Topic
NQS
About: NQS is a research topic. Over the lifetime, 337 publications have been published within this topic receiving 4226 citations.
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TL;DR: In this article, the derivatization of amphetamine and methamphetamine with 1,2-naphthoquinone-4-sulfonate (NQS) into solid-phase extraction is described.
Abstract: The derivatization of amphetamine and methamphetamine with
1,2-naphthoquinone-4-sulfonate (NQS) into solid-phase extraction
cartridges (C
18
) is described. Optimum conditions were the use
of carbonate–hydrogencarbonate buffer of pH 10, a 10 min reaction
time at 25 °C and an NQS concentration of 9.6 ×
10
-
3
M. The accuracy and the
precision of the method were tested. The results obtained with the
proposed liquid–solid procedure were compared with those obtained
with a traditional liquid–liquid extraction with hexane–ethyl
acetate. The procedure was used to measure amphetamine in pharmaceutical
and urine samples
22 citations
TL;DR: In this article, a simple HPLC method was developed for the determination of glyphosate and its main metabolite aminomethylphosphonic acid residues in soil samples based on a pre-column derivatization with 1,2-naphthoquinone-4-sulfonate (NQS).
Abstract: A simple selective high-performance liquid chromatography (HPLC) method has been developed for the determination of glyphosate and its main metabolite aminomethylphosphonic acid residues in soil samples based on a pre-column derivatization with 1,2-naphthoquinone-4-sulfonate (NQS). The reaction is performed at pH 9.4 and 60°C for 5 min. The separation of glyphosate was carried out in a C18 column using a 1% acetic acid–methanol (40:60, v/v) mobile phase and UV detection. An experimental design approach based on the central composite design is used to investigate the dependence of the derivatization variables of pesticide. The concentration of NQS and reaction temperature were found to be statistically significant. The limits of detection obtained were 0.064 mg kg−1 for glyphosate and 0.098 mg kg−1 for its metabolite. The proposed method was applied successfully to the analysis of real soil samples from corn crops. The proposed method is easier and faster compared to other ones.
21 citations
TL;DR: This method has been successfully applied to the determination of Ami in pharmaceutical samples and is based on the fact that a russety product can be formed by the reaction between aminophylline (Ami) and sodium 1, 2-naphthoquine-4-sulfonate (NQS) in pH 13.00 buffer solution.
21 citations
TL;DR: In this paper, a natural mineral, such as quartz sand (NQS), was modified with a small amount of goethite to yield a Goethite-coated Quartz sand (GCQS) adsorbent that was used for depolluting water contaminated with a series of phenolic acids that have various numbers and positions of hydroxyl groups in the benzene ring.
20 citations
TL;DR: In this article, a chemical spot test for piperazine analogues present in unknown seized materials using the spectrophotometric reagent, sodium 1,2-naphthoquinone-4-sulphonate (NQS), was presented.
Abstract: The increasingly large quantities of potentially illicit samples received for confirmatory analysis highlights the importance and demand for preliminary testing procedures that are simple, rapid, selective, inexpensive and able to be used in the field. Colour testing fulfils the aforementioned requirements and is a technique frequently employed to achieve presumptive identification. Piperazine analogues (often marketed as ‘legal ecstasy’) are a group of psychoactive substances that have recently become established on the illicit drug market and are not effectively discriminated or identified by current colour testing methods. Herein, we report on the development and validation of a chemical spot test for piperazine analogues present in unknown seized materials using the spectrophotometric reagent, sodium 1,2-naphthoquinone-4-sulphonate (NQS). Primary testing revealed that NQS reacts almost instantly to form an intense, bright orange-red coloured complex with the representative piperazine 1-benzylpiperazine (BZP) at room temperature. The results of the test, assessed by colour development, were evaluated visually and variables affecting the coloured reaction were optimised. The colour test method was validated to meet requirements for use in preliminary screening, providing qualitative and reliable presumptive test results. Validation studies show that the characteristic colour change is unique to the piperazine class at room temperature, and is unaffected by the presence of common cutting agents, i.e. glucose and caffeine, in test samples of 5% purity, and other drugs such as N-methyl-3,4-methylenedioxyamphetamine (MDMA). The NQS reagent stability was found to be limited to storage in a refrigerated environment for no more than one week before results were affected. The operational limit of detection was found to be 40 μg.
20 citations