines. In the GC-HS method, the composition and purity of the sample solvent have significant effects on the recovery and quality of the chromatogram. Sigma-Aldrich/Fluka developed high-purity solvents specifically for GC-HS applications (Figure 3). These solvents, microfiltered at 0.2 µm and packed under inert gas, offer the following benefits:

High purity and longer shelf life
Cleaner blanks and improved analyte recoveries
No major interference peaks in elution range
Specifications matching USP, Ph.Eur. & ICH guidelines

Figure 3. Fluka’s High Purity Headspace Grade vs an Organic Synthetic Grade - Using GC-MS and SPME on DMSO

1. Pentane
2. Hexane
3. Isopropyl ether

4. Dimethylpentane
5. Isooctane
6. Diisobutylene

7. Trimethylcyclopentane
8. Dimethylcyclopentanone

The organic synthesis grade showed many peaks not detected in the GC-HS grade DMSO. The GC-HS grade produced a cleaner headspace blank and showed no major interference peaks in the elution range of the target analytes.

Fluka Brand headspace solvents are manufactured under strictly controlled processes, including micro-filtration and packaging under an inert atmosphere. This ensures their suitability for meeting the demands of headspace analysis.

Featured Products

LC-MS Ultra CHROMASOLV Solvents and Additives		Qty	Cat. No.
Acetonitrile	≥ 99.9%*	1 L, 2 L	14261
Methanol	≥ 99.9%	1 L, 2 L	14262
Water		1 L, 2 L	14263
Trifluoroacetic acid	≥ 99.0% **	1 mL, 2 mL	14264
Formic acid	≥ 98%**	1 mL, 2 mL	14265
Ammonium formate	**	25 g	14266
Ammonium acetate	**	25 g	14267
* tested for UHPLC-MS ** suitable for UHPLC-MS

LC-MS CHROMASOLV Solvents	Cat. No.
Water	39253
Acetonitrile	34967
Methanol	34966
2-Propanol	34965
Ethyl acetate	34972
LC-MS CHROMASOLV Solvent Blends	Cat. No.
Acetonitrile with 0.1% TFA	34976
Methanol with 0.1% TFA	34974
Acetonitrile with 0.1% formic acid	34668
Acetonitrile with 0.1% ammonium acetate	34669
Acetonitrile with 0.1% formic acid and 0.01% TFA	34676
Water with 0.1% TFA	34978
LC-MS CHROMASOLV Mobile Phase Additives	Cat. No.
Trifluoroacetic acid, puriss p.a.	40967
Formic acid, puriss p.a.	56302
Acetic acid, puriss p.a.	49199
Ammonium formate, puriss p.a.	55674

GC Headspace Solvents	Qty	Cat. No.
N,N-Dimethylacetamide, puriss. p.a.	1L	44901
Dimethyl sulfoxide, puriss. p.a.	1L	51779
Cyclohexanone, puriss. p.a.	1L	68809
1-Methyl-2-pyrrolidinone, puriss. p.a.	1L	69337
N,N-Dimethylformamide, puriss. p.a.	1L	51781
1,3-Dimethyl-2-imidazolidinone, puriss. p.a.	1L	67484
Water	1L	53463

Broader Selection of Quality Pesticide Standards Now Available from Sigma-Aldrich	back to top

Sigma-Aldrich now provides analysts with one of the broadest offerings of standards for pesticide analysis available. Recent additions to our portfolio include proficiency testing samples, NIST traceable certified reference materials and matrix standards for monitoring sample preparation methods. These products, along with our 2000 plus pesticide standards, allow Sigma-Aldrich to fulfill the needs of many laboratories, including those that are ISE/ISO 17025 accredited.

NEW! Certified Reference Materials (CRMs)
Our newly expanded pesticide standard line includes certified reference materials in the form of neats and matrix standards.

Fluka TraceCERT® pesticide CRMs are certified in a double accredited laboratory fulfilling ISO/IEC 17025 and ISO Guide 34 using high performance quantitative NMR (HP-qNMR®) for content determination with direct traceability to NIST and SI. This measurement technique for purity offers a superior level of accuracy, calculated uncertainties and lot-specific values when compared to other CRMs in the marketplace.

Sigma-Aldrich RTC pesticide CRMs are available as either “real world” soil or sediment natural matrices or natural matrices in which selected analytes have been fortified to give analytical profiles that meet the needs of the market. A robust statistical program is used in determining the certified values of these CRMs, utilizing data developed from multi-laboratory analysis supported by in-house data. Most CRMs are method specific and are supplied with certificates that show an uncertainty, expanded uncertainty confidence interval, and a prediction value, in addition to the mean value and standard deviation from the mean.

Neat and Single-Component Solutions
We stock more than 1800 isotope-labeled and non-isotope labeled neat and single component solutions for shipment every day, including Fluka brand PESTANAL® grade standards. PESTANAL grade products are high-purity standards of herbicides, pesticides and their metabolites. Most have a purity >99%. Each PESTANAL standard is formulated for single use to reduce waste and packaged in glass ampuls. A batch specific assay for each standard is provided on the product label, and details of this assay are found on the certificate of analysis accompanying each purchase.

Second Source Products
To complement our PESTANAL grade standards, we provide Chem Service brand pesticide and pesticide metabolite standards. Many other second source pesticide standards are available from within Sigma-Aldrich. It is our goal to provide these products to you in a timely manner, making it convenient to order all your chromatography supplies from Sigma-Aldrich. Standards are shipped with documentation and expiration dates.

Multi-Component Calibration Mixtures
Analysts performing multi-residue pesticide analyses can select from a variety of Supelco brand pesticide calibration mixtures for their application. These quantitative mixtures eliminate the time and money associated with sourcing individual raw materials, preparing the mix, and then disposing of unused hazardous materials.

Manufacturing and testing information is available for each Supelco brand calibration mixture in the form of a data packet. Each data packet documents the rigorous analytical methods used to verify raw material identity and purity, and provides verification of analyte purity and final concentration accuracy. Data packets are free of charge.

The composition of Sigma-Aldrich RTC Proficiency Testing Samples and Certified Reference matrix standards will vary from lot-to-lot. This is because these products are prepared from natural matrices; some are fortified.

NEW! Proficiency Test Samples
Through Sigma-Aldrich RTC, accredited ISO 17025 testing laboratories can now source certified soil, water and sludge proficiency test (PT) samples to evaluate their laboratory’s competency for performing pesticide analyses and calibration. Laboratories can choose to participate in our quarterly or semiannual PT programs, or simply purchase PT samples.

The advantages of choosing Sigma-Aldrich RTC PTs include:

Most PT samples are supplied in duplicate. The duplicate can be used to report additional methods or be retained as a QC standard, using the study values.
Advanced tracking – methods, analysts, accreditation and equipment can be reported for the same analyte at no extra charge
Evaluation reports can be sent to your Accreditation Authority (AA) for no additional charge.

Custom Standard Formulation Services
We recognize that a stock product may not always be appropriate for your applications. That’s why we have dedicated staff ready to formulate, test, and package pesticide calibration standards according to your exact specifications. Our chemists will gladly discuss stability and solubility concerns with you, and make suggestions where needed to improve the quality of your purchase. If you are interested in a customized pesticide standard, please feel free to contact us by email: customstandards@sial.com. Or, use the quote request form at our website sigma-aldrich.com/standards

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