determination of risperidone in tablets in the presence of its

Acta Poloniae Pharmaceutica ñ Drug Research, Vol. 66 No. 5 pp. 461ñ470, 2009 ISSN 0001-6837 

Polish Pharmaceutical Society 

ANALYSIS 

DETERMINATION OF RISPERIDONE IN TABLETS IN THE PRESENCE OF 

ITS DEGRADATION PRODUCTS AND PLACEBO-DERIVED CONSTITUENTS 

ANNA MAåLANKA*, JAN KRZEK and ALEKSANDER PATRZA£EK 

Department of Inorganic and Analytical Chemistry, Jagiellonian University, Collegium Medicum, 

9 Medyczna St., 30-688 KrakÛw, Poland 

Abstract: New chromatographicñdensitometric assay was developed for identification and determination of 

risperidone in pharmaceutical formulations. Thin-layer chromatographic plates (TLC-F 254 ) as a stationary phase 

and n-butanolñacetic acidñwater (12:3:5 v/v/v) as a mobile phase were used for separation. Densitometric 

measurements were done for all constituents at λ = 280 nm. A decrease in stability of risperidone was observed 

in acidic, basic and antioxidant solutions. Degradation of active pharmaceutical ingredient was consistent with 

first-order kinetics and unrelated to the solution. This assay is specific for risperidone. No interference of tablet 

origin adjuvants and degradation products were observed. Moreover, high sensitivity, limit of detection (0.22 

µg/spot), limit of quantitation (0.67 µg/spot), recovery (98.2ñ100.82%), broad linear range (0.09 µg/spot to 

1.40 µg/spot) and accuracy (1.87% RSD) are characteristic traits of the chromatographicñdensitometric assay. 

Keywords: pharmaceutical preparation analysis, TLC, densitometry, risperidone 

Risperidone represents atypical neuroleptics 

and is classified on the basis of chemical constitution 

among neuroleptics that are derivatives of various 

heterocyclic systems with cyclic structure. 

Risperidone is a tetrahydropyrido[1,2-a]-pyrimidin- 

4-one derivative with 6-fluoro-3-(4-piperidinyl)- 

1,2-benzisoxazole group, as shown below (1): 

Risperidone ñ 4-[2-[4-(6-fluorobenzo[d]isoxazol-3- 

yl)-1-piperidyl]ethyl]-3-methyl-2,6-diazabicyclo[4.4.0]deca-1,3-dien-5-one 

Absorption assay by infrared spectrophotometry and 

liquid chromatography (LC) are recommended for 

estimation of the quality of risperidone by determination 

of substance according to Polish 

Pharmacopoeia VII. High-performance liquid chromatography 

(HPLC) is used for purity analysis. 

However, a method of chloric(VII) acid titration 

with potentiometric determination of end-point is 

used for quantitative analysis (2). 

Chromatographic methods, mainly LC and 

HPLC, have significant role in determination of 

risperidone and its impurities. HPLC, liquid chromatography 

coupled with mass spectrometry 

(LC/MS) and nuclear magnetic resonance (NMR) 

were used for identification and structural analyses 

of impurities and degradation products of risperidone 

(3-5). Determinations of risperidone and 9- 

hydroxyrisperidone, an active metabolite, in biological 

material were accomplished using LC/MS 

method (6ñ15). Determination of risperidone and its 

degradation products in tablets (16, 17), and biologic 

material (18ñ23) were performed using HPLC 

method coupled with mass spectrometry or spectrophotometric 

detection. TLC 60-F 254 plates and 

acetonitrileñmethanolñ1-propanolñtriethanolamine 

(8.5:1.2:0.6:0.2 v/v/v/v) mobile phase were used for 

separation of degradation products of risperidone. 

Densitometric measurements were used for detection 

under UV light at λ = 280 nm (17). Capillary 

electrophoresis (CE) was also used as a separation 

method for determination of risperidone (24, 25). 

Polarography (26), chemiluminescence (27) and 

colorimetry (28) were used amongst other analytical 

* Corresponding author: e-mail: amasl@cm-uj.krakow.pl 

461

462 ANNA MAåLANKA et al. 

methods for the determination of risperidone in 

tablets and biological material. 

This research paper deals with the development 

of new chromatographicñdensitometric assay 

for identification and determination of risperidone in 

tablets and its degradation products that can occur in 

acidic and basic solutions, as well as in the presence 

of oxidizing or reducing agents. 

EXPERIMENTAL 

Apparatus 

(a) TLC ñ Densitometer ñ Scanner 3 equipped 

in Cats 4.0x software, Linomat IV (Camag, Muttenz, 

Switzerland); (b) TLC aluminum plates covered by 

silica gel (20 ◊ 20 cm, Merck, Germany) that were cut 

into 10 ◊ 10 cm plates; (c) Chromatographic chamber 

18 ◊ 9 ◊ 18 cm (Sigma Aldrich); (d) Balance scale, 

WPA 60/C model, 0.1 mg accuracy (Radwag, 

Poland); (e) Bench centrifuge, MPW-223e model 

(MPW Med. Instruments, Poland). 

Reagents 

Methanol (POCH, Gliwice, Poland), 1-butanol 

(Chempur, Piekary ålπskie, Poland), acetic acid 

(Chempur, Piekary ålπskie, Poland), all analytical 

grade. 

Reference substances and formulations 

A substance that meets requirements of Polish 

Pharmacopoeia VI and European Pharmacopoeia 

Monographs was used during studies: Risperidone 

CRS ñ LGC Promochem Sp.z o.o, Poland; coated 

tablets of Risperdal (4 mg) manufactured by 

Janssen-Cilag, France, placebo: lactose, corn starch, 

microcrystalline cellulose, hydroxypropyl methyl 

cellulose, magnesium stearate, anhydrous colloidal 

silica, sodium lauryl sulfate. 

Reference solutions 

Amount of 5.6 mg of comparative substance 

was dissolved in 5.0 mL of methanol and mixed. 

Solutions at the following concentrations: 0.560 

mg/mL, 0.280 mg/mL, 0.140 mg/mL, 0.070 mg/mL, 

0.035 mg/mL and 0.0175 mg/mL were obtained by 

dilution of stock solution with methanol. 

Solutions for stability analysis 

Coated tablets of Risperdal formulation were 

used after removing a coating by water wetting. 

Powdered tablet mass corresponding to 32.0 mg of 

risperidone was extracted with 16.0 mL of methanol 

followed by shaking for 15 min. Suspension was 

centrifuged at 3000 rpm and supernatant was collected. 

Each time, the volume of 1.5 mL of solution 

was evaporated to dryness. 

Acidic solution 

A volume of 4 mL 0.5 mol/L HCl was added to 

dried residue. The solution was poured into 0.5-mL 

glass vials. The solutions were heated at 100 O C, 

simultaneously samples for further studies were collected 

after 1, 2, 3 and 5 h. After cooling down, the 

collected solutions were diluted immediately with 

methanol at a ratio of 1:1. 

Basic solution 

Volumes of 1 mL methanol and 3 mL of 0.5 

mol/L NaOH were added to dried residue. Dissolved 

solution was poured into 0.5-ml glass vials. 

Solutions were heated at 100 O C and simultaneously 

samples for further studies were collected after 1, 2, 

3 and 5 h. After cooling down, the solutions were 

diluted immediately with methanol at a ratio of 1:1. 

Oxidant solution 

A volume of 4-mL 0.9 mol/L H 2 O 2 ñmethanol 

solution was added to the dried residue. The solution 

was left at room temperature (RT). Samples for further 

studies were collected after 0.5, 1, 2 and 5 h. 

Reductant solution 

A volume of 4-mL waterñmethanol 0.1 mol/L 

Na 2 S 2 O 3 solution was added to dried sample. The 

solution was left at RT. Samples for further studies 

were collected after 1, 2, 7 h and 14 days. 

Pharmaceutical agent solution for risperidone determination 

Powdered tablet mass corresponding to 4.0 mg 

of risperidone was extracted with 4.0 mL of 

methanol, shaken for 15 min and centrifuged. 

Supernatant was diluted 10 times with methanol. 

Chromatographic analysis 

Volumes of 5 mL of reference solution and 

degradation solutions were applied to chromatographic 

plates (TLC, 10 ◊ 10 cm) using an applicator. 

Chromatograms were developed as far as 9.5 

cm, using mobile phase: n-butanolñacetic 

acidñwater (12:3:5 v/v/v), dried at RT and recorded 

under UV light. Densitometric recording was done 

at λ = 280 nm. This wavelength was chosen on the 

basis of directly recorded spectrum on chromatogram. 

Retardation factor value (R F ~ 0.49) and 

UV absorption spectrum recorded directly from 

chromatogram were used for identification of 

risperidone.

Determination of risperidone in tablets in the presence of... 463 

Table 1. Parameters of separation. 

Constitues TLC plates HPTLC plates 

(1) : (2) R F(1) R F(2) α R s R F(1) R F(2) α R s 

Risperidone : peak 2 

solution HCl 

~0.49 ~0.79 4.00 4.21 ~0.53 ~0.78 3.18 4.09 

peak 2 : Risperidone 

solution NaOH 

~0.43 ~0.48 1.22 0.70 ~0.44 ~0.51 1.32 0.91 


solution NaOH 

~0.48 ~0.72 2.77 3.43 ~0.51 ~0.70 2.23 3.22 


solution H 2 O 2 

~0.48 ~0.50 1.08 0.63 ~0.53 ~0.56 1.13 0.60 

R F ñ retardation factor, a ñ separation factor, R s ñ resolution factor 

R s ñ resolution factor, R s = 2 ◊ (distance between the centers of two adjacent spots)/(sum of the widths of the two spots in the direction 

of development) 

Table 2. Percentage content of risperidone in the presence of degradation products in solutions: NaOH, HCl, H 2 O 2 and Na 2 S 2 O 3 . Kinetics 

parameters of degradation reaction in individual solutions. 

0.5 mol/L NaOH 0.5 mol/L HCl 0.9 mol/L H 2 O 2 0.1 mol/L Na 2 S 2 O 3 

Content of Content of Content of Content of 

Time risperidone Time risperidone Time risperidone Time risperidone 

[%] [%] [%] [%] 

1 h 0.073 1 h 0.074 0.5 h 0.031 1 h 0.150 

2 h 0.066 2 h 0.072 1 h 0.028 2 days 0.150 

3 h 0.062 3 h 0.069 2 h 0.027 7 days 0.150 

5 h 0.055 5 h 0.065 5 h 0.020 14 days 0.150 

k = 0.0692 h -1 ± 0.0267 h -1 k = 0.0334 h -1 ± 0.0062 h -1 k = 0.0926 h -1 ± 0.0396 h -1 

t 0.1 = 1.52 h t 0.1 = 3.15 h t 0.1 = 1.37 h ó- 

t 0.5 = 10.01 h t 0.5 = 20.75 h t 0.5 = 7.48 h 

k ñ reaction rate constant, t 0.1 ñ degradation time of 10% substrate, t 0.5 ñ degradation time of 50% substrate 

Kinetics estimation 

Determination of risperidone was done by the 

use of kinetics parameters (29). 

Assay validation 

Assay validation was done by determination of 

specificity, accuracy, linearity, limit of detection 

and quantification, stability, and robustness (30). 

Specificity 

Assay specificity was determined by comparing 

peak areas, R F values and absorption spectra recorded 

for reference solution in the presence of placebo. 

Model mixtures containing lactose, starch corn, 

microcrystalline cellulose, hydroxypropyl methyl 

cellulose, magnesium stearate, anhydrous colloidal 

silica and sodium lauryl sulfate were prepared (Fig. 

1). Placebo was added to these model mixtures. 

Accuracy 

Assay accuracy was determined by estimating 

recovery percentage (%E) for chosen constituents. 

Known amount of reference substances (80% to 120% 

declared content) were added to model solutions already 

containing placebo constituents. Recovery in percentage 

value was calculated on the basis of determined content 

of individual constituents to weighed amount (Table 3). 

Precision 

Consistency of experimentally determined results 

was checked on the model solutions prepared by dissolving 

the substance in methanol. Five determinations 

were done for each model solution (Table 3). 

Indirect precision 

Determination was done for the model solutions 

by two analytical chemists in two different 

days. In each case, five determinations were done 

for each model solution (Table 3). 

Linearity 

Linearity was determined as the relationship of 

peak areas (p [mm 2 ]) to mass [mg/spot]. Five meas-


Figure 1. Densitogram of methanol solution of placebo constituents of pharmaceutical formulation after extraction of 1.0 g of powdered 

mass with 10.0 mL of methanol. 

Fig. 2. Densitogram of methanol extract of risperidone from pharmaceutical formulation. 

urements were done for concentrations 0.018 

mg/mL to 0.280 mg/mL, applying 5.0 mL of each 

solution. The measurement of linearity of risperidone 

was shown as a straight line equation with the 

content of correlation coefficient (r): p = 4134.3 ◊ m 

+ 742.9, r = 0.99657. 

Limit of detection (LOD) and limit of quantitation 

(LOQ) 

Using standard deviation and slope of a 

straight line coefficient, the values of LOD and LOQ 

were determined using the following equations: 

LOD = 3.3 ◊ S y /a, LOQ = 10 ◊ S y /a, where: S y ñ 

error of estimation, a ñ slope of a straight line coefficient 

(Table 3). 

Stability 

Methanol extract was prepared from 

Risperdal tablets at concentration 1.0 mg/mL of 

risperidone. The methanol extract was stored at RT 

and also at 5 O C for 7 days. Determination of the 

content was done ex tempore (without pretreat-


Fig. 3. Absorption spectrum of risperidone recorded directly from chromatogram 

Fig. 4. Densitogram of risperidone (peak 1) and its degradation product (peak 2) in acidic solution. 

ment) and after 24 h, 48 h and a whole week 

against reference solutions prepared directly before 

determination (Table 4). 

Robustness 

The impact of replacement of TLC 60-F 254 

plates with HPTLC-F 254 plates covered by silica 60 

was studied. Volume of 5 µL of each solution after 

hydrolysis in HCl and NaOH solutions were 

applied on both types of plates. Then, the plates 

have undergone chromatographic analysis. 

Separation and resolution factors were calculated 

for two adjacent peaks on the basis of developed 

densitograms (Table 1). 

Determination of risperidone in pharmaceutical 

formulation 

Usability of this assay was proved on pharmaceutical 

formulation. The results are presented in 

Table 2.


Fig. 5. Densitogram of risperidone (peak 3) and its degradation product (peak: 1, 2 and 4) in basic solution. 

Fig. 6. Densitogram of risperidone (peak 1) and its degradation product (peak: 2) in hydrogen peroxide solution. 

RESULTS AND DISCUSSION 

According to assumption made in this paper, 

new chromatographicñdensitometric assay allows 

for simultaneous identification and quantity analysis 

of risperidone in pharmaceutical formulations in the 

presence of degradation products occurring in 

acidic, basic and hydrogen peroxide solutions. 

Good results of chromatographic separation 

were obtained by using n-butanolñacetic acidñwater 

(12:3:5 v/v/v) mobile phase and TLC-F 254 plates 

covered with silica gel 60. Peak of risperidone is 

symmetrical and well-shaped under developing conditions. 

It allows for easy identification and quality 

analysis (Fig. 1, 2). 

Characteristic absorption spectrum recorded 

directly from chromatograms can be useful for identity 

studies. Moreover, this spectrum allows to 

choose analytical wavelength at λ = 280 nm (Fig. 3). 

Risperidone-origin peaks (R F ~ 0.49) always 

occur close to degradation products on recorded 

chromatograms for studied and comparative solutions


Fig. 7. Densitogram of risperidone in sodium thiosulfate(VI) solution. 

Fig. 8. Logarithmic dependence of risperidone concentration to degradation time in HCl, NaOH and hydrogen peroxide solutions. 

Regressionequations: 1: log c = 0.0145 ◊ t ñ 1.1178, in acidic solution; 2: log c = 0.0297 ◊ t ñ 1.1129, in basic solution; 3: log c = 0.0402 

◊ t ñ 1.4968, in hydrogen peroxide solution. 

in established conditions. It could be assumed that 

this assay is specific against tested constituent and it 

guarantees that the obtained results are reliable. 

Exemplary densitograms of degradation products 

of risperidone are presented in Figures 4ñ7. The 

peaks of products degradation origin that differ with 

retention coefficient values, which depend on solution 

of their origin, are observed on chromatographic 

densitograms in acidic, basic and hydrogen peroxide 

solutions. 

Separation of risperidone from its degradation 

products was satisfactory under studied conditions 

(Table 1). No significant differences were observed 

when stationary phase was changed by replacement 

of TLC with HPTLC plates. 

The presence of one degradation product of 

risperidone in a solution of 0.5-mol/L acetic acid (R F 

~ 0.79) was observed together with the peak of 

tested constituent (R F ~ 0.49) under developing 

conditions (Fig. 4). Three degradation products


Table 3. Assay validation parameters. 

Validation parameters Value of validation parameter Statistical estimation 

LOD 

[mg/spot] 

0.222 ó- 

LOQ 

[mg/spot] 

0.672 ó- 

95,96 x ñ = 98.27 

Recovery 97,81 S x = 2.332 

80 % 101,29 t 95% = ±2.89 

[%] 96,27 RSD = 2.37 

100,03 

101,89 

Recovery 99,76 x ñ = 99.60 

100 % 98,40 S x = 1.761 

[%] 97,41 t 95% = ±2.18 

100,55 RSD = 1.76 

101,63 

Recovery 100,58 x ñ = 100.82 

120 % 101,30 S x = 1.162 

[%] 101,70 t 95% = ±1.44 

98,90 RSD = 0.01 

4,10 

4,02 x ñ = 4.00 

Precision 3,92 S x = 0.075 

[mg/4 mL] 3,93 t 95% = ±0.093 

4,03 RSD = 1.87 

3,97 

Indirect precision 3,91 x ñ = 4.01 

[mg/4 mL] 3,96 S x = 0.100 

Analytical chemist I 4,11 t 95% = ±0.125 

4,14 RSD = 2.50 

3,91 

Indirect precision 4,12 x ñ = 4.01 

[mg/4 mL] 4,08 S x = 0.103 

Analytical chemist I 3,90 t 95% = ±0.128 

4,07 RSD = 2.56 

Regression equation p = 3729.9 ◊ m + 212.1 

Correlation coefficient r = 0.99411 ó- 

R F ñ retardation factor; x ñ ñ mean value; S x ñ standard deviation, t 95% ñ confidence interval for 95% probability; RSD ñ relative standard 

deviation; p ñ peak surface area [mm 2 ]; m ñ mass [mg/spot]; r ñ correlation coefficient 

(R F ~ 0.40, R F ~ 0.48 and R F ~ 0.72) were observed 

in a solution of 0.5 mol/L sodium hydroxide (Fig. 5). 

Degradation product with R F ~ 0.50 was detected in 

the presence of hydrogen peroxide (Fig. 6). No 

influence of sodium thiosulfate(VI) was observed on 

robustness of risperidone (Fig. 7). 

In conclusion, the solution, where the stability 

of risperidone was studied, has an impact on type 

and number of degradation products that differ with 

the values of retardation factor. It has to be highlighted 

that the impact of degradation process on 

method specificity was not observed. 

Interesting conclusions can be made on the 

basis of concentrations change of risperidone to time 

of measurement. Degradation process is independent 

on conditions but is consistent with kinetics of 

the first-order reaction (Fig. 8). 

Reaction rate constant (k) demonstrates various 

values in different solutions. Degradation is the 

fastest in hydrogen peroxide solution (k = 0.0926 h -1 ), 

followed by basic solution (k = 0.0692 h -1 ) and the 

slowest in acidic solution (k = 0.0334 h -1 ). 

Risperidone maintains its stability during 14 days of 

storage in the presence of reducing agent.


Table 4. Stability of methanol extract of risperidone from tablets. 

Content of stored solution at 23 O C [µg] 

Content of stored solution at 5 O C [µg] 

Ex tempore After 1 day After 2 days After 7 days After 1 day After 2 days After 7 days 

1.10 1.15 1.20 1.17 1.15 1.15 1.13 

Table 5. Determination results of the content of risperidone in the pharmaceutical formulation studied. 

Formulation Determined content Statistical 

(declared content) [mg/tablet] estimation 

4.10 x ñ = 4.00 

Risperdal 4.02 S x = 0.075 

3.92 t 0,95 = ±0.093 

(4 mg/tablet) 3.93 RSD = 1.87% 

4.03 E = 0.00% 

x ñ ñ mean value; S x ñ standard deviation, t 95% ñ confidence interval for 95% probability; RSD ñ relative standard deviation; E ñ relative 

error 

A suggestion can be made on the basis of the 

calculated values t 0.1 and t 0.5 that the smallest impact 

on stability of risperidone has the reducing agent and 

the highest one has hydrogen peroxide (Table 2). 

This new chromatographicñdensitometric 

method has high sensitivity (LOD = 0.222 mg, LOQ 

= 0.672 µg). A recovery of tested substance was 

98.27%, 99.60% and 100.82% for the levels of: 

80%, 100% and 120%, respectively. Linearity range 

was within 0.087 mg/spot to 1.400 µg/spot. This 

method is very accurate (RSD = 1.87%). No impact 

on the results and values was observed during testing 

this method by two different analytical chemists 

(RSD = 2.50% and 2.56%) (Table 3). 

Methanol extracts of risperidone made from 

pharmaceutical formulation have maintained their 

stability for 7 days during storage in 5 O C or RT 

(Table 4). 

This assay is also specific against placebo constituents, 

as well as degradation products (Fig. 1). 

Quantity analysis of risperidone was done in pharmaceutical 

formulation (Table 5). Developed assay 

has satisfactory accuracy and precision. The determined 

content of pharmaceutical formulation was 

like declared. Relative error is 0.00%. 

CONCLUSION 

Developed chromatographicñdensitometric 

assay allows for fast and direct determination of 

risperidone in the presence of constituents from 

placebo formulation and degradation products. 

This assay is very sensitive and has broad linearity 

range, good accuracy and precision. It can be 

used for quality evaluation of pharmaceutical formulations 

during manufacturing and distribution, as 

well as their stability. 

REFERENCES 

1. Zejc A., Gorczyca M.: Chemistry of drugs (in 

Polish), PZWL, Warszawa 2002. 

2. Polish Pharmacopoeia VI, Polish 

Pharmaceutical Society, Warszawa 2002. 

3. Sattanathan P., Babu J.M., Vyas K.: J. Pharm. 

Biomed. Anal. 24, 598 (2005). 

4. Tomar R.S., Joseph T.J., Murthy A.S.: J. 

Pharm. Biomed. Anal. 36, 231 (2004). 

5. Bharathi Ch., Chary D.K., Kumar M.S.: J. 


6. Roman M., Kronstrand R., Lindstedt.: J. Anal. 

Toxicol. 32, 147 (2008). 

7. LLerena A., Berecz R., Dorado P., De la Garza 

C.S., Norberto M.J., C·ceres M., GutiÈrrez J.R.: 

J. Chromatogr. B 783, 213 (2003). 

8. Remmerie B.M.M., Sips L.L.A., De Vries R., 

De Jong J., Schothuis A.M., Hooijschuur 

E.W.J., Van de Merbel N.C.: J. Chromatogr. B 

783, 461 (2003). 

9. De Meulder M., Remmerie B.M.M., de Vries 

R., Sips L.L.A., Boom S., Hooijschuur E.W.J., 

van de Merbel N.C., Timmerman P.M.M.B.L.: 

J. Chromatogr. B 870, 8 (2008). 

10. »abowska B., Cox S.L., Vinks A.A.: J. 

Chromatogr. B 852, 497 (2007). 

11. Zhang L., Jiao Z., Yao Z., Zhong Y., Zhong M., 

Yu Y.: Chromatographia 61, 245, (2005). 

12. Janowska E.: Probl. Forensic Sci. 58, 103 

(2004).


13. Zhang G., Terry Jr. A.V., Bartlett M.G.: J. 

Chromatogr. B 858, 276 (2007). 

14. Zhang G., Terry Jr. A.V., Bartlett M.G.: Rapid 

Commun. Mass Spectrom. 21, 920 (2007). 

15. Kirschbaum K.M., Finger S., Vogel F., Burger 

R., Gerlach M., Riederer P., Hiemke C.: 

Chromatographia 67, 321 (2008). 

16. Orkoula M.G., Kontoyannis C.G.: J. Pharm. 

Biomed. Anal. 47, 631 (2008). 

17. El-Sherif ZA., El-Zeany B., El-Houssini OM.: 

J. Pharm. Biomed. Anal. 36, 975 (2005). 

18. Kirchherr H., K¸hn-Velten W.N.: J. 

Chromatogr. B 843, 100 (2006). 

19. Huang M., Shentu J., Chen J.: J. Zhejiang Univ. 

Sci. B 9, 114 (2008). 

20. Nagasaki T., Ohkubo T., Sugawara K.: J. 


21. Zhang G., Terry Jr. A.V., Bartlett, M.G.: J. 

Chromatogr. B 856, 20 (2007). 

22. Moody D.E., Laycock J.D., Huang W., J. Anal. 

Toxicol. 28, 494 (2004). 

23. Zhou Z., Li X., Li K., Xie Z., Cheng Z., Peng 

W., Wang F., Li H.: J. Chromatogr. B 

802, 257 (2004). 

24. Danel C., Chaminade P., Odou P., BartÈlÈmy 

C., Azarzar D., Bonte J.-P., Vaccher C.: 

Electrophoresis 28, 2683 (2007). 

25. Danel C., BarthÈlÈmy C., Azarzar D.: J. 

Chromatogr. A 1163, 228 (2007). 

26. Jeyaseelan C., Jugade R., Joshia A.P.: Croat. 

Chem. Acta 79, 541, (2006). 

27. Xie X.F., Shao X.D., Song Z.H.: Chem. Pap. 

60, 288 (2006). 

28. Hassan,W.E.-S.: Chem. Pharm. Bull. 56, 1092 

(2008). 

29. Atkins P. W. Physical chemistry (Polish translation), 

PWN, Warszawa 2007. 

30. ICH guideline Q2B, Validation of Analytical 

Procedures: Methodology (CPMP CH/281/95), 

Geneva, Switzerland (1996). 

Received: 23. 03. 2009

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