Investigation of polychlorinated biphenyl removal from contaminated soil using microwave-generated steam.

A feasibility study of polychlorinated biphenyl (PCB) removal from contaminated soils using microwave-generated steam (MGS) was performed. Initial experimental results show that MGS effectively removed PCBs from contaminated soil with an overall removal efficiency of greater than 98% at a steam-to-soil mass ratio of 3:1. Removal efficiency was found to be dependent upon the amount of steam employed, expressed as a mass ratio of steam applied to soil mass. Evaporation was identified as a major mechanism in removing PCBs from the soil. Rapid expansion and evaporation of pore water by microwave dielectric heating accelerated evaporation rates of PCB molecules. Increased solubility of PCBs into the heated aqueous phase is also hypothesized. Together these effects increase mass-transfer rates, thus enhancing removal of PCBs from the soil.

Comparison of real-time instruments used to monitor airborne particulate matter.

Measurements collected using five real-time continuous airborne particle monitors were compared to measurements made using reference filter-based samplers at Bakersfield, CA, between December 2, 1998, and January 31, 1999. The purpose of this analysis was to evaluate the suitability of each instrument for use in a real-time continuous monitoring network designed to measure the mass of airborne particles with an aerodynamic diam less than 2.5 microns (PM2.5) under wintertime conditions in the southern San Joaquin Valley. Measurements of airborne particulate mass made with a beta attenuation monitor (BAM), an integrating nephelometer, and a continuous aerosol mass monitor (CAMM) were found to correlate well with reference measurements made with a filter-based sampler. A Dusttrak aerosol sampler overestimated airborne particle concentrations by a factor of approximately 3 throughout the study. Measurements of airborne particulate matter made with a tapered element oscillating microbalance (TEOM) were found to be lower than the reference filter-based measurements by an amount approximately equal to the concentration of NH4NO3 observed to be present in the airborne particles. The performance of the Dusttrak sampler and the integrating nephelometer was affected by the size distribution of airborne particulate matter. The performance of the BAM, the integrating nephelometer, the CAMM, the Dusttrak sampler, and the TEOM was not strongly affected by temperature, relative humidity, wind speed, or wind direction within the range of conditions encountered in the current study. Based on instrument performance, the BAM, the integrating nephelometer, and the CAMM appear to be suitable candidates for deployment in a real-time continuous PM2.5 monitoring network in central California for the range of winter conditions and aerosol composition encountered during the study.

Observations and model simulations of carbon monoxide emission factors from a California highway.

A series of twelve intensively monitored 1-hr CO dispersion studies were conducted near Davis, CA, in winter 1996. The experimental equipment included twelve CO sampling ports at elevations up to 50 m, three sonic anemometers, a tethersonde station, aircraft measurements of wind and temperature profile aloft, and a variety of conventional meteorological equipment. The study was designed to explore the role of vehicular exhaust buoyancy during worst-case meteorological conditions, such as low winds oriented in near-parallel alignment with the road during a surface-based nocturnal inversion. From the study, field estimates of the CO emission factor (EF) from a California vehicle fleet were computed using two different methods. The analysis suggests that the CT-EMFAC/EMFAC (EMission FACtor) models currently used to conduct federal conformity modeling significantly overpredict CO emissions for high-speed, free-flowing traffic on California highways.

Is total knee replacement more painful than total hip replacement?

BACKGROUND: During its use in pain management the patient-controlled analgesia (PCA) devices are capable of registering the course of treatment at patient request, the condition of drug delivery and total amount of drug being given. The patients could determine the need of medication to their own satisfaction while forced treatment by the bias of the health care personnel is avoided and the safety of patients is further warranted. In pain relief with this device, the number of requests for analgesia and the dose of analgesic used can be easily measured. Therefore, it is more objective to compare the pain intensity among different types of operation when PCA device is used. Using PCA morphine consumption as a parameter, we attempted to elucidate the difference of intensity of pain associated with total hip and total knee replacements by comparing their morphine requirement. METHODS: In this prospective cohort study, 50 patients who underwent either total hip replacement (THR, n = 24) or total knee replacement (TKR, n = 26) were enrolled. After recovery from general anesthesia when the patients first complained intense pain in the recovery room, morphine was given intravenously in titration with a calculated loading dose in 30 min to achieve an acceptable analgesia (VAS < or = 3) followed by morphine PCA at 1 mg bolus with a lockout interval of 6 min. The patients were then followed for 48 h. During and at the end of the course the data relevant to pain score, total dose, demand, delivery, and adverse effects were recorded for assessment. RESULTS: With the use of PCA, the pain scores were similar in both surgical groups in the 48 h observation. Total consumption of morphine in THR was 13.2 +/- 8.1 mg as against 19.7 +/- 5.7 mg in TKR in postoperative day 1 and 25.2 +/- 12.7 mg as against 34.1 +/- 13.9 mg in postoperative day 2 (P < 0.05, t-test). Demand/delivery ratio was not statistically significant between the 2 groups at 24 and 48 h (t-test). Minor adverse effects were seen in both groups but the differences were not significant. CONCLUSIONS: Using PCA morphine consumption as parameter, we can distinguish the magnitude of pain intensity between 2 major orthopedic surgeries. The deeper and more extensive operation would in total hip replacement does not mean that it is a more painful procedure than total knee replacement. Several speculations are proposed.

Enzyme-linked immunosorbent assay for the pyrethroid permethrin.

Permethrin is a predominant pyrethroid widely used in agriculture and public health. A competitive enzyme-linked immunosorbent assay (ELISA) for the detection of permethrin was developed. Two haptens, the trans- and cis-isomers of 3-(4-aminophenoxy)benzyl-3-(2, 2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate, were synthesized and conjugated with thyroglobulin as immunogens. Four antisera were generated and screened against six different coating antigens. The resulting ELISA has an I(50) value of 2.50 microg/L and relatively low cross-reactivities with other major pyrethroids, such as esfenvalerate, cypermethrin, deltamethrin, and cyfluthrin. Methanol was found to be the best solvent for this ELISA, with optimal sensitivity observed at a concentration of 40% (v/v). The assay parameters are unchanged at pH values between 5.0 and 8.0, whereas higher ionic strengths (>0.2 M PBS) strongly suppress the absorbances. River water samples fortified with permethrin were analyzed according to this method and validated by GC-MS. Good recoveries and correlation with spike levels were observed, suggesting this immunoassay is valuable for environmental monitoring and toxicological studies at parts per trillion levels of permethrin.

Acute jaundice in pregnancy: acute fatty liver or acute viral hepatitis?

In this case, the difficulty in differential diagnosis between acute viral hepatitis and acute fatty liver of pregnancy was analyzed. These 2 conditions often raise controversal question regarding the decision making on emergency anesthesia for cesarean section to avert complications and optimize management. The dilemma in which an anesthesiologist is put is whether to promise the anesthesia straightaway in the face of a demonstrable acute jaundice in pregnancy to advise a postponement of surgery until a turn for the better. In this embarrassing situation, the authors suggest that a postpronement of surgery is rational to observe the development during which both the mother and the fetus should be closely monitored. Once the necessity of a cesarean section outweighs the benefit of transitional conservative treatment, it should be performed immediately.

The peripheral analgesic effect of tramadol in reducing propofol injection pain: a comparison with lidocaine.

BACKGROUND AND OBJECTIVES: Tramadol and metoclopramide have a local anesthetic effect similar to lidocaine following intradermal injection. When metoclopramide was retained in the venous system for 1 minute, it was found to be as effective as lidocaine in reducing propofol injection pain. Using this metoclopramide model, the effects of tramadol in reducing pain on propofol injection was investigated. METHODS: One hundred five patients were randomly allocated to receive 50 mg tramadol (group T), 60 mg lidocaine (group L), or normal saline (group NS) as pretreatment to reduce pain on propofol injection. Following venous occlusion with a tourniquet (70 mm Hg), one of the drugs was intravenously administered. Venous retention of the drug was maintained for 1 minute. Immediately after the tourniquet release, intravenous injection of 100 mg propofol (10 mL) at a rate of 0.5 mL/s followed. Pain assessment was made after each injection. RESULTS: Transient minor injection pain and local skin reactions were significantly greater with tramadol than with lidocaine (P < .05). Both tramadol and lidocaine significantly reduced the incidence and intensity of propofol injection pain when compared with normal saline (P < .05). CONCLUSIONS: Using -minute retention in veins, both tramadol and lidocaine significantly reduced propofol injection pain. A local anesthetic activity is postulated.

Pain on injection of propofol: the mitigating influence of metoclopramide using different techniques.

BACKGROUND: Metoclopramide administered intravenously (i.v.) immediately before injection of propofol, after mixing with propofol, or after a rubber tourniquet for 1 min before propofol injection will reduce pain induced by propofol injection. In this study, these three different techniques in reducing propofol injection pain with metoclopramide were compared with lidocaine or saline to evaluate the most effective method in reducing propofol injection pain. METHODS: In a randomized, semi-double-blind treatment, 175 patients were included into this study. Patients in group A were pretreated with metoclopramide 10 mg i.v. before propofol (2 mg/kg) induction. Patients in group B were induced with a mixture of propofol and metoclopramide. Patients in group C were pretreated with metoclopramide i.v. with a rubber tourniquet on the arm for 1 min followed by propofol administration. Groups D and E were identical to group C except for the replacement of pretreatment with either lidocaine (40 mg) or saline, respectively. RESULTS: Groups A, C and D (with active pain prophylaxis) showed a significantly less incidence of pain than the saline control group (E) as propofol was injected. There was no significance difference between metoclopramide and lidocaine in reducing propofol injection pain using a tourniquet technique. The intensity of the propofol injection pain (verbal pain score) was stronger with saline as compared with the other groups. CONCLUSIONS: We conclude that i.v. retention of metoclopramide with tourniquet is as good as lidocaine and may be a useful alternative for reducing pain on propofol injection.

The effects of tramadol versus fentanyl in attenuating hemodynamic response following tracheal intubation.

BACKGROUND: Tramadol is a novel central acting analgesic. It has been used as a complement to general anesthesia and an effective agent for postoperative analgesia. However, the influence of tramadol on the hemodynamic response following laryngoscopy and tracheal intubation is less known. METHODS: Forty patients of both sexes, 16-50 year old, ASA physical status I or II, scheduled for elective surgery were randomly divided into equal groups in this prospective, double blind study. After obtaining the baseline data, the patient was given 3 micrograms/kg fentanyl (Group F) or 3 mg/kg tramadol (Group T). Then induction of anesthesia in a uniform and standardized manner was carried out by an anesthesiologist who was blind to the medication. The hemodynamic parameters were measured and recorded immediately after induction but prior to laryngoscopy, 3, 6, and 9 min after intubation, and before incision. We also observed any unusual effect in the postoperative care unit. Chi-square test, Student's t-test and paired t-test were used for statistical comparison. A P less than 0.05 was considered statistically significant. RESULTS: All patients had a successful induction and intubation. Differences in baseline values were not significant, nor were the differences in the values following induction. After laryngoscopy and intubation, heart rate increased significantly above the baseline level in both groups. The increase of heart rate was significantly more at 6 and 9 min (P < 0.05) and lasted longer in the tramadol group. After intubation, systolic, mean and diastolic arterial pressure (SAP, MAP, DAP) increased significantly above baseline in both groups too, except for DAP in fentanyl group. At 6 and 9 min, the MAP and DAP were significantly higher in tramadol than in fentanyl group (P < 0.05). Six patients in tramadol group had mild pain on injection of tramadol. CONCLUSIONS: When administered right before thiopental induction, 3 mg/kg tramadol did not display a better attenuation against the increase of hemodynamic profiles than did 3 micrograms/kg fentanyl following tracheal intubation.

Local anesthetic effect of tramadol, metoclopramide, and lidocaine following intradermal injection.

BACKGROUND AND OBJECTIVES: We observed clinically that tramadol and metoclopramide appear to have local anesthetic action. Tramadol is a central-acting analgesic. Metoclopramide is a commonly used antiemetic. The local anesthetic effect of tramadol in reducing propofol injection pain has never been mentioned, although it was speculated with metoclopramide. METHODS: We conducted a double-blind, placebo-controlled study by injecting tramadol or metoclopramide intradermally in 10 healthy volunteers (5 men, 5 women; age 25-56 years). Each subject received 0.5 mL of four solutions in random order on the volar side of the forearm. These solutions were 25 mg tramadol, 5 mg metoclopramide, 5 mg lidocaine, and 0.5 mL normal saline. Pain on injections and the degree of local anesthesia (tested by pinprick, light touch, and cold) at each site was reported on a 0-3 scale at designed time intervals. RESULTS: Like 1% lidocaine, tramadol and metoclopramide demonstrated loss of sensation for pinprick, light touch, and cold for 15 minutes after intradermal injection (P < .01 ). CONCLUSIONS: Intradermal tramadol or metoclopramide can produce local anesthetic effect.

Application of spinal pain mapping in the diagnosis of low back pain--analysis of 104 cases.

BACKGROUND: Low back pain is probably the most common pain problem seen in a general pain clinic and the cause of low back pain can be enigmatic at times. Often the pain sources are difficult to identify with the conventional diagnostic modalities. Spinal pain mapping is a sequence of well organized nerve block procedures. We undertook this study to evaluate the usefulness of this modality in diagnosing low back pain of uncertain etiology. METHODS: In this prospective study, 104 consecutive adult patients who underwent spinal pain mapping were examined and analyzed. All patients had intractable low back pain of undetermined etiology after medical history, physical examination and 4-view roentgenographic evaluation of the lumbar spine had been undertaken to locate it. In addition, 41 patients (39%) had one or more of the following tests done, which included CT, MRI, EMG/NC but all failed to delineate the causes of the pain. All patients failed to respond to the conservative therapies. RESULTS: With pain mapping the source of pain was found to be caused by sacro-iliac joint in 6%, lumbar nerve root in 20%, facet joint in 24%, combined lumbar nerve root and facet disease in 24%, internal disc disorder in 7%, combined facet and sacro-iliac joint in 4% and lumbar sympathetic dystrophy in 2% of patients. Pain mapping failed to demonstrate the causes of the pain in the remaining 13% of the patients. CONCLUSIONS: Considering the difficult nature of this group of patients, spinal pain mapping provided a useful functional approach to the diagnosis of low back pain with obscure etiology in 87% of patients in our series.

Negative pressure pulmonary oedema induced by direct suctioning of endotracheal tube adapter.

PURPOSE: Negative pressure pulmonary oedema (NPPE) is a well-recognized but rare complication secondary to upper airway obstruction such as laryngeal spasm during emergence from general anaesthesia. Cauterization of the second and third thoracic sympathetic ganglia is a treatment for hyperhidrosis of the hands. We report a case of NPPE induced by direct suctioning of the endotracheal tube adapter during thoracic sympathetic ganglionectomy without recognized upper airway obstruction. CLINICAL FEATURES: A 19-yr-old otherwise healthy, non-smoking man was scheduled for elective bilateral chest endoscopic ablation of the second and third thoracic sympathetic ganglion for hyperhidrosis of the hands under general anaesthesia. To view and cauterize the ganglion with the endoscope, the surgeon requested cessation of positive pressure ventilation. As the surgeon could not satisfactorily visualize the target ganglia, he requested brief application of wall suction via the ETT tube adapter. A pressure of -100 mmHg was generated which lasted for three to four seconds. The goal was to reduce further the lung volume by increasing the pneumothorax produced by the endoscope. The patient developed negative pressure pulmonary oedema without upper airway obstruction. CONCLUSION: This case demonstrated that intrathoracic negative pressure generated by direct ETT adapter suctioning may produce pulmonary oedema similar to that induced by laryngeal spasm during the emergence of general anaesthesia.

A case study in innovative outreach--combining training, research, and technology transfer to address real-world problems.

Outreach, training, technology transfer, and research are often treated as programmatically distinct activities. The interdisciplinary and applied aspects of the Superfund Basic Research Program offer an opportunity to explore different models. A case study is presented that describes a collaborative outreach effort that combines all of the above. It involves the University of California's Davis and Berkeley program projects, the University of California Systemwide Toxic Substances Research and Teaching Program, the U.S. Navy's civilian workforce at the former Mare Island Naval Shipyard, Vallejo, California (MINSY), a Department of Defense (DoD) Environmental Education Demonstration Grant program, and the Private Industry Council of Napa and Sonoma counties in California. The effort applied a Superfund-developed technology to a combined waste, radium and polychlorinated biphenyl contamination, stemming from a problematic removal action at an installation/restoration site at MINSY. The effort demonstrates that opportunities for similar collaborations are possible at DoD installations.

Denitrification and nitric oxide reduction in an aerobic toluene-treating biofilter.

The presence of significant denitrification activity in an aerobic toluene-treating biofilter was demonstrated under batch and flow-through conditions. N2O concentrations of 9.2 ppmv were produced by denitrifying bacteria in the presence of 15% acetylene, in a flow-through system with a bulk gas phase O2 concentration of >17%. The carbon source for denitrification was not toluene but a byproduct or metabolite of toluene catabolism. Denitrification conditions were successfully used for the reduction of 60 ppmv nitric oxide to 15 ppmv at a flow rate of 3 L min-1 (EBRT of 3 min) in a fully aerated, 17% v/v O2 (superficially aerobic) biofilter. Higher NO removal efficiency (97%) was obtained by increasing the toluene supply to the biofilter.

Intradermal injection of tramadol has local anesthetic effect: a comparison with lidocaine.

BACKGROUND: We observed that intravenous retention of tramadol with a pneumatic tourniquet on the arm inflated to 70 mmHg for one minute could effectively reduce the subsequent propofol injection pain. Tramadol is a central-acting analgesic. The local analgesic effect of tramadol on reducing propofol injection pain is not well known. METHODS: To explore this problem we conducted a double-blind study on intradermal injections of tramadol 25 mg, lidocaine 5 mg and normal saline (all in 0.5 ml volume) which were given to each of the 10 healthy volunteers on the forearm at random. Pain on injections and the degree of local analgesia to pinprick, light touch and cold at each injection site were scored on a 0-4 scale at designated intervals. RESULTS: 5% tramadol, similar to 1% lidocaine, rendered loss of sensation to pin prick, light touch and cold for 30 min after intradermal injection as compared with normal saline (p < 0.01). CONCLUSIONS: We concluded that intradermal injection of tramadol or lidocaine can produce local anesthetic effect.

Comparison of intravenous retention of fentanyl and lidocaine on local analgesia in propofol injection pain.

BACKGROUND: With a tourniquet on arm for arresting venous blood flow, we evaluated the efficacy of intravenous (i.v.) retention of fentanyl and lidocaine in reducing the pain on i.v. propofol injection during general anesthesia. METHODS: One hundred and twelve patients were studied. Following a venous occlusion by a tourniquet inflated to 70 mmHg, patients in Group A (n = 38) received normal saline (NS) 3 ml, while those in Group B (n = 37) and in Group C (n = 37) respectively received fentanyl 150 micrograms or 3 ml and 2% lidocaine 3 ml (60 mg). The venous retention of drug was maintained for 1 min, followed immediately by tourniquet release and propofol 100 mg i.v. injection over 20 s. RESULTS: Both fentanyl and lidocaine treatments (Groups B and C) were significantly better than placebo (Group A) in reducing pain on propofol injection (p < 0.005). Lidocaine 60 mg was more effective than fentanyl 150 micrograms in reduction of pain associated with i.v. propofol (p < 0.001). Injection of fentanyl itself caused pain in 28% of patients as compared to 2% in the lidocaine group. Mild local skin erythema was noted in 14% of patients with fentanyl venous retention versus 0% of patients with lidocaine venous retention. CONCLUSIONS: Intravenous retention of fentanyl 150 micrograms, although less effective than that of lidocaine (p < 0.001), showed local analgesic effect in reducing the pain on propofol injection. The hypothetic mechanisms of action were speculated.

Speciation of arsenic oxides using laser desorption/ionization time-of-flight mass spectrometry.

Positive and negative ion mass spectra of arsenic trioxide (As2O3) and arsenic pentaoxide (As2O5) have been obtained by single-step laser desorption/ionization time-of-flight mass spectrometry. Pulsed UV radiation at 266 nm was used for the simultaneous desorption and ionization of the solid sample. High-mass cluster ions that are unique to the oxidation state of each oxide sample appear in the negative ion mass spectra. The As2O3 produces As3O5-, while the As2O5 yields As3O8-. The formation of unique negative cluster ions presents the capability for arsenic oxidation state speciation by laser desorption/ionization mass spectrometry. The ability of time-of-flight mass spectrometry to examine the relative amounts of each arsenic oxide present in a series of mixtures is discussed. Application of our speciation technique to a model incinerator sample is demonstrated.

Shortening and superlon-wrapping the downstream tube can increase the useful range of the blood warmer.

BACKGROUND: Hypothermia occurs frequently in clinical anesthesia. Many apparatus were introduced to keep intravenous fluid warm. But at low to medium flow rates little effects have been achieved because of heat lost along the tube. Superlon, an industrial heat-preserving material widely used in air conditioning to prevent temperature change, has never been used in the blood warmer. METHODS: The study was performed in three groups group I using standard (120 cm) unwrapped tube (Animac AM-4 set), group II using a shortened downstream tube (60 cm), and group III using the downstream tube which was further wrapped with superlon (Super LTD). The blood warmer used was identical in all 3 groups. We recorded the fluid temperatures at different points downstream at various flow rates. The values were then compared among groups. RESULTS: The fluid temperatures before entering the warmer were around 20 degrees C and 37 degrees C at the 2 cm post-warmer points at various flow rates. The end point temperatures rose with flow rates and were the highest in group III and lowest in group I at each flow rate (p < 0.01). In group III the temperature could be kept above 32 degrees C at a very low flow rate (150 ml/h) and above 35 degrees C at 300 ml/h. In group I, 1,000 to 2,000 ml/h were needed to keep the same temperature. CONCLUSIONS: These refinements increase the useful range of the Animac AM-4 warmer and make it useful in pediatric rapid fluid resuscitation and current fluid management. Moreover, they are easy to set up, inexpensive, and can be applied to any kind of blood warmers.

Dioxinlike properties of a trichloroethylene combustion-generated aerosol.

Conventional chemical analyses of incineration by-products identify compounds of known toxicity but often fail to indicate the presence of other chemicals that may pose health risks. In a previous report, extracts from soot aerosols formed during incomplete combustion of trichloroethylene (TCE) and pyrolysis of plastics exhibited a dioxinlike response when subjected to a keratinocyte assay. To verify this dioxinlike effect, the complete extract, its polar and nonpolar fractions, some containing primarily halogenated aromatic hydrocarbons, were evaluated for toxicity using an embryo assay, for antiestrogenicity using primary liver cell cultures, and for the ability to transform the aryl hydrocarbon receptor into its DNA binding form using liver cytosol in a gel retardation assay. Each of these assays detect dioxinlike effects. Medaka (Oryzias latipes) embryos and primary liver cell cultures of rainbow trout (Oncorhynchus mykiss) were exposed to concentrations of extract ranging from 0.05 to 45 micrograms/l. Cardiotoxicity with pericardial, yolk sac, and adjacent peritoneal edema occurred after exposure of embryos to concentrations of 7 micrograms/l or greater. These same exposure levels were associated with abnormal embryo development and, at the higher concentrations, death. Some of the fractions were toxic but none was as toxic as the whole extract. In liver cells, total cellular protein and cellular lactate dehydrogenase activity were not altered by in vitro exposure to whole extract (0.05-25 micrograms/l). However, induction of cytochrome P4501A1 protein and ethoxyresorufin O-deethylase activity occurred. In the presence of whole extract, estradiol-dependent vitellogenin synthesis was reduced. Of the fractions, only fraction 1 (nonpolar) showed a similar trend, although vitellogenin synthesis inhibition was not significant. The soot extract and fractions bound to the Ah receptor and showed a significantly positive result in the gel retardation/DNA binding test. Chemical analyses using GC-MS with detection limits for 2,3,7,8-tetrachlorodibenzo-p-dioxin and dibenzofuran in the picomole range did not show presence of these compounds. Our results indicate that other chemicals associated with TCE combustion and not originally targeted for analysis may also pose health risks through dioxinlike mechanisms.

Laser desorption/ionization time-of-flight mass spectrometry of nitrated polycyclic aromatic hydrocarbons.

Mass spectra of four nitrated polycyclic aromatic hydrocarbons (nitro-PAHs), 9-nitroanthracene, 1-nitropyrene, 2-nitro-9-fluorenone, and 2-nitrofluorene, have been investigated using single-step laser desorption/ionization time-of-flight mass spectrometry. Pulsed UV radiation at 266 or 213 nm was used for desorption and ionization of solid samples deposited on an aluminum probe. The positive molecular ion which was observed for each nitro-PAH was of greater relative intensity when 213 nm radiation was used. A strong [M - NO]+ peak was observed in all spectra, and an intense NO+ signal accompanied the [M - NO]+ signal when 213 nm was used but was only weakly present when 266 nm was used. Comparison of the various spectra suggests that nitro-PAHs undergo an excited state nitro-nitrite rearrangement, followed by loss of NO. Multiphoton ionization of the NO fragment appears to be the principal route of formation of NO+ during laser desorption/ionization when 213 nm radiation is used. The presence of the carbonyl group in 2-nitro-9-fluorenone leads to unique and prominent fragments involving losses of CO from the carbonyl bridge.