HPLC Method for Analysis of Paraquat on Obelisc R by SIELC Technologies

Paraquat is a widely used, non-selective herbicide known for its high efficacy in controlling a wide range of weeds. It has been an important tool in agriculture since its introduction in the mid-20th century. However, its use is accompanied by significant safety concerns due to its high toxicity.

Paraquat can be retained and analyzed on a Obelisc R mixed-mode stationary phase column using an isocratic analytical method with a simple mobile phase of water, Acetonitrile (MeCN), and a ammonium format as a buffer. This analysis method can be detected an Evaporative Light Scattering Detector (ELSD), or any other evaporative detection method (CAD, ESI-MS)

HPLC Method for Analysis of Paraquat, Diquat on BIST B+ by SIELC Technologies.

Paraquat is a widely used, non-selective herbicide known for its high efficacy in controlling a wide range of weeds. It has been an important tool in agriculture since its introduction in the mid-20th century. However, its use is accompanied by significant safety concerns due to its high toxicity.

Diquat is an organic dication that is used as a contact herbicide. It has the chemical formula C₁₂H₁₂Br₂N₂. It is considered moderately toxic and harmful if swallowed, inhaled, or absorbed through skin. It degrades slowly when in nature due to bonding strongly to minerals and organic particles. Due to that, it is no longer approved for use in the European Union.

Paraquat, Diquat are two of the most popular herbicides on the market. With fairly similar structures and interactions with typical ion-exchange columns, they are usually extremely difficult to separate. Using SIELC’s newly introduced BIST™ method, Paraquat, Diquat, which protonate in water, can be retained on a positively-charged anion-exchange BIST B+ column. There are two keys to this retention method: 1) a multi-charged, negative buffer, such as Sulfuric acid (H2SO4), which acts as a bridge, linking the positively-charged herbicide analytes to the positively-charged column surface and 2) a mobile phase consisting mostly of organic solvent (such as MeCN) to minimize the formation of a solvation layer around the charged analytes. What allows these two compounds to be separated using BIST™ is the slight difference in charge position between the two analytes. Since the analytes interact so close to the surface, the minor difference in charge distribution is magnified and therefore significantly affects each analyte’s retention ability. Using this new and unique analysis method, Paraquat and Diquat can be retained and UV detected at 250 nm.

Description

HPLC Method for Mepiquat, Paraquat, Diquat, Chlormequat on Obelisc R by SIELC Technologies

There is a need to separate different herbicides and pesticides in one run with LC/MS compatible conditions. Paraquat, diquat and glyphosate were separated on reversed-phase tri-modal cation- and anion-exchange column (Obelisc R) and on HILIC/ion-exchange columns (Obelisc N). Method explores unique properties of mixed-mode stationary phase which retains and separates cations like paraquat and diquat and anions/zwitter-ions like glyphosate in one run. Since columns are compatible with 100% organic and 100% water, a wide range of gradients can be used for analysis as well as isocratic conditions where it is desired. Method can be used for quantitation of these compounds in various matrices (soil, ground water, crops, food, etc.)

Paraquat, diquat and glyphosate were separated on reversed-phase tri-modal cation- and anion-exchange column (Obelisc R) and on HILIC/ion-exchange columns (Obelisc N). Method explores unique properties of mixed-mode stationary phase which retains and separates cations like paraquat and diquat and anions/zwitter-ions like glyphosate in one run. Since columns are compatible with 100% organic and 100% water, a wide range of gradients can be used for analysis as well as isocratic conditions where it is desired. Method can be used for quantitation of these compounds in various matrices (soil, ground water, crops, food, etc.)

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.

Paraquat and diquat are two of most widely used herbicides in the world. Both compounds are toxic for humans and animals. Presence of paraquat and diquat in water is regulated by EPA. Paraquat and diquat have two quaternary amines, making them very polar molecules. Paraquat and diquat also have similar formula. Due to low hydrophobicity and highly basic properties, they show limited retention on reversed-phase columns and produce very poor peak shape due to the residual silanol interactions. Primesep AB and Obelisc R column retain and separate these two compounds with perfect peak shape.

Paraquat and diquat are two of most widely used herbicides in the world. Both compounds are toxic for humans and animals. Presence of paraquat and diquat in water is regulated by EPA. Paraquat and diquat have two quaternary amines, making them very polar molecules. Paraquat and diquat also have similar formula. Due to low hydrophobicity and highly basic properties, they show limited retention on reversed-phase columns and produce very poor peak shape due to the residual silanol interactions. Obelisc R column retains and separates these two compounds with perfect peak shape. Method can be used for analysis of paraquat and diquat in soil, ground and drinking water, and other samples. Method allows to separate both compounds in one run without ion-pairing reagent.