Pesticide is a more generic term that includes herbicides, fungicides and insecticides in its definition. Herbicides are used to control unwanted plants, they are also known as weedkillers. Insecticides are used to kill insects. Fungicides are used to kill parasitic fungi. All are heavily used in agriculture. By using HPLC, many different pesticides can be separated and their retention characteristics controlled using the Newcrom B mixed-mode column.

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Dextromethorphan is one of the common cough suppressants used in many drug composition. It is in tablets and syrups as an antitussive drug. Composition often has preservatives like parabens. Dextromethorphan is a hydrophobic, basic drug which is used as a bromide salt in drug compositions. Dextromethorphan and two parabens (methyl paraben and propyl paraben) were separated on Primesep C reversed-phase cation-exchange column. Several impurities were observed and are well separated from the main components of the drug composition. Method can be used for various formulations in QC and production environment.

Halide ions are usually analyzed by ion-chromatography with a conductivity detector. Mixed-mode chromatography in combination with ELSD is offering a valuable alternative to ion-chromatography with conductivity detection. Chloride, bromide and iodide were separated on a Primesep SB mixed-mode anion-exchange column. Mobile phase is compatible with ELSD and LC/MS.

Ion chromatography is usually used for analysis of hydrophilic organic and inorganic ions. Same separation can be achieved on HILIC/mixed-mode Obelisc N HPLC columns. Obelisc N HPLC columns have very polar groups on their surface: one of the groups is basic and the other acidic. In case of low organic concentration, two groups are connected by hydrophilic linker. Obelisc N column can be used as cation-exchange and anion-exchange column. This allows to separate positively and negatively charged molecules in one run. Five anions (chloride, bromide, methanesulfonate, nitrate and perchlorate) along with one cation (sodium) were separated in one run. Method is compatible with ELSD, CAD and LC/MS and can be used for analysis of various hydrophilic and hydrophobic cations and anions in one HPLC run.

The majority of drugs in the pharmaceutical industry are administered in salt form. The presence of two counter-ions very often necessitates the use of two methods. The nature of these counterparts in drugs can be an inorganic cation and organic acid, inorganic anion and organic base, and organic cation and organic anion. Furthermore, the properties of the molecules will result in a differing stoichiometry. The task of simultaneous quantitation of counter-ions can be achieved by using mixed-mode columns. The general approach for analysis is based on properties of corresponding counter-ions. Hydrophobic basic drugs, like dextromethorphan, verapamil, trimipramine, and corresponding acidic counter-ions (chloride, chlorate, bromide, bromate, perchlorate, maleate, fumarate,tartrate, succinate, phosphate, citrate, benzosulfonate, toleuensulfonate) can be separated and quantitated in the same run on reversed-phase anion-exchange column. Basic hydrophobic drugs are retained by the reversed-phase mechanism, and counter-ions are retained by the reversed-phase and anion-exchange mechanism. Some polar counter-ions are retained only by the anion-exchange mechanism. Retention time and selectivity of HPLC separation of drugs and counter-ions can be achieved by changing the amount of acetonitrile and the amount of ions in the mobile phase. The detection technique depends on the properties of the counter-ions. In case of low or no UV activity, ELSD can be employed if the counter-ion forms a non-volatile salt with the mobile phase additive (ammonium formate). This HPLC method can be used for simultaneous quantitation of other basic drugs and counter-ions. The presence of two mechanisms of retention allows control over retention times of drug and counter-ion independently, and even allows a change of order of elution when necessary.

Ionic liquid is an ionic compound which is liquid at room (or close to room) temperature. Most of the ionic liquids are in a dynamic equilibrium where at any time more than 99.99% of the liquid is made up of ionic, rather than molecular, species. Room-temperature ionic liquids consist of bulky cation (for example, substituted imidazolium) compounds. A wide range of anions is used as counter ions in ionic liquids: organic and inorganic anions such as chloride, iodide, tetrafluoroborate, hexafluorophosphate, bistriflimide, triflate, tosylate. Ionic liquids are widely used as solvents in organic reactions. When products are isolated from ionic liquids, they need to be analyzed for residual ionic liquid content.
Because both constituents of the ionic liquid are very different in terms of charge and hydrophobic properties, it is impossible to analyze entire ionic liquids by traditional chromatography. An effective and universal method for analysis of ionic liquids is developed on an Obelisc R HPLC column. Components on the ionic liquids are retained based on ionic and hydrophobic interactions. Obelisc R column has both positively and negatively charged ionic groups, making it possible to retain and separate cations and anions of ionic liquids on one column. Method can be used for quantitative of various ionic liquids containing organic and inorganic ions. Retention time of basic component can be effectively adjusted by pH, stronger anionic and hydrophobic counter-ions might require higher buffer concentration. Composition can be monitored by combination of UV and ELSD or by LC/MS.

Primesep 100 and Primesep B columns connected in series allow the quantitation of sodium chloride and potassium bromide ions in one injection. The Primesep B column retains the chloride and bromide anions by anion exchange, and the Primesep 100 retains the sodium and potassium cations by cation exchange. The retention can be adjusted by changing the water/acetonitrile ratio in the mobile phase. The separation uses a mobile phase mixture of water, acetonitrile (MeCN, ACN) and ammonium acetate with evaporative light scattering detection (ELSD).

Primesep 100 and Primesep B columns connected in series allow the quantitation of sodium chloride and potassium bromide ions in one injection. The Primesep B column retains the chloride and bromide anions by anion exchange, and the Primesep 100 retains the sodium and potassium captions by cation exchange. The separation uses a mobile phase mixture of water, acetonitrile (MeCN, ACN) and trifluoroacetic acid (TFA) with evaporative light scattering detection (ELSD).

Primesep 100 separates the monovalent cations, lithium, potassium, and sodium, and the divalent cations, zinc, manganese, and calcium. The cations are resolved by cation exchange. The mobile phase mixture of water, acetonitrile (MeCN, ACN) and trifluoroacetic acid (TFA) is evaporative light scattering detection (ELSD) compatible.

Dextromethorphan is used as a temporary cough suppressant in many medications. The elution time of dextromethorphan and bromide can be reversed in HPLC chromatography on a Primesep B2 reverse-phase (RP) column with embedded basic ion-pairing groups by only changing the concentration of buffer in a simple mobile phase of water and acetonitrile (MeCN, ACN). Buffer is trifluoroacetic acid (TFA). UV detection at 210nm.

Primesep C separates a mixture of quaternary amines by a combination of cation exchange, complex formation, and hydrophic interactions. Methyltriethylammonium, tetraethylammonium, and tetramethylammonium cations as well as bromide counter ion are separated on a short 50 mm column. The separation uses a mobile phase mixture of water, acetonitrile (MeCN, ACN) and triethylamine acetate with evaporative light scattering detection (ELSD).