View on hplc.cloud

Main source of contamination of environment by perchlorates are rocket fuels, car airbags, and fireworks.
EPA developed regulation of the perchlorate level in drinking water which already adapted by several states.
The most convenient, universal and very sensitive way to measure perchlorate is chromatography.
SIELC developed a simple, rugged, and selective HPLC method which allows to measure perchlorate in different matrices including drinking water.
This method allows to measure simultaneously other chloro containing ions such as chloride, and chlorate.
The method shows high selectivity and specificity.
The mobile phase is a simple mixture of water acetonitrile and ammonium formate.
The column used in the analysis has advanced surface chemistry with long chain holding a terminal positively changed functional group.

View on hplc.cloud

Paraquat, diquat and glyphosate are three of most widely used herbicides in the world. Paraquat and diquat are very polar and very basic quaternary amines. Glyphosate is an aminophosphonic analog of glycine. It is very polar and acidic at most of the pH of the mobile phase. Since glyphosate and the quats have opposite charges no ion-pairing method can be developed for the mixture of basic and acidic herbicides. All three herbicides were separated on the Obelisc R tri-modal column. Paraquat and diquat are retained by a cation-exchange mechanism, and glyphosate is retained by weak reversed-phase and strong anion-exchange mechanisms. This method can be used for analysis of common herbicides in fruits, vegetables, ground water, drinking water and other matrices. Method is LC/MS compatible and can be used to determine trace levels of herbicides.

Mepiquat is a plant growth regulator that is monitored by EPA in water. It is a quaternary amine that is very polar in nature. Mepiquat and other hydrophilic amines are not retained on reversed-phase columns, and produce poor peak shape due to residual silanol interactions. Ion-pairing reagent is required to retain mepiquat. Ion-pairing reagents are not compatible with LC/MS detection and most environmental application require high sensitivity methods to determine very low level of contaminants. Obelisc R mixed-mode column can be used for EPA methods for determination of common pesticides, herbicides and insecticides where analysis of very polar ionic compounds is required.

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.

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 divalent cations, zinc and manganese, from their counter ion, chloride. The cations are retained by cation exchange and the chloride anion is eluted by ion exclusion. The mobile phase mixture of water, acetonitrile (MeCN, ACN) and ammonium acetate is evaporative light scattering detection (ELSD) compatible.

Primesep 100 allows the quantitation of sodium and zinc cations in a drug product sample. The cations are retained by cation exchange and the drug product is retained by hydrophobic, reversed-phase mechanisms. The separation uses a mobile phase mixture of water, acetonitrile (MeCN, ACN) and trifluoroacetic acid (TFA) with evaporative light scattering detection (ELSD) and UV detection.

High nitrate concentrations in water and soil can be toxic to humans, fish and domestic animals.  Chloride can be used for analysis of water contamination. Primesep D column can be used to separate and quantify both ions.  The baseline separation between chloride and nitrate can be increased by decreasing the ammonium formate concentration in the mobile phase.  Evaporative Light Scattering Detection (ELSD) used.