Ray Liu - Academia.edu (original) (raw)
Papers by Ray Liu
IEEE Transactions on Information Forensics and Security, 2007
Rapid technology development and the widespread use of visual sensors have led to a number of new... more Rapid technology development and the widespread use of visual sensors have led to a number of new problems related to protecting intellectual property rights, handling patent infringements, authenticating acquisition sources, and identifying content manipulations. This paper introduces nonintrusive component forensics as a new methodology for the forensic analysis of visual sensing information, aiming to identify the algorithms and parameters employed inside various processing modules of a digital device by only using the device output data without breaking the device apart. We propose techniques to estimate the algorithms and parameters employed by important camera components, such as color filter array and color interpolation modules. The estimated interpolation coefficients provide useful features to construct an efficient camera identifier to determine the brand and model from which an image was captured. The results obtained from such component analysis are also useful to examine the similarities between the technologies employed by different camera models to identify potential infringement/licensing and to facilitate studies on technology evolution.
Journal of Chromatography A, 1987
N-(Trifluoroacetyl)-l-prolyl- (N-TFA-l-prolyl-) d- and l-amphetamine diastereoisomers were separa... more N-(Trifluoroacetyl)-l-prolyl- (N-TFA-l-prolyl-) d- and l-amphetamine diastereoisomers were separated by high-performance liquid chromatography and confirmed by an interfaced mass spectrometer system, using the commercially available N-3,5-(dinitrobenzoyl)phenylglycine chiral column. A separation factor of 1.52 and resolution of 3.8 were observed. N-TFA-l-prolyl-d- and -l-methamphetamine diastereoisomers were only partially resolved. The chiral stationary phase-solute interactions were studied by varying the mobile phase (2-propanol in hexane). Results indicate the separation mechanism proceeds via dipolar and hydrogen-bond interactions between the chiral stationary phase and the solute. A modified "dipole-stacking" model takes into account these interactions and explains the difference in separability observed for N-TFA-l-prolyl-d- and -l-amphetamine and N-TFA-l-prolyl-d- and -l-methamphetamine.
Journal of Food and Drug Analysis
This paper reviews gas chromatography-mass spectrometry (GC-MS) methods for the analysis of amphe... more This paper reviews gas chromatography-mass spectrometry (GC-MS) methods for the analysis of amphetamines, ketamines, opioids, cocaine, and other abused drugs in urine that were developed by authors in Taiwanese institutions, and published during the 2000 to early 2008 period. Information on sample preparation, derivatization, internal standard, GC column, detection mode, and validation data for the reported methods are summarized in table format to facilitate readers' reference and adaptation.
Journal of Food and Drug Analysis
Journal of Forensic Sciences
Journal of Forensic Sciences
ABSTRACT
Journal of Analytical Toxicology
Heroin, methamphetamine and ketamine have been the most commonly abused drugs in Taiwan. The pres... more Heroin, methamphetamine and ketamine have been the most commonly abused drugs in Taiwan. The presence of these drugs and their metabolites in postmortem specimens has been routinely monitored in our laboratory mostly by gas chromatographic-mass spectrometric methods. This study aimed to evaluate a more effective approach to simultaneously quantify these analytes (i.e., amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), morphine, codeine, 6-acetylmorphine, 6-acetylcodeine, ketamine and norketamine) in postmortem urine and blood specimens by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Samples (1 mL) were extracted via solid-phase extraction, evaporated and reconstituted in the mobile phase for injection into the LC-MS-MS system. Respective deuterated analogs of these analytes were used as internal standards. Chromatographic separation was achieved by an Agilent Zorbax SB-Aq analytical column at 50°C. Mass spectrometric analysis was performed by electrospray ionization in positive-ion dynamic multiple reaction monitoring mode with optimized collision energy for respective precursor ion selected for each analyte, and the monitoring of two transition ions. Performance characteristics were assessed using drug-free samples that were fortified with 50-1,000 ng/mL of the 10 analytes. Analytical parameters evaluated and resulting data are as follows: (i) average extraction recoveries (n = 3) were better than 80%, except for MDMA (71%) and morphine (74%); (ii) inter-day and intra-day precision ranges (%CV) were 1.59-8.80% and 0.57-3.89%, respectively; (iii) calibration linearity (r 2), detection limit and quantitation limit for all analytes were >0.999, 1 and 5 ng/mL, respectively; (iv) matrix effects (ion suppression) were observed for three analytes, but were satisfactorily compensated for by the deuterated internal standards adopted in the analytical protocol. This method was successfully applied to the analysis of specimens collected from unknown death cases from various district prosecutors' offices in Taiwan, and was also found helpful to understanding whether the detected opiates were derived from heroin or legal morphine/codeine-containing medications.
Journal of analytical toxicology, Jan 24, 2017
Screening and confirming the presence of drugs and toxic compounds in various matrices are import... more Screening and confirming the presence of drugs and toxic compounds in various matrices are important and challenging tasks routinely faced by forensic and clinical laboratories. Recent advances in the liquid chromatographic and mass spectrometric technologies have provided an opportunity for the development of more specific and effective approaches to achieve the "screening" and "confirmation" goals in a single analytical step. The objectives of this study are: (i) the establishment of an ultra-high performance liquid chromatographic, quadrupole time-of-flight mass spectrometric mass spectrometric and MS-MS spectral database, including 1,200 compounds of interest; and (ii) the development of an effective protocol, using this database and three searching algorithms, for general unknown screening of these compounds. The established database and protocol were evaluated through the analysis of 30 external proficiency test and 100 postmortem samples and found to be si...
Journal of Biochemical and Biophysical Methods, 2002
Forensic Sci Int, 2001
Isotopic analogs of the analytes are currently preferred internal standards (IS) for quantitative... more Isotopic analogs of the analytes are currently preferred internal standards (IS) for quantitative analyses of drugs and their metabolites in biological matrices by GC/MS procedures. Contributions of the analyte and the IS to the intensities of ions designated for the IS and the analyte, respectively--an undesirable phenomenon termed "cross-contribution"--greatly weakens the effectiveness of this approach. The cross-contribution phenomenon has been, in the past, evaluated by a "direct measurement" approach, in which intensities of interested ions were measured in two separate experiments using equal quantities of the analyte and the IS. Alternate procedures that may generate improved results are hereby studied. For the "improved direct measurement" approach, ion intensity data derived from the previously reported direct measurement procedure are first normalized before being used to calculate the extent of cross-contribution. An "internal standard" approach is also developed, in which a set amount of a third compound is incorporated into these two separate experiments, thus allowing corrections of ion intensity data that are imbedded with variations inherent to separate experiments. Finally, a "standard addition" approach, involving a series "addition" of "standards", generates multiple data points; thus, providing a mechanism to validate the resulting cross-contribution data. Secobarbital/(2)H(5)-secobarbital and secobarbital/(13)C(4)-secobarbital pairs are adapted as the exemplar systems for this study.
J Agr Food Chem, 1984
... J. Dairy Sci. 1982, Cerkylis, J.; P ub , 0. W.; Farrell, HM, Jr. Lipids 1983,18,55-58. ... 19... more ... J. Dairy Sci. 1982, Cerkylis, J.; P ub , 0. W.; Farrell, HM, Jr. Lipids 1983,18,55-58. ... 1982, Noble, RC “Lipid Metabolism in Ruminant Animals”; Christie, WW, Ed.; Pergamon Press: New York, 1981. Parks, 0. W.; Keeney, M.; Schwartz, DPJ Dairy Sci. 1961,44, 1940-1943. ...
Forensic science review, 1993
Recent implementation of urine drug-screening policies in the workplace has resulted in an increa... more Recent implementation of urine drug-screening policies in the workplace has resulted in an increase in the submission of substituted urine specimens. Donor verification of urine specimens often becomes necessary when the origin of a specimen is in question or when a positive drug test is contested. Methods reported for the identification of the urine donor include the analysis of blood group antigenic substances (ABH and Lewis systems), polymorphic proteins (group-specific component, haptoglobin, and orosomucoid), and deoxyribonucleic acid (DNA). Since the concentrations of the antigenic substances and polymorphic proteins in urine are typically low, most serological procedures adapt a concentration step enhancing the presence of these substances in the resulting residue by a factor ranging from 100 to 3,000. Conventional (and a two-dimensional) absorption-inhibition and electrophoresis procedures can then be applied to characterize the antigenic substances and polymorphic proteins....
Yao xue xue bao = Acta pharmaceutica Sinica, 2015
A simple and selective HPLC method for simultaneous determination and quantification of anthraqui... more A simple and selective HPLC method for simultaneous determination and quantification of anthraquinones, lignans and flavonoids in Xiao-Cheng-Qi Tang (XCQT), Hou-Po-San-Wu Tang (HPSWT) and Hou-Po-Da-Huang Tang (HPDHT) was developed and validated. An Agilent Zorbax SB-C 18 (4.6 mm x 250 mm, 5 µm) column with the mobile phase of acetonitrile and 0.5% acetic acid aqueous solution in gradient elution mode was used. The flow rate was 1.0 mL · min(-1) at 30 °C, and injection volume was 10 µL. The detection wavelength was set at 254 nm and 294 nm simultaneously for the quantitative analysis. The current HPLC assay was validated for linearity, intra-day and inter-day precisions, accuracy, recovery and stability. The method was applied to the content comparison of the gallic acid, cinnamic acid, sennoside A, sennoside B, rhein, emodin, aloe-emodin, chrysophanol, physcion, magnolol, honokiol, narirutin, naringin, hesperidin, neohesperidin, hesperetin, naringenin and nobiletin in XCQT, HPSWT an...
Forensic Science Review
ABSTRACT
Biomedical & environmental mass spectrometry
ABSTRACT
Forensic Science Review
With sound analytical methodology, good laboratory practice, and intact specimen chain-ofcustody,... more With sound analytical methodology, good laboratory practice, and intact specimen chain-ofcustody, test result interpretation is the final element dictating the action to be taken following drug urinalysis. From a technical viewpoint, false test results may be reported as a result of adulteration, including the alteration of metabolic process through the intentional use of foreign material, or the outright addition of adulterants to specimens. Unintended exposure through contact or inhalation may result in the detection of targeted drug analytes at low levels, while the use of certain licit food and medicinal items, such as a salad dressing, a bagel containing poppy seeds, and Tylenol ® III, may produce positive results using commonly reporting cutoff levels. For those specimens that test positively, the following factors should be considered when interpreting the meaning of a quantitative result: analyte stability, urine water content, and time lapse between drug exposure and specimen collection.
Journal of Forensic Sciences
Journal of Oil & Fat Industries
IEEE Transactions on Information Forensics and Security, 2007
Rapid technology development and the widespread use of visual sensors have led to a number of new... more Rapid technology development and the widespread use of visual sensors have led to a number of new problems related to protecting intellectual property rights, handling patent infringements, authenticating acquisition sources, and identifying content manipulations. This paper introduces nonintrusive component forensics as a new methodology for the forensic analysis of visual sensing information, aiming to identify the algorithms and parameters employed inside various processing modules of a digital device by only using the device output data without breaking the device apart. We propose techniques to estimate the algorithms and parameters employed by important camera components, such as color filter array and color interpolation modules. The estimated interpolation coefficients provide useful features to construct an efficient camera identifier to determine the brand and model from which an image was captured. The results obtained from such component analysis are also useful to examine the similarities between the technologies employed by different camera models to identify potential infringement/licensing and to facilitate studies on technology evolution.
Journal of Chromatography A, 1987
N-(Trifluoroacetyl)-l-prolyl- (N-TFA-l-prolyl-) d- and l-amphetamine diastereoisomers were separa... more N-(Trifluoroacetyl)-l-prolyl- (N-TFA-l-prolyl-) d- and l-amphetamine diastereoisomers were separated by high-performance liquid chromatography and confirmed by an interfaced mass spectrometer system, using the commercially available N-3,5-(dinitrobenzoyl)phenylglycine chiral column. A separation factor of 1.52 and resolution of 3.8 were observed. N-TFA-l-prolyl-d- and -l-methamphetamine diastereoisomers were only partially resolved. The chiral stationary phase-solute interactions were studied by varying the mobile phase (2-propanol in hexane). Results indicate the separation mechanism proceeds via dipolar and hydrogen-bond interactions between the chiral stationary phase and the solute. A modified "dipole-stacking" model takes into account these interactions and explains the difference in separability observed for N-TFA-l-prolyl-d- and -l-amphetamine and N-TFA-l-prolyl-d- and -l-methamphetamine.
Journal of Food and Drug Analysis
This paper reviews gas chromatography-mass spectrometry (GC-MS) methods for the analysis of amphe... more This paper reviews gas chromatography-mass spectrometry (GC-MS) methods for the analysis of amphetamines, ketamines, opioids, cocaine, and other abused drugs in urine that were developed by authors in Taiwanese institutions, and published during the 2000 to early 2008 period. Information on sample preparation, derivatization, internal standard, GC column, detection mode, and validation data for the reported methods are summarized in table format to facilitate readers' reference and adaptation.
Journal of Food and Drug Analysis
Journal of Forensic Sciences
Journal of Forensic Sciences
ABSTRACT
Journal of Analytical Toxicology
Heroin, methamphetamine and ketamine have been the most commonly abused drugs in Taiwan. The pres... more Heroin, methamphetamine and ketamine have been the most commonly abused drugs in Taiwan. The presence of these drugs and their metabolites in postmortem specimens has been routinely monitored in our laboratory mostly by gas chromatographic-mass spectrometric methods. This study aimed to evaluate a more effective approach to simultaneously quantify these analytes (i.e., amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), morphine, codeine, 6-acetylmorphine, 6-acetylcodeine, ketamine and norketamine) in postmortem urine and blood specimens by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Samples (1 mL) were extracted via solid-phase extraction, evaporated and reconstituted in the mobile phase for injection into the LC-MS-MS system. Respective deuterated analogs of these analytes were used as internal standards. Chromatographic separation was achieved by an Agilent Zorbax SB-Aq analytical column at 50°C. Mass spectrometric analysis was performed by electrospray ionization in positive-ion dynamic multiple reaction monitoring mode with optimized collision energy for respective precursor ion selected for each analyte, and the monitoring of two transition ions. Performance characteristics were assessed using drug-free samples that were fortified with 50-1,000 ng/mL of the 10 analytes. Analytical parameters evaluated and resulting data are as follows: (i) average extraction recoveries (n = 3) were better than 80%, except for MDMA (71%) and morphine (74%); (ii) inter-day and intra-day precision ranges (%CV) were 1.59-8.80% and 0.57-3.89%, respectively; (iii) calibration linearity (r 2), detection limit and quantitation limit for all analytes were >0.999, 1 and 5 ng/mL, respectively; (iv) matrix effects (ion suppression) were observed for three analytes, but were satisfactorily compensated for by the deuterated internal standards adopted in the analytical protocol. This method was successfully applied to the analysis of specimens collected from unknown death cases from various district prosecutors' offices in Taiwan, and was also found helpful to understanding whether the detected opiates were derived from heroin or legal morphine/codeine-containing medications.
Journal of analytical toxicology, Jan 24, 2017
Screening and confirming the presence of drugs and toxic compounds in various matrices are import... more Screening and confirming the presence of drugs and toxic compounds in various matrices are important and challenging tasks routinely faced by forensic and clinical laboratories. Recent advances in the liquid chromatographic and mass spectrometric technologies have provided an opportunity for the development of more specific and effective approaches to achieve the "screening" and "confirmation" goals in a single analytical step. The objectives of this study are: (i) the establishment of an ultra-high performance liquid chromatographic, quadrupole time-of-flight mass spectrometric mass spectrometric and MS-MS spectral database, including 1,200 compounds of interest; and (ii) the development of an effective protocol, using this database and three searching algorithms, for general unknown screening of these compounds. The established database and protocol were evaluated through the analysis of 30 external proficiency test and 100 postmortem samples and found to be si...
Journal of Biochemical and Biophysical Methods, 2002
Forensic Sci Int, 2001
Isotopic analogs of the analytes are currently preferred internal standards (IS) for quantitative... more Isotopic analogs of the analytes are currently preferred internal standards (IS) for quantitative analyses of drugs and their metabolites in biological matrices by GC/MS procedures. Contributions of the analyte and the IS to the intensities of ions designated for the IS and the analyte, respectively--an undesirable phenomenon termed "cross-contribution"--greatly weakens the effectiveness of this approach. The cross-contribution phenomenon has been, in the past, evaluated by a "direct measurement" approach, in which intensities of interested ions were measured in two separate experiments using equal quantities of the analyte and the IS. Alternate procedures that may generate improved results are hereby studied. For the "improved direct measurement" approach, ion intensity data derived from the previously reported direct measurement procedure are first normalized before being used to calculate the extent of cross-contribution. An "internal standard" approach is also developed, in which a set amount of a third compound is incorporated into these two separate experiments, thus allowing corrections of ion intensity data that are imbedded with variations inherent to separate experiments. Finally, a "standard addition" approach, involving a series "addition" of "standards", generates multiple data points; thus, providing a mechanism to validate the resulting cross-contribution data. Secobarbital/(2)H(5)-secobarbital and secobarbital/(13)C(4)-secobarbital pairs are adapted as the exemplar systems for this study.
J Agr Food Chem, 1984
... J. Dairy Sci. 1982, Cerkylis, J.; P ub , 0. W.; Farrell, HM, Jr. Lipids 1983,18,55-58. ... 19... more ... J. Dairy Sci. 1982, Cerkylis, J.; P ub , 0. W.; Farrell, HM, Jr. Lipids 1983,18,55-58. ... 1982, Noble, RC “Lipid Metabolism in Ruminant Animals”; Christie, WW, Ed.; Pergamon Press: New York, 1981. Parks, 0. W.; Keeney, M.; Schwartz, DPJ Dairy Sci. 1961,44, 1940-1943. ...
Forensic science review, 1993
Recent implementation of urine drug-screening policies in the workplace has resulted in an increa... more Recent implementation of urine drug-screening policies in the workplace has resulted in an increase in the submission of substituted urine specimens. Donor verification of urine specimens often becomes necessary when the origin of a specimen is in question or when a positive drug test is contested. Methods reported for the identification of the urine donor include the analysis of blood group antigenic substances (ABH and Lewis systems), polymorphic proteins (group-specific component, haptoglobin, and orosomucoid), and deoxyribonucleic acid (DNA). Since the concentrations of the antigenic substances and polymorphic proteins in urine are typically low, most serological procedures adapt a concentration step enhancing the presence of these substances in the resulting residue by a factor ranging from 100 to 3,000. Conventional (and a two-dimensional) absorption-inhibition and electrophoresis procedures can then be applied to characterize the antigenic substances and polymorphic proteins....
Yao xue xue bao = Acta pharmaceutica Sinica, 2015
A simple and selective HPLC method for simultaneous determination and quantification of anthraqui... more A simple and selective HPLC method for simultaneous determination and quantification of anthraquinones, lignans and flavonoids in Xiao-Cheng-Qi Tang (XCQT), Hou-Po-San-Wu Tang (HPSWT) and Hou-Po-Da-Huang Tang (HPDHT) was developed and validated. An Agilent Zorbax SB-C 18 (4.6 mm x 250 mm, 5 µm) column with the mobile phase of acetonitrile and 0.5% acetic acid aqueous solution in gradient elution mode was used. The flow rate was 1.0 mL · min(-1) at 30 °C, and injection volume was 10 µL. The detection wavelength was set at 254 nm and 294 nm simultaneously for the quantitative analysis. The current HPLC assay was validated for linearity, intra-day and inter-day precisions, accuracy, recovery and stability. The method was applied to the content comparison of the gallic acid, cinnamic acid, sennoside A, sennoside B, rhein, emodin, aloe-emodin, chrysophanol, physcion, magnolol, honokiol, narirutin, naringin, hesperidin, neohesperidin, hesperetin, naringenin and nobiletin in XCQT, HPSWT an...
Forensic Science Review
ABSTRACT
Biomedical & environmental mass spectrometry
ABSTRACT
Forensic Science Review
With sound analytical methodology, good laboratory practice, and intact specimen chain-ofcustody,... more With sound analytical methodology, good laboratory practice, and intact specimen chain-ofcustody, test result interpretation is the final element dictating the action to be taken following drug urinalysis. From a technical viewpoint, false test results may be reported as a result of adulteration, including the alteration of metabolic process through the intentional use of foreign material, or the outright addition of adulterants to specimens. Unintended exposure through contact or inhalation may result in the detection of targeted drug analytes at low levels, while the use of certain licit food and medicinal items, such as a salad dressing, a bagel containing poppy seeds, and Tylenol ® III, may produce positive results using commonly reporting cutoff levels. For those specimens that test positively, the following factors should be considered when interpreting the meaning of a quantitative result: analyte stability, urine water content, and time lapse between drug exposure and specimen collection.
Journal of Forensic Sciences
Journal of Oil & Fat Industries