Fast fiber mode decomposition with a lensless fiber-point-diffraction interferometer: publisher's note.

This publisher's note contains corrections to Opt. Lett.46, 2501 (2021)OPLEDP0146-959210.1364/OL.426833.

Fast fiber mode decomposition with a lensless fiber-point-diffraction interferometer.

Recently, the growing interest in few-mode fibers in telecommunications and high-power lasers has stimulated the demand for fiber mode decomposition (MD). Here we present a fast fiber MD method with a lensless fiber-point-diffraction interferometer. The complex amplitude at the fiber end is achieved by the polarization phase-shifting technique and the lensless imaging technique. Then, the eigenmode coefficients are determined by the mode orthogonal operations of the complex amplitude. In the experiment, the SMF-28e fiber containing 10 linear polarized modes at the wavelength of 632.8 nm is studied for MD. The decomposition of the 50 * 50 pixels interferograms takes only 0.0168 s. The similarity of the intensity patterns of the testing light is larger than 97% before and after the MD. This new, to the best of our knowledge, method can achieve fast and accurate 10-mode MD without using any imaging systems.

Fentanyl and Driving Impairment.

The incidence of fentanyl in forensic toxicology analyses in the USA has dramatically increased over the past several years. The increase in death cases has been well studied; however, little has been reported on the impact to drug impaired driving. Fentanyl driving while under the influence of drugs (DUID) case data from 2014 to 2019 is presented. The data were obtained from three toxicology laboratories in the Northeast, Southeast, and Midwest regions of the USA. Fentanyl whole blood concentrations ranged from 0.1 to 157 ng/mL in living drivers with a 466% to 524% increase in fentanyl-positive DUID cases from 2014 to 2019, depending on the US region. The vast majority of fentanyl cases involved poly-drug use. Twenty case histories are presented where fentanyl was the only drug identified. The mean (standard deviation) fentanyl concentration for these cases was 5.2 ± 3.8 ng/mL with a median of 3.7 ng/mL, and the concentrations ranged from 2.0 to 16 ng/mL. Naloxone administration was documented in exactly half of these cases similar to another study involving carfentanil-impaired driving. The case histories also demonstrate that some recreational opioid users may display limited signs of impairment either due to tolerance or naloxone administration. The top three observations in common among the cases were the driver was found unresponsive behind the wheel, the vehicle left the travel lane or roadway, and the driver was involved in a crash. The increase in fentanyl use not only poses a risk for overdose and death, but is also a significant concern for traffic safety. This study supports the movement of fentanyl from a Tier II drug to Tier I due to its significant potential for impairment and increase in prevalence in impaired driving cases.

Driving Under the Influence of Drugs: When the Law Misses the Mark.

According to Florida law, an individual is not guilty of driving under the influence of drugs unless impairment is observed and is due to one or more controlled drugs listed in the Florida Statutes. Many prescription drugs, over-the-counter drugs and novel psychoactive compounds that can cause significant impairment are not included in this list. Five other states within the USA including Alaska, Hawaii, Massachusetts, New York and Oregon have similar or other restrictive language in their impaired driving statutes. From January of 2007 to February of 2018, 1,344 blood specimens and 1,796 urine specimens were analyzed for drugs in impaired driving cases in Palm Beach County, Florida. Over the past 11 years, 21% (212 out of 1,028) of all drug-positive blood specimens and 47% (711 out of 1,527) of all drug-positive urine specimens contained at least one non-controlled drug, often mixed with controlled drugs. Despite documentation of observed impairment with the concurrent identification of impairing drugs, an impaired driving charge could not be supported due to the phrasing of the law in Florida. If the intent of drug-impaired driving laws is to improve safety by removing impaired drivers from the road, a more all-encompassing "any impairing drug" law would be more appropriate. Linking the charge to a drug possession law framework or using other restrictive language is not the most effective means to improve road safety.

Cost/Benefit Analysis of Case Management Policies in a DUI Lab.

A study was previously conducted and published describing the magnitude of the under-reporting of drugs in driving under the influence (DUI) cases by using a blood drug screen (BDS) case management protocol and to determine whether not reporting those drugs would have a meaningful impact on the DUI cases. A follow-up study presented herein was conducted to generate a larger dataset for evaluation and to compare the results to the original study. For this follow-up study of 576 cases, the laboratory BDS protocol was modified so that a BDS was performed for all felony cases and all misdemeanor cases with a BAC < 0.15 g/dL, regardless of the officer's request. A cost analysis estimate was also conducted using purchasing and statistical data for calendar year 2014. It was estimated that on average a BDS had a materials cost 30 times greater than a BAC and required over six times as much analyst time. To perform a BDS on every case as has been recommended, the estimated analysis materials cost and analyst time were 218 and 193% of the old protocol, respectively. The results of this follow-up study futher support the insufficiency of presenting drug positivity as a justification for completing drug analysis on every DUI case. For the vast majority of cases with a BAC > 0.08 g/dL, the drugs detected are not significant for supporting a DUI and do not warrant the substantial increase in analysis cost and time required.

An Efficient, Robust Method for the Determination of Cannabinoids in Whole Blood by LC-MS-MS.

Due to the high prevalence of cannabinoids in forensic toxicology casework, it is desirable to have an efficient method that uses a small volume of blood and requires a minimal sample preparation. Although many methods have been reported, they are often labor intensive, require special sample preparation materials, use 1 mL or more of specimen or are difficult to replicate. The liquid chromatography with tandem mass spectrometry (LC-MS-MS) method presented herein employs a rapid and simple liquid-liquid extraction, has been successfully applied in two different laboratories, uses 0.5 mL of specimen and was extensively validated. The validated limit of detection and limit of quantitation were 1 ng/mL for delta-9-tetrahydrocannabinol (THC) and 11-hydroxy-delta-9-tetrahydrocannabinol (OH-THC) and 5 ng/mL for 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THCA). Each analyte demonstrated a zero-order linear range (r2 > 0.990) with 1/x weighting of 1-40 ng/mL for THC and OH-THC and 5-200 ng/mL for THCA. The coefficient of variation of replicate analyses was within 14%. Bias was within ±13% of the prepared concentration. The validated method provides a sensitive, efficient and robust procedure for the quantitation of cannabinoids in blood using LC-MS-MS and a sample volume of 0.5 mL.

Long-Term Blood Alcohol Stability in Forensic Antemortem Whole Blood Samples.

The effect of long-term room temperature storage on the stability of ethanol in whole blood specimens was investigated. One hundred and seventeen preserved whole blood case samples (110 of 117 with two tubes of blood in each case) were used for this study. One tube from each case was initially tested for blood alcohol concentration (BAC) for criminal driving under the influence proceedings. Cases positive for ethanol ranged in BAC from 0.023 to 0.281 g/dL. The second tube, if present, remained sealed. All blood samples were then stored at room temperature. After 5.4-10.3 years, the opened tubes were reanalyzed for BAC by the same laboratory that performed the initial testing using the same method and same instrumentation. After the same storage period, the unopened tubes were sent to a different laboratory, using a different method and different instrumentation, and reanalyzed for BAC after a total of 5.6-10.5 years of room temperature storage. Seven samples initially negative for alcohol remained negative. All samples initially positive for ethanol demonstrated a decrease in BAC over time with a statistically significant difference in loss observed based on blood sample volume and whether or not the tube had been previously opened. The decrease in BAC ranged from 0.005 to 0.234 g/dL. Tubes that were not previously opened and were more than half full demonstrated better BAC stability with 89% of these tubes demonstrating a loss of BAC between 0.01 and 0.05 g/dL.

Case management in a DUI lab: effect on drugs reported.

An evaluation of an internal laboratory decision to implement a protocol for limiting drug testing based on ethanol concentration in laboratory analysis for driving under the influence (DUI) cases is presented. The described case management strategy is supported by known impairment of ethanol at relatively high concentrations, difficulty assigning a level of contributing impairment from drugs in the presence of high ethanol levels and the likelihood that the drug results may be suppressed at trial. Although the results of this study reinforce the assertion that such protocols lead to the under reporting of drugs in DUI cases, for the majority of cases, 95% in this study, the drug analysis results were not significant and did not warrant the time and resources needed for the additional blood drug testing. Furthermore, the study demonstrated that a high drug positivity rate does not necessarily mean that those drug results are legally or pharmacologically meaningful. Additional research should be conducted with quantitative drug results and casework impact of blood drug screen protocols as previous studies only report drug positivity rates and not whether the drug results would be meaningful to the case.

Identification of volatiles by headspace gas chromatography with simultaneous flame ionization and mass spectrometric detection.

Volatiles are frequently abused as inhalants. The methods used for identification are generally nonspecific if analyzed concurrently with ethanol or require an additional analytical procedure that employs mass spectrometry. A previously published technique utilizing a capillary flow technology splitter to simultaneously quantitate and confirm ethyl alcohol by flame ionization and mass spectrometric detection after headspace sampling and gas chromatographic separation was evaluated for the detection of inhalants. Methanol, isopropanol, acetone, acetaldehyde, toluene, methyl ethyl ketone, isoamyl alcohol, isobutyl alcohol, n-butyl alcohol, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane (Norflurane, HFC-134a), chloroethane, trichlorofluoromethane (Freon®-11), dichlorodifluoromethane (Freon®-12), dichlorofluoromethane (Freon®-21), chlorodifluoromethane (Freon®-22) and 1,2-dichlorotetrafluoroethane (Freon®-114) were validated for qualitative identification by this method. The validation for qualitative identification included evaluation of matrix effects, sensitivity, carryover, specificity, repeatability and ruggedness/robustness.

Ethanol analysis by headspace gas chromatography with simultaneous flame-ionization and mass spectrometry detection.

Ethanol is the most frequently identified compound in forensic toxicology. Although confirmation involving mass spectrometry is desirable, relatively few methods have been published to date. A novel technique utilizing a Dean's Switch to simultaneously quantitate and confirm ethyl alcohol by flame-ionization (FID) and mass spectrometric (MS) detection after headspace sampling and gas chromatographic separation is presented. Using 100 µL of sample, the limits of detection and quantitation were 0.005 and 0.010 g/dL, respectively. The zero-order linear range (r(2) > 0.990) was determined to span the concentrations of 0.010 to 1.000 g/dL. The coefficient of variation of replicate analyses was less than 3.1%. Quantitative accuracy was within ±8%, ±6%, ±3%, and ±1.5% at concentrations of 0.010, 0.025, 0.080, and 0.300 g/dL, respectively. In addition, 1,1-difluoroethane was validated for qualitative identification by this method. The validated FID-MS method provides a procedure for the quantitation of ethyl alcohol in blood by FID with simultaneous confirmation by MS and can also be utilized as an identification method for inhalants such as 1,1-difluoroethane.

A study of blood alcohol stability in forensic antemortem blood samples.

The effect of long-term storage on alcohol stability in preserved forensic antemortem blood samples was investigated. Thirty-two whole blood case samples (each with two tubes of blood) were used for this study. One tube from each case was analyzed for blood alcohol concentration (BAC) for court proceedings of driving under the influence (DUI), and all blood samples were then stored under refrigeration. After the storage time (ranging from 13 to 39 months) both tubes of blood for each case were reanalyzed for BAC and the results were compared to the original analysis. Seven samples originally negative for alcohol analysis remained negative. The comparative data for 25 samples demonstrated various losses in BAC in both tubes. A significant loss with a mean of 0.015g/dL, was observed in previously opened tubes compared to a mean loss of 0.010g/dL in unopened tubes. In order to determine the effect of other storage conditions, the same blood samples were then stored at room temperature for 6 months followed by 38°C for 7 and 28 days and analyzed for BAC at the end of each storage time period. The seven alcohol negative cases remained negative when stored at room temperature or at 38°C. Six months of storage at room temperature decreased BAC further for both tubes of the alcohol positive cases with a mean loss of 0.014g/dL. Further storage at 38°C for 7 days did not cause any significant change in BAC. Storage at 38°C for 28 days caused some loss in BAC which was determined to be significant by statistical analysis.

Quantitation of opioids in whole blood by electron impact-gas chromatography-mass spectrometry.

Opioids are frequently encountered in Forensic Toxicology casework. A PubMed literature search was conducted to find a method using electron impact-gas chromatography-mass spectrometry to examine whole blood specimens. A previously published method was identified, and an updated version was provided by the State of North Carolina Office of the Chief Medical Examiner. This procedure was used as a starting point for development and validation of a refined procedure to be used in the Palm Beach County Sheriff's Office Forensic Toxicology laboratory for routine analysis of antemortem forensic toxicology case samples. Materials and instrumentation common to most forensic toxicology laboratories were utilized while obtaining detection limits from 1 to 10 ng/mL and quantitation limits of 2.5 to 10 ng/mL using 1 mL of whole blood. Target compounds were chosen based on applicability to the method as well as availability and common use in the United States and include dihydrocodeine, codeine, morphine, hydrocodone, 6-monoacetylmorphine, hydromorphone, oxycodone, and oxymorphone. Each analyte demonstrated two zero-order linear ranges (r(2) > 0.990) over the concentrations evaluated (from 2.5 to 500 ng/mL). The coefficient of variation of replicate analyses was less than 12%. Quantitative accuracy was within ± 27% at 2.5 ng/mL, ± 11% at 10 ng/mL, and ± 8% at 50 ng/mL. The validated method provides a more sensitive procedure for the quantitation of common opioids in blood using standard laboratory equipment and a small amount of sample.

Quantitation of benzodiazepines in whole blood by electron impact-gas chromatography-mass spectrometry.

Benzodiazepines are frequently encountered in forensic toxicology. A literature search was conducted to find a simple method using electron impact-gas chromatography-mass spectrometry (EI-GC-MS) to examine whole blood specimens for the most commonly encountered benzodiazepines in the United States. A recently published method was identified in the literature search and used as a starting point for development of a new procedure to be used for routine analysis of forensic toxicology case samples. The procedure was then developed and validated as a rapid and efficient method for the screening and quantitation of benzodiazepines in blood using liquid-liquid extraction and EI-GC-MS in selective ion monitoring mode. Materials and instrumentation common to most forensic toxicology laboratories were utilized while obtaining LODs from 5 to 50 ng/mL and LOQs of 50 ng/mL or less using 1 mL of sample. Target compounds were chosen based on availability and common use in the United States and include diazepam, desalkylflurazepam, nordiazepam, midazolam, oxazepam, temazepam, lorazepam, clonazepam, and alprazolam (relative elution order). The linear range (r2 > 0.990) was validated from 50 to 1000 ng/mL for all analytes. The CV of replicate analyses at both 50 and 200 ng/mL was less than 4%. Quantitative accuracy was within +/- 16% at 50 ng/mL and within +/- 7% at 200 ng/mL. The validated method provides an efficient procedure for the quantitation of a broad range of the most common benzodiazepines in blood at meaningful limits of detection and quantitation using standard laboratory equipment and a small amount of sample.