Recent developments in detection techniques for high-performance liquid chromatography. Part I. Spectroscopic and electrochemical detectors. A review

A novel polymeric activated ester reagent has been developed that improves final detectability and chromatographic performance in high-performance liquid chromatography (HPLC) for virtually all primary and secondary amines or amine analogues. This has involved the synthesis, characterization of final reagent, optimization of derivatization and separation conditions, and determination of analytical figures of merit. The polymeric reagent contained an activated ester linkage to the 9-fluorenyl group, which imparted ultraviolet (UV) and fluorescence (FL) detector properties to the final derivatives. Kinetic studies of these solid-phase (heterogeneous) reactions have been conducted, and specific rate constants were compared with those of the analogous solution reaction for the same substrates. Percent derivatizations have reached 90% and 70% for primary and secondary amines, respectively, under optimized conditions. High reaction reproducibility has been obtained by using the on-line approach, for more than 50 separate injections of the same amine substrate with a single solid-phase reactor. These solid-phase derivatizations have led to detection limits for typical amines in the low-parts-per-billion range. The final, overall methods can provide rapid, automatable, accurate, and precise detection and quantitation of primary/secondary amines and amine-like compounds in real-world sample matrices. As an illustrative example, amphetamine spiked in urine has been derivatized off-line and on-line, with minimum sample preparation, and detected via HPLC-UV/FL with acceptable accuracy and precision.

Section: Characterization Of Synthesized External Standardsmentioning

confidence: 99%

Section: Characterization Of Synthesized External Standardsmentioning

confidence: 99%

Polymeric activated ester reagents for off-line and on-line derivatizations of amine nucleophiles in high-performance liquid chromatography with ultraviolet and fluorescence detection

Gao¹,

Chou²,

Krull³

1989

“…Many approaches to metal speciation involve the combination of chromatographic separation with element-specific atomic spectroscopic detection (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). Two factors determine the success of such combinations.…”

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confidence: 99%

Laser-enhanced ionization as a selective detector for the liquid chromatographic determination of alkyltins in sediment

Epler¹,

O’Haver²,

Turk³

et al. 1988

6, 11), led to variable recoveries and low values for most elements (Table IV). Hydrofluoric acid has been used for the dissolution of geologic samples (6). There has also been a report of HF use with some biological samples, particularly when silicon analyses are needed (3). However, when HF was added to our system, unacceptable amounts of particulate matter remained after digestion of the fecal samples; there were poor recoveries of most elements except for phosphorous and zinc. Digestions seemed to be more complete with nitric acid-hydrogen peroxide or nitric-perchloric acid combinations. However, some elements, including iron and copper, were poorly recovered when these combinations were used.We have successfully used our method to digest a wide range of diet, food, and fecal samples with differing fat contents. Traditional open flask digestion procedures (9) generally require up to 20 mL of a 1:5 perchloric-nitric mixture and 8-13 h to digest a 0.5-g sample of either freeze-dried feces or diet in an open 50-mL Erlynmeyer flask on a hot plate.Compared with this open-flask, hot-plate procedure, the microwave procedure offers considerable advantages in speed and safety. Blank values are lower because less acid is required and the sample is not exposed to a hood environment for long periods of time. The closed system maintains sample integrity well and thus permits the determination of more volatile elements. In a preliminary study, we obtained 97-105% recoveries of added boron by using the closed microwave digestion method, whereas boron recoveries were nil when conventional nitric-perchloric digestion techniques (9) were used. Thus, the microwave digestion method is relatively safe, simple, and rapid with good precision and accuracy. This procedure seems to be particularly suited for providing digested samples for elemental determinations by ICP-ES.

“…(7) Tukey, J. W. EDA Exploratory Data Analysis; Addison-Wesley: Reading, MA, 1977. High-pressure liquid chromatography (HPLC) has become an indispensable tool of the preparative chemist. The easy detection of the elution of compounds of interest can be accomplished by various methods, which vary in sensitivity and selectivity (1). By far, the most routinely employed detection methods involve absorption or emission spectroscopy or the shift in the refractive index of the eluting stream.…”

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confidence: 99%

Photoelectrochemical detector for high-pressure liquid chromatography

Fox¹,

Tien²

1988

A flow-through photoelectrochemical detector (TI02/Pt) suitable for attachment to a high-pressure liquid chromatograph Is described. The detector Is sensitive to many oxldizable functional groups and Is capable of detecting as little as 1.6 pg of aniline. The relative peak heights of signals engendered by pairs of eluting compounds correlate roughly with the relative rates of photolnduced oxidation of Isomeric butanols on analogous semiconductor suspensions.