Evaluation of poly(ethylene terephthalate) photostabilisation using FTIR spectrometry of evolved carbon dioxide

Carbon dioxide evolution from poly(ethylene terephthalate) (PET) films during ultraviolet (UV) exposure has been monitored using FTIR interrogation of the atmosphere surrounding the test pieces. Measurement periods as little as 4 h could easily discriminate between CO₂ emission rates when tests were conducted to investigate the effect of using different reaction atmospheres or of including UV absorber in the PET samples. Samples containing UV absorbers either homogeneously distributed through the film or in thin surface layers (∼0.7 μm thick) were also tested. Relatively small reductions in CO₂ emission rates were observed with samples containing UV absorbers but the rates were not very sensitive to the distribution and concentration of the absorbers. A thin surface layer containing only 2% stabiliser (equivalent to 0.23% stabiliser when averaged over the whole film thickness) provided oxidation reduction similar to that observed when 1% stabiliser was distributed evenly throughout the sample. Tests were conducted in wet oxygen, dry oxygen and dry nitrogen. For as-received bi-axially drawn PET film containing no absorber, the CO₂ emission rate under UV illumination in wet oxygen was much higher than in dry oxygen or dry nitrogen. For as-received PET the difference between the rates observed in dry oxygen and dry nitrogen was small. For PET films that had been pre-exposed to UV (for 9 days) prior to insertion into the in situ CO₂ measurement cell the rate of CO₂ generation in oxygen was significantly larger than that in nitrogen. In both nitrogen and oxygen the presence of UV absorbers significantly decreased the rate of CO₂ generation.     

Photon gated transport at the glass nanopore electrode

The interior surface of the glass nanopore electrode was modified with spiropyran moieties to impart photochemical control of molecular transport through the pore orifice (15-90 nm radius). In low ionic strength acetonitrile solutions, diffusion of a positively charged species (Fe(bpy)(3)(2+)) is electrostatically blocked with approximately 100% efficiency by UV light-induced conversion of the neutral surface-bound spiropyran to its protonated merocyanine form (MEH+). Transport through the pore orifice is restored by either irradiation of the electrode with visible light to convert MEH+ back to spiropyran or addition of a sufficient quantity of supporting electrolyte to screen the electrostatic field associated with MEH+. The transport of neutral redox species through spiropyran-modified glass nanopores is not affected by light, allowing photoselective transport of redox molecules to the electrode surface based on charge discrimination. The glass nanopore electrode can also be employed as a photochemical trap, by UV light conversion of surface-bound spiropyran to MEH+, preventing Fe(bpy)(3)(2+) initially in the pore from diffusing through the orifice.     

Spectral properties of selected UV-blocking and UV-transmitting covering materials with application for production of high-value crops in high tunnels

The spectral properties of selected UV-blocking and UV-transmitting covering materials were characterized by means of a UV-VIS spectroradiometer or a UV-VIS spectrometer to provide researchers and growers with guidelines for selecting suitable materials for use in studying the effects of ambient solar UV radiation on the production of tomatoes and other high-value crops in high tunnels. A survey was made of a wide range of plastic covering materials to identify commercially available products that had the desired characteristics of transmitting high levels of photosynthetically active radiation and of being stable under ambient solar UV radiation. The study was focused on evaluating films that either blocked or transmitted UV wavelengths below 380 nm to determine comparative growth, yield and market quality and to provide a tool for integrated pest management. Based on this survey, two contrasting covering materials of similar thickness (0.152 mm) and durability (4-year polyethylene), one a UV-blocking film and the other a UV-transmitting film, were selected and used to cover two high tunnels at Beltsville, MD. Spectroradiometric measurements were made to determine comparative spectral irradiance in these two high tunnels covered with these materials and under ambient solar UV radiation. Comparative measurements were also made of selected glass and plastic materials that have been used in UV exclusion studies.     

Assessment of processing and polymorphic form effect on the powder and tableting properties of microcrystalline celluloses I and II

Microcrystalline cellulose I (MCCI) is an excipient used as a diluent, disintegrant, glidant and binder for the production of pharmaceutical tablets. In this work, microcrystalline cellulose II (MCCII) was obtained from cotton fibers by basic treatment with 7.5 N NaOH followed by an acid hydrolysis. MCCI and MCCII materials were processed by wet granulation, dry granulation and spray drying. Either the polymorphic form or processing had no effects on the particle morphology or particle size. However, MCCII powders had a higher porosity, less packing tendency, degree of crystallinity, degree of polymerization and density, but a faster disintegration than MCCI. The tensile strength of MCCI was highly affected by the wet and dry granulation processes. Most of the resulting powder and tableting properties were dependent on the polymorphic form of cellulose, rather than on the processing employed.     

Quantitative ultraviolet measurements on wetted thin-layer chromatography plates using a charge-coupled device camera

This paper presents the first study of the UV imaging of spots on thin-layer chromatographic plates whilst still wet with solvent. Imaging of spots of benzophenone during and after development was carried out using a charge-coupled device camera. Limits of detection were found to be 5ng on a wetted plate and 3ng for a dry plate and the relationship between peak area and sample loading was found to be linear in the low nanogram range over an order of magnitude for both wet and dry modes with r(2) values>0.99. It was found that UV measurements on wet glass-backed plates suffer from low sensitivity; however, the use of aluminium-backed plates gave increased sensitivity. The apparent absorption coefficient epsilon(app) of 10AUm(2)g(-1) at 254nm is consistent with reflection of the light from the aluminium surface with a double pass through the sorbent layer, and suggests that use of aluminium-backed plates should enable monitoring of separations by UV absorbance during TLC development.     

Evolution of the precipitation kinetics,morphologies, permeation performances,and crystallization behaviors of polyvinylidenefluoride (PVDF) hollow fiber membrane by adding different molecular weight polyvinylpyrrolidone (PVP)

Polyvinylidenefluoride (PVDF) hollow fiber membranes were fabricated by wet spinning (wet/wet) and dry‐jet wet spinning (dry/wet; 3 cm air gap) processes with four types of polyvinylpyrrolidone (PVP) of different molecular weight as additives. Evolution of the precipitation kinetics, morphologies, permeation performances, and crystallization behaviors of the as‐spun PVDF membranes were investigated. The PVDF membranes were well characterized by numerous state‐of‐the‐art analytical techniques: scanning electron microscopy (SEM), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and attenuated total reflectance fourier Transform Infrared (FTIR‐ATR) and elucidated accompanying with its precipitation kinetics obtained by light transmittance measurements. The precipitation kinetics results confirm that four PVDF/PVP/NMP dopes experience instantaneous demixing mechanism and the precipitation rate decreases as PVP molecular weight increases. Little peaks are found in the precipitation curves of the PVDF dopes containing PVP of low molecular weight. The SEM images indicate that the middle sponge‐like layer sandwiched by double finger‐like layers becomes thinner for the special precipitation behaviors. Visible large pores exist in the internal surfaces of the PVDF membranes spun by both wet/wet and dry/wet spinning processes. The increase in PVP molecular weight restricts the formation of large pores in the internal surfaces of the PVDF membranes for the increase in dope viscosity. The pure water permeability (PWP) of the as‐spun PVDF membranes increases initially and then decreases as PVP molecular weight increases. The largest PWP flux of 316.7 L m^?2 h^?1 bar^?1 is obtained for the PVDF membrane containing PVP K25 by wet/wet spinning process. The rejections for bovine serum albumin (BSA) by the as‐spun PVDF membranes range from 35.4 to 82.9%. It illustrates that typical PVDF ultrafiltration membranes were obtained in this research. The melting temperature(T_m) of the PVDF hollow fiber membranes decreases with the increase in the PVP molecular weight as a whole. IR spectra and XRD patterns verify the exclusive formation of β crystalline phase structure in the as‐spun PVDF membranes. Copyright © 2010 John Wiley & Sons, Ltd.     

Enhanced UV‐B Radiation Increases Glyphosate Resistance in Velvetleaf (Abutilon theophrasti)

Depletion of the ozone layer leads to increasing UV‐B radiation on the earth's surface, which may affect weeds and their responses to herbicides. However, the effect of increased UV‐B radiation on weeds and the interaction of weeds and herbicides are still obscure. The objective of this study was to compare glyphosate efficacy on velvetleaf that was grown under with and without increased UV‐B radiation. Leaf area, dry weight and net photosynthesis of velvetleaf seedlings were adversely affected by increased UV‐B radiation. Leaf cuticle wax significantly increased by 28% under increased UV‐B radiation. Glyphosate efficacy on velvetleaf, evaluated by shoot dry weight, was significantly decreased by increased UV‐B radiation. Exposure to increased UV‐B radiation significantly decreased ¹⁴C‐glyphosate absorption from 49% to 43%, and also resulted in less ¹⁴C‐glyphosate translocation out of treated leaves and less glyphosate accumulation in newly expanded leaves. The decrease in glyphosate efficacy was due to changes in absorption and distribution, which were attributed to increased cuticle wax and decreased photosynthesis caused by increased UV‐B radiation. These results suggest that the responses of weeds to herbicides may be affected by increased UV‐B radiation, to the extent that higher rates may be required to achieve the desired effects.     

The combined effects of acetic acid, formic acid, and hydroquinone on Debaryomyces hansenii physiology

The combined effects of inhibitors present in lignocellulosic hydrolysates was studied using a multivariate statistical approach. Acetic acid (0–6 g/L), formic acid (0–4.6 g/L) and hydroquinone (0–3 g/L) were tested as model inhibitors in synthetic media containing a mixture of glucose, xylose, and arabinose simulating concentrated hemicellulosic hydrolysates. Inhibitors were consumed sequentially (acetic acid, formic acid, and hydroquinone), alongside to the monosaccharides (glucose, xylose, and arabinose). Xylitol was always the main metabolic product. Additionally, glycerol, ethanol, and arabitol were also obtained. The inhibitory action of acetic acid on growth, on glucose consumption and on all product formation rates was found to be significant (p≤0.05), as well as formic acid inhibition on xylose consumption and biomass production. Hydroquinone negatively affected biomass productivity and yield, but it significantly increased xylose consumption and xylitol productivity. Hydroquinone interactions, either with acetic or formic acid or with both, are also statistically signficant. Hydroquinone seems to partially lessen the acetic acid and amplify formic acid effects. The results clearly indicate that the interaction effects play an important role on the xylitol bioprocess.     

Effects of Suplementary Ultraviolet‐B Irradiance on Maize Yield and Qualities: A Field Experiment¶

Stratospheric ozone depletion has caused an increase in the amount of ultraviolet‐B (UV‐B) radiation reaching the earth's surface. Numerous investigations have demonstrated that the effect of UV‐B enhancements on plants includes reduction in grain yield, alteration in species competition, susceptibility to disease and changes in plant structure and pigmentation. Many experiments examining UV‐B radiation effects on plants have been conducted in growth chambers or greenhouses. It has been questioned whether the effect of UV‐B radiation on plants can be extrapolated to field responses from indoor studies because of the unnaturally high ratios of UV‐B/ ultraviolet‐A radiation (320–400 nm) and UV‐B/photosynthetically active radiation (PAR) in many indoor studies. Field studies on UV‐B radiation effect on plants have been recommended to use the UV and PAR irradiance provided by natural light. This study reports the growth and yield responses of a maize crop exposed to enhanced UV‐B radiation and the UV‐B effects on aize seed qualities under field conditions. Enhanced UV‐B radiation caused a significant reduction in the dry matter accumulation and the maize yield in turn was affected. With increased UV‐B radiation the flavonoid accumulation in maize leaves increased and the contents of chlorophyll a, b and (a+b) of maize leaves were reduced. The levels of protein, sugar and starch of maize seed decreased with enhanced UV‐B radiation, whereas the level of lysine increased with enhanced UV‐B radiation.     

The properties of SBS-g-VP copolymer membrane prepared by UV photografting without degassing

The grafting of 4-vinylpyridine (VP) onto styrene-butadiene-styrene triblock copolymer membrane (SBS) was induced by UV-radiation without degassing to obtain the SBS-g-VP copolymer membrane. The graft copolymer membrane was characterized by electron spectroscopy for chemical analysis (ESCA) and scanning electron microscope (SEM). The tensile strengths and elongations of dry and wet SBS-g-VP copolymer membranes were measured. The contact angle of dry and wet SBS-g-VP graft copolymer membranes with different amount of grafting were determined. By using Kaelble's equation and the contact angle data, the surface energy of dry and wet SBS-g-VP graft copolymer membranes were determined. The protein absorption of fibrinogen and albumin on the SBS-g-VP membranes were evaluated. It was found that the oxygen content in the SBS-g-VP copolymer membrane increased with increasing grafting degree which resulted from the UV photografting without degassing. The tensile strength of dry SBS-g-VP membrane increased with increasing degree of grafting but the elongation decreased. The tensile strengths and elongations of wet SBS-g-VP were significantly lower than those of SBS. The surface energy of dry and wet SBS-g-VP were determined by using Kaelble's equation and the contact angle data. It was found that the surface energy of SBS-g-VP membrane increased. The surface energy of wet SBS-g-VP was higher than that of dry SBS-g-VP. The absorption of albumin and fibrinogen decreased with increasing grafting degree and then levelled off.     

UV accelerated aging and aging resistance of dihydroxy poly(p‐phenylene benzobisoxazole) fibers

By introducing binary hydroxyl groups into poly(p‐phenylene benzoxazole) (PBO) macromolecular chains, we synthesized dihydroxy poly(p‐phenylene benzobisoxazole) (DHPBO) polymers and then prepared DHPBO fibers by dry‐jet wet‐spinning. Comparative studies were performed between intrinsic PBO fibers and DHPBO fibers. The effects of hydroxyl polar groups on improving the UV aging resistance of PBO fibers were investigated. With the introduction of hydroxyl groups, substantial changes in the chemical structures and surface morphologies of DHPBO fibers were observed. As proved by tensile testing and intrinsic viscosity measurement, the UV resistance of DHPBO fibers is obviously improved compared to that of intrinsic PBO fibers. XRD results indicate that the UV aging of these fibers occurs mainly on the surfaces of fibers. Based on these results, the mechanism of UV aging of PBO fibers was discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation and structure-property studies on copolypeptides of γ-methyl glutamate-glutamic acid and γ-methyl glutamate–γ-benzyl glutamate

A series of copolypeptides of poly(methyl glutamate-glutamic acid) (PBC) and poly(methyl benzyl glutamate) (PMB) were prepared from homopolymeric poly(methyl D-glutamate) (PMDG) via a variety of synthetic routes. Following their characterization, these copolymers were then investigated via dynamic mechanical spectroscopy, stress-strain analysis (wet and dry), and wide-angle x-ray scattering (WAXS). It was found that the copolymers could be prepared from homopolymeric PMDG with minimal chain degradation or side reactions. The mechanical properties of either series did not follow a simple trend, in that specific properties such as Young's modulus went through either a maximum or minimum with composition ratio of the two comonomers. based on the WAXS studies, some rationalization for this behavior was established. Specifically, the nature of the side-chain interaction, and therefore chain packing, was strongly affected by comonomer ratio.     

Negatively charged sol-gel column with stable electroosmotic flow for online preconcentration of zwitterionic biomolecules in capillary electromigration separations

A negatively charged sol-gel coating was developed for on-line preconcentration of zwitterionic biomolecules in capillary electrophoresis (CE), using asparagine and myoglobin as representative zwitterionic bioanalytes. The sol-gel coating was created by using a solution containing three precursors: mercaptopropyltrimethoxysilane (MPTMS), tetramethoxysilane (TMOS), and n-octadecyltriethoxysilane (C18-TEOS). The resulting sol-gel coating contained chemically bonded mercaptopropyl functional groups that were further oxidized by hydrogen peroxide to the corresponding sulfonic acid moieties. Such a surface-bonded sol-gel coating can carry a negative charge over a wide range of pH due to the presence of deprotonated sulfonic acid groups. Under favorable pH conditions, the negatively charged sol-gel coating can facilitate the extraction of positively charged analytes from a zwitterionic sample through electrostatic interaction. This principle was employed to extract myoglobin and asparagine by passing aqueous samples of these zwitterionic analytes through a negatively charged sol-gel column. The extracted analytes were then desorbed and focused via local pH change and stacking. The local pH change was accomplished by passing a buffer solution with a pH above the solute p/ value, while a dynamic pH junction between the sample solution and the background electrolyte was utilized to facilitate solute focusing. The sorption/desorption phenomena could, perhaps, also be explained on the basis of ion-exchange and local pH junction effects. On-line preconcentration and analysis results obtained on sulfonated sol-gel columns were compared with those obtained on an uncoated fused silica capillary of identical dimensions using conventional sample injections. Using UV detection, the presented sample preconcentration technique provided a sensitivity enhancement factor (SEF) on the order of 3 x 10(3) for myoglobin, and 7 x 10(3) for asparagine.     

Effects of elevated ultraviolet radiation and endophytic fungi on plant growth and insect feeding in Lolium perenne, Festuca rubra, F. arundinacea and F. pratensis.

Plants of perennial ryegrass (Lolium perenne L.), red fescue (Festuca rubra L.), tall fescue (F. arundinacea Schreb.) and meadow fescue (F. pratensis Huds) were exposed at an outdoor facility located in Edinburgh, UK to modulated levels of UV-B radiation (280-315 nm) using banks of cellulose diacetate filtered UV-B fluorescent lamps that also produce UV-A radiation (315-400 nm). The plants were derived from a single clone of each species and were grown both with and without colonization by naturally-occurring fungal endophytes. The UV-B treatment was a 30% elevation above the ambient erythemally-weighted level of UV-B during July to October. Growth of treated plants was compared with plants grown under elevated UV-A radiation alone produced by banks of polyester filtered lamps and with plants grown at ambient levels of solar radiation under banks of unenergized lamps. At the end of the treatment period, sample leaves were collected for feeding trials with the desert locust Schistocerca gregaria (Forsk). The UV-B treatment produced no effects on the aboveground biomass of any of the four grasses. The UV-B treatment and the UV-A control exposure both increased plant height and the number of daughter plants formed by rhizome growth in F. rubra. There were significant effects of endophyte presence on the total fresh and dry weights of F. arundinacea and F. rubra, on fresh weight only in F. pratensis, and on the fresh and dry weights of inflorescence in F. arundinacea and L. perenne. There were no effects of UV treatments on the absolute amounts of leaf consumed or on the feeding preferences of locusts for leaves with or without endophyte in three species: F. rubra, F. arundinacea and L. perenne. In F. pratensis there was no effect of UV treatment on the weight of leaves consumed but a significant UV x endophyte interaction caused by a marked change in feeding preference between leaves with and without endophyte that differed between the UV-B treatment and UV-A control exposures. The alkaloid compounds known as lolines were analysed in leaves of F. pratensis and were only found in plants grown with endophyte. However, there was no significant relationship between total loline content and insect feeding preference. These effects illustrate the potential complexities of species interactions under increasing levels of UV-B. The experiment also demonstrates the importance of appropriate controls in UV lamp supplementation experiments for interpretation of both plant growth and insect feeding effects.     

On the role of oxygen in fabricating microfluidic channels with ultraviolet curable materials

We present the effects of oxygen on the irreversible bonding of a microchannel using an ultraviolet (UV) curable material of polyurethane acrylate (PUA). Microchannels were fabricated by bonding a top layer with impressions of a microfluidic channel and a bottom layer consisting of a PUA coating on a glass or a polyethylene terephthalate (PET) film substrate. The resulting channel is a homogeneous conduit of the PUA material. To find optimal bonding conditions, the bottom layer was cured under different oxygen concentration and UV exposure time at a constant UV intensity (10 mW cm(-2)). Our experimental and theoretical studies revealed that the channel bonding is severely affected by the concentration of oxygen either in the form of trapped air or permeated air out of the channel. In addition, an optimal UV exposure time is needed to prevent clogging or non-bonding of the channel.     

Heteropogon contortus BL‐1 (Pilli Grass) and Elevated UV‐B Radiation: The Role of Growth,Physiological, and Biochemical Traits in Determining Forage Productivity and Quality

Exposure to elevated UV‐B (eUV‐B) is well known for its phytotoxicity, although studies made with UV‐B exposure and its impact on grasses are limited especially from tropical countries including India. In this study, responses of a valuable grass species, Heteropogon contortus BL‐1, were assessed under eUV‐B (over ambient UV‐B) at different growth stages. Damage caused by eUV‐B was observed in the form of membrane damage and loss of pigments at early stages of growth, whereas tannin, phenol, and protein contents showed their increments at all the growth stages, to overcome the imposed stress. Reducing sugar showed its decline at all the growth stages, whereas starch and sucrose contents were higher mostly at later ages of plant growth. eUV‐B caused a marked variations in anatomical structures with increase of mesophyll and spongy parenchymatous cells in leaves to reduce severity of irradiation, to maintain the growth and productivity. The study also highlights the significant negative influence of eUV‐B on the growth of H. contortus BL‐1 and its adaptive strategy to minimize the negative impacts. With the progression of age, plants although adopted to UV‐B stress with maintenance of productivity, but palatability of forage was affected due to increment of tannin content.     

The effects of UV radiation A and B on diurnal variation in photosynthesis in three taxonomically and ecologically diverse microbial mats

Photosynthetic primary production, the basis of most global food chains, is inhibited by UV radiation. Evaluating UV inhibition is therefore important for assessing the role of natural levels of UV radiation in regulating ecosystem behavior as well as the potential impact of stratospheric ozone depletion on global ecosystems. As both photosynthesis and UV fluxes are subject to diurnal variations, we examined the diurnal variability of the effect of UV radiation on photosynthesis in three diverse algal mats. In one of the mats (Cyanidium caldarium) a small mean decrease in primary productivity over the whole day occurred when both UVA and UVB were screened out. In two of the mats (Lyngbya aestuarii and Zygogonium sp.) we found a mean increase in the total primary productivity over the day when UVB alone was screened and a further increase when UVA and UVB were both screened out. Variations in the effects of UV radiation were found at different times of the day. This diurnal variability may be because even under the same solar radiation flux, there are different factors that may control photosynthetic rate, including nutritional status and other physiological processes in the cell. The results show the importance of assessing the complete diurnal productivity. For some of the time points the increase in the mean was still within the standard deviations in primary productivity, illustrating the difficulty in dissecting UV effects from other natural variations.     

Recycling of process streams in ethanol production from softwoods based on enzymatic hydrolysis

In ethanol production from lignocellulose by enzymatic hydrolysis and fermentation, it is desirable to minimize addition of fresh-water and waste-water streams, which leads to an accumulation of substances in the process. This study shows that the amount of fresh water used and the amount of waste water thereby produced in the production of fuel ethanol from softwood, can be reduced to a large extent by recycling of either the stillage stream or part of the liquid stream from the fermenter. A reduction in fresh-water demand of more than 50%, from 3 kg/kg dry raw material to 1.5 kg/kg dry raw material was obtained without any negative effects on either hydrolysis or fermentation. A further decrease in the amount of fresh water, to one-fourth of what was used without recycling of process streams, resulted in a considerable decrease in the ethanol productivity and a slight decrease in the ethanol yield     

Shear-precipitated chitosan powders,fibrids, and fibrid papers: Observations on their formation and characterization

Chitosan powders and fibrids were prepared by shear precipitation of dissolved chitosan in a coagulating solution of sodium hydroxide. Following neutralization by washing and an alcohol dehydration step, the white to off-white powders were fine and free flowing. The dried fibrids had a highly oriented, ribbon-like shape that in bulk gave a lofty appearance and soft hand. Chitosan fibrids were readily converted to sheet structures by typical paper-making procedures. The resulting chitosan papers were either smooth, flexible, and largely translucent when pressed dry from the moist mat, or were soft and opaque white when the moist mat was soaked in alcohol before drying. X-ray diffraction, SEM, and optical microscopy were used to characterize the different chitosan powders, fibrids, and papers. Chitosan fibrid papers were found to have tensile properties comparable to that of cellulosic papers, though the wet strength and water sorption of chitosan fibrid papers was higher than that of the cellulose controls. ©1995 John Wiley & Sons, Inc.     

The Effects of Ambient Solar UV Radiation on Alkaloid Production by Erythroxylum novogranatense var. novogranatense†

Truxillines are alkaloids produced by Erythroxylum species and are thought to be derived from the UV‐driven dimerization of cinnamoylcocaines. This study was conducted to determine the effects of ambient UV radiation on the production of truxillines in Erythroxylum novogranatense var. novogranatense. Field plants were grown under shelters covered with plastic filters that were transparent to UV radiation, filtered UV‐B, or both filtered UV‐B and UV‐A radiation. The treatments had no significant effect on plant biomass or specific leaf weight. Absorption values in the UV‐C and UV‐A region of acidified‐methanol leaf extracts were higher for plants exposed to UV radiation compared to the no UV radiation treatment. There was a trend in decreasing levels of trans‐cinnamoylcocaine and a statistically significant decrease in levels of cis‐cinnamoylcocaine in the leaves of plants exposed to UV radiation compared to the no UV radiation treatment. Truxilline levels increased in leaves from plants exposed to UV radiation compared to the no UV radiation treatment. Most significantly, the ratio of truxillines to total cinnamoylcocaines in the leaves was affected by UV, increasing with increased UV exposure. The results support the hypothesis that UV radiation is involved in the formation of truxillines from cinnamoylcocaines.