Sol-Gel Titania-Coated Needles for Solid Phase Dynamic Extraction-GC/MS Analysis of Desomorphine and Desocodeine

ANALYTICAL SCIENCES NOVEMBER 2011, VOL. 27 1107 2011 © The Japan Society for Analytical Chemistry

Sol-gel Titania-Coated Needles for Solid Phase Dynamic Extraction-GC/MS Analysis of Desomorphine and Desocodeine

Chi-Ju SU, Sankarewaran SRIMURUGAN, Chinpiao CHEN, and Hun-Chi SHU†

Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5 – 5000 ppb), and satisfactory linearity, with R2 values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0 – 5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

(Received June 30, 2011; Accepted September 17, 2011; Published November 10, 2011)

The development of new techniques for the analysis of abuse preconcentration matrix. Almost all commercially available drugs has received much attention, mainly due to a growing SPME fibers are prepared with fused silica fiber, which is concern about physical addiction. Morphine based opiates form fragile and should be handled with care. To overcome this an important class of drugs in this category. The extreme drawback, researchers have developed a number of metal oxide 14,15 16 17 18,19 analgesic properties associated with these molecules are limited such as Al2O3, ZnO, ZrO2 and TiO2 coating in metal in view of their certain undesirable effects, of which “physical supporting wire with different coating techniques. These addiction” is the most serious one.1 Desomorphine is a morphine coating techniques include direct-pasting,15 electrodeposition,14,16 derivative that has similar sedative and analgesic effects, and is chemical oxidation20–22 and sol-gel techniques.23–26 The sol-gel around 10 times more potent than morphine, with the rapid process usually involves catalytic hydrolysis of the alkoxide onset of actions. In addition, desomorphine has a short duration precursors and polycondensation of the hydrolyzed products in of action, with relatively little nausea or respiratory depression the sol solution to form a macromolecular network structure of compared to equivalent doses of morphine.2,3 The fact that sol-gel metal oxides.27,28 Sol-gel coating technology is a good desocodeine and desomorphine (structures shown in Fig. 1) option for SPME wire preparation in these coating techniques. have abuse potential raises the possibility of a future threat in Among the metal oxides, TiO2 has gained great interest in the drug abuse field.4 Recently, desomorphine has become analytical chemistry because of its good chemical stability, popular in Russia. It can be prepared by handicraft techniques durability, non-toxicity and cost effectiveness. Nanocrystalline from codeine containing medicines which are widely available TiO2 has become a promising material for adsorbing, from drugstores without prescriptions. Desomorpine is more preconcentrating, and separating metal ions, and organic toxic, more addictive, and much cheaper than other opiates and analytes. Several studies have been conducted on the application it could become a much more dangerous problem.5 The methods of titania in chromatographic separations, due to its superior pH such as gas chromatography–mass spectrometry (GC-MS) using stability and mechanical strength compared with silica. Titania- selected-ion monitoring (SIM) or tandem mass spectrometry packed HPLC columns, capillary electrophoresis capillaries and (MS-MS) are the most frequently adopted techniques for an fused silica capillaries for capillary zone electrophoresis and efficient analysis of controlled substances.6–11 However, the capillary electrochromatography displayed enhanced stability of intricate part of these analytical methods is the preparation and the preconcentration of the analyte, which is a time-consuming process. Therefore, the time and reagents saving pretreatment methods are being sought. Solid-phase microextraction (SPME), developed in 1990, is an attractive and effective procedure combining sample extraction and concentration with sample introduction in GC and HPLC.12,13 It is based on the partitioning of analytes between a liquid or gaseous sample matrix and an immobilized sorbent as the

† To whom correspondence should be addressed. E-mail: [email protected] Fig. 1 Chemical structures of desocodeine and desomorphine. 1108 ANALYTICAL SCIENCES NOVEMBER 2011, VOL. 27 the packing material over a range of pH (3 – 12) and permitted trace level analysis of different analytes.29–31 SPME technique employing titania coated alumina fiber and copper wire for aromatic hydrocarbons24 and aliphatic alcohols25 have been developed. One recent modification of SPME is the solvent- free microextraction technique namely solid-phase dynamic Fig. 2 Schematic diagram of adsorption device (SPDE needle). extraction (SPDE) which uses a sorbent coating on the inner wall of a stainless-steel needle instead of the usual coated fiber.32 Reduced fragility of the fiber and enlarged extraction capacity are the significant advantages of the latter method. Successful spectrometric detector (MSD), Model 5975C, split/splitless applications of SPDE in analysis of bioactive molecules include injector and chemstation software was used for this study. amphetamines,33–35 cannabinoids and synthetic designer drugs in A DB-35MS capillary column (30 m × 0.25 mm i.d.; film hair samples.36 The adsorbents employed in these techniques thickness, 0.25 μm) in a pulsed splitless mode was utilized for function either by partitioning into a “liquid-like” phase or by the separation of the analytes. Helium gas with a flow rate of physically interacting with the analytes. These coatings are 1.0 mL min–1 was used as a carrier gas. The temperature generally solids that contain pores or high surface areas in program for the experiments was as follows: The initial column which the extraction can be accomplished by trapping the temperature was held at 50°C for 1 min and then raised at analytes in internal pores. In this regard, the development of 5°C min–1 to 100°C; it was maintained there for 1 min and new coating materials is mainly aimed at the achievement of further ramped at 5°C min–1 to a final temperature of 250°C and superior selectivity with regard to target analytes or specific held there for 20 min. The temperature of injection port and classes of compounds as well as at the development of less transfer line was held at 290 and 280°C, respectively. To breakable and more stable supports.23 In a word, sol-gel titania determine the retention times and characteristic mass fragments, coated on the inner walls of the needles will be a good choice as electron impact (EI) mass spectra of the analytes were recorded the new coating materials in SPDE for desocodeine and by total ion monitoring. For quantitative analysis, the chosen desomorphine analysis. To the best of our knowledge, titania- diagnostic mass fragments were monitored in the selected ion based SPME and SPDE as tools for opiate drug analysis have monitoring (SIM) mode: codeine (tR 38.6 min; m/z 299, 229, not been reported. 162); deoxycodeine (tR 34.7 min; m/z 283, 229, 214); This paper aims at the development of SPDE needles with desocodeine (tR 34.2 min; m/z 285, 270, 228); desocodeine-d3 titania particles as a new coating material for the analysis of (tR 34.2 min; m/z 288, 273, 228); desomorphine (tR 34.5 min; opiate drugs, namely desocodeine and desomorphine, at trace m/z 271, 228, 214). levels. The TiO2 particles were formed from corresponding titanium alkoxides employing a sol-gel method and were coated Preparation of SPDE needles onto the inside of the needle. Preliminary experiments were The method for preparation of the sol-gel mixture was adopted performed to optimize the new coating material with respect to from the literature.38 The coating of the SPDE needles was the coating material preparation, the number of coatings and the achieved using a stable and homogeneous sol solution prepared duration of coating on the needle, extraction time, and desorption as described below: 10 mL of anhydrous isopropanol was added temperatures. Finally the performance of the obtained needle to a solution of titanium isopropoxide (0.8 mL) taken in a was evaluated for the urine samples containing desocodeine and beaker and stirred for 10 min. To this clear solution was desomorphine. subsequently added 1.16 mL of ethanol and 0.1 mL of water and this mixture was stirred for an additional 30 min to initiate the hydrolysis of titanium alkoxide. Acidification of the solution Experimental to pH 3.0 using 34% HCl resulted in polycondensation of the hydrolyzed precursor to a three dimensional polymeric network. Reagents and chemicals At lower pH (<3.0), a faster condensation of the titania particles Isopropanol, titanium isopropoxide (99.9%), hydrochloric leads to a gel interfering the film formation during the coating acid, and absolute alcohol were purchased from Aldrich. process. At higher pH (5.0 – 6.0), a white suspension of Codeine phosphate was supplied by the National Bureau of particles was formed that was unsuitable for coating the needle. Controlled Drugs, Department of Health, Taiwan. Desocodeine, The clear solution formed at pH 3.0 was stirred for 30 min and 2 2 desomorphine, [ H3]-desocodeine and [ H3]-desomorphine were then passed through the needle using a syringe pump, resulting synthesized by the synthetic routes37 shown in Supporting in a thin film of titania on the inner walls of the needle. The Information (Schemes S1 and S2). The purity of all the coated needle was air-dried for 1 h and aged at 450°C for 5 h to synthesized compounds were found to be >99% by GC-MS. establish anatase phase for the titania particles and also to The SPDE needles (70 mm × 0.6 mm i.d., conical needle tip remove any of the volatile contaminants. The processed needle with side port) were coated with TiO2 particles formed by the was then combined with the second needle as described earlier sol-gel method. The needles were attached to a second needle in Fig. 2, and used directly for the extraction process. (38 mm × 1.2 mm i.d.) and sealed air-tight with the help of a teflon thread, as shown in Fig. 2. This modification facilitates SPDE of controlled substances from aqueous samples and urine easier connection with external syringes during the extraction A standard stock solution of desocodeine and desomorphine and desorption of analytes. SupelcoTM solid phase in dichloromethane was diluted in the range of 1 ppb to 100 ppm microextraction fiber holder and fibers coated with 100 μm with water (pumping off CH2Cl2 prior to dilution). The diluted polydimethylsilosane (PDMS, Catalog No. 57330-u) were aqueous sample containing desocodeine was extracted by purchased from Supelco (Bellefonte, PA). flushing 0.3 mL of the sample through the SPDE needle using a syringe pump with a flow rate of 0.5 mL h–1 for 36 min. The GC-MS operating conditions needle was then dried under a slow stream of argon and An Agilent 7890 gas chromatograph equipped with a mass immediately inserted into the hot injection port (290°C) of the ANALYTICAL SCIENCES NOVEMBER 2011, VOL. 27 1109

GC in pulsed splitless mode and kept for 10 min. The analytes were thermally desorbed and moved through the capillary Results and Discussion column by helium gas and finally detected by MS. In the case of spiked urine samples made from blank urine and desocodeine, Optimization of sol-gel preparation of titania as sorbent for 0.45 mL of 0.9 N NaOH was added to 0.5 mL of urine sample SPDE needle (containing 1 – 1000 ppb desocodeine) to make the solution The extraction efficiency and the selectivity of SPDE needles basic, this solution was then mixed with 0.05 mL of 1 ppm coated with sol-gel titania film largely depend on the preparation internal standard and sampled as described above. Two different of the sol-gel. A stable polymeric sol with required properties methods were adopted in the use of internal standard such as small particle size depends on the ability to control the 2 ([ H3]-desocodeine) for the analysis of test solution. In one of hydrolysis and condensation reactions during the sol-gel the methods (SPDE-1), the standard (1.5 ng) is added to the process. In addition to the pH and the amount of water analytes and extracted with the SPDE needle. On the other employed, the duration of the condensation process significantly hand, the interaction of analytes and internal standard during the affect the above process. SPDE needles with titania film extraction associated with the first process was prevented by prepared under different sol-gel reaction times displayed a huge direct injection of the standard (1 μL of 50 ppb, 0.05 ng) into difference in the extraction efficiency for desocodeine as model GC (SPDE-2) prior to desorption of the analytes from SPDE extract (Fig. 3, n = 3 for each group). needle. The time lag of the latter method is merely 10 s; thus, The SPDE needle coated with titania film that formed in the retention times of desocodeine and internal standard have no 30 min showed maximum extraction efficiency in comparison to significant difference. films formed under either shorter or extended time intervals. The differences in the morphology, the surface area, and the

pore volume of the TiO2 particles formed under different reaction times account for the large differences in the efficiency of the SPDE needles. The micrographs of the sol-gel needles 120 formed from 20, 30, and 40 min reaction times that were obtained by scanning electron microscopy are shown in Fig. 4. 100 A dense and uniform film comprising spherical nanoparticles

% with porous surfaces was found in the cases of all the needles. , 80 e s

n Significant differences include a uniform distribution of particles o p s

e 60 in three dimensions, and narrow range particle-size (20 – 70 nm) r

v for the titania film formed in 30 min (Fig. 4e). In other cases, ti a l 40 e the particulates are sparse, with the size of the particles R drastically reduced under longer stirring times (Fig. 4f). 20 Similarly the pore structures of titania formed in 30 min are small (around 600 nm), uniform and deep (Fig. 4b) The 0 0 10 20 30 40 50 60 120 360 structural features provide high surface area and a large Sol-gel time / min stationary phase loading supporting to a high extraction capacity for titania formed in 30 min reaction time. The pore size of Fig. 3 Effect of sol-gel reaction time on desocodeine extraction. titania formed in 30 min is around three times larger than the

Fig. 4 Scanning electron microscopy images of inner surfaces of needle blocks coated with titanium dioxide film stirred for 20 min (a), 30 min (b), and 40 min (c) at 30000 magnifications. (d), (e), and (f) represent the corresponding images at 105 magnifications. 1110 ANALYTICAL SCIENCES NOVEMBER 2011, VOL. 27

120 400 (a) 350 100 300 % , a e 80 e 250 s r a

o n p

k 200 s 60 e ea r 150 P v e i 40 .

a t 100 l e

R 50 20 0 0 0 10 20 30 40 50 60 70 0 1 2 3 Time / min Coating layer 35 (b) Fig. 5 Effect of TiO2 film coating on desocodeine extraction. 30

25 4 0 1

x 20 , ea r a

15 pore sizes of these prepared by dip-coating of anodized alumina k ea using sol-gel method26 and in SPME titania wire fabricated by P 10 22 in situ oxidation with H2O2 for DDT analysis. 5

Effect of the coating layers 0 0 10 20 30 40 50 60 70 The optimized condition for sol-gel preparation was utilized Time / min for multiple coating of the needle to study its effect on the extraction efficiency. The initially coated needle was air dried, Fig. 6 Effect of extraction time on (a) codeine (1 ppm) and (b) aged at 450°C for 1 h and subjected for second coating with a desocodeine (■, 1 ppm; ◆, 10 ppm). freshly prepared sol-gel, and processed further as performed for the first coating. A needle with three similar coatings was also prepared for comparison. The peak area for the extraction of desocodeine with SPDE needles coated once, twice and thrice some apparent particle aggregation (∼300 nm) as a result of with coating material is given in Fig. 5 (n = 3 for each group). reunion of nanoparticles could be observed. This will decrease In the case of repeated coatings, the efficiency of the needles the surface area and therefore deteriorate the extraction was poor, as a result of dramatic changes in the film morphology. efficiency of the TiO2 film. A similar trend was observed at Most metal surfaces interacted with organic molecules through lower concentration (1 ppm desocodeine). In Fig. 6a, the physisorption or chemical reactions of their thin external oxide codeine due to the higher polarity has comparatively much less layer.39 Thus the thin external oxide layer became damaged and response, and displays maximum extraction at 50 min. A the extraction efficiency deteriorated. The particle size tends to similar result was found in SPME technique employing sol-gel become much bigger and the shape of the particles is more titania coated for aliphatic alcohols analysis if the extraction irregular than that obtained with one deposition, these could be time is longer than 5 min.25 In contrast, for longer extraction caused by either the growth of initially formed particles or the times (from 40 to 90 min), a saturation in extraction is observed 22 aggregation of newly formed particles. In a word, the repeated in the titania wire fabricated by in situ oxidation with H2O2. coating process reduces the surface area of titania and therefore deteriorated the extraction efficiency of the TiO2 film. A similar Effects of desorption temperature and time result has been reported in core-shell composite coating titania The desorption temperature and the duration of desorption are with liquid phase deposition.40 important parameters that allow successful desorption of all the analytes from the needle coating with a minimum carryover that Effect of extraction time may influence the peak shape of the analyte and consequently The adsorption time of analytes on SPDE needles is an the sensitivity of the method. The optimized SPDE needles important parameter in achieving equilibrium between the were desorbed at different injection temperatures of 270, 280, stationary phase and the analyte. Extraction of desocodeine was 290, and 300°C, compatible with the maximum temperature therefore performed with the optimized needle at different supported by the chromatographic column and the needle. times, ranging from 12 to 60 min. The results are given as the A high degree of desorption was found with an injection port plot of peak area against the adsorption time of 10 ppm temperature of 290°C as shown in Fig. 7a. A different time desocodeine in Fig. 6b. In contrast to the expected trend, period of desorption was then performed at the optimized no saturation in extraction was observed at extended times. temperature of 290°C and the results are shown in Fig. 7b. A maximum extraction was seen for 36 min exposure, beyond A linear increase in peak intensity was observed with respect to which the needle efficiency was considerably lower. SEM the duration time. However, longer desorption times (beyond images of sol-gel needles after extraction times of 12, 36, and 10 min) generated additional impurities in GC-MS, probably as 60 min were recorded to get insights about the morphology and a result of thermal degradation of the analyte. Therefore an the nature of the titania film (Fig. S1, in Supporting Information). optimum desorption time of 10 min was adopted as a The surface morphology was similar for extractions at 12 and compromise for further experiments. 36 min, with similar particle sizes and pore volumes. On the other hand, the needle used for a longer extraction (60 min) Salting out displays larger pores with shallow depth. More interestingly, The amount of desocodeine extracted by the needle can be ANALYTICAL SCIENCES NOVEMBER 2011, VOL. 27 1111 increased by decreasing its solubility in water. This could be of the analytes in order to test the quantitative performance of achieved by increasing the ionic strength in the solution by the methods. The samples (in the range 1 – 1000 ng/g), assayed addition of salt. The effect of ionic strength on the extraction following two different methods of internal standard addition efficiency was determined by analyzing solutions containing and the results obtained, are listed in Table 2. The results different amounts of NaCl (Fig. 8). The extraction efficiency indicate that the proposed conditions provided satisfactory decreased with the increase in the amount of salt added and linearity within the concentration ranges examined, irrespective saturated beyond 0.02 g addition. SEM images of titania film of the matrix exploited. The wide linear range (from used for extracting desocodeine containing 0.02 g of NaCl 5 – 5000 ppb) and satisfactory linearity with R2 values from displayed rough surfaces with irregular particle sizes (Fig. S2, 0.9958 to 0.9999 and prominent sensitivity, LOQs in Supporting Information). Considerable reductions in the (1.0 – 5.0 ng/g), are obtained. The sensitivity of the method number and volume of the pores were observed due to the involving independent addition of internal standard (SPDE-2) is extended blocking of pores by large flakes of NaCl. In addition, slightly superior to the co-extraction method (SPDE-1) (Table 2, aggregation of titania nanoparticles to larger particles of size entries 1 – 4). Furthermore, the consumption of internal 120 – 180 nm were observed in the presence of added salt. The standard in SPDE-2 is only 3.3% of the co-extraction method combined surface modification hampers the adsorption rate and (SPDE-1), showing a much better reagent economy in SPDE-2. adsorption volume of the analyte. Therefore, external addition However, SPDE-1 has the advantage of correcting the effect of of salt was avoided in further experiments. In contrast, the salt in urine sample. When complex matrix samples are applied, salt-out effects have been found in titania based SPME for the SPDE-1 method is recommended. The more polar and high aromatic hydrocarbons24 and aliphatic alcohols analysis.25 The melting desomorphine displayed lower responses with relatively optimal conditions of the SPDE needle were reviewed and are higher LOQ for water sample around 250 ng/g. The further listed in Table 1. derivation will expectantly improve the sensitivity of desomorphine by reducing the analyte polarity. The GC-MS Quantitative characteristics of the two SPDE methods chromatograms of four different analytes with sufficient The optimized conditions were applied to standard solutions resolution and sensitivity in water and urine are shown in Fig. 9. The broad shape of codeine (peak 4) is probably caused by the

100 (a) 120 %

, 80 ce n

a 100 d %

60 , un b ce a

n e 80 v a

ti 40 a l e

R 60 bund a

20 e v

i 40 t a 0 l e

270 280 290 300 R 20 Temperature / oC 0 100 (b) 0 0.01 0.02 0.03 NaCl / g 80 % , , ce n

a Fig. 8 Effect of addition of salt on desocodeine extraction. d 60 n bu a

v 40 ti

a Table 1 Optimal conditions of the SPDE needle l e R 20 Factor Study range Optimization

0 Sol-gel stirring time/min 0 – 360 30 5 10 20 25 Coating layer 0 – 3 One layer Time / min Injection temperature/°C 270 – 300 290 Adsorption time/min 12 – 60 36 Desorption time/min 5 – 25 10 Fig. 7 (a) Effects of desorption temperature and (b) desorption time.

Table 2 Performance of the SPDE methods

Method Analyte Solvent Internal standard (calibration) Linear range, ppb Regression line R2 LOQa, ppb

b 2 SPDE-1 Desocodeine H2O [ H3]-Desocodeine (adsorption) 5 – 1000 Y = 0.0185x + 0.1559 0.9990 5 b 2 SPDE-1 Desocodeine Urine [ H3]-Desocodeine (adsorption) 50 – 1000 Y = 0.0100x – 0.0819 0.9990 5 c 2 SPDE-2 Desocodeine H2O [ H3]-Desocodeine (instrument) 5 – 1000 Y = 0.0480x – 0.0695 0.9943 1 c 2 SPDE-2 Desocodeine Urine [ H3]-Desocodeine (instrument) 50 – 1000 Y = 0.0667x + 4.1272 0.9967 2 c 2 SPDE-2 Desomorphine H2O [ H3]-Desomorphine 250 – 5000 Y = 0.0119x – 2.5611 0.9957 250

a. LOQ: S/N > 10. b. SPDE-1 method is addition of internal standard to solution before adsorption procedure. c. SPDE-2 method is the injection of internal standard before thermal desorption procedure. 1112 ANALYTICAL SCIENCES NOVEMBER 2011, VOL. 27 polarity of codeine being higher than that of desocodeine. the optimal temperature is not enough for codeine to vaporize As mentioned early, the codeine due to the higher polarity has completely. comparatively much less response, and displays maximum extraction at 50 min (Fig. 6a). The optimal condition for Reproducibility of the proposed method desocodeine such as extraction time is too short for codeine and The reproducibility of the developed method was determined by the interday precision. An intermediate concentration (100 ppb) of the analyte in the calibration curve range was tested. Two extractions of independently prepared urine samples containing desocodeine (100 ppb) and the deuterated internal standard (50 ppb) were labelled as day 1 and day 3 samples, respectively; these gave the intraday relative standard deviations (RSDs). Table 3 shows that recovery was 99.5 and 101% in two extractions, while the mean inter-batch RSD was calculated to be ca. 10.8%. This result confirmed the reproducibility of the new coating material for desocodeine extraction and its suitability for GC-MS. The capacity of the needle is decided by the intersection (2.5 ppm) of two calibration lines in the range of 1 ppb to 100 ppm. The SPDE needle can be reused for three times after being regenerated at 500°C for 10 min. The 60% activity retained in the SPDE needle used three times for extraction shows that regeneration and urine sample will

deteriorate the extraction efficiency of the TiO2 film. Furthermore, the 10 times regeneration will cause 50% activity loss. The study in headspace extraction or preparation of the 41 TiO2 film with anodic oxidation method probably can prolong the lifetime of this TiO2 film. The further derivation will improve the stability of TiO2 film to reduce the hydration and polarity of analytes.

Comparison with Supelco SPME fiber The spiked urine samples were studied to compare the SPDE method with SupelcoTM solid phase microextraction polydimethylsiloxane (PDMS) fibers (Table 4). The results Fig. 9 GC-MS chromatograms of simultaneous analysis of 250 ppb deoxycodeine, desocodeine, desomorphine, codeine for SPDE-2 in indicate that SPDE-1 and SPDE-2 provided better LOQs (5.0 (a) water and (b) urine sample. 1, Desocodeine (tR, 34.24 min), and 2.0 ng/g, respectively) than the SPME method (50 ng/g) for 2 [ H3]-desocodeine (tR, 34.19 min); 2, desomorphine (tR, 34.49 min); 3, desocodeine analysis in urine. The more polar desomorphine deoxycodeine (tR, 34.65 min); 4, codeine (tR, 38.63 min). shows lower response in SPME method (LOQ 500 ng/g).

Table 3 Results of inter-batch reproducibility

Day 1 (n = 3)a Day 3 (n = 3)a

Desoco deine spiked Desoco deine SPDE-2 Recovery, Desoco deine spiked Desoco deine SPDE-2 Recovery, in urine, ppb result, ppb % in urine, ppb result, ppb %

100 93.2 93.2 100 113 113 93.2 93.2 93.2 93.2 112 112 97.0 97.0 Average 99.5 99.5 Average 101.1 101.1 SD 11.0 SD 10.5 RSD, % 11.1 RSD, % 10.4

2 a. SPDE-2 method was followed and [ H3]-desocodeine: 50 ng.

Table 4 Comparison of analytical characteristics for SPDE method with Supelco polydimethylsiloxane SPME fiber in spiked urine samples

Method Analyte spiked in urine, ppb Result (mean ± SD, n = 3), ppb Recovery, % Linear range, ppb LOQa, ppb

SPDE-1b Desocodeine 100 99.8 ± 5.1 99.8 50 – 1000 5 SPDE-2c Desocodeine 100 99.4 ± 10.1 99.4 50 – 1000 2 SPMEd Desocodeine 100 95.1 ± 3.5 95.1 50 – 5000 50 SPDE-1b Desomorphine 1000 930 ± 52 93.0 250 – 5000 250 SPMEd Desomorphine 1000 890 ± 44 89.0 250 – 5000 500 a. LOQ: S/N > 10. b. SPDE-1 method is addition of internal standard to solution before adsorption procedure. c. SPDE-2 method is the injection of internal standard before thermal desorption procedure. d. SPME method: 100 μm of polydimethylsiloxane (PDMS) fibers from Supelco were used. The analytical conditions are the same as those for the SPDE-1 method. ANALYTICAL SCIENCES NOVEMBER 2011, VOL. 27 1113

The 500 ng/g LOQ is relatively higher than SPDE-1 method Chromatogr., B, 1996, 677, 241. (LOQ 250 ng/g). The satisfactory recoveries (95.1 – 99.8%) were 9. W. U. Ya-Hsueh, L. Keh-Liang, C. Su-Chin, and C. Yan- obtained in all methods for desocodeine analysis. However, a Zin, J. Chromatogr., B, 2008, 870, 192. higher recovery (93%) in SPDE-1 method than in SPME method 10. T. J. Kauppila, N. Talaty, T. Kuuranne, T. Kotiaho, R. (89%) for desomorphine analysis is observed. The wide linear Kostiainen, and R. G. Cooks, Analyst, 2007, 132, 868. ranges (from 5 – 5000 ppb) are obtained in all methods for 11. M. Gergov, P. Nokua, E. Vuori, and I. Ojenperä, Forensic desocodeine and desomorphine analysis. SPME method shows Sci. Int., 2009, 186, 36. slightly better RSD (3.7% for desocodeine and 4.9% for 12. J. Pawliszyn, “Application of Solid Phase Microextraction”, desomorphine) than SPDE-1 method (5.1% for desocodeine and 1999, R. S. C. Chromatography Monograph, Cambridge, 5.6% for desomorphine). The advantages of SPDE method are 573. proven with better sensitivity and recovery for desocodeine and 13. H. Kataoka, Curr. Pharm. Anal., 2005, 1, 65. desomorphine analysis. 14. D. Djozan, Y. Assadi, and S. H. Haddadi, Anal. Chem., 2001, 73, 4054. 15. M. Liu, Y. Hu, J. Zhao, Y. Xu, and Y. Guan, J. Chromatogr., Conclusions A, 2006, 1108, 149. 16. D. Djozan and L. Abdollahi, Chromatographia, 2003, 57, 799. A new SPDE needle coated with mesoporous titania formed by 17. D. Budziak, E. Martendal, and E. Carasek, J. Chromatogr., the sol-gel method for the extraction of opiate drugs is described. A, 2007, 1164, 18. The surface porosity of the coating material responsible for the 18. X. Li, J. Gao, and Z. Zeng, Anal. Chim. Acta, 2007, 590, 26. large surface area largely depends on the preparation of the 19. Y. Wu, B. Hu, W. Hu, Z. Jiang, and B. Li, J. 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