• Journal of Food Hygiene and Safety
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• v.18 no.4
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• pp.195-201
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• 2003

An easily available, simultaneous identification/determination procedure for sildenafil, homosildenafil, tadalafil, vardenafil in adulterated health related foods was established by using a combination of three different analytical methods; thin layer chromatography(TLC), liquied chromatography-mass spectrometry (LC/MS) and high-performance liquied chromatography (HPLC)/photo-diode-array detector. The sample solution for TLC was applied to silica gel 60 $F_{254}$ plates with ethylacetate/acetonitrile/25%ammonia (90:10:5) as a developing solvent. Spots were located under UV radiation at 254 nm and dragendolfs reagent. Mass spectra of the compounds by LC/MS were investigated with electrospray ionization (ESI) interface, under positive ion mode. The HPLC analysis was performed on a column of capcell pack $C_{18}$ (UG120, 4.6${\times}$250mm I.D. 5 ${\mu}$m)with 0.1% sodium 1-hexansulfonate (in 0.1% phosphoric acid)/acetnitrile (73:27) as a mobile phase, and effluent was minitored with a photo-diode-applied to commercial foods, Sildenafil content was inthe range of 0.4mg/g~360.9 mg/g from 7 out of 35 samples. Homosildenafil content was in the range of 2.2 mg/g~336.0 mg/g from 7 out of 35 samples. Tadalafil content was 429.3 mg/g, 9.6 mg/500 mg from 2 out of 35 samples. The procedure described here is available for the screening of sildenafil, homosildenafil, tadalafil, vardenafil.

• Analytical Science and Technology
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• v.16 no.6
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• pp.488-498
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• 2003

By LC/MS/MS, the analytical method of sildenafil and its analogues (homosildenafil, vardenafil and tadalafil) used as used medical treatment of impotence was established. electrosprary ionization (ESI) and atmospheric pressure chemical ionization (APCI) as a ionization method were applied. Several parameter were varied and the sensitivity and reproducibility were compared. In LC/ESI-MS method, capillary voltage, cone voltage, extractor, entrance and RF lens to create appropriate productr ions for multiple reaction monitoring (MRM) were variable parameter, but the formation of the other product ions except the precursor ion could not detect. And the value of entrance, collision energy, exit, corona voltage, cone voltage, extractor, RF lens, cone gas, and desolvation gas in APCI mode were varied, only the creation pattern of fragment ions by the change of RF lens value were detected, and the limit of detection was decreased due to the increase of S/N. Ten millimole ammonium formate (pH 4.8):acetonitrile=70:30 by isocratic elution in HPLC system was shown the maximum sensitivity in MS, the detection limit of sildenafil, homosildenafil, vardenafil and tadalafil obtained by ESI-MRM were 0.10, 0.025, 0.025, and $0.25{\mu}g/mL$ at S/N>5, respectively.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2004.05a
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• pp.49-68
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• 2004

New analogues of Sildenafil (Viagra${\circledR}$)were identified in the imported Chinese herb drinks, which have been added illegally for affecting penile erectile dysfunction. In order to elucidate the chemical structures of Sildenafil analogues, separation and purification were carried out and followed by analysis of the routine 1D and 2D NMR spectroscopy and FAB mass spectrometry. Based on analytical data one compound was maned as Homosildenafil contains ethylpiperazine switched with methylpiperazine of Sildenafil and the other one was called an Hongdenafil contains ethylpiperazine switched with methylpiperazine and acetyl group instead of sulfonyl group of Sildenafil. As results, Homosildenafil and Hongdenafil were put on the list as new inspection items of the imported food for protectiong public health in Korea.

• Analytical Science and Technology
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• v.17 no.6
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• pp.520-526
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• 2004

To determine 6 anti-impotence drug-like compounds such as sildenafil, vardenafil, tadalafil, homosildenafil, hydroxyhomosildenafil and hongdenafil in food, simultaneously, high performance liquid chromatography was applied. In the case of solid sample, it was extracted in organic solvents after homogenizing with mortar and pestle. Whereas liquid sample was just diluted in water and then extracted in organic solvents. Maximum lengths of UV for targets have been identified on photodiode array spectra. As results, vardenafil, hongdenafil, hydroxyhomosildenafil, sildenafil, homosildenafil, and tadalafil were eluted in order using $C_{18}$ column in acetonitrile containing phosphoric acid as the mobile phase. The maximum wavelength (${\lambda}_{max}$) was 216 nm for vardenafil, 233 and 282 nm for hongdenafil, 222 and 293 nm for hydroxyhomosildenafil, sildenafil and homosildenafil, and 284 nm for tadalafil. The overall recoveries were ranged from 95% to 109% and the limit of detection was about 0.04 mg/kg at signal/noise>3. Levels of targets in the selected food samples were 1.7 (hongdenafil) ~ 63 (tadalafil) mg/one dose.

• Journal of environmental and Sanitary engineering
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• v.22 no.3
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• pp.89-96
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• 2007

To determine 8 anti-impotence drug/drug-like compounds such as sildenafil, vardenafil, tadalafil, homosildenafil, hydroxyhomosildenafil, aminotadalafil, pseudovardenafil and hongdenafil in foods, simultaneously, high performance liquid chromatography(HPLC) and liquid chromatography-mass spectrometry (LC/MS) were used. The HPLC/UV analysis was performed on a column of capcellpak $C_{18}$ with 0.1% sodium-1-hexansulfonate in 0.2M ammonium formate/acetonitrile as a mobile phase. Mass spectra of the compounds by LC/MS were investigated with SCAN mode(Mass range and Fragment voltage) and SIM(Selected Ion Monitoring) mode (Ion target and Fragment voltage). The results follow as; 1. The HPLC/UV analysis was detected from 5 out of 63 samples. The content of sildenafil was in the range of 32.80 ppm ${\sim}$ 60.13 ppm from 4 out of 5 samples. The contents of sildenafil, vardenafil, homosildenafil were in the range 47.14 ppm from 1 out of 5 samples. 2. The conformed result of LC/MS was equal of detected from 5 out of 63 samples in HPLC/UV analysis. An easily available, simultaneous determination of 8 standards in adulterated health related foods was established by using a combination of LC/MS methods.

• Analytical Science and Technology
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• v.20 no.1
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• pp.78-83
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• 2007

To perform proficiency test for determining anti-impotence drug-like compounds in food, interlaboratory test has been done. Targets were 6 such as sildenafil, tadalafil, vardenafil, homosildenafil, hydroxy-homosildenafil and pseudo-vardenafilI. Total 13 institutes were participated and all is in charging of food analysis. To do double blind test, the reference materials were made as 13 different ginseng drink samples and each sample had random 3 targets. By the official method for anti-impotence drug-like compounds in food code, sample was just diluted in water, extracted in organic solvents, determined by HPLC/UV and then confirmed by LC/MS. The analytical duration was 60 days after receiving sample. Ten out of 13 institutes were satisfied by evaluation of Z-score and RSZ according to the regulation for managing analytical quality assurance.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.396.1-396.1
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• 2002

HPTLC(High Performance Thin Layer Choromatography) method was developed for rapid and precise analysis of Sildenafil and modified Sildenafils(Vardenafil. Homosildenafil, Tadanafil). Chromatographic conditions were Optimized for simultaneous analysis of them and each specific UV spectra were obtained. The calibration curve of Sildenafil and modified Sildenafils had a linearity in the range of 1.0 ~ 56.5 $\mu$/ml at 254nm. The Limit of Detection(LOD) and the limit of Quantification(LOQ) of Sildenafil and modified Sildenafils were 0.8$\mu$/ml and 1.0$\mu$g/ml. (omitted)

• Analytical Science and Technology
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• v.21 no.2
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• pp.65-83
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• 2008

It is noted that illegal hazardous foods containing unauthorized drugs or synthetic drung analogues are increasing. Especially, reported are unknown compounds that have the modified chemical structures of the anti-impotence drugs such as sildenafil, vardenafil, and tatalafil. In addition, it is very reserved, since illegal synthetic compounds having similar chemical structures modified from anti-impotence drug to avoid the government inspection are not proved their safety at all. This review in ulation to food safety, lists the illegal compounds added to foods and describes about the analytical methods to chanacterize 16 anti-impotence drug analogues such as homosildenafil, hongdenafil, pseudovardenafil, aminotadalafil, hydroxyhomosildenafil, hydroxyhongdenafil, dimethylsildenafil, xanthoanthrafil, hydroxyvardenafil, norneosildenafil, demethylhongdenafil, piperidinohongdenafil, carbodenafil, thiosildenafil, dimethylthiosildenafil, and acetylvardenafil.

• Analytical Science and Technology
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• v.16 no.1
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• pp.32-38
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• 2003

The rapid and sensitive determination method of sildenafil and its related compounds (Vardenafil, Homosildenafil, Tadanafil.) has been investigated using high performance thin layer choromatography (HPTLC). Optimizing separation conditions and simultaneous determination method of these compounds were studied. The calibration curves of those compounds at 254 nm was found to be linear in the range of $1.0{\sim}56.5{\mu}g/mL$, respectively. The detection limts (LOD) and quantification limits (LOQ) of these were found to be $0.8{\sim}1.8{\mu}g/mL$ and $1.0{\sim}2.3{\mu}g/mL$. The coefficient of variation (C.V.) were less than 2.5%. Finally, the present method was applied to determine sildenafil and its related substances in dietary supplement.