Application of On-Line HPLC−¹H NMR to Environmental Samples:  Analysis of Groundwater near Former Ammunition Plants

Abstract

Coupling of HPLC to NMR was applied for the first time to the analysis of environmental samples, i.e., water samples from an ammunition hazardous waste site. Using the continuous flow mode at very low flow rates (< or = 0.017 mL/min) and large volume injection (400 microL), the confirmation of many nitroaromatic compounds could be achieved down to the microgram-per-liter level after solid phase extraction of a groundwater sample from a former ammunition production site. At a flow rate of 0.006 mL/min, it is possible to detect less than 29 nmol (5 micrograms) of 1,3-dinitrobenzene injected on a 75 mm x 4 mm reversed phase C-18 column (particle size, 5 microns). The results obtained by HPLC-NMR are compared to those obtained by HPLC-PDA (photodiode array) of the same sample, demonstrating that many more compounds can be identified by the former compared to the latter method as a result of coelution of major and minor components in the HPLC chromatogram.

Quality control of herbal medicines

“…With the help of this hyphenation, in most cases, one could identify the chromatographic peaks directly on-line by comparison with literature data or with standard compounds, which made the LC-DAD-MS becomes a powerful approach for the rapid identification of phytochemical constituents in botanical extracts, and it can be used to avoid the time-consuming isolation of all compounds to be identified [149]. Recently, the hyphenation between HPLC and NMR are also available [150][151][152][153][154], which might become a vital and an attractive analytical tool for the analysis of drugs in biological fluids and for the analysis of herbal medicines [155]. In fact the tendency of the hyphenation or multi-hyphenation of the chromatography with the common used four spectroscopic detectors, say UV, Fouriertransformation infrared spectrum, MS and NMR, for structure elucidation of chemical compounds, is in progress.…”

Reversed phase liquid chromatography trace analysis of pesticides in soil by on‐column sample pumping large volume injection and UV detection

“…Rezai et al [14] enhanced detection sensitivity by LVI in micro RP-HPLC technique. Further development was thorough study of LVI techniques [15] and on-line LVI-HPLC-1H NMR [16]. Cappiello et al [17] used LVI in micro RP-HPLC analysis of acidic pesticides.…”

New approach to large‐volume injection in reversed‐phase high performance liquid chromatography: Determination of atrazine and hydroxyatrazine in soil samples

“…A systematic study of injection techniques including LVI with the aim of selecting the appropriate sample volume to achieve maximum detection sensitivity and resolution with HPLC columns of 1.0, 2.1, and 4.6 mm internal diameter, respectively, was conducted by Bakalyar et al [11]. Cappiello et al [12] used LVI of acidic pesticides in micro RP-HPLC analysis and Godejohann et al [13] applied a similar approach in on-line HPLC and 1 H NMR to analysis of groundwater near former ammunition plants. The cationic herbicides paraquat and diquat were monitored in human serum and urine by Itagaki et al [14] using ionpairing bare-silica stationary phase HPLC following a single acidification step of sample pretreatment and LVI.…”