| Fluorescent derivatization is an effective method of increasing the detection sensitivity and selectivity of chromatography. Some compounds exhibit no significant native fluorescence or have only weak fluorescence signal, consequently, chemical derivatization using chromogenic or fluorescent labels is an efficient method to reach highly sensitive detection of these compounds in capillary electrophoresis (CE) and high performance liquid chromatography (HPLC).The new fluorescent derivatization reagent,6-oxy-(N-succinimidylacetate)-9-(2'-methoxycarbonyl) fluorescein (SAMF), has been continued to apply in these paper. it has good photostability and relatively pH-independent fluorescence with satisfying reactive selectivity. Using SAMF as a pre-column label reagent reacted withγ-aminobutyric acid compounds, such as gabapentin and baclofen. We developed four methods which exhibit high efficiency, sensitivity and selectivity by HPLC and CE. Our research has mainly the following aspects:(1) Two kinds of rapid, sensitive and reproducible methods for the determination of gabapentin in urine based on HPLC with UV-Vis and fluorescent detection, respectively, were developed for the first time using SAMF as a pre-column label reagent. The highest derivatization efficiency was obtained in phosphate buffer (pH=7.25) at room temperature for 10 min. The chromatographic separation was carried out using a mixture of methanol and water containing 5.0×10-3 mol l-1 sodium citrate buffer (pH=5) as a mobile phase with UV-Vis detection atλ=455 nm and fluorescent detection (FLD) atλex/λem=488/520 nm, respectively. A calibration curve ranging from 1.0×10-8 mol l-1 to 1.0×10-6 mol l-1 was shown to be linear. The concentration limit of detection (LOD) was 1.0×10-8 mol l-1 and 2.5×10-10 mol l-1 (signal to noise ratio=3) for HPLC-UV-Vis and HPLC-FLD, respectively. The proposed methods were applied to the determination of gabapentin in urine samples with satisfying results.(2) A CE-LIF method for the determination of gabapentin in human serum using SAMF as a derivatizing reagent was established.γ-Aminobutyric acid (GABA) was used as an internal standard (I.S.). The best derivative condition was obtained in phosphate buffer (pH=8) at room temperature for 10 min. Optimal separation and detection were obtained with a background electrolyte (BGE) of 3.5×10-2 mol l-1 phosphate buffer (pH=5.5) and laser-induced fluorescence detection emited at 473 nm. The method developed for GBP was linear over the concentration range of 4.0×10-9 mol l-1 to 4.0×10-7 mol l-1. The LOD was 2.0×10-10 mol l-1. The sensitive method was used to the determination of GBP in serum samples.(3) It was the first time that SAMF was developed as a fluorescent probe for the analysis of baclofen in human serum based on CE with LIF detection. Gabapentin was selected as an internal standard. SAMF reacted with baclofen and gabapentin rapidly at 30℃in phosphate buffer (pH=7.5) for 10 min. The derivatives were baseline separation in 3.5×10-3 mol l-1 phosphate buffer (pH=5.6) and detection of LIF was emited at 473 nm. The analytical process only needed 12 min. The linear calibration range was 4.0×10-9 mol l-1 to 4.0×10-7 mol l-1. The LOD was 6.0×10-10 mol l-1. All the results showed that the proposed method had advantages of high-speed, sensitivity, economy and good stability for the determination of baclofen in serum samples.(4) SAMF was used as pre-column label reagentfor the sensitve analysis of gabapentin and baclofen in serum by CE with LIF detection successfully. Glycine was used as an internal standard. The final BGE consisted of 3×10-2 mol l-1 phosphate buffer (pH=5) and enabled separation within 16 min. It was observed that after 15 min the derivatization reaction was complete at 25℃in phosphate buffer (pH=8). The LOD was 4×10-10 mol l-1.
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