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Year : 2007  |  Volume : 39  |  Issue : 1  |  Page : 39--42

Purification of urine samples to improve detection limit of anabolic agents

Madhusudhana I Reddy, A Beotra, S Jain, T Kaur, Ranjit Lal 
 Dope Control Centre, Sports Authority of India, J. N. Stadium, New Delhi - 110 003, India

Correspondence Address:
A Beotra
Dope Control Centre, Sports Authority of India, J. N. Stadium, New Delhi - 110 003
India

Abstract

Objective: To investigate recovery percentage of clenbuterol, nandrolone, stanozolol, and epimetendiol by two different solid phase extraction procedures viz. XAD2 (polystyrene divinylbenzene) and SPE columns (C18, Samprep, Rankem) so as to improve detection limit of anabolic steroids. Materials and Methods: The urine samples were spiked with different concentrations of drugs. The preliminary work was done with six samples, each of clenbuterol, nandrolone, and epimetendiol at 1, 2, 5, and 10 ng/mL and of stanozolol at 5,10, 20, and 40 ng/mL that were processed and injected into high resolution mass spectrometer. Later the study was limited to clenbuterol and epimetendiol at 2, 5, and 10 ng/mL concentrations. The data were analysed by comparing XAD2 and SPE column values. Results: The results show that the recovery percentage of nandrolone and stanozolol at various concentrations did not signify any difference between the two columns. However, there was a significant increase in the recovery of clenbuterol at 2 ng/mL ( P <0.002), 5 ng/mL ( P <0.001), and 10 ng/mL ( P <0.001) concentrations, where as for epimetendiol there was significant increase in the recovery at 2, 5, and 10 ng/mL ( P <0.01) with SPE column compared to XAD2 column. Conclusion: It is possible to enhance the detection limit of clenbuterol and epimetendiol by SPE column compared to XAD2 column. This procedure may be used for confirmation of suspicious samples found in routine testing.



How to cite this article:
Reddy MI, Beotra A, Jain S, Kaur T, Lal R. Purification of urine samples to improve detection limit of anabolic agents.Indian J Pharmacol 2007;39:39-42


How to cite this URL:
Reddy MI, Beotra A, Jain S, Kaur T, Lal R. Purification of urine samples to improve detection limit of anabolic agents. Indian J Pharmacol [serial online] 2007 [cited 2020 Aug 11 ];39:39-42
Available from: http://www.ijp-online.com/text.asp?2007/39/1/39/30762


Full Text

 Introduction



The International Olympic Committee (IOC) and World Anti-Doping Agency (WADA) have banned the use of anabolic androgenic steroids (AAS) in sports in 1976 and 2002, respectively. To impose the ban, urine samples of sport persons are tested for anabolic steroids and their metabolites by Gas Chromatography-Mass Spectrometer (GC-MS) and high-resolution mass spectrometer (HRMS).[1] The samples are extracted for unconjugated and conjugated steroids with varying chemical properties. After extraction, the steroids are derivatized to yield trimethyl silyl derivatives for detection by GC/MS and HRMS. Use of HRMS for AAS has improved the detection limit of few steroids viz nandrolone, stanozolol, epimetendiol and clenbuterol. Approximately 50 AAS fall in the WADA banned list.[2] The detection limit for all anabolic steroids is 10 ng/mL except clenbuterol, nandrolone, stanozolol, methyl testosterone, and epimetendiol that are to be detected at 2 ng/mL in urine samples. These four drugs are to be detected in lower concentration compared to rest of anabolic steroids (detection limit is 10 ng/mL); hence, sample purification is required to facilitate detection at 2 ng/mL. Sample preparation also needs improvement to improve the detection limit of these steroids apart from improved instrumentation. Improvement of sample preparation may be achieved by the use of various solid phase extraction procedures,[3],[4],[5] HPLC clean up[6],[7] or Immunoaffinity Chromatography (IAC) gels.[8],[9],[10],[11] The objective of present study was to investigate the recovery percentage of clenbuterol, nandrolone, stanozolol, and epimetendiol by two simple solid phase extraction procedures, using XAD2 and SPE columns.

 Materials and Methods



Reference standards and chemicals

The reference standards of clostebol and clenbuterol were purchased from Sigma-Aldrich (St Louis, MO, USA) and of nandrolone, stanozolol, epimetendiol from National Analytical Research Laboratory (National Measurement Institute, Sydney, Australia). The derivatizing reagent N-methyl-N-Trimethysilyltrifluoroacetamide (MSTFA), iodo-TMS and Dithioerythritol were purchased from Sigma-Aldrich (St Louis, MO, USA). The hydrolyzing enzyme b-glucuronidase, E. coli is purchased from Roche, Germany. All other reagents and chemicals such as methanol, diethyl ether, and anhydrous sodium sulphate were of analytical grade or HPLC grade.

Two types of solid phase extraction columns were used. The Amberlite XAD2 was purchased from Sigma-Aldrich (St Louis, MO, USA) and C-18 Samprep; 100 mg/3 mL from Rankem, India was purchased.

Extraction procedure

The samples were processed by XAD2 extraction[12] and SPE column.

XAD2 extraction: About 2 mL of centrifuged urine was passed into pre-prepared XAD2 column and 50 mL of clostebol (conc. 2.5 ng/mL) was added as the internal standard. The column was eluted with 2.5 mL of methanol and the eluent dried under nitrogen evaporator at 60C. To this was added 1 mL of 0.2 M-phosphate buffer pH-7.0 and 50 L of b-glucuronidase ( E. coli ) and the mixture was incubated at 60C for 60 minutes. The hydrolysate was alkalinized by adding 250 L of 7% potassium carbonate solution to adjust the pH of the mixture between 9 and 10. About 5 mL of distilled diethyl ether was added and mixed by moderate horizontal mixing in the shaker for 10 minutes. The ether layer was transferred to a labeled, glass test tube and the ether evaporated at 60C under the nitrogen evaporator. After evaporation of diethyl ether the tube was placed for 10-15 minutes in a dessicator containing P 2 O 5, to remove traces of moisture if any.

SPE extraction: SPE columns were conditioned with 2 mL of methanol and equal amount of distilled water. The procedure followed was similar to that of XAD2 extraction.

Derivatization procedure

The dried residue was dissolved in 50 L of MSTFA/iodo-TMS/dithioerythritol (1000/2/2:v/v/w) mixture. The mixture was incubated at 60C for 15 min and then transferred into 200 L conical glass vials. Nearly 2 mL was injected into HRMS for analysis.

Instrumentation and conditions

HRMS was used for evaluation of concentration of the samples. The parameters of gas chromatograph [Table 1] and Mass Spectrometer [Table 2] are mentioned.

 Results



Limit of detection (LOD)

Limit of detection was defined as the lowest level at which a compound could be identified in urine samples, with diagnostic ions present with a signal to noise (S/N) ratio greater than 3. A single diagnostic ion 405.2640, 546.3493, 335.0690, and 448.3193 was used to determine the LOD of nandrolone, stanozolol, clenbuterol, and epimetendiol in urine sample, respectively, by HRMS. The LODs of clenbuterol and epimetendiol as required by WADA is 2 ng/mL.[2]

Recovery, accuracy, and precision

The preliminary work was done with six spiked urine samples of each of clenbuterol, nandrolone, and epimetendiol at 1, 2, 5, and 10 ng/mL and stanozolol at 5, 10, 20, and 40 ng/mL and were analyzed with HRMS. The results showed that for nandrolone and stanozolol the drug recovery at various concentrations (upto 10 ng/mL) was not different between two columns [Table 3],[Table 4]. At 20 and 40 ng/mL, recovery of stanozolol was significantly more ( P n =10) and processed with XAD2 and SPE columns.

Clenbuterol . The percentage recovery was 30.45, 46.63, and 41.60% with XAD2 and 72.09, 72.16, and 89.24% with SPE columns [Table 5]. The recovery percentage was significantly higher with SPE column extraction. The significance levels were P P Epimetendiol . The recovery percentage for 2, 5, and 10 ng/mL with XAD2 were 105, 69.69, 66.63, and 136.87, 104.69, and 99.65% with SPE [Table 5]. The recovery percentage was significantly higher with SPE column extraction. The significance level were, P P P P <0.000) at 20 and 40 ng/mL with XAD2 extraction. However, improvement in recovery of Stanozolol at higher concentration (20 and 40 ng/mL) is not of much value because it is required to improve detection at lower concentration (2 and 5 ng/mL). The purification techniques for Stanozolol reported are Immunoaffinity chromatography (IAC)[9] and use of Oasis cartridges.

There was a significant increase in the recovery of clenbuterol and epimetendiol at different concentrations, which necessitates the need to do confirmation testing with C 18 SPE columns. Though use of C-18 Sep-pak columns for extraction of clenbuterol has been reported.[13] There is no study comparing recovery percentage of two types of extraction. Further use of SPE columns for epimetendiol extraction has not been reported in literature so far. The purification techniques used for epimetendiol are based on HPLC clean up[6] and IAC gels.[6]

 Conclusion



Based on the present work it is concluded that recovery of Clenbuterol and Epimetendiol has improved with SPE columns compared to existing XAD2 columns at various concentrations. Hence, it can be used for confirmation of samples found positive for clenbuterol and epimetendiol.

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