Ciborowski M, Icardo M Catalá, Mateo J V García, Martínez Calatayud J
Departamento de Química Analítica, Universidad de Valencia, Valencia, Spain.
J Pharm Biomed Anal. 2004 Nov 19;36(4):693-700. doi: 10.1016/j.jpba.2004.08.020.
The present manuscript deals with a simple and sensitive flow-injection method for the chemiluminescent determination of thiazides. The method is based on the on-line photodegradation and chemiluminescent determination of the resulting photo-fragments. The on-line photodegradation is performed in basic medium by using a photoreactor consisting of a 550cm long x 0.8mm ID piece of PTFE tubing helically coiled around an 8W low-pressure mercury lamp. The determination of the photo-irradiated thiazides is performed by a chemiluminescent oxidative reaction with Ce(IV) in sulphuric acid medium. A heterogeneous group of thiazides (indapamide, metolazone, hydroflumethiazide, chlorthalidone and bendroflumethiazide) has been studied. Hydrochlorothiazide was selected as a test substance. The "on-line" photochemical reaction approach allows the sensitive chemiluminescent determination of thiazides which do not present native chemiluminescence in the absence of sensitizers such as Rhodamine 6G. Linear calibration graphs were typically over the range 0.5-12 microgml(-1) (indapamide, metolazone, hydroflumethiazide and chlorthalidone); and over the range 0.5-5 microgml(-1) (hydrochlorothiazide). Limits of detection ranged between 0.005 microgml(-1) (hydrochlorothiazide) and 0.06 microgml(-1) (bendroflumethiazide). The relative standard deviation for the test substance was 2.0% for 2 microgl(-1) of the drug (n = 11) and the throughput was 65 h(-1) in all cases. The assessment of the photodegradation step on the molecular structure of thiazides was established by recording UV and fluorimetric spectra. The viability of the on-line photoinduced fluorescent determination of hydroflumethiazide and bendroflumethiazide was confirmed. The method was also applied to the determination of hydrochlorothiazide in commercially available formulation.
本手稿介绍了一种用于噻嗪类药物化学发光测定的简单且灵敏的流动注射方法。该方法基于对所得光碎片的在线光降解和化学发光测定。在线光降解在碱性介质中进行，使用一个由550厘米长、内径0.8毫米的聚四氟乙烯管螺旋缠绕在一个8瓦低压汞灯周围组成的光反应器。经光照射的噻嗪类药物的测定通过在硫酸介质中与铈（IV）的化学发光氧化反应进行。研究了一组不同的噻嗪类药物（吲达帕胺、美托拉宗、氢氟噻嗪、氯噻酮和苄氟噻嗪）。选择氢氯噻嗪作为测试物质。“在线”光化学反应方法能够对在没有诸如罗丹明6G等敏化剂时不呈现天然化学发光的噻嗪类药物进行灵敏的化学发光测定。线性校准曲线通常在0.5 - 12微克/毫升（吲达帕胺、美托拉宗、氢氟噻嗪和氯噻酮）范围内；以及在0.5 - 5微克/毫升（氢氯噻嗪）范围内。检测限在0.005微克/毫升（氢氯噻嗪）和0.06微克/毫升（苄氟噻嗪）之间。对于2微克/升的药物，测试物质的相对标准偏差为2.0%（n = 11），并且在所有情况下通量为65次/小时。通过记录紫外和荧光光谱确定了光降解步骤对噻嗪类药物分子结构的影响。证实了在线光诱导荧光法测定氢氟噻嗪和苄氟噻嗪的可行性。该方法还应用于市售制剂中氢氯噻嗪的测定。
