UNIVERSITY OF CALIFORNIA AGRICULTURAL EXPERIMENT STATION COLLEGE OF AGRICULTURE benj. ide wheeler, president THOMAS FORSYTH HUNT. Dean and Director BERKELEY CIRCULAR No. 105 August, 1913 ANALYSES OF INSECTICIDES FOR USERS BY GEORGE P. GRAY The California Insecticide Law* provides that "the . . . Directory of the agricultural experiment station of the University of California shall, upon the receipt of a sample of insecticide, accompanied with a nominal fee of one dollar furnish to the USER of said commercial insecticide such examination or analysis of the sample as will sub- stantially establish the conformity or non-conformity of the said insecticide to the guarantee under which it is sold." This nominal fee of one dollar does not nearly cover the actual cost of analysis in most cases, but is required largely as a guarantee of good faith and to prevent indiscriminate sending of samples. It seems a wise provision of the law and if properly used by the growers throughout the state would materially aid them in obtaining reliable materials for combating their insect enemies, as well as in aiding the officials charged with the enforcement of the law, in detecting fraudulent materials on the market. To assist in carrying out the provisions of this part of the law, the following rules have been made, and consumers are requested to submit samples for analysis in accordance therewith. RULES AND REGULATIONS 1. The laboratory will not usually make a complete analysis of a sample but only such "examination or analysis as will substantially establish the conformity or non-conformity of the said insecticide to the guarantee under which it is sold". 2. Analvsis will not be made for dealers. * Statutes of California of 1911, Chap. 653, Sec. 13. 3. All samples submitted must be labelled or tagged showing: 1. Name of sender. 2. Date of sampling. 3. Name of person who took the sample. 4. Manufacturer or guarantors and dealer. 5. Guarantee under Avhich it was purchased. 4. When a sample is sent for analysis, a certificate properly filled out, should be mailed at the same time, together with the fee of one dollar. (A blank form of certificate is attached to this cir- cular and may be used. Additional copies will be sent on application.) 5. Samples should never be placed in paper bags. Glass is always the preferable container, although an air-tight tin can may be used if it is certain that the substance is non-corrosive and dry. 6. The container should always be scrupulously clean and dry and made air tight. 7. Bottles containing liquids should not be entirely filled, except in the case of lime-sulphur solutions. An air cushion of an inch or more above the liquid allows for the expansion of the contents in case of unusual heat during transit. Stoppers should be securely fastened Corrosive liquids should be sent in glass stoppered bottles. 8. When a sample is received for analysis which appears to have been improperly taken or packed, the sample will not be analysed, and the fee returned, unless a new lot can be obtained. 9. Send samples by parcel post or by express, CHARGES PRE- PAID TO, INSECTICIDE LABORATORIES UNIVERSITY OF CALIFORNIA BERKELEY, CAL. IMPORTANCE OF CAREFUL SAMPLING Many serious disputes and misunderstandings have been occa- sioned by submitting for analysis a sample which did not truly represent the material from which it was taken on account of care- lessness or more often through a misunderstanding of the principles involves. The sampling of the material is no less important than a correct analysis and should never be done in a haphazard manner nor trusted to anyone not thoroughly responsible. An unfair sample may easily cause more trouble than is obvious on first thought. Many substances deteriorate very rapidly when exposed to the air. The outer portions in the package may absorb or lose moisture, oxidize, or lose some volatile constituent, or in some way change in composition. Common examples of such changes are, the air slaking of lime, the absorption of water by lye, and the decomposition of cyanide by exposure to the air. It is evident that samples taken from different parts of such substances would differ quite materially in composition and a sample from a newly opened package would be quite different from one taken after long exposure to air and moisture. An analysed sample from such material, which had undergone pro- longed exposure, without proper mixing will be of no value whatever in indicating the value of the chemical and certainly will not repre- sent the contents of the package before opening, in any case. Samples taken under such conditions may involve the retailer, the jobber, and the manufacturer in unjust suspicions, of adulteration, or of dealing in inferior products. The integrity or the ability of the analyist may also be questioned when in reality the sampling was at fault. METHODS OF SAMPLING Having in mind these general remarks about the importance of careful sampling, the following suggestions are made, with the hope that they will be of use in sampling insecticides. If the material to be sampled is fine grained, or a liquid, and is of uniform composition throughout, no special caution need be observed, except that it should be thoroughly mixed and a portion taken from each container. These portions may be all placed together and if too large for shipment they may be mixed and smaller samples taken out for analysis. If the material is a liquid, or paste, and is not of uniform compo- sition throughout, special attention should be given to the mixing and drawing of the sample before the heavier portions have settled. If the material is in lumps, several pieces should be taken from different parts of each package. If this produces a sample too large, the lumps may be broken into smaller pieces and thoroughly mixed upon a clean floor or table and divided by the method of quartering as follows : The material is spread out in a circular flat heap and divided into quarters and the two diagonally opposite quarters removed. The two remaining quarters are again thoroughly mixed and again quartered and treated as before, the process being repeated until a. sample is obtained of the desired size. If the material is a mixture of lumps and .fine particles, care must be exercised to remove lumps and fine particles in proportion to their abundance in the material. Large samples may be quartered as above after breaking- up the larger pieces in each quartering. Materials which appear to be of different composition in different parts of the package should be entirely removed from the package and mixed before sampling, if this is impracticable without removal. In general a sample should not be sent from an old stock of goods except for the purpose of determining the amount of deterioration or some such purpose. INSECTICIDES REQUIRING EXTRA CARE IN SAMPLING CYANIDS, when exposed to the air attract moisture and change to carbonates, losing a large percentage of cyanogen. A sample for analysis should be taken from a freshly opened commercial package and there should be several pieces from each package. The sample should be placed in dry tin or glass and sealed from the air. The operation of sampling should be performed with all possible haste as the attraction of moisture and decomposition is very rapid. The fine residue at the bottom of the case after the lumps have been used should never be submitted as representing the contents of the original package. SAL-SODA (Sodium carbonate), POTASSIUM CARBONATE. These substances lose or gain moisture on exposure to the air and change to the less alkaline bi-carbonates. A thorough mixing is neces- sary before sampling. Only freshly opened packages should be sampled. CAUSTIC SODA AND POTASH, when exposed to the air attract moisture and change to carbonates. If the material is in lumps, the same precautions are in order as suggested for cyanids. If granu- lated, a thorough mixing and removal of a portion of each package will suffice, avoiding any unnecessary exposure since the absorption is very rapid. SULPHURIC ACID, rapidly absorbs moisture from the air in great quantities. The sample should be drawn from freshly opened containers and immediately placed in a clean dry bottle, provided with tightly fitting ground glass stopper. The bottle should not be entirely filled. The stopper should be tied down with twine and the head dipped into melted parrafin, sealing wax or some similar material. Sawdust is probably the most easily obtainable packing for the bottle and is quite satisfactory. LIME, QUICKLIME, HYDRATED LIME. Quicklime (unslaked lime), as is well known, decomposes or slakes on exposure to air and very soon becomes a white powder called air slaked lime. This powder is a mixture of hydrated lime and carbonate of lime, being produced by the combined action of the moisture and carbon dioxide of the air. Pure hydrated lime should contain no carbonates but carbonates are formed very soon when this is exposed to the air. Any lime should therefore be sampled from a freshly opened package. The thorough mixing of the material before sampling or the removal of portions from different parts of the package are necessary in sampling these substances. LIME SULFUR solutions deteriorate very rapidly when exposed to the air, throwing free sulfur out of solution and oxidizing to sul- fates. Samples should always be taken from freshly opened packages and immediately placed in clean dry bottles. Cork stoppers will do but must be tied down. The bottle in this case should be nearly full to lessen the oxidizing influence of the air. FORMALIN (Formaldehyde), loses strength very rapidly if the package is left open. A sample should be an original package if possible. POWDERED DRUGS, Pyrethrum, Hellebore, Tobacco, Etc. The insecticidal value of many such compounds is lessened on exposure to air and light. Samples therefore should be taken from the freshly opened packages only. SIZE OF SAMPLE As a rule ONE POUND of a solid or ONE QUART of a liquid should be sent as a sample. In case of expensive materials somewhat less than the above may be sent if the substance is of a uniform nature and not liable to deterioration. PACKING SAMPLES Corrosive substances should always be packed in some absorbant material such as sawdust. It is more important to have the packing firmly pressed around the package to prevent shifting than to have a large quantity of loose packing. Stoppers and covers of boxes should be securely fastened. ADDEESSING Samples and letters to secure prompt attention should be addressed as follows: INSECTICIDE LABORATORY UNIVERSITY OF CALIFORNIA BERKELEY, CAL. [Note. — Certificate on opposite page may be filled out, and mailed to above address.] DON'T FAIL TO MAIL CERTIFICATE PROPERLY FILLED OUT AT THE SAME TIME THAT THE SAMPLE IS SENT, WITH ENCLOSURE OF THE FEE OF $1.00. CERTIFICATE Entitling the BONA FIDE USER of insecticide material in the State of California to nominal fees for the examination of snch material. Insecticide Laboratory, University of California, Berkeley, Cal. This is to certify that I am not a dealer in, nor agent for the sale of any insecticide or fungicide, and that the material, a sample of which I have sent you for analysis, was purchased by me , 191 for my own use and not for sale. The material is said to contain the following active ingredients : and inert ingredients I wish it analysed or examined to determine. The Manufacturer, Brand and Dealer are I enclose the analysis fee of one dollar. (Signature) (Address) (Date)