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Cite this: Anal. Methods, 2015, 7, 8241
Rapid and simple detection of pethidine hydrochloride injection using surface-enhanced Raman spectroscopy based on silver aggregates† Mei-Ling Zhang, Wu-Li-Ji Hasi,* Xiang Lin, Xiao-Rong Zhao, Xiu-Tao Lou, Si-qin-gao-wa Han, Dian-Yang Lin* and Zhi-Wei Lu* A portable Raman spectrometer was used for the rapid detection using surface-enhanced Raman spectroscopy (SERS) of pethidine hydrochloride injection by employing a silver colloid as the SERS active substrate. Different substrates and aggregation agents were investigated in order to explore the optimum conditions for the SERS detection of pethidine hydrochloride injection. Under the optimum experimental conditions, excellent reproducibility and stability of SERS detection was guaranteed. In addition, the limit of detection (LOD) for pethidine hydrochloride injection in water was low at 0.1 mg mL1 with an analytical enhancement factor of 5.3 104, which is extremely far below typical administered dosages (50 mg mL1). Finally, a good linear relationship between the Raman intensity and concentration was obtained for pethidine hydrochloride injection in water at a concentration range from 0.1 to 10 mg mL1
Received 19th July 2015 Accepted 15th August 2015
(R2 ¼ 0.999), which lays a favourable foundation for the semi-quantitative analysis of the concentration
DOI: 10.1039/c5ay01882j
of pethidine hydrochloride injection. In general, the capabilities reported here demonstrate that the SERS method is convenient, rapid and efficient, and has good potential in clinical applications for point-of-
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care detection and real-time monitoring.
Introduction Pethidine hydrochloride (C15H21NO2$HCl) injection, as one of the most common antalgic drugs, has been widely used for clinical treatment by surgeon doctors in previous years.1 Although pethidine hydrochloride injection is suitable for all kinds of pain, it is also an analogue of an illicit drug which must abide strictly by the national special management regulations to avoid possible abuse such as the incorrect dosage, substitution of one drug for another, and the infusion of a drug that was not actually prescribed by intravenous (IV) therapy.2,3 Among these examples of abuse, overdose represents a noteworthy challenge to emergency room (ER) personnel, since it can bring about a variety of symptoms. What's more, if used illegally for a long time, mild cases will cause myocardial infarction, hypothermia, seizures, hallucinations, or arrhythmias and severe cases may cause toxicity or even death.1,4,5 Thus, hospital medication safety efforts are primarily focused upon the monitoring of illicit drugs. The prescription should be retained for two years for future reference, and the colour of the prescription should be distinguished from other medicines as well. In addition, the
National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001, China. E-mail:
[email protected]; Zhiwei_Lu@ sohu.com † Electronic supplementary 10.1039/c5ay01882j
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illicit drugs must be detected frequently to provide an effective guarantee for the strict control of them. At present, to detect pethidine hydrochloride injection, various methods have been reported such as HPLC,6,7 GC,8,9 GC/ MS10 and spectrophotometry11 etc., these methods are all capable of determining drug abuse and providing quantication analysis. However, these methods most usually require complex pre-treatments as well as large-scale instruments, which make the existing methods not conducive for rapid and real-time determination. Therefore, it is of great practical signicance to develop a simple, sensitive and inexpensive method for the real-time identication of pethidine hydrochloride injection. Since the rst observation of an enhanced Raman signal of pyridine adsorbed on a roughened silver electrode by Fleischmann et al.12 in 1974, surface enhanced Raman spectroscopy (SERS) has been a powerful vibrational spectroscopy technique that allows for the highly sensitive structural detection of low concentration analytes.13,14 Using gold, silver and other metal nanostructures as a SERS active substrate can signicantly improve the enhancement effect, which can be mainly attributed to the amplication of the electromagnetic elds generated by the excitation of localized surface plasmas on the rough surface of the metal.15 Ag nanoparticles have been the focus of much research and more than six orders of magnitude of SERS enhancement has been achieved routinely.16 In addition, both Raman and SERS spectroscopic investigations can be performed without the
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Analytical Methods
interference of water, thus these techniques can be used for the research of organic and biochemical substances in their natural environment.17,18 However, one major problem that arises in applying Raman spectroscopy is that normal Raman spectroscopy is quite weak and is always obscured by uorescence. Therefore, the SERS technique has been widely used in various elds including food safety, drug monitoring, bioanalysis and materials characterization,19–24 resulting from its signicant advantages including eminent specicity, narrow spectral band peaks and high sensitivity.25,26 Meanwhile, a portable Raman spectrometer can be used in SERS detection, instead of large-scale equipment, which provides the rapid detection of illicit drugs in a convenient spot. In this letter, we have developed a rapid and simple SERS method to detect pethidine hydrochloride injection utilizing the combination of a portable Raman spectrometer with a silver colloid (Fig. 1). The SERS enhancement efficiency of several silver aggregates induced by different aggregation agents has been investigated. At the same time, great repeatability and stability of the SERS detection were ensured. Further, the SERS spectra of pethidine hydrochloride injection at different concentrations in water were collected. Eventually, the potential application of SERS technology in the quantitative measurement of pethidine hydrochloride injection was illustrated. The SERS detection method is reliable, fast and simple to operate, thus, it can be used for the monitoring of illicit drugs in a realistic environment.
Experimental Materials Silver nitrate (AgNO3) and sodium citrate were obtained from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). Pethidine hydrochloride injection (50 mg mL1) was obtained from Yichang Humanwell Pharmaceutical co., Ltd (Hubei, China). Potassium iodide (KI) and sodium chloride (NaCl) were obtained from Xilong Chemical Co., Ltd (Beijing, China).
Fig. 1
Paper
Sodium bromide (NaBr) was obtained from Tianjin Kemiou Chemical Reagent Co., Ltd (Tianjin, China). A quartz wafer was obtained from Nantong optical technology co., Ltd (Nantong, China) and deionized water was used for all procedures. All chemicals were used as received. Sample preparation A pethidine hydrochloride standard stock solution (100 mg mL1) was prepared at rst. A series of concentrations of standard pethidine hydrochloride solutions were then prepared by diluting the stock solution with deionized water to obtain concentrations of 10, 7.5, 5, 2.5, 1, 0.5, 0.25 and 0.1 mg mL1. Water was used as the blank control. Preparation of silver colloid The silver colloid was prepared according to the method of Lee and Meisel.27 Briey, 45 mg of silver nitrate was added to 250 mL of deionized water, which was then brought to boil in a ask under vigorous stirring. 5 mL of 1% sodium citrate was added, and the solution was kept boiling for 1 hour. The silver colloid was cooled naturally aer the solution turned to greenish brown. Finally, the silver colloid was stored at 4 C. SERS measurements Raman spectra were recorded by a portable compact laser Raman spectrometer BWS415-785H (B&W Tek, Inc.). The excitation wavelength of the laser was 785 nm and the Raman spectra were collected over the range of 175 to 3200 cm1 with a spectral resolution of better than 3 cm1. The beam was converged using a lens with a focal length of 6.8 mm, and the spot size of the focused laser beam was about 10 mm in diameter. The spectral measurements were conducted with a 5 s exposure time and a laser power of 30 mW unless otherwise stated, and the SERS spectra were collected over a certain period of time (
